CN112729160A - Projection calibration method, device and system based on telecentric imaging and storage medium - Google Patents

Projection calibration method, device and system based on telecentric imaging and storage medium Download PDF

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CN112729160A
CN112729160A CN202110009843.8A CN202110009843A CN112729160A CN 112729160 A CN112729160 A CN 112729160A CN 202110009843 A CN202110009843 A CN 202110009843A CN 112729160 A CN112729160 A CN 112729160A
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phase error
error value
longitudinal
transverse
determining
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CN112729160B (en
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李嘉茂
王贤舜
朱冬晨
张晓林
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Shanghai Institute of Microsystem and Information Technology of CAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/2433—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures for measuring outlines by shadow casting
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/80—Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration

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  • Computer Vision & Pattern Recognition (AREA)
  • Theoretical Computer Science (AREA)
  • Length Measuring Devices By Optical Means (AREA)
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Abstract

The invention relates to the technical field of computer vision, and discloses a projection calibration method, device and system based on telecentric imaging and a storage medium. The projection calibration method comprises the steps of screening a plurality of reference points of a calibration plate, thus eliminating the reference points which are not on the same plane, obtaining phase coordinates, namely a transverse phase and a longitudinal phase, of the reference points on the same plane, further obtaining pixel coordinates of the reference points on the same plane on an imaging plane of a projector, and completing calibration of the projector by calculating internal parameters and external parameters of the projector. The projection calibration method has the characteristic of high calibration accuracy.

Description

Projection calibration method, device and system based on telecentric imaging and storage medium
Technical Field
The invention relates to the technical field of computer vision, in particular to a projection calibration method, a device and a system based on telecentric imaging and a storage medium.
Background
With the development of microfabrication technology, the production of precision engineering micro-parts puts increasing demands on metrology. Precision systems, such as micro-electromechanical systems (MEMS) and micro-optical devices, contain assemblies of micro-features with dimensions on the order of microns to millimeters. Many non-contact optical methods have been used to determine the shape of objects, such as confocal microscopy, white light interferometry, and triangulation-based projection of microscopic fringes. While confocal microscopy and white light interferometry provide resolution in the nanometer range, the microscopic fringe projection method provides a fast and reliable method for measuring field sizes on the order of 1 mm to several cm.
Phase Shift Projection Fringe Profilometry (PSPFP) has the advantages of non-contact, full-field measurement capability, high profile sampling density, and low environmental vulnerability. With the phase shift detection scheme, even under the condition of excessive image noise, the detection precision of a part of ten thousand fields of view can be achieved. Conventional microscopic fringe projection methods use a zoom stereomicroscope as the base optical system, with one camera port adapted for fringe projection by LCD, LCOS or DMD. However, the depth of field of a microscope is limited to sub-millimeter levels, which is often insufficient to measure the full depth of a three-dimensional object at once. The large depth of field can be obtained by adding a vertical translation stage of an object, but the system is complex and has low efficiency. Furthermore, the calibration for phase-depth conversion using a precision translation stage is very complicated and requires a reference surface, which directly results in measurement errors. Compared with the traditional lens, the telecentric lens has the characteristic of orthogonal projection and has the advantages of small distortion, constant magnification, increased depth of field and the like. Therefore, telecentric lenses have become a key component in the development of high-precision measurement applications.
Since the real points on the calibration plate are convex and not in a plane, the calibration of the projector directly using the existing phase shift projection fringe profile method is not accurate.
Disclosure of Invention
The invention aims to solve the technical problem of inaccuracy of projection calibration of a projector in the prior art.
In order to solve the above technical problem, the present application discloses, in one aspect, a projection calibration method based on telecentric imaging, including:
acquiring a horizontal and longitudinal stripe image projected to a calibration plate by a projector through a camera, wherein the calibration plate is provided with a plurality of reference points which are not on the same plane;
determining a three-dimensional transverse coordinate set and a three-dimensional longitudinal coordinate set according to the transverse and longitudinal stripe image;
determining a transverse phase error value set according to the three-dimensional transverse coordinate set, and determining a longitudinal phase error value set by using the three-dimensional longitudinal coordinate set;
determining a first transverse phase error value according to the transverse phase error value set and a preset transverse phase error value, and determining a first longitudinal phase error value by using the longitudinal phase error value set and a preset longitudinal phase error value;
if the first transverse phase error value is greater than a first threshold value and the first longitudinal phase error value is greater than a second threshold value, determining a current transverse phase error value set from the transverse phase error value set, wherein a second transverse phase error value corresponding to each reference point in the current transverse phase error value set is less than or equal to a third threshold value, and determining a current longitudinal phase error value set from the longitudinal phase error value set, wherein a second longitudinal phase error value corresponding to each reference point in the current longitudinal phase error value set is less than or equal to a fourth threshold value;
correcting the first transverse phase error value and the first longitudinal phase error value based on the current transverse phase error value set and the current longitudinal phase error value set, and determining a current three-dimensional transverse coordinate set and a current three-dimensional longitudinal coordinate set based on the corrected first transverse phase error value and the corrected first longitudinal phase error value until the first transverse phase error value is less than or equal to the first threshold value and the first longitudinal phase error value is less than or equal to the second threshold value;
acquiring the transverse phase and the longitudinal phase corresponding to the residual reference points from the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set;
determining the pixel coordinates of the residual reference points on the projector imaging plane according to the transverse phase and the longitudinal phase corresponding to the residual reference points;
and determining the internal parameters and the external parameters of the projector according to the pixel coordinates of the residual reference points on the imaging plane of the projector and the three-dimensional coordinates of the residual reference points in the world coordinate system, and completing the projection calibration of the projector.
The present application further discloses in another aspect a projection calibration apparatus, which includes:
the acquisition module is used for acquiring a transverse and longitudinal stripe image projected to a calibration board by a projector through a camera, and the calibration board is provided with a plurality of reference points which are not on the same plane;
the first determining module is used for determining a three-dimensional transverse coordinate set and a three-dimensional longitudinal coordinate set according to the transverse and longitudinal stripe image;
the second determining module is used for determining a transverse phase error value set according to the three-dimensional transverse coordinate set and determining a longitudinal phase error value set by using the three-dimensional longitudinal coordinate set;
the third determining module is used for determining a first transverse phase error value according to the transverse phase error value set and a preset transverse phase error value, and determining a first longitudinal phase error value by using the longitudinal phase error value set and a preset longitudinal phase error value;
a fourth determining module, configured to determine a current set of lateral phase error values from the set of lateral phase error values if the first lateral phase error value is greater than a first threshold value and the first longitudinal phase error value is greater than a second threshold value, where a second lateral phase error value corresponding to each reference point in the current set of lateral phase error values is less than or equal to a third threshold value, and determine a current set of longitudinal phase error values from the set of longitudinal phase error values, where a second longitudinal phase error value corresponding to each reference point in the current set of longitudinal phase error values is less than or equal to a fourth threshold value;
a correction module, configured to correct the first lateral phase error value and the first vertical phase error value based on the current lateral phase error value set and the current vertical phase error value set, and determine a current three-dimensional lateral coordinate set and a current three-dimensional vertical coordinate set based on the corrected first lateral phase error value and the corrected first vertical phase error value until the first lateral phase error value is less than or equal to the first threshold, and the first vertical phase error value is less than or equal to the second threshold;
the acquisition module is used for acquiring the transverse phases and the longitudinal phases corresponding to the remaining reference points from the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set;
a fifth determining module, configured to determine pixel coordinates of the remaining reference points on an imaging plane of the projector according to the lateral phase and the longitudinal phase corresponding to the remaining reference points;
and the sixth determining module is used for determining the internal parameters and the external parameters of the projector according to the pixel coordinates of the residual reference points on the imaging plane of the projector and the three-dimensional coordinates of the residual reference points in the world coordinate system, so as to finish the projection calibration of the projector.
The present application also discloses in another aspect a projection calibration system, comprising a control unit, a camera system, a projector system, and a calibration plate;
the control unit is connected with the projector system, the projection system is used for projecting transverse and longitudinal stripes to the calibration plate, the calibration plate is provided with reference points, and the reference points are not on the same plane;
the control unit is connected with the camera system, and the camera system is used for sending the acquired transverse and longitudinal stripe images projected to the calibration board by the projector to the control unit;
the control unit is used for controlling the work of the projector and the work of the camera system and receiving the transverse and longitudinal stripe images which are sent by the camera system and projected to the calibration board by the projector; determining a three-dimensional transverse coordinate set and a three-dimensional longitudinal coordinate set according to the transverse and longitudinal stripe image; determining a transverse phase error value set according to the three-dimensional transverse coordinate set, and determining a longitudinal phase error value set by using the three-dimensional longitudinal coordinate set; determining a first transverse phase error value according to the transverse phase error value set and a preset transverse phase error value, and determining a first longitudinal phase error value by using the longitudinal phase error value set and a preset longitudinal phase error value; if the first transverse phase error value is greater than a first threshold value and the first longitudinal phase error value is greater than a second threshold value, determining a current transverse phase error value set from the transverse phase error value set, wherein a second transverse phase error value corresponding to each reference point in the current transverse phase error value set is less than or equal to a third threshold value, and determining a current longitudinal phase error value set from the longitudinal phase error value set, wherein a second longitudinal phase error value corresponding to each reference point in the current longitudinal phase error value set is less than or equal to a fourth threshold value; correcting the first transverse phase error value and the first longitudinal phase error value based on the current transverse phase error value set and the current longitudinal phase error value set, and determining a current three-dimensional transverse coordinate set and a current three-dimensional longitudinal coordinate set based on the corrected first transverse phase error value and the corrected first longitudinal phase error value until the first transverse phase error value is less than or equal to the first threshold value and the first longitudinal phase error value is less than or equal to the second threshold value; acquiring the transverse phase and the longitudinal phase corresponding to the residual reference points from the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set; determining the pixel coordinates of the residual reference points on the projector imaging plane according to the transverse phase and the longitudinal phase corresponding to the residual reference points; and determining the internal parameters and the external parameters of the projector according to the pixel coordinates of the residual reference points on the imaging plane of the projector and the three-dimensional coordinates of the residual reference points in the world coordinate system, and completing the projection calibration of the projector.
The present application also discloses in another aspect an apparatus comprising a processor and a memory, wherein the memory stores at least one instruction or at least one program, and the at least one instruction or the at least one program is loaded by the processor and executes the above-mentioned projection calibration method based on telecentric imaging.
The present application also discloses in another aspect a computer-readable storage medium, in which at least one instruction or at least one program is stored, and the at least one instruction or the at least one program is loaded and executed by a processor to implement the above-mentioned projection calibration method based on telecentric imaging.
By adopting the technical scheme, the projection calibration method based on telecentric imaging provided by the application has the following beneficial effects:
the projection calibration method comprises the steps of screening a plurality of reference points of a calibration plate, so as to eliminate the reference points which are not on the same plane, acquiring phase coordinates, namely a transverse phase and a longitudinal phase, of the reference points on the same plane, further acquiring pixel coordinates of the reference points on the same plane on an imaging plane of a projector, further acquiring internal and external parameters of the projector, and completing calibration of the projector. Therefore, the projector is calibrated based on the pixel coordinates of the reference points on the calibration plate of the same projection plane on the imaging plane of the projector, and the projection calibration method disclosed by the application has the advantage of high calibration accuracy.
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In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a system framework diagram of a projection calibration method according to the present application;
FIG. 2 is a flow chart of a projection calibration method in an alternative embodiment of the present application;
FIG. 3 is a schematic view of a pattern of a calibration plate of the present application;
FIG. 4 is a schematic view of a fringe pattern projected by the present application;
FIG. 5 is a flow chart of a projection calibration method in another alternative embodiment of the present application;
FIG. 6 is a flow chart of a projection calibration method in another alternative embodiment of the present application;
FIG. 7 is a flow chart of a projection calibration method in another alternative embodiment of the present application;
FIG. 8 is a schematic diagram of the relationship between various coordinates in an alternative embodiment of the present application;
FIG. 9 is a flow chart of a projection calibration method in another alternative embodiment of the present application;
fig. 10 is a schematic structural diagram of a projection calibration apparatus according to an alternative embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or server that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
As shown in fig. 1, fig. 1 is a system framework diagram of an application of a projection calibration method provided in the present application. The system comprises a terminal 101, a camera system 102 and a projector system 103, the terminal 101 being communicatively connected to the camera system 102 and the projector system 103 respectively, the terminal 101 can control the projector system 103 to project horizontal and vertical stripes of a preset phase onto a calibration board, the camera system 102 obtains a fringe image by photographing the calibration plate after projecting the fringe pattern, and transmits the stripe image to the terminal 101, so that the terminal 101 can analyze and process the stripe image, further calculating and screening out the pixel coordinates of the corresponding reference points on the same plane of the calibration plate on the imaging plane of the projector, and the determination of the internal parameters and the external parameters of the projector can be completed according to the pixel coordinates of the reference points on the imaging plane of the projector and the three-dimensional coordinates of the reference points in the world coordinate system, so that the projection calibration of the projector is realized. Thus, a more accurate projection calibration result can be obtained.
Optionally, the terminal 101 comprises a control unit, by which the terminal 101 enables control of the camera system 102 and the projector system 103.
Alternatively, the processing steps of the streak image in the above steps up to the determination step of obtaining the internal and external parameters of the projector may be implemented in a server connected to the terminal 101, and the server may feed back the processed information to the terminal.
Alternatively, the terminal 101 may be a physical device of the type of a smartphone, desktop computer, tablet computer, notebook computer, digital assistant, smart wearable device, or the like; wherein, wearable equipment of intelligence can include intelligent bracelet, intelligent wrist-watch, intelligent glasses, intelligent helmet etc.. Of course, the terminal 101 is not limited to the electronic device with certain entities, but may also be software running in the electronic device, for example, the terminal 101 may be a web page or an application provided by a service provider to a user.
Alternatively, the terminal 101 may comprise a display screen, a storage device and a control unit connected by a data bus. The display screen is used for displaying data such as images or videos of the target object, and the display screen can be a touch screen of a mobile phone or a tablet computer. The storage device is used for storing program codes, data and data of the shooting device, and the storage device may be a memory of the terminal 101, and may also be a storage device such as a smart media card (smart media card), a secure digital card (secure digital card), and a flash memory card (flash card). Alternatively, the control unit may also be called a processor, and the processor may be a single-core or multi-core processor.
A specific embodiment of a projection calibration method based on telecentric imaging according to the present application is described below, and fig. 2 is a flowchart of a projection calibration method according to an alternative embodiment of the present application, and the present specification provides the method operation steps as in the embodiment or the flowchart, but more or less operation steps can be included based on conventional or non-inventive labor. The order of steps recited in the embodiments is merely one manner of performing the steps in a multitude of orders and does not represent the only order of execution. In practice, the system or server product may be implemented in a sequential or parallel manner (e.g., parallel processor or multi-threaded environment) according to the embodiments or methods shown in the figures. Specifically, as shown in fig. 2, the method may include the following steps:
s201: the image of the horizontal and vertical stripes projected by the projector to the calibration board is collected by the camera, as shown in fig. 3, fig. 3 is a schematic diagram of the pattern of the calibration board of the present application. The calibration plate is provided with a plurality of reference points 104, and the reference points 104 are not on the same plane.
In this embodiment, the camera system includes a camera telecentric lens; the projector system comprises a projection telecentric lens; the straight line of the focal length of the camera telecentric lens and the straight line of the focal length of the projector telecentric lens form a preset included angle, so that a standard optical system for measuring the micro-projection profile based on the telecentric lens is formed.
In this embodiment, fig. 3(a) is a drawing of a calibration board with a checkerboard, where the reference points 104 are corner points of the checkerboard, and the corner points are intersections of horizontal and vertical lines, as can be seen from fig. 3(a), the number of the reference points 104 on the calibration board is 9, and if it is desired to acquire more data sets, the number of the reference points 104 may be appropriately increased. Based on the technical limitation of the prior art for manufacturing the calibration board, actually, the reference points 104 are not all in one plane, however, in the prior art, the projector is calibrated in the same plane based on the reference points 104, and the result of the projection calibration is inaccurate, so that the application provides a projection calibration method to solve the problems existing in the prior art.
Optionally, a coordinate system is provided on the calibration plate, by means of which the three-dimensional coordinates of each reference point 104 on the calibration plate can be determined, i.e. corresponding to the three-dimensional coordinates (X) in the world coordinate system described belowW，YW，ZW) The method is used for subsequently calculating the internal parameters and the external parameters of the projector; it should be noted that although the reference points 104 on the calibration board are not actually on the same plane, the reference points 104 on the same plane, i.e. the Z of the reference points 104, can be screened out by the projection calibration method of the present applicationW＝0。
In another alternative embodiment, as shown in fig. 3(b), the calibration board may also be a standard board for drawing dots, and the reference point 104 is a centroid point corresponding to each dot.
In this embodiment, as shown in fig. 4, fig. 4 is a schematic diagram of a stripe pattern projected by the present application. As shown in fig. 4(a), the projector may project a plurality of spaced and parallel horizontal stripes onto the calibration board for a plurality of times, and similarly, as shown in fig. 4(b), the projector may also project a plurality of spaced and parallel longitudinal stripes onto the calibration board for a plurality of times, so as to obtain a horizontal phase and a longitudinal phase corresponding to each reference point in the subsequent step.
In an optional embodiment, the process of obtaining the fringe images includes projecting horizontal and vertical fringes with different phases in batches by a projector, that is, projecting horizontal and vertical fringes with one phase at a time, acquiring a plurality of fringe images by a final camera, where the fringe phases of the fringe images are different, optionally projecting fringes with four phases by the projector, and in a subsequent step, calculating the phase of each reference point by using a four-step phase-shifting algorithm, that is, the horizontal phase and the vertical phase corresponding to each reference point, or calculating by using a two-step, three-step, five-step, or other N-step phase-shifting algorithm as needed, where correspondingly, the phases corresponding to the N-step phase-shifting algorithm are N.
The following description will take a classical 4-step phase-shifting algorithm as an example. 4 times of transverse stripe images are projected to the calibration board through the projector, the transverse stripe image projected each time is a sinusoidal stripe of one phase, and meanwhile, a camera is used for acquiring the transverse stripe images.
In general, the stripe image may be represented in grayscale as:
Figure BDA0002884601370000091
wherein, R (u, v) is the anisotropic reflectivity of the object surface, A (u, v) is the background intensity, B (u, v)/A (u, v) represents the contrast of the grating stripe, phi (u, v) represents the phase value, K is equal to {0,1,2,3},2 pi K/4 represents the phase shift increment, namely, each phase increment of the 4-step phase shift algorithm is pi K/2.
Listing the four equations for k e 0,1,2,3, the phase can be calculated as:
Figure BDA0002884601370000092
the phase phi (u, v) obtained by the formula (2) is a folded phase, and as can be seen from the above description, the phase phi (u, v) is a transverse phase, and similarly, the longitudinal phase value is a longitudinal stripe projected by the projector to the calibration plate, and the longitudinal phase can be calculated according to the formulas (1) and (2). Optionally, phase expansion may be performed according to a commonly-used multi-frequency phase expansion algorithm or a gray code encoding method, so as to obtain an absolute phase, and then a horizontal phase and a vertical phase of each pixel point on the image may be obtained.
In this embodiment, the stripe image is an image including a checkerboard and a plurality of horizontal and vertical stripes.
S202: and determining a three-dimensional transverse coordinate set and a three-dimensional longitudinal coordinate set according to the transverse and longitudinal stripe image.
Alternatively, as can be seen from the above, the horizontal and vertical fringe image may be an image set including a plurality of single phase images, or may be a fringe image.
In an alternative embodiment, as shown in fig. 5, fig. 5 is a flowchart of a projection calibration method in another alternative embodiment of the present application. Step S202, comprising:
s2021: determining, from the transverse longitudinal stripe image, camera pixel coordinates of each of the plurality of reference points, the transverse phase of each of the plurality of reference points, and the longitudinal phase of each of the plurality of reference points.
Optionally, the horizontal phase corresponding to each reference point is calculated based on the phase of the horizontal stripe in the horizontal and vertical stripe image, the vertical phase corresponding to each reference point is calculated based on the vertical stripe in the horizontal and vertical stripe image, and the calculation method may be obtained based on the 4-step phase-shifting algorithm.
S2022: and determining the three-dimensional transverse coordinate of each reference point by using the camera pixel coordinate of each reference point and the transverse phase of each reference point, and determining the three-dimensional longitudinal coordinate of each reference point by using the camera pixel coordinate of each reference point and the longitudinal phase of each reference point.
That is, the three-dimensional lateral coordinates of each reference point include the camera pixel coordinates and the lateral phase, i.e., can be written as (u, v, φ)v) Wherein (u, v) is the camera pixel coordinate of the reference point, phivFor the transverse phase of the reference point, the three-dimensional longitudinal coordinate of the reference point can be noted as (u, v, φ) similarlyh),φhIs the longitudinal phase of the reference point.
S2023: and obtaining the three-dimensional transverse coordinate set based on the three-dimensional transverse coordinate of each reference point, and obtaining the three-dimensional longitudinal coordinate set based on the three-dimensional longitudinal coordinate of each reference point.
That is, the three-dimensional set of lateral coordinates may be represented as { u }i,vi,φviAnd f, wherein i is a natural number greater than zero, and when there are 9 reference points on the calibration plate, i is 9, that is, i represents the number of the reference points on the calibration plate. Similarly, the three-dimensional set of longitudinal coordinates may be represented as { u }i,vi,φhi}。
S203: and determining a transverse phase error value set according to the three-dimensional transverse coordinate set, and determining a longitudinal phase error value set by using the three-dimensional longitudinal coordinate set.
In an alternative embodiment, as shown in fig. 6, fig. 6 is a flowchart of a projection calibration method in another alternative embodiment of the present application. In step S203, determining a set of lateral phase error values according to the three-dimensional lateral coordinate set includes:
s601: and fitting by using the three-dimensional transverse coordinate set to determine a first plane equation.
That is, the first plane equation fitted from the set of three-dimensional transverse coordinates is for u, v, and φvOptionally, the parameters of the first plane equation may be obtained through the three-dimensional transverse coordinates of the plurality of reference points, and then the first plane equation is determined by fitting.
S602: and determining the estimated transverse phase of each reference point according to the first plane equation and the three-dimensional transverse coordinate set.
That is, according to the first plane equation determined in step S601 and u and v corresponding to each reference point, the transverse phase Φ of each reference point on the first plane equation can be obtainedvI.e. estimated transverse phase of each reference point
Figure BDA0002884601370000101
S603: and obtaining the second transverse phase error value of each reference point according to the estimated transverse phase of each reference point and the corresponding transverse phase.
Optionally, the second transversal phase error value is denoted as M, then
Figure BDA0002884601370000111
Or
Figure BDA0002884601370000112
S604: the set of transversal phase error values is derived based on the second transversal phase error value for the each of the plurality of reference points.
Optionally, the set of lateral phase error values is { M }iI is a natural number greater than zero.
In an alternative embodiment, as shown in fig. 7, fig. 7 is a flowchart of a projection calibration method in another alternative embodiment of the present application. In step S203, determining a set of longitudinal phase error values by using the set of longitudinal coordinates includes:
s701: and determining a second plane equation according to the longitudinal coordinate set.
That is, the second plane equation fitted according to the three-dimensional longitudinal coordinate set is about u, v and phivOptionally, parameters of the second plane equation may be obtained through the three-dimensional longitudinal coordinates of the plurality of reference points, and then the second plane equation is determined by fitting.
S702: and determining the estimated longitudinal phase of each reference point according to the second plane equation and the three-dimensional longitudinal coordinate set.
That is, according to the second plane equation determined in step S701 and u and v corresponding to each reference point, the longitudinal phase Φ of each reference point on the second plane equation can be obtainedhExpressed as estimated longitudinal phase of each reference point
Figure BDA0002884601370000113
S703: and obtaining the second longitudinal phase error value of each reference point according to the estimated longitudinal phase of each reference point and the corresponding longitudinal phase.
Optionally, the second longitudinal phase error value is recorded as N, then
Figure BDA0002884601370000114
Or
Figure BDA0002884601370000115
S704: the set of vertical phase error values is obtained based on the second vertical phase error value for the each of the plurality of reference points.
Optionally, the set of longitudinal phase error values is { N }iI is a natural number greater than zero.
S204: and determining a first transverse phase error value according to the transverse phase error value set and a preset transverse phase error value, and determining a first longitudinal phase error value by using the longitudinal phase error value set and a preset longitudinal phase error value.
In an optional implementation manner, the determining, in step S204, a first lateral phase error value according to the set of lateral phase error values and a preset lateral phase error value includes: determining a maximum transverse phase error value from the transverse phase error value set, wherein the maximum transverse phase error value is the second transverse phase difference value with the largest value in the transverse phase error value set; and determining the first transversal phase error value according to the maximum transversal phase error value and the preset transversal phase error value.
That is, when the maximum lateral phase error value is En, En equals to max { M {iAnd optionally, K may be obtained according to a formula K ═ (Ep-En)/En, and En and Ep.
In an optional implementation manner, the determining, in step S204, a first longitudinal phase error value by using the set of longitudinal phase error values and a preset longitudinal phase error value includes: determining a maximum longitudinal phase error value from the longitudinal phase error value set, wherein the maximum longitudinal phase error value is the second longitudinal phase difference value with the largest value in the longitudinal phase error value set; and determining the first longitudinal phase error value according to the maximum longitudinal phase error value and the preset longitudinal phase error value.
That is, when the maximum longitudinal phase error value is Fn, Fn is max { N ═ NiAnd (e) a preset longitudinal phase error value denoted Fp, and a first longitudinal phase error value denoted L, where L may be obtained according to the formula L ═ Fp-Fn)/Fn, and Fn and Fp.
Optionally, the preset lateral phase error value and the preset longitudinal phase error value may be calculated in steps S903 and S904, which are described below, may be set according to an empirical value, and may also be set to infinite values in the first calculation process, so that the first lateral phase error value obtained in step S204 is inevitably greater than the first threshold, the first longitudinal phase is inevitably greater than the second threshold, and the removing steps S205 to S207 in the subsequent steps are required.
In an optional implementation manner, after step S204, the method further includes: if the first transverse phase error value is less than or equal to a first threshold value, and the first longitudinal phase error value is less than or equal to a second threshold value, determining the pixel coordinates of each reference point in the plurality of reference points on the projector imaging plane based on the transverse phase and the longitudinal phase corresponding to each reference point in the plurality of reference points; and determining the internal parameters and the external parameters of the projector according to the pixel coordinates of each reference point in the imaging plane of the projector, and completing the projection calibration of the projector.
That is, when the first threshold is t1 and the second threshold is t2, K ≦ t1，L≦t2Optionally, t1＝t2If 0.1, it is determined that the reference points in the calibration plate are all located in the same plane, and it is not necessary to reject and screen the reference points, but it is directly possible to determine the reference points based on the phi of each reference pointvAnd phihAnd obtaining the pixel coordinates of each reference point in the projector imaging plane by the following phase recovery formula (3):
Figure BDA0002884601370000131
wherein N isvIndicating the number of cycles of the lateral stripe, NhIndicating the number of cycles of the longitudinal stripes; that is, the NvNumber of horizontal stripes within the image width, NhIndicating the number of longitudinal stripes in the image length.
Alternatively, the image size is the size of a calibration plate as shown in fig. 3(a) or fig. 3 (b).
Optionally, according to a conversion relationship between the pixel coordinate of each reference point on the imaging plane of the projector and the three-dimensional coordinate of the corresponding world coordinate system, the internal parameter and the external parameter of the projector are solved, that is, the projection calibration of the projector is completed. Solving the intrinsic parameters and the extrinsic parameters of the projector will be described below, and since the solving of the intrinsic parameters and the extrinsic parameters of the projector are the same as those of the camera model, for convenience of description, the camera model will be described below as an example, as shown in fig. 8, where fig. 8 is a schematic diagram of relationships among various coordinates in an alternative embodiment of the present application. Wherein, the world coordinate system: xw, Yw, Zw; camera coordinate system: xc, Yc, Zc; image coordinate system: x, y; pixel coordinate system: u and v. The distance between the camera coordinate system and the image coordinate system is the distance from the point O to the point Oc in the figure, corresponding to the magnification m.
As can be seen from the figure, suppose (u)0，v0) Represents O1In the u-v coordinate system, assuming that the length and width of a pixel are dx and dy, respectively, the relationship between the pixel coordinate system and the image coordinate system is as follows:
Figure BDA0002884601370000132
Figure BDA0002884601370000133
the simultaneous writing of equation (4) and equation (5) into a matrix can be expressed as follows:
Figure BDA0002884601370000134
thus, as can be seen in FIG. 8, the relationship of the camera coordinate system to the image coordinate system is as follows:
Figure BDA0002884601370000135
combining equation (6) and equation (9) can obtain the relationship between the pixel coordinate system and the camera coordinate system as follows:
Figure BDA0002884601370000141
then
Figure BDA0002884601370000142
I.e. the internal reference matrix of the camera, marked as Gc。
And the conversion of the camera coordinate system to the world coordinate system can be represented by a homogeneous coordinate matrix consisting of a rotation matrix R and a translation vector T, which is represented as follows:
Figure BDA0002884601370000143
then the camera coordinate system is related to the world coordinate system according to equation (11) as follows:
Figure BDA0002884601370000144
then
Figure BDA0002884601370000145
I.e. the external reference matrix of the camera, marked as Hc。
By combining equations (8) and (10), the relationship between the pixel coordinate system and the world coordinate system can be obtained as follows:
Figure BDA0002884601370000146
when the world coordinate system is established, it is on the XOY plane on the calibration board, so that for all observed reference points (corner points), its Z isWAlternatively, where dx is dy and V is m/dx is given to each pixel, equation (11) can be simplified as follows:
Figure BDA0002884601370000147
for each reference point, there is the above model relationship, so for N reference points the following system of equations can be obtained:
Figure BDA0002884601370000151
through the system of equations, the method can be obtained
Figure BDA0002884601370000152
Because r is11，r12,r21,r22The method is characterized in that the method comprises the steps of rotating matrix elements, enabling the degree of freedom to be 3, adding tx and ty to the rotating matrix elements to form 5 degrees of freedom, solving the six values according to pixel coordinates and world coordinates corresponding to a plurality of reference points, and solving to obtain an external parameter matrix H of the cameracAlso known as the extrinsic parameters of the camera.
Then r is put11，r12,r21,r22Substituting the six values of tx, ty into equation (12), the magnification m of the camera and the internal reference matrix G can be solvedcAlso known as intrinsic parameters of the camera.
Similarly, the pixel coordinates (u) of all reference points on the calibration plate on the projector imaging plane can be obtained according to the formula (3)p，vp) Then the camera H can be solved according to the abovecAnd GcSolving the internal parameter H of the projector in the same steppAnd an external parameter GpAnd will not be described herein.
S205: if the first transversal phase error value is greater than a first threshold value and the first longitudinal phase error value is greater than a second threshold value, determining a current set of transversal phase error values from the set of transversal phase error values, the second transversal phase error value corresponding to each reference point in the current set of transversal phase error values being less than or equal to a third threshold value, and determining a current set of longitudinal phase error values from the set of longitudinal phase error values, the second longitudinal phase error value corresponding to each reference point in the current set of longitudinal phase error values being less than or equal to a fourth threshold value.
That is, when the third threshold is setThe value is t3, the fourth threshold value is t4, K > t1, and L > t2, then from { M }iObtaining a new set of transversal phase error values as a current set of transversal phase error values, where M ≦ t3 corresponding to each reference point in the current set of transversal phase error values, and then from { N ≦ t3iObtaining a new set of vertical phase error values as a current set of vertical phase error values, where N corresponding to each reference point in the current set of vertical phase error values is less than or equal to t4, and optionally, t3 is 0.02 as t 4.
S206: correcting the first transversal phase error value and the first vertical phase error value based on the current transversal phase error value set and the current vertical phase error value set, and determining a current three-dimensional transversal coordinate set and a current three-dimensional vertical coordinate set based on the corrected first transversal phase error value and the corrected first vertical phase error value until the first transversal phase error value is less than or equal to the first threshold value and the first vertical phase error value is less than or equal to the second threshold value.
That is, the above steps S203-S206 are repeated until all the reference points in the current three-dimensional transverse coordinate set and all the reference points in the current three-dimensional longitudinal coordinate set satisfy the following condition: k ≦ t1, L ≦ t 2.
In an alternative embodiment, as shown in fig. 9, fig. 9 is a flowchart of a projection calibration method in another alternative embodiment of the present application. The modifying the first transversal phase error value and the first vertical phase error value based on the current set of transversal phase error values and the current set of vertical phase error values comprises:
s901: and determining the current three-dimensional transverse coordinate set according to the current transverse phase error value set, and determining the current three-dimensional longitudinal coordinate set based on the current longitudinal phase error value set.
Optionally, in step S901, a point set corresponding to the current set of transverse phase error values determined in step S205 may be determined according to the current set of transverse phase error values, and then a three-dimensional transverse coordinate corresponding to each reference point is found from the current three-dimensional transverse coordinate set according to the point set, and a current three-dimensional transverse coordinate set is formed based on the three-dimensional transverse coordinate corresponding to each reference point.
S902: and determining the current transverse phase error value set according to the current three-dimensional transverse coordinate set, and determining the current longitudinal phase error value set based on the current three-dimensional longitudinal coordinate set.
That is, after obtaining a new current three-dimensional horizontal coordinate set based on step S901, steps S203-S205 may be repeated to determine a current horizontal phase error value set satisfying a preset condition and a current vertical phase error value set satisfying the preset condition, specifically, the preset condition is a condition that satisfies a relationship among the first threshold, the second threshold, the third threshold, and the fourth threshold in step S205.
S903: and taking the maximum transverse phase error value as a current preset transverse phase error value, and taking the maximum longitudinal phase error value as a current preset longitudinal phase error value.
That is, the current Ep is equal to En determined by step S204, and the current Fp is equal to Fn determined by step S204.
S904: and determining the first transverse phase error value according to the current transverse phase error value set and the current preset transverse phase error value, and determining the first longitudinal phase error value by using the current longitudinal phase error value set and the current preset longitudinal phase error value.
Optionally, the way of determining K and L in step S904 is the same as that in step S204, and therefore, the description thereof is omitted here.
S207: and acquiring the transverse phases and the longitudinal phases corresponding to the remaining reference points from the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set.
That is, the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set which can satisfy the preset condition are obtained according to step S206, optionally, a reference point in the intersection is obtained according to the intersection of the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set, and the reference point is used as a remaining reference point, and based on the remaining reference point, the corresponding transverse phase and longitudinal phase can be determined from the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set.
S208: and determining the pixel coordinates of the residual reference points on the projector imaging plane according to the transverse phase and the longitudinal phase corresponding to the residual reference points.
In an optional embodiment, the determining the pixel coordinates of the remaining reference points in the projector imaging plane according to the transverse phase and the longitudinal phase corresponding to the remaining reference points includes:
and determining the pixel coordinates of the residual reference point on the projector imaging plane according to the transverse phase of the residual reference point, the longitudinal phase of the residual reference point, the period number of the transverse stripes and the period number of the longitudinal stripes.
Alternatively, the pixel coordinates of all remaining reference points in the projector imaging plane may be calculated according to equation (3).
S209: and determining the internal parameters and the external parameters of the projector according to the pixel coordinates of the residual reference points on the imaging plane of the projector and the three-dimensional coordinates of the residual reference points in the world coordinate system, and completing the projection calibration of the projector.
Optionally, the detailed description has been given above for determining the internal parameter and the external parameter of the projector based on the N reference points on the calibration board, and then the determination methods of the remaining reference points based on the calibration board are the same, and are not described herein again.
The application further discloses a projection calibration device, as shown in fig. 10, fig. 10 is a schematic structural diagram of the projection calibration device in an alternative embodiment of the application. The projection calibration device comprises:
the acquisition module 1001 is used for acquiring a horizontal and vertical stripe image projected to a calibration board by a projector through a camera, wherein the calibration board is provided with a plurality of reference points, and the reference points are not on the same plane;
a first determining module 1002, configured to determine a three-dimensional lateral coordinate set and a three-dimensional longitudinal coordinate set according to the lateral stripe image;
a second determining module 1003, configured to determine a transverse phase error value set according to the three-dimensional transverse coordinate set, and determine a longitudinal phase error value set by using the three-dimensional longitudinal coordinate set;
a third determining module 1004, configured to determine a first lateral phase error value according to the lateral phase error value set and a preset lateral phase error value, and determine a first longitudinal phase error value by using the longitudinal phase error value set and a preset longitudinal phase error value;
a fourth determining module 1005, configured to determine a current set of lateral phase error values from the set of lateral phase error values if the first lateral phase error value is greater than the first threshold value and the first longitudinal phase error value is greater than the second threshold value, where a second lateral phase error value corresponding to each reference point in the current set of lateral phase error values is less than or equal to the third threshold value, and determine a current set of longitudinal phase error values from the set of longitudinal phase error values, where a second longitudinal phase error value corresponding to each reference point in the current set of longitudinal phase error values is less than or equal to the fourth threshold value;
a modification module 1006, configured to modify the first lateral phase error value and the first vertical phase error value based on the current lateral phase error value set and the current vertical phase error value set, and determine a current three-dimensional lateral coordinate set and a current three-dimensional vertical coordinate set based on the modified first lateral phase error value and the modified first vertical phase error value until the first lateral phase error value is less than or equal to the first threshold, and the first vertical phase error value is less than or equal to the second threshold;
an obtaining module 1007, configured to obtain the horizontal phase and the vertical phase corresponding to the remaining reference point from the current three-dimensional horizontal coordinate set and the current three-dimensional vertical coordinate set;
a fifth determining module 1008, configured to determine pixel coordinates of the remaining reference points on the projector imaging plane according to the lateral phase and the longitudinal phase corresponding to the remaining reference points;
a sixth determining module 1009, configured to determine the internal parameter and the external parameter of the projector according to the pixel coordinate of the remaining reference point on the imaging plane of the projector and the three-dimensional coordinate of the remaining reference point in the world coordinate system, so as to complete the projection calibration of the projector.
In an alternative embodiment, the apparatus comprises:
the second determining module is used for fitting and determining a first plane equation by utilizing the three-dimensional transverse coordinate set;
the second determining module is configured to determine an estimated lateral phase of each reference point according to the first plane equation and the three-dimensional lateral coordinate set; the second determining module is configured to obtain the second transverse phase error value of each reference point according to the estimated transverse phase of each reference point and the corresponding transverse phase; the second determining module is configured to obtain the set of transversal phase error values based on the second transversal phase error value of each of the plurality of reference points.
In an alternative embodiment, the apparatus comprises:
the second determining module is used for determining a second plane equation according to the longitudinal coordinate set;
the second determining module is configured to determine an estimated longitudinal phase of each reference point according to the second plane equation and the three-dimensional longitudinal coordinate set; the second determining module is configured to obtain the second longitudinal phase error value of each reference point according to the estimated longitudinal phase of each reference point and the corresponding longitudinal phase; the second determining module is configured to obtain the set of longitudinal phase error values based on the second longitudinal phase error value for each of the plurality of reference points.
In an alternative embodiment, the apparatus comprises:
the third determining module is configured to determine a maximum lateral phase error value from the set of lateral phase error values, where the maximum lateral phase error value is the second lateral phase difference value with the largest value in the set of lateral phase error values;
the third determining module is configured to determine the first lateral phase error value according to the maximum lateral phase error value and the preset lateral phase error value.
In an alternative embodiment, the apparatus comprises:
the third determining module is configured to determine a maximum longitudinal phase error value from the longitudinal phase error value set, where the maximum longitudinal phase error value is the second longitudinal phase difference value with the largest value in the longitudinal phase error value set;
the third determining module is configured to determine the first longitudinal phase error value according to the maximum longitudinal phase error value and the preset longitudinal phase error value.
In an alternative embodiment, the apparatus comprises:
the correction module is used for determining the current three-dimensional transverse coordinate set according to the current transverse phase error value set and determining the current three-dimensional longitudinal coordinate set based on the current longitudinal phase error value set;
the correction module is used for determining the current transverse phase error value set according to the current three-dimensional transverse coordinate set and determining the current longitudinal phase error value set based on the current three-dimensional longitudinal coordinate set;
the correction module is used for taking the maximum transverse phase error value as a current preset transverse phase error value and taking the maximum longitudinal phase error value as a current preset longitudinal phase error value;
the correction module is configured to determine the first lateral phase error value according to the current set of lateral phase error values and the current preset lateral phase error value, and determine the first vertical phase error value by using the current set of vertical phase error values and the current preset vertical phase error value.
In an alternative embodiment, the apparatus comprises:
the fourth determining module is configured to determine, if the first transverse phase error value is smaller than or equal to a first threshold value and the first longitudinal phase error value is smaller than or equal to a second threshold value, pixel coordinates of each of the plurality of reference points on the projector imaging plane based on the transverse phase and the longitudinal phase corresponding to each of the plurality of reference points;
the fourth determining module is used for determining the internal parameter and the external parameter of the projector according to the pixel coordinates of each reference point in the imaging plane of the projector, and completing the projection calibration of the projector.
In an alternative embodiment, the apparatus comprises:
the first determining module is configured to determine, from the transverse and longitudinal stripe image, camera pixel coordinates of each of the plurality of reference points, the transverse phase of each of the plurality of reference points, and the longitudinal phase of each of the plurality of reference points;
the first determining module is configured to determine a three-dimensional lateral coordinate of each reference point by using the camera pixel coordinate of each reference point and the lateral phase of each reference point, and determine a three-dimensional longitudinal coordinate of each reference point by using the camera pixel coordinate of each reference point and the longitudinal phase of each reference point;
the first determining module is configured to obtain the three-dimensional lateral coordinate set based on the three-dimensional lateral coordinate of each reference point, and obtain the three-dimensional longitudinal coordinate set based on the three-dimensional longitudinal coordinate of each reference point.
In an alternative embodiment, the apparatus comprises:
the fifth determining module is configured to determine pixel coordinates of the remaining reference point on the projector imaging plane according to the lateral phase of the remaining reference point, the longitudinal phase of the remaining reference point, the number of cycles of the lateral stripe, and the number of cycles of the longitudinal stripe.
The present application also discloses in another aspect an apparatus comprising a processor and a memory, wherein the memory stores at least one instruction or at least one program, and the at least one instruction or the at least one program is loaded by the processor and executes the above-mentioned projection calibration method based on telecentric imaging.
The present application also discloses in another aspect a computer-readable storage medium, in which at least one instruction or at least one program is stored, and the at least one instruction or the at least one program is loaded and executed by a processor to implement the above-mentioned projection calibration method based on telecentric imaging.
It should be noted that: the sequence of the embodiments of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. And specific embodiments thereof have been described above. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
The above description is only exemplary of the present application and should not be taken as limiting, and any modifications, equivalents, improvements and the like that are made within the spirit and principle of the present application should be included in the scope of the present application.

Claims (15)

1. A projection calibration method based on telecentric imaging is characterized by comprising the following steps:
acquiring a transverse and longitudinal stripe image projected to a calibration plate by a projector through a camera, wherein the calibration plate is provided with a plurality of reference points which are not on the same plane;
determining a three-dimensional transverse coordinate set and a three-dimensional longitudinal coordinate set according to the transverse and longitudinal stripe images;
determining a transverse phase error value set according to the three-dimensional transverse coordinate set, and determining a longitudinal phase error value set by using the three-dimensional longitudinal coordinate set;
determining a first transverse phase error value according to the transverse phase error value set and a preset transverse phase error value, and determining a first longitudinal phase error value by using the longitudinal phase error value set and a preset longitudinal phase error value;
if the first transverse phase error value is greater than a first threshold value and the first longitudinal phase error value is greater than a second threshold value, determining a current transverse phase error value set from the transverse phase error value set, wherein a second transverse phase error value corresponding to each reference point in the current transverse phase error value set is less than or equal to a third threshold value, and determining a current longitudinal phase error value set from the longitudinal phase error value set, wherein a second longitudinal phase error value corresponding to each reference point in the current longitudinal phase error value set is less than or equal to a fourth threshold value;
correcting the first transverse phase error value and the first longitudinal phase error value based on the current transverse phase error value set and the current longitudinal phase error value set, and determining a current three-dimensional transverse coordinate set and a current three-dimensional longitudinal coordinate set based on the corrected first transverse phase error value and the corrected first longitudinal phase error value until the first transverse phase error value is less than or equal to the first threshold value, and the first longitudinal phase error value is less than or equal to the second threshold value;
acquiring transverse phases and longitudinal phases corresponding to the remaining reference points from the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set;
determining the pixel coordinates of the residual reference points on the projector imaging plane according to the transverse phase and the longitudinal phase corresponding to the residual reference points;
and determining internal parameters and external parameters of the projector according to the pixel coordinates of the residual reference points on the imaging plane of the projector and the three-dimensional coordinates of the residual reference points in the world coordinate system, and completing the projection calibration of the projector.
2. The projection calibration method according to claim 1, wherein said determining a set of lateral phase error values from said set of three-dimensional lateral coordinates comprises:
fitting and determining a first plane equation by utilizing the three-dimensional transverse coordinate set;
determining an estimated transverse phase of each reference point according to the first plane equation and the three-dimensional transverse coordinate set;
obtaining a second transverse phase error value of each reference point according to the estimated transverse phase of each reference point and the corresponding transverse phase;
deriving the set of lateral phase error values based on the second lateral phase error value for the each of the plurality of reference points.
3. The projection calibration method according to claim 1, wherein said determining a set of longitudinal phase error values using said set of longitudinal coordinates comprises:
determining a second plane equation according to the longitudinal coordinate set;
determining an estimated longitudinal phase of each reference point according to the second plane equation and the three-dimensional longitudinal coordinate set;
obtaining a second longitudinal phase error value of each reference point according to the estimated longitudinal phase of each reference point and the corresponding longitudinal phase;
deriving the set of longitudinal phase error values based on the second longitudinal phase error value for the each of the plurality of reference points.
4. The projection calibration method according to claim 1, wherein determining a first lateral phase error value according to the set of lateral phase error values and a preset lateral phase error value comprises:
determining a maximum transverse phase error value from the transverse phase error value set, wherein the maximum transverse phase error value is the second transverse phase difference value with the largest value in the transverse phase error value set;
and determining the first transverse phase error value according to the maximum transverse phase error value and the preset transverse phase error value.
5. The projection calibration method according to claim 4, wherein the determining a first longitudinal phase error value by using the longitudinal phase error value set and a preset longitudinal phase error value comprises:
determining a maximum longitudinal phase error value from the longitudinal phase error value set, where the maximum longitudinal phase error value is the second longitudinal phase difference value with the largest value in the longitudinal phase error value set;
and determining the first longitudinal phase error value according to the maximum longitudinal phase error value and the preset longitudinal phase error value.
6. The projection calibration method of claim 5, wherein the correcting the first lateral phase error value and the first longitudinal phase error value based on the current set of lateral phase error values and the current set of longitudinal phase error values comprises:
determining the current three-dimensional transverse coordinate set according to the current transverse phase error value set, and determining the current three-dimensional longitudinal coordinate set based on the current longitudinal phase error value set;
determining the current transverse phase error value set according to the current three-dimensional transverse coordinate set, and determining the current longitudinal phase error value set based on the current three-dimensional longitudinal coordinate set;
taking the maximum transverse phase error value as a current preset transverse phase error value, and taking the maximum longitudinal phase error value as a current preset longitudinal phase error value;
and determining the first transverse phase error value according to the current transverse phase error value set and the current preset transverse phase error value, and determining the first longitudinal phase error value by using the current longitudinal phase error value set and the current preset longitudinal phase error value.
7. The projection calibration method according to claim 1, wherein after determining a first lateral phase error value according to the set of lateral phase error values and a preset lateral phase error value and determining a first longitudinal phase error value by using the set of longitudinal phase error values and a preset longitudinal phase error value, the method further comprises:
if the first transverse phase error value is less than or equal to a first threshold value, and the first longitudinal phase error value is less than or equal to a second threshold value, determining the pixel coordinates of each reference point in the plurality of reference points on the projector imaging plane based on the transverse phase and the longitudinal phase corresponding to each reference point in the plurality of reference points;
and determining internal parameters and external parameters of the projector according to the pixel coordinates of each reference point in the plurality of reference points on the imaging plane of the projector, and completing the projection calibration of the projector.
8. The projection calibration method according to claim 1, wherein the determining a three-dimensional lateral coordinate set and a three-dimensional longitudinal coordinate set from the lateral stripe image comprises:
determining, from the transverse longitudinal stripe image, camera pixel coordinates of each of the plurality of reference points, the transverse phase of each of the plurality of reference points, and the longitudinal phase of each of the plurality of reference points;
determining a three-dimensional lateral coordinate of each reference point using the camera pixel coordinate of each reference point and the lateral phase of each reference point, and determining a three-dimensional longitudinal coordinate of each reference point using the camera pixel coordinate of each reference point and the longitudinal phase of each reference point;
and obtaining the three-dimensional transverse coordinate set based on the three-dimensional transverse coordinate of each reference point, and obtaining the three-dimensional longitudinal coordinate set based on the three-dimensional longitudinal coordinate of each reference point.
9. The projection calibration method according to claim 1, wherein the determining the pixel coordinates of the remaining reference points in the projector imaging plane according to the transverse phase and the longitudinal phase corresponding to the remaining reference points comprises:
and determining the pixel coordinates of the residual reference points on the projector imaging plane according to the transverse phase of the residual reference points, the longitudinal phase of the residual reference points, the periodicity of the transverse stripes and the periodicity of the longitudinal stripes.
10. The projection calibration method according to claim 1, wherein the reference points comprise corner points or dots.
11. A projection calibration device, comprising:
the acquisition module is used for acquiring a transverse and longitudinal stripe image projected to a calibration board by a projector through a camera, the calibration board is provided with a plurality of reference points, and the reference points are not on the same plane;
the first determining module is used for determining a three-dimensional transverse coordinate set and a three-dimensional longitudinal coordinate set according to the transverse and longitudinal stripe images;
the second determining module is used for determining a transverse phase error value set according to the three-dimensional transverse coordinate set and determining a longitudinal phase error value set by using the three-dimensional longitudinal coordinate set;
a third determining module, configured to determine a first lateral phase error value according to the lateral phase error value set and a preset lateral phase error value, and determine a first longitudinal phase error value by using the longitudinal phase error value set and a preset longitudinal phase error value;
a fourth determining module, configured to determine, if the first lateral phase error value is greater than a first threshold and the first longitudinal phase error value is greater than a second threshold, a current lateral phase error value set from the lateral phase error value set, where a second lateral phase error value corresponding to each reference point in the current lateral phase error value set is less than or equal to a third threshold, and determine a current longitudinal phase error value set from the longitudinal phase error value set, where a second longitudinal phase error value corresponding to each reference point in the current longitudinal phase error value set is less than or equal to a fourth threshold;
a correction module, configured to correct the first lateral phase error value and the first longitudinal phase error value based on the current set of lateral phase error values and the current set of longitudinal phase error values, and determine a current three-dimensional lateral coordinate set and a current three-dimensional longitudinal coordinate set based on the corrected first lateral phase error value and the corrected first longitudinal phase error value until the first lateral phase error value is less than or equal to the first threshold, and the first longitudinal phase error value is less than or equal to the second threshold;
the acquisition module is used for acquiring the transverse phase and the longitudinal phase corresponding to the residual reference point from the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set;
a fifth determining module, configured to determine, according to the lateral phase and the longitudinal phase corresponding to the remaining reference point, a pixel coordinate of the remaining reference point on an imaging plane of a projector;
and the sixth determining module is used for determining the internal parameters and the external parameters of the projector according to the pixel coordinates of the residual reference points on the imaging plane of the projector and the three-dimensional coordinates of the residual reference points in the world coordinate system, so as to finish the projection calibration of the projector.
12. A projection calibration system is characterized by comprising a control unit, a camera system, a projector system and a calibration board;
the control unit is connected with the projector system, the projection system is used for projecting transverse and longitudinal stripes to the calibration plate, reference points are arranged on the calibration plate, and the reference points are not on the same plane;
the control unit is connected with the camera system, and the camera system is used for sending the acquired transverse and longitudinal stripe images projected to the calibration board by the projector to the control unit;
the control unit is used for controlling the work of the projector and the work of the camera system and receiving a transverse and longitudinal stripe image which is sent by the camera system and projected to a calibration board by the projector; determining a three-dimensional transverse coordinate set and a three-dimensional longitudinal coordinate set according to the transverse and longitudinal stripe images; determining a transverse phase error value set according to the three-dimensional transverse coordinate set, and determining a longitudinal phase error value set by using the three-dimensional longitudinal coordinate set; determining a first transverse phase error value according to the transverse phase error value set and a preset transverse phase error value, and determining a first longitudinal phase error value by using the longitudinal phase error value set and a preset longitudinal phase error value; if the first transverse phase error value is greater than a first threshold value and the first longitudinal phase error value is greater than a second threshold value, determining a current transverse phase error value set from the transverse phase error value set, wherein a second transverse phase error value corresponding to each reference point in the current transverse phase error value set is less than or equal to a third threshold value, and determining a current longitudinal phase error value set from the longitudinal phase error value set, wherein a second longitudinal phase error value corresponding to each reference point in the current longitudinal phase error value set is less than or equal to a fourth threshold value; correcting the first transverse phase error value and the first longitudinal phase error value based on the current transverse phase error value set and the current longitudinal phase error value set, and determining a current three-dimensional transverse coordinate set and a current three-dimensional longitudinal coordinate set based on the corrected first transverse phase error value and the corrected first longitudinal phase error value until the first transverse phase error value is less than or equal to the first threshold value, and the first longitudinal phase error value is less than or equal to the second threshold value; acquiring transverse phases and longitudinal phases corresponding to the remaining reference points from the current three-dimensional transverse coordinate set and the current three-dimensional longitudinal coordinate set; determining the pixel coordinates of the residual reference points on the projector imaging plane according to the transverse phase and the longitudinal phase corresponding to the residual reference points; and determining internal parameters and external parameters of the projector according to the pixel coordinates of the residual reference points on the imaging plane of the projector and the three-dimensional coordinates of the residual reference points in the world coordinate system, and completing the projection calibration of the projector.
13. The projection calibration system of claim 12, wherein the camera system comprises a camera telecentric lens;
the projector system comprises a projection telecentric lens;
and a preset included angle exists between a straight line where the focal length of the camera telecentric lens is positioned and a straight line where the focal length of the projector telecentric lens is positioned.
14. An apparatus comprising a processor and a memory, wherein the memory stores at least one instruction or at least one program, and the at least one instruction or the at least one program is loaded by the processor and executes the method for telecentric imaging based projection calibration according to any one of claims 1-10.
15. A computer-readable storage medium, wherein at least one instruction or at least one program is stored in the storage medium, and the at least one instruction or the at least one program is loaded and executed by a processor to implement the method for telecentric imaging based projection calibration according to any one of claims 1 to 10.
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