CN107918278B - Automatic focus following method for film and television lens - Google Patents

Automatic focus following method for film and television lens Download PDF

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CN107918278B
CN107918278B CN201711137633.7A CN201711137633A CN107918278B CN 107918278 B CN107918278 B CN 107918278B CN 201711137633 A CN201711137633 A CN 201711137633A CN 107918278 B CN107918278 B CN 107918278B
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focus
data
follower
following
equation
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CN107918278A (en
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徐欣
张颖
杨流海
巢俊
周晴
冯兵
朱登明
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TAICANG INSTITUTE OF COMPUTING TECHNOLOGY CHINESE ACADEMY OF SCIENCES
JIANGSU PRODUCTIVITY PROMOTION CENTER
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TAICANG INSTITUTE OF COMPUTING TECHNOLOGY CHINESE ACADEMY OF SCIENCES
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • G05B13/04—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
    • G05B13/042—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators in which a parameter or coefficient is automatically adjusted to optimise the performance

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Abstract

The invention discloses an automatic focus following method for a film and television lens, which comprises the following steps: s1: the PC software end sends and receives the data of the focus follower, and controls the servo motor to control the lens focus ring through a data signal; s2: establishing a functional relation between the focus follower data and the actual physical data; s3: an automatic focus following scheme is generated. The invention realizes the communication between the PC software end and the focus follower, constructs the functional relation between the focus follower data and the actual physical data, and realizes the automatic focus follower scheme. The method can be applied to the film and television shooting field, and provides a set of software-controlled focus following implementation scheme for focus following personnel.

Description

Automatic focus following method for film and television lens
Technical Field
The invention relates to the field of computer software, in particular to an automatic focus following method for a film and television lens.
Background
The focus tracking in movie shooting refers to changing the focal length as a person or object approaches or moves away from the camera while shooting a lens so that it remains in precise focus.
In actual shooting, a person in focus needs to try each focus position, mark a lens, and operate the focus follower to focus while paying attention to the walking position of an actor and the progress of a plot when shooting.
With the development of the technology, a wireless focus following system appears, the focus is not required to be marked on a lens, a focus following person can still control the focus through a wireless controller even if the person is far away from a camera for 300 meters through a wireless radio frequency technology, and the action of the person is completely liberated by benefiting from a wireless remote control function, so that the person can be concentrated in focus control only by keeping a proper distance with the photographer without considering the position of the photographer and the position of a connecting line.
With the development of shooting technology, the need for a focus following system controlled by software is increasing. The method adopts COM serial port communication, sends command data to a focus follower, controls a focus ring to realize real-time focus following, provides a software-controlled focusing method for shooting personnel on a movie shooting site, and can store lens data and provide materials for post-production.
At present, an existing wireless tracking system, such as Cmotion, TILTA, etc., has a function of controlling a focus ring through software, but the control of the focus ring does not implement a one-to-one mapping relation with an actual distance, that is, a user of physical data of a focus distance does not know, and meanwhile, although the software provides a control function, the movement transition between the positions of the focus ring still needs to be controlled by a worker, and automatic focus following is not implemented.
Disclosure of Invention
The purpose of the invention is as follows: in order to overcome the defects in the prior art, the invention provides an automatic focus following method for a film and television lens, which can solve the defects in the prior art.
The technical scheme is as follows: the invention relates to an automatic focus following method for a film and television lens, which comprises the following steps:
s1: the PC software end sends and receives the data of the focus follower, and controls the servo motor to control the lens focus ring through a data signal;
s2: establishing a functional relation between the focus follower data and the actual physical data;
s3: an automatic focus following scheme is generated.
Further, the step S2 specifically includes the following steps:
s2.1: controlling the lens focal ring to rotate to the corresponding scale Y { Y1,y2...,ynN data in total, and recording the focus follower data X { X corresponding to each scale1,x2,...,xn}；
S2.2: and fitting a function curve between the focus tracker data and the actual physical focusing data, and calculating curve parameters.
Further, the step S2.2 specifically includes the following steps:
s2.21: taking scale Y { Y1,y2...,ynThe reciprocal of, i.e. the actual physical focus data, is recorded as
Figure GDA0002774279200000021
S2.22: separately calculate ∑ xi 2、∑xi、
Figure GDA0002774279200000022
And
Figure GDA0002774279200000023
wherein i 1,2., n;
s2.23: constructing a matrix:
Figure GDA0002774279200000024
s2.24: establishing a mathematical model aX + b + Y 'of Y' and X as 0, and calculating parameters according to the formula (1)
Figure GDA0002774279200000025
Figure GDA0002774279200000026
Further, the step S3 specifically includes the following steps:
s3.1: establishing the focus f by equation (2)1To the focal point f2Focal position equation for the change transition:
f(t)＝a0+a1t+a2t2+a3t3 (2)
in the formula (2), a0、a1、a2、a3For the parameter to be calculated, t is the focus f1To the focal point f2The time of the change process;
establishing the focus f by equation (3)1To the focal point f2Varying the speed of the transitionDegree equation, establishing the focus f by equation (4)1To the focal point f2Acceleration equation for change transitions:
Figure GDA0002774279200000027
Figure GDA0002774279200000028
s3.2: solving a according to the constraint relation shown in the formula (5)0、a1、a2、a3To obtain a specific form of the focal position equation f (t):
Figure GDA0002774279200000031
in the formula (5), T is a focal point f1Transition to focus f2The actual required run time;
s3.3: obtaining a one-to-one mapping relation between the focal position and the focus follower data according to the focal position equation f (t) obtained in the step S3.2 and the functional relation between the focus follower data and the actual physical data obtained in the step S2;
s3.4: and sending the focus follower data corresponding to the focus position to a focus follower to realize automatic focus follower.
Further, in step S1, the PC software sends and receives focus follower data via the serial port.
Has the advantages that: compared with the prior art, the invention has the following beneficial effects:
1) the automatic transition process from one focus to another focus is realized, and compared with the traditional manual control, the efficiency and the accuracy of a software-controlled focal ring are improved;
2) the mathematical model is used for fitting the focus follower data and the actual physical focusing data, so that the accuracy of controlling physical focusing is improved.
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FIG. 1 is a diagram illustrating step S1 according to an embodiment of the present invention;
fig. 2 is a schematic diagram of step S3 according to the embodiment of the present invention.
Detailed Description
The technical solution of the present invention will be further described with reference to the following detailed description and accompanying drawings.
The specific embodiment discloses an automatic focus following method for a film and television lens, which comprises the following steps:
s1: the PC software end sends and receives the data of the focus follower through the serial port, and controls the servo motor to control the lens focus ring through a data signal, as shown in figure 1.
S2: establishing a functional relation between the focus tracker data and the actual physical data, specifically comprising the following steps:
s2.1: controlling the lens focal ring to rotate to the corresponding scale Y { Y1,y2...,ynN data in total, and recording the focus follower data X { X corresponding to each scale1,x2,...,xn}；
S2.2: fitting a function curve between the focus follower data and the actual physical focusing data, and calculating curve parameters, wherein the method specifically comprises the following steps of:
s2.21: taking scale Y { Y1,y2...,ynThe reciprocal of, i.e. the actual physical focus data, is recorded as
Figure GDA0002774279200000041
S2.22: separately calculate ∑ xi 2、∑xi、
Figure GDA0002774279200000042
And
Figure GDA0002774279200000043
wherein i 1,2., n;
s2.23: constructing a matrix:
Figure GDA0002774279200000044
s2.24: establishing a mathematical model aX + b + Y 'of Y' and X as 0, and calculating parameters according to the formula (1)
Figure GDA0002774279200000045
Figure GDA0002774279200000046
S3: generating an automatic focus following scheme, as shown in fig. 2, specifically includes the following steps:
s3.1: establishing the focus f by equation (2)1To the focal point f2Focal position equation for the change transition:
f(t)＝a0+a1t+a2t2+a3t3(2)
in the formula (2), a0、a1、a2、a3For the parameter to be calculated, t is the focus f1Time to focus change process;
establishing the focus f by equation (3)1To the focal point f2Changing the velocity equation of the transition process, establishing the focus f by equation (4)1To the focal point f2Acceleration equation for change transitions:
Figure GDA0002774279200000047
Figure GDA0002774279200000048
s3.2: solving a according to the constraint relation shown in the formula (5)0、a1、a2、a3To obtain a specific form of the focal position equation f (t):
Figure GDA0002774279200000049
in the formula (5), T is a focal point f1TransitionTo the focal point f2The actual required run time;
s3.3: obtaining a one-to-one mapping relation between the focal position and the focus follower data according to the focal position equation f (t) obtained in the step S3.2 and the functional relation between the focus follower data and the actual physical data obtained in the step S2;
s3.4: and sending the focus follower data corresponding to the focus position to a focus follower to realize automatic focus follower.
Therefore, the specific embodiment realizes the communication between the software and the focus follower, constructs the functional relation between the data of the focus follower and the actual physical data, realizes a set of focus transition scheme, and finally realizes the application of automatic focus following. The method can be applied to the film and television shooting field, and provides a set of software-controlled focus following implementation scheme for focus following personnel.

Claims (4)

1. A method for automatically following focus of a film and television lens is characterized by comprising the following steps: the method comprises the following steps:
s1: the PC software end sends and receives the data of the focus follower, and controls the servo motor to control the lens focus ring through a data signal;
s2: establishing a functional relation between the focus follower data and the actual physical data;
s3: generating an automatic focus following scheme;
the step S3 specifically includes the following steps:
s3.1: establishing the focus f by equation (2)1To the focal point f2Focal position equation for the change transition:
f(t)＝a0+a1t+a2t2+a3t3 (2)
in the formula (2), a0、a1、a2、a3For the parameter to be calculated, t is the focus f1To the focal point f2The time of the change process;
establishing the focus f by equation (3)1To the focal point f2Changing the velocity equation of the transition process, establishing the focus f by equation (4)1To the focal point f2Acceleration equation for change transitions:
Figure FDA0002774279190000011
Figure FDA0002774279190000012
s3.2: solving a according to the constraint relation shown in the formula (5)0、a1、a2、a3To obtain a specific form of the focal position equation f (t):
Figure FDA0002774279190000013
in the formula (5), T is a focal point f1Transition to focus f2The actual required run time;
s3.3: obtaining a one-to-one mapping relation between the focal position and the focus follower data according to the focal position equation f (t) obtained in the step S3.2 and the functional relation between the focus follower data and the actual physical data obtained in the step S2;
s3.4: and sending the focus follower data corresponding to the focus position to a focus follower to realize automatic focus follower.
2. The method for automatically tracking a film and television lens according to claim 1, wherein: the step S2 specifically includes the following steps:
s2.1: controlling the lens focal ring to rotate to the corresponding scale Y { Y1,y2...,ynN data in total, and recording the focus follower data X { X corresponding to each scale1,x2,...,xn}；
S2.2: and fitting a function curve between the focus tracker data and the actual physical focusing data, and calculating curve parameters.
3. The method for automatically tracking a film and television lens according to claim 2, wherein: the step S2.2 specifically includes the steps of:
s2.21: taking scale Y { Y1,y2...,ynThe reciprocal of, i.e. the actual physical focus data, is recorded as
Figure FDA0002774279190000021
S2.22: separately calculate ∑ xi 2、∑xi、
Figure FDA0002774279190000022
And
Figure FDA0002774279190000023
wherein i 1,2., n;
s2.23: constructing a matrix:
Figure FDA0002774279190000024
s2.24: establishing a mathematical model aX + b + Y 'of Y' and X as 0, and calculating parameters according to the formula (1)
Figure FDA0002774279190000025
Figure FDA0002774279190000026
4. The method for automatically tracking a film and television lens according to claim 1, wherein: in step S1, the PC software sends and receives focus follower data via the serial port.
CN201711137633.7A 2017-11-16 2017-11-16 Automatic focus following method for film and television lens Active CN107918278B (en)

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JP2008015273A (en) * 2006-07-06 2008-01-24 Olympus Imaging Corp Camera system and digital camera
JP2009258680A (en) * 2008-03-27 2009-11-05 Panasonic Corp Camera system, camera body, interchangeable lens unit, focus control method, and program
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KR101932546B1 (en) * 2014-09-30 2018-12-27 한화테크윈 주식회사 Apparatus and method for finding optimal zooming speed in auto-focus camera
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