CN101982741A - Underwater light field sampling and simulating method - Google Patents

Abstract

The invention relates to an underwater light field sampling and simulating method which designs an underwater light field sampling device and realizes the simulation of an underwater light field based on sampled data. The method comprises the following steps: (1) designing an underwater panoramic illumination sampling device; (2) enabling the sampling device designed in step (1) to descend from the water surface to a set depth at a constant speed, and simultaneously acquiring a group of equally-spaced underwater sampled data changing with the depth; (3) after sampling underwater illumination images in step (2), respectively carrying out a noise smoothing treatment on each group of illumination images, and splicing the illumination images sampled by two fisheye cameras at the same depth into a whole panoramic illumination image; and (4) after obtaining a group of panoramic illumination images at different depths in step (3), calculating the panoramic illumination image at the depth in which a scene stays, adding scene model data, and carrying out underwater illumination rendering by a ray tracing algorithm. Based on the characteristics of high attenuation degree of visible light in the underwater environment and complex interference in water, according to the method in the invention, the underwater illumination model is established; and the method has the advantages of strong sense of reality and easy implementation.

Description

A kind of sampling of light field under water and analogy method

Technical field

The present invention relates to a kind of sample devices of light field under water, and propose to utilize sampled data to realize the analogy method of light field under water, belong to the virtual reality technology field.

Background technology

Research to illumination under water mainly concentrates on agriculture field.Because aquatic animals and plants is subjected in the water illumination effect big especially,, after the illumination condition of life changes, whole aquatic organism chain there is very big influence especially for the animals and plants of certain depth life.Therefore the underwater environment illumination modeling based on True Data has just had crucial realistic meaning.

Under water light field and land light field main 2 different: (1) decay of light under water is big; (2) owing to have various fouling products in the water, make the scattering of light phenomenon very serious.Light is when water transmission, and it is by exponential damping, and its mutual relationship can be represented by the formula:

$I\left(x\right)=I*e^{-\frac{x}{d}}$

Wherein I represents primary light intensity, and x represents propagation distance, and d represents the attenuation coefficient of propagation medium, is different for the light attenuation coefficient of different wave length, and is serious more in the long more decay of water medium wavelength.In water, scattering of light phenomenon majority is that the existence owing to water-borne glue body particle causes, even in very clean, transparent water, the decay of the light that is caused by scattering reaches 60%.

Present illumination simulated object mainly can be divided into indoor scene illumination simulation and two classes are simulated in outdoor environment illumination.Domestic external correlative study is also fewer, mainly is the strong characteristics of visible light transmittance in water of utilizing low band still not to the correlative study of light field simulation under water, is similar to the effect of photoenvironment under water by setting the generation of illumination color.

By French maritime study and the seabed photoenvironment system that utilizes center exploitation, at first considered the difference of water to the absorptivity of the light of different wave length, use to be difficult for absorbed light scene is under water played up; Considered also that in addition impurity makes the effect of generation have illumination characteristics under water comparatively really to irreflexive influence that illumination produces in the water.

Debevec proposes a kind of simple effective method and is used for measuring certain incident light radiancy of a bit locating in the scene in " Rendering synthetic objects into real scenes ", in conjunction with the global illumination algorithm, to the dummy object in the scene quite true to nature draw out correct synthetic lighting effect.But this method only is applicable to the light field sampling of static scene.

On the whole, existing scene illumination analogy method under water exists that calculated amount is big, the sense of reality by force, does not have deficiencies such as physical characteristics, can't carry out the simulation of scene illumination under water of high validity.

Summary of the invention

The objective of the invention is to solve the sampling and the problem of modelling of light field under water, overcome the not high problem of illumination simulates real solidity in the existing simulation system, utilize the true samples data to set up illumination model under water, for simulation underwater environment in visual effect field provides a kind of effective scene rendering intent, simultaneously also for agricultural research under water light field provide a kind of visual scheme to the influence of hydrophyte.

For finishing purpose of the present invention, the technical solution used in the present invention is: design a kind of sampling apparatus and the method for sampling of light field under water, and propose a kind of method of light field simulation under water based on sampling:

Being designed to of described a kind of sampling apparatus of light field under water:

This device outside is equipped with waterproof case, two flake video cameras of placing dorsad that instrument mainly comprises, depth calibrator, the gravity sensing instrument, equally spacedly in the process that equipment sinks obtain both direction illumination, sample the simultaneously current depth information and the X deflection angle of sampling apparatus, the deposit data of sampling is in memory device.

The process of the described method of sampling of light field under water is:

(1) sample devices is put into water and maintenance level;

(2 controls are equipped in the water decline at the uniform velocity, simultaneously by the equally spaced data of obtaining of data line transmission signal control device;

(3) execution in step (2) periodically drops to designated depth up to sampling apparatus, the sampling apparatus sampled data;

(4) sampled data is handled

Described step (4) is further divided into following substep:

(1) noise spot in the removal light image;

(2) the image amalgamation that two flake video cameras are caught is the panorama illumination pattern;

(3) the gravity sensor horizontal measuring instrument in the use device obtains horizontal direction, and panorama illumination pattern travel direction is proofreaied and correct.

The process of described illumination analogy method under water is:

(1) utilizes the Water Depth Information at current scene place, calculate the light field of the current degree of depth;

(2) model of place is added in the light field of the current degree of depth that calculates, adopt the ray trace algorithm that scene is carried out illumination under water and play up.

Compared with prior art, the invention has the beneficial effects as follows:

(1) it is not strong to have overcome the sense of reality of present underwater environment illumination simulation, and illumination information does not have the problem of physical reliability, and the present invention samples to illumination under water really, generates the underwater environment illumination model;

(2) the present invention can play up the real illumination of carrying out of scene under water.

Description of drawings

Fig. 1 is sampling apparatus figure of the present invention;

Fig. 2 is sampling of illumination under water of the present invention and analogy method process flow diagram;

Fig. 3 is the synoptic diagram of irradiation rendering method under water of the present invention.

Embodiment

The invention will be further described below in conjunction with drawings and Examples.

Step 1 provides the design drawing of the sampling apparatus of panorama illumination under water as shown in Figure 1, installs composed as follows described:

(1) is a 0.5*0.5*0.3m ³The steel cube frame, this framework is the agent structure of illumination sampling apparatus.

(2) be the pressure type depth measurement device, be used for the degree of depth under water at timing sampling device place.

(3) be fish-eye camera, be used for timing sampling light conditions under water, two fish-eye cameras of placing dorsad have been installed in the device, can sample the distribution situation of whole illumination under water.

(4) be the gravity sensor horizontal measuring instrument, be used for the deflection angle of pen recorder and horizontal direction.

Step 2 as shown in Figure 2, the process flow diagram of the illumination method of sampling under water that provides.

Step 2.1 is built after the sampling apparatus, and sampling apparatus is put into water.At the uniform velocity the decline in water of control sampling apparatus is controlled sampling instrument simultaneously and is carried out data sampling, and after sampling apparatus arrived designated depth, sampling instrument quit work, and reclaimed sampling apparatus.

The image that step 2.2 pair fisheye camera photographs carries out medium filtering, image is carried out smooth noise handle.Because the existence of a lot of visible impurity is arranged in the water, adopt medium filtering not only can remove noise but also can keep boundary information in the image, two dimension median filter is output as

g(x，y)＝med{f(x-k，y-l)，(k，l∈W)}

Wherein (x, y), (x y) is respectively original image and handle the two-dimensional space of back image to g to f, and W is a two dimension pattern plate, and med represents to get the intermediate value of each point in the territory, according to irregular characteristics of impurity under water, adopts the 3*3 zone as unified template.

The light image that step 2.3 is taken two fisheye cameras is mapped to two hemisphere surface respectively, calculates the scope that minimum euclidean distance is determined splicing regions, and two hemisphere surface are spliced into a panorama illumination pattern that is mapped in sphere.

Gravity sensor horizontal measuring instrument in step 2.4 use device obtains deflection angle with horizontal direction, and (ψ θ), proofreaies and correct illumination sphere travel direction.

Step 2.5 is calculated the underwater environment illumination pattern of the current degree of depth.

Extract the panorama illumination pattern of two sampling depths adjacent, its RGB is represented to change HIS represent, utilize bathymetric data that two panorama illumination patterns are carried out interpolation, calculate the light field of scene depth, the result is gone back to the image that RGB represents with current scene.The interpolation calculation formula is: the colour vision value of the point in the current environment illumination pattern for (h, i, s):

$(h,i,s)=({\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HSA00000263158200011.png,HSA00000263158200021.png"\; state="\{\{state\}\}">h</figure-callout>}}_1,{\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="HSA00000263158200011.png,HSA00000263158200021.png"\; state="\{\{state\}\}">i</figure-callout>}}_1,s_1)+\frac{(h_0,i_0,s_0)-({\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HSA00000263158200011.png,HSA00000263158200021.png"\; state="\{\{state\}\}">h</figure-callout>}}_1,{\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="HSA00000263158200011.png,HSA00000263158200021.png"\; state="\{\{state\}\}">i</figure-callout>}}_1,s_1)}{h_0-{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HSA00000263158200011.png,HSA00000263158200021.png"\; state="\{\{state\}\}">h</figure-callout>}}_1}$

Wherein, (h ₀, i ₀, s ₀) and (h ₁, i ₁, s ₁) represent the colour vision value of adjacent depth-sampling point, h respectively ₀With h ₁The degree of depth of two neighbouring sample points of expression.

Step 2.6 adds model of place information, utilizes the panorama illumination pattern of the current degree of depth that scene is carried out illumination and plays up.

As shown in Figure 3, comprise a cube and a spheroid that is placed on it in this scene, be example so that this scene is played up.Model of place is added in the illumination pattern of setting up according to process flow diagram 2 of panorama under water, and from viewpoint position divergent-ray to scene, if ray and panorama illumination pattern intersect, the intensity of illumination of then getting the joining place is as incident intensity; If ray and object scene intersect, then send reflection ray and proceed light with combining by the intersection point place, intersect up to light and panorama illumination pattern.

The part that the present invention does not elaborate belongs to those skilled in the art's known technology.

The above only is a preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (5)

1. light field sampling apparatus and analogy method under water, sampling apparatus is specifically designed to gathers light field under water, it is characterized in that comprising:

(1) a kind of sampling apparatus of light field under water of design is used to gather under water light image, X deflection angle and depth information under water;

(2) utilize the sampling of the described sampling apparatus of light field under water to obtain under water the degree of depth, light image, X deflection angle data under water, illumination pattern is carried out smooth noise to be handled, the light image of the same degree of depth is pieced together the panorama illumination pattern, and proofread and correct according to X deflection angle;

(3) utilize the described discrete sampling of the light field under water data of obtaining, calculate the panorama illumination pattern of expression scene place degree of depth light field;

(4) add model of place information, take all factors into consideration influencing each other between the model of place, determine to observe viewpoint, use the ray trace algorithm that scene is carried out illumination under water and play up.

2. a kind of sampling of light field under water according to claim 1 and analogy method, it is characterized in that: the light field sampling apparatus is as follows under water in the described step (1):

Apparatus main body is made of steel framework, and bucker protection interior instrument is installed on framework; The data sampling instrument comprises two flake video cameras of placing dorsad, is used to obtain the gravity sensor horizontal measuring instrument at device horizontal deflection angle, and depth calibrator carries out data sampling by the data line control instrument.

3. a kind of sampling of light field under water according to claim 1 and analogy method, it is characterized in that: panorama light image joining method is as follows in the described step (2):

(1) will be under water the light image that obtains of light field sampling apparatus be mapped to dome-type surface under the world coordinate system respectively; The coordinate conversion formula is: the coordinate of establishing illumination pattern for (u, v), the length of side of illumination pattern is l, be transformed into coordinate under the world coordinate system be respectively (x ', y ', z ') and (x ", y ", the formula of z ") is as follows:

$d=\sqrt{{(u-\frac{l}{2})}^2+{(v-\frac{l}{2})}^2}$

$\left\{\begin{array}{c}{x}^{\&prime;}=\sqrt{1-d^2}\\ y^{\&prime;}=u-\frac{l}{2}\\ z^{\&prime;}=v-\frac{l}{2}\end{array}\right.$ $\left\{\begin{array}{c}{x}^{\&prime;\&prime;}=-\sqrt{1-d^2}\\ y^{\&prime;\&prime;}=\frac{l}{2}-u\\ z^{\&prime;\&prime;}=\frac{l}{2}-v\end{array}\right.;$

(2) determine the splicing regions of two hemisphere face images; At first calculate two hemisphere face maximal margin color of pixel Euclidean distances and υ, increase the coincident area then and recomputate this regional color Euclidean distance and υ ',, overlap regional in the time of will precedingly once using as splicing regions if this value increases; Overlap the zone if this value reduces then to continue to increase, reduce to finish up to υ '; The formula that calculates the brightness Euclidean distance is: establish the image pixel color value and represented that by R, G, B then υ can be expressed as:

$\mathrm{\&upsi;}=\sqrt{{(R_1-R_2)}^2+{(G_1-G_2)}^2+{(B_1-B_2)}^2}.$

4. a kind of sampling of light field under water according to claim 1 and analogy method is characterized in that panorama illumination pattern angle correction method is as follows in the described step (2):

Utilize the X deflection angle of optical field acquisition device acquisition under water that the spherical panorama light image that generates is carried out angle modification; If 1 P on the sphere (x, y, brightness value z) they are η, the data of gravity sensor horizontal measuring instrument sampling (ψ ', θ '), represent that respectively the vertical deflection angle is that ψ ', X deflection angle are θ ', the computing formula of then revised P ' (x ', y ', z ') is:

$\left\{\begin{array}{c}r=\sqrt{x^2+y^2+z^2}\\ d=\sqrt{x^2+y^2}\\ \mathrm{\&psi;}=\arctan \frac{y}{x}\\ \mathrm{\&theta;}=\arccos \frac{d}{r}\end{array}\right.$ $\left\{\begin{array}{c}{x}^{\&prime;}=r\&CenterDot;\sin (\mathrm{\&psi;}+{\mathrm{\&psi;}}^{\&prime;})\&CenterDot;\cos (\mathrm{\&theta;}+{\mathrm{\&theta;}}^{\&prime;})\\ y^{\&prime;}=r\&CenterDot;\sin (\mathrm{\&psi;}+{\mathrm{\&psi;}}^{\&prime;})\&CenterDot;\sin (\mathrm{\&theta;}+{\mathrm{\&theta;}}^{\&prime;})\\ z^{\&prime;}=r\&CenterDot;\cos (\mathrm{\&psi;}+{\mathrm{\&psi;}}^{\&prime;})\end{array}\right..$

5. a kind of sampling of light field under water according to claim 1 and analogy method, it is characterized in that: the method for calculating the panorama illumination pattern of representing scene place degree of depth light field in the described step (3) is as follows:

Extract the panorama illumination pattern of two sampling depths adjacent, its RGB is represented to change HIS represent, utilize bathymetric data that two panorama illumination patterns are carried out interpolation, calculate the panorama illumination pattern of the scene place degree of depth with current scene.

Images