CN114185169A - Scattering screen parameter optimization method, scattering screen and readable storage medium - Google Patents
Scattering screen parameter optimization method, scattering screen and readable storage medium Download PDFInfo
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Abstract
The invention discloses a scattering screen parameter optimization method, a scattering screen and a readable storage medium, wherein the method is applied to optical field display, and equipment for realizing the optical field display comprises a projector array and the scattering screen, wherein the scattering screen is divided into N areas, the N areas are set to be non-uniform scattering angles, and N is a positive integer; the method comprises the following steps: constructing a cost function related to a similarity variable or a fringe spacing variable; optimizing the cost function according to a preset optimization algorithm, and determining an extreme value of the cost function; determining an optimized scattering angle according to the extreme value of the cost function; and the N scattering angles corresponding to the extreme values are the optimized scattering angles. The technical problem that in the prior art, after light emitted by a projector passes through a directional scattering screen, pictures received by human eyes cannot be well spliced, slits or overlapping exist, and the light field display effect is poor is solved.
Description
Technical Field
The invention relates to the field of light field display, in particular to a scattering screen parameter optimization method, a scattering screen and a readable storage medium.
Background
The light field display refers to a display mode of reconstructing light rays emitted by an object through projectors, as shown in fig. 1A, each projector constructs light rays emitted by each point on the object in different directions, and if enough projectors project enough light rays, the method is equivalent to constructing light rays emitted by a plurality of points forming the surface of the object in different directions. Therefore, when the human eyes receive the light rays emitted by the projector at different angles, the human eyes can feel that the human eyes can observe objects from different angles, and the light field display in the real sense is realized.
For realizing real light field display, on one hand, because a large number of projectors are needed for projection and a large number of data processing are needed, in the actual light field display, the field of view in the vertical direction is sacrificed, and only the light rays emitted by the object in the horizontal direction are reconstructed. Therefore, in the light field display, light rays are scattered at a large angle in the vertical direction, so that an observer can observe a complete picture at different heights. On the other hand, because the projector has a certain physical size, the light reconstructed in the horizontal direction has a certain interval, that is, an observer can see discontinuous pictures, and therefore, in the light field display, the light needs to be scattered at a small angle in the horizontal direction, so that the observer can see continuous pictures. At this time, each light ray emitted from the projector forms a vertical bar on the observation plane after being subjected to the large-angle vertical scattering and the small-angle horizontal scattering, as shown in fig. 1B. The viewer will see a plurality of vertical bars from different projectors at one position, so that a complete picture is formed, as shown in fig. 1C.
In the existing light field display scheme, a projector array is combined with a directional scattering screen to realize light field display. As shown in fig. 1D, the light projected by the projector passes through the scattering screen, and the direction of the light is not changed, but the light is scattered at a small angle along the horizontal direction (x direction) and is scattered at a large angle along the vertical direction (y direction). In the directional scattering screen used in the existing scheme, light rays are incident on the scattering screen from any angle, the direction of emergent light is unchanged, the scattering angles are the same, and the directional scattering screen is a directional scattering screen with a uniform scattering angle. For projectors in different positions, the widths of stripes seen by human eyes and the intervals of adjacent viewed stripes are different, as shown in fig. 1C, the directional scattering screen with uniform scattering angle is used, the images of the projectors received by the human eyes cannot be well spliced, and slits or overlapping exist, so that the light field display effect is poor.
Disclosure of Invention
The invention aims to provide a method for optimizing parameters of a scattering screen, the scattering screen and a readable storage medium, which are used for solving the technical problem that in the prior art, after light emitted by a projector passes through a directional scattering screen, pictures received by human eyes cannot be well spliced, slits or overlapping exist, and the light field display effect is poor.
In order to achieve the above object, a first aspect of the embodiments of the present invention provides a method for optimizing parameters of a scattering screen, which is applied to optical field display, where an apparatus for implementing the optical field display includes a projector array and a scattering screen, light emitted from the projector array enters human eyes after being scattered by the scattering screen, the scattering screen is divided into N regions, the N regions are set to non-uniform scattering angles, and N is a positive integer; the method comprises the following steps:
constructing a cost function related to a similarity variable or a fringe spacing variable; the similarity variable is used for indicating the similarity between an actual projection picture which can be received by human eyes at the target viewpoint and an ideal projection picture; the fringe spacing variable is used to indicate the sum of adjacent projector fringe spacings receivable by the human eye at the target viewpoint; the similarity variable and the fringe spacing variable are both related to N scattering angles of the N regions;
optimizing the cost function according to a preset optimization algorithm, and determining an extreme value of the cost function;
determining an optimized scattering angle according to the extreme value of the cost function; and the N scattering angles corresponding to the extreme values are the optimized scattering angles.
Optionally, the method for calculating the similarity between the actual projection picture that can be received by the human eye at the target viewpoint and the ideal projection picture includes:
calculating the similarity between the actual projection picture and the ideal projection picture according to a structural similarity algorithm SSIM; wherein the target viewpoint refers to the position of human eyes; the number of the target viewpoints is one or more; when a plurality of target viewpoints are provided, taking the sum of the sub cost functions corresponding to the plurality of target viewpoints as the cost function; the actual projection picture is a picture obtained by calculation according to a three-dimensional object image and a preset projector stripe calculation method; the ideal projection picture refers to a picture corresponding to the target viewpoint in the three-dimensional object image.
Optionally, the preset method for calculating the projector fringe includes:
aiming at each pixel point emitted by a projector, calculating the spot position and spot size of the pixel point projected on the scattering screen; calculating a light ray scattering angle of the light spot in a preset direction according to the size of the light spot and a scattering angle of an area where the light spot is located, wherein the preset direction is a horizontal direction or a vertical direction; judging whether the light of the light spot of the pixel point scattered by the scattering screen can enter human eyes positioned at the target viewpoint or not according to the light scattering angle and the position of the target viewpoint;
calculating all pixel points which are emitted by each projector and can be received by human eyes at the target viewpoint;
obtaining projector stripes which are emitted by the projector and can be received by human eyes at the target viewpoint according to all the pixel points;
and calculating all projector stripes emitted by the projectors in the projector array and capable of being received by human eyes, and generating the actual projection picture according to all the projector stripes.
Optionally, the method for calculating the sum of the adjacent projector fringe intervals received at the target viewpoint includes:
aiming at each pixel point emitted by a projector, calculating the spot position and spot size of the pixel point projected on the scattering screen; calculating a light ray scattering angle of the light spot in a preset direction according to the size of the light spot and a scattering angle of an area where the light spot is located, wherein the preset direction is a horizontal direction or a vertical direction; judging whether the light of the light spot of the pixel point scattered by the scattering screen can enter human eyes positioned at the target viewpoint or not according to the light scattering angle and the position of the target viewpoint;
calculating all pixel points which are emitted by each projector and can be received by human eyes at the target viewpoint;
obtaining projector stripes which are emitted by the projector and can be received by human eyes at the target viewpoint according to all the pixel points;
calculating all projector stripes emitted by projectors in the projector array and capable of being received by human eyes;
calculating the sum of the intervals between the adjacent projector stripes in all the projector stripes as the sum of the projector stripe intervals; when two adjacent projector stripes overlap, the overlapping width is used as the interval between the two adjacent projector stripes.
Optionally, the preset optimization algorithm is one of a genetic algorithm, a particle swarm algorithm, or a steepest descent method.
Optionally, optimizing the cost function according to a preset optimization algorithm includes:
initializing a population, wherein the population comprises M individuals, the information of each individual is used for indicating the respective scattering angle of the N areas, and M is a positive integer;
calculating a cost function for each of the individuals;
judging whether a preset condition for stopping optimization calculation is met;
if yes, determining an extreme value of the cost functions of the M individuals;
if not, iterating the M individuals according to the preset optimization algorithm.
Optionally, the condition for stopping the optimization calculation is at least one of the following:
the times of the optimized calculation reach the set times;
the average value of the cost functions of the M individuals meets a preset condition;
the cost function of at least one of the M individuals meets a preset condition.
Optionally, when the preset optimization algorithm is a genetic algorithm, iterating the M individuals according to the preset optimization algorithm includes:
calculating an adaptation value for each of the individuals; wherein the adaptive value of the individual refers to a value of a cost function of the individual;
reselecting M individuals from the population based on the adaptive value of each individual and a preset selection algorithm;
and carrying out cross variation on the reselected M individuals to generate a next generation of population.
A second aspect of the embodiments of the present invention provides a scattering screen, which is applied to a light field display device, where the light field display device further includes a projector array, light emitted from the projector array enters human eyes after being scattered by the scattering screen, the scattering screen includes N regions, the N regions are set to be non-uniform scattering angles, and N is a positive integer.
Optionally, the scattering screen is a micro-lens array; or the diffuser screen comprises a horizontal cylindrical lens array and a vertical cylindrical lens array.
A third aspect of the embodiments of the present invention provides a computer-readable storage medium, on which a computer program is stored, which, when executed by a processor, causes the processor to execute the method of the first aspect.
A fourth aspect of the embodiments of the present invention provides a light field display method applied to a light field display device, where the light field display device includes a projector array and a scattering screen, and light emitted from the projector array enters human eyes after being scattered by the scattering screen, and the method includes:
emitting light corresponding to the image to be projected through the projector array;
when the light rays are incident to different areas of the scattering screen, the light rays are subjected to non-uniform scattering through the different areas of the scattering screen; wherein the diffuser screen is divided into N regions having non-uniform scattering angles, N being a positive integer.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
in the scheme of the embodiment of the invention, the scattering angles of N areas are set as non-uniform scattering angles, a cost function related to a similarity variable or a fringe spacing variable is constructed, the cost function is optimized according to a preset optimization algorithm, an extreme value of the cost function is determined, then N scattering angles corresponding to the extreme value are determined as optimized scattering angles, as the similarity variable or the fringe spacing variable can reflect the splicing quality, the higher the similarity is and the smaller the fringe spacing is, the better the splicing quality is, therefore, a group of scattering angle parameters (namely N scattering angles) which can enable the fringes emitted by each projector to be spliced approximately and perfectly at a target view point are found by optimizing the cost function, then the group of scattering angle parameters are set as the scattering angles of each area of the scattering screen, so that the problem existing in the prior art is solved that after light emitted by the projector passes through the directional scattering screen, the technical problem that the light field display effect is poor due to the fact that the pictures at the target view point cannot be well spliced and slits or overlapping exists, and the technical effect of improving the splicing quality of each projector at the target view point is achieved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without inventive exercise:
FIG. 1A is a schematic view of a light field display;
FIGS. 1B-1C are schematic diagrams of projector stripes;
FIG. 1D is a schematic diagram of the light path of light through a diffuser screen;
FIG. 2 is a schematic flow chart of a scattering angle optimization method according to an embodiment of the present invention;
fig. 3 is a schematic light path diagram of a plurality of pixel point light rays emitted by the projector according to the embodiment of the present invention;
fig. 4 is a schematic flowchart of an iterative method based on a preset optimization algorithm according to an embodiment of the present invention;
FIG. 5 is a schematic flow chart of a population iteration method based on a genetic algorithm according to an embodiment of the present invention;
FIG. 6 is a comparison graph of light field display effects before and after the scattering angle optimization method according to the embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a microlens array according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a lenticular lens array according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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 invention.
In the embodiment of the invention, the action principle of the scattering screen in the space light field is explained first.
As shown in fig. 1C and 1D, the spatial light field device includes a projector array and a diffuser screen disposed in the light exit direction of the projector array, and the user is typically positioned on the other side of the diffuser screen for viewing, as shown by the human eye position in fig. 1D. The scattering screen can be a plane scattering screen or a curved surface scattering screen. After light projected by the projector passes through the scattering screen, the direction of the light is not changed, but the light is scattered along the x direction at a small angle and is scattered along the y direction at a large angle. Thus, each ray emitted from the projector will be scattered into a vertical bar after passing through the projector, as shown in fig. 1C. When the human eyes are located at a certain position, for each projector, light beams within a certain angle range enter the human eyes after being scattered by the scattering screen. The effect is that human eyes see the vertical bars with certain width on the scattering screen, and a complete picture is spliced by the vertical bars.
In the embodiment of the present invention, the projector in the projector array may be an LCD (Liquid Crystal Display) projector, a DLP (Digital Light processing) projector, an LCOS (Liquid Crystal on Silicon) projector, or an optical fiber scanning projector.
In the embodiment of the invention, the directional scattering screen with non-uniform scattering is designed through an optimization algorithm and is used for seamless splicing of light field display pictures. The diffuser screen comprises N regions set at non-uniform scattering angles. The scattering angle optimization method comprises the following steps of obtaining a scattering angle, wherein N is a positive integer, the value of N can be set according to actual needs, the scattering angle in the horizontal direction or the vertical direction can be optimized when the scattering angle is optimized, and the scattering angle in the horizontal direction and the vertical direction can also be optimized simultaneously. When dividing the region, the region may be divided at equal intervals or may be divided at unequal intervals. For example: when the scattering angle in the horizontal direction is optimized, the scattering screen may be divided into N regions in the horizontal direction, which is not limited in the present invention.
In the embodiment of the present invention, a scattering angle to be optimized is taken as an example of a scattering angle in the horizontal direction. Fig. 2 is a schematic flow chart of a scattering angle optimization method according to an embodiment of the present invention, which includes the following steps.
In step 201, a cost function related to a similarity variable or a fringe spacing variable is constructed.
Wherein the similarity variable is used for indicating the similarity between an actual projection picture received at the target viewpoint and an ideal projection picture; the fringe spacing variable is used to indicate the sum of adjacent projector fringe spacings received at the target viewpoint.
In the embodiment of the invention, the similarity variable and the fringe interval variable are both related to the scattering angles of the N regions, the scattering angles of the N regions are changed, correspondingly, the similarity and the fringe interval can also be changed, the similarity variable or the fringe interval variable can reflect the splicing quality, the higher the similarity is, the smaller the fringe interval is, the better the splicing quality is, therefore, the extreme value of the cost function can be obtained by optimizing the cost function, and then, the optimal group of scattering angles is selected.
In the embodiment of the present invention, the extreme value of the cost function may be a maximum value or a minimum value of the cost function, for example, if the similarity is S, the cost function may be S, and when the cost function is optimized, the cost function is optimized to the maximum value, so that the similarity is the highest; when the cost function is (1-S), the cost function can be optimized to the minimum value, so that the similarity of 1 minus is minimum; another example is: the cost function can be the sum of the fringe intervals, and when the cost function is optimized, the minimum value of the cost function value can be optimized, so that the fringe intervals are minimum.
Therefore, in the scheme, a group of scattering angle parameters which enable the stripes emitted by each projector to be spliced approximately perfectly at the target viewpoint are found by optimizing the cost function, and then the group of scattering angle parameters are set as the scattering angles of all areas of the scattering screen, so that the technical problem that in the prior art, after the light emitted by the projectors passes through the directional scattering screen, the pictures received by human eyes cannot be spliced well, slits or overlapping exist, and the light field display effect is poor is solved, and the technical effect of improving the splicing quality of each projector at the target viewpoint is realized.
Next, how to construct the cost function will be explained.
In one possible implementation, the cost function is a function of a similarity variable at the target viewpoint. Therefore, the cost function can be constructed by calculating the similarity between the received actual projection picture and the three-dimensional object picture in an ideal case (i.e. the picture corresponding to the target viewpoint in the three-dimensional object picture) at the target viewpoint. In the embodiment of the invention, the cost function can be set to be S or (1-S), and the range of the similarity S is 0-1.
In the embodiment of the present invention, a Structural SIMilarity algorithm (SSIM) may be used to calculate the picture SIMilarity. As shown in fig. 3, the target viewpoint is the position E of the observer/human eye, and Eu and Ep are the edges of the pupil of the human eye. The number of target viewpoints may be one or more; when a plurality of viewpoints are set, the similarity S between the actual projection picture seen by the viewpoints and the three-dimensional object picture under the ideal condition can be calculated, and the sum of the sub cost functions corresponding to the viewpoints is taken as the total cost function. In the embodiment of the present invention, the number of target viewpoints may be set according to factors such as an application scenario and a size of a spatial environment, and a value of the target viewpoints may be 1 to 10, 1 to 20, or more, which is not limited in the present invention.
In the embodiment of the invention, the actual projection picture can be calculated according to the three-dimensional object image and the preset projector stripe calculation method. As shown in fig. 3, S1 to Sn indicate pixel positions (spot positions) projected on the diffuser by the projector. The preset streak calculation method includes the following steps.
Step 1, calculating the spot position and spot size of a single pixel point emitted by the projector on the scattering screen. The spot size is Ds ═ Dp × tan (fp/L), where Dp is the size of a single pixel point emitted by the projector, fp is the focal length of the projection lens of the projector, and L is the distance from the projector to the center of the diffuser (if the projectors are arranged along a circular arc with the center of the circle at the center of the diffuser, then L is the radius of the circular arc where the projector array is located). According to the position of the projector, a light equation of the central light PP1 of the pixel point can be obtained, if S1 is the intersection point of the light PP1 and the scattering screen, the intersection point position S1 is the position of the light spot, wherein the position of the projector is the position of the projector in a coordinate system established by taking the center of the scattering screen as an origin.
And 2, dividing a common display area of the scattering screen. Taking the horizontal direction (X direction) as an example, the common display area is divided into Ms dots at equal intervals, and the distance between adjacent dots is made equal to or slightly smaller than Ds. Assuming that the size of the common display area is Ls, the point at the position of-Ls/2 is the first point S1(S1 is the intersection point of the light PP1 and the scattering screen), and then-Ls/2 + Ls/Ms is the coordinates of the second point, and the coordinates of each point after the common display area is divided can be calculated in turn.
And step 3, S1 is a first point, Sn is an nth point, and the range of the size of the light spot (Siu, Sid) of each projector pixel on the scattering screen is (-0.5 × Ds + x (i), 0.5 × Ds + x (i)), wherein x (i) is the position of the ith division point, and i is a positive integer less than or equal to n.
And 4, calculating the scattering angle of the light spot. Considering only the X direction, assuming that the projector is located at (xp, zp), the diffuser is located at a plane where z is 0, the projector projects onto the common display area, the angle of the principal ray of the X (i) th point is θ i arctan ((X (i) -xp)/(0-zp)), and after the rays corresponding to the two edges of the X (i) th spot exit from the diffuser, the angles of the ray scattering are θ i1 ═ θ i- θ p 0.5+ θ s, θ i2 ═ θ i + θ p 0.5+ θ s, where the beam divergence angle is θ p, i.e., the divergence angle of the rays of the projector projecting a single pixel, and the diffuser scattering angle is θ s.
Referring to fig. 5, please continue to refer to fig. 5, where E is the pupil position of the observer, the pupil position of the observer is calculated, and only the horizontal direction is considered, the position of the eyes of the observer is (xe, ze), where the position of the eyes of the observer is the position of the eyes of the observer in the coordinate system established by using the center of the diffuser screen as the origin, and the pupil size is De, and the pupil range of the human eye is represented as (xe-0.5 De, xe +0.5 De) by the horizontal position of the pupil edge (Eu, Ep).
And 6, calculating whether the light spot can enter the human eye, as shown in fig. 5, when the ith light spot of the common display area is spread to the distance ze of the human eye, the light spot range (Piu, Pid) is (-0.5 Ds + x (i) + ze tan (theta i1), 0.5 Ds + x (i) + ze tan (theta i2), and if the range is overlapped with the pupil range of the human eye, the human eye can see the light spot.
According to the method from the step 1 to the step 6, the pixels which can enter human eyes in all the pixel points (including S1-Sn) projected by the projector can be calculated, so that the projector stripes which can be observed by the human eyes and emitted by the projector can be obtained.
Similarly, for other projectors in the projector array, the same method can be used to calculate the stripes that can be observed at the positions where the human eyes are located, and further, according to the viewpoint position of the observer, an image composed of all the stripes that the observer sees, that is, an actual projection picture can be obtained. For observers at different positions, the corresponding projector stripes and the actual projection pictures can be calculated by adopting the same method.
In the embodiment of the invention, if the three-dimensional object picture under the ideal condition is a real-scene three-dimensional object, the picture can be obtained by taking a picture by using a camera at the position of an observer; if the object is a virtual three-dimensional object, a picture obtained by photographing with a virtual camera can be taken in software.
In another possible implementation, the cost function is a function of a variable of a fringe interval at a target viewpoint, please refer to fig. 3, which illustrates that all pixels capable of entering human eyes in pixel points projected by a single projector can be calculated, so that projector fringes observed by human eyes can be obtained. Further, the interval between adjacent projector stripes can be calculated by the positions of the projector stripes, when the stripes are overlapped, the overlapped width of the stripes is taken as the stripe interval, and the interval is always a non-negative number. The cost function is the sum of the adjacent projector spacings at the target viewpoint. Similarly, when multiple views are set, the intervals can be superimposed as a cost function for different views.
Next, a scattering angle optimization method in the embodiment of the present invention will be described by taking a preset optimization algorithm as an example of a genetic algorithm. As shown in fig. 4, the following steps are included.
In the embodiment of the present invention, the number of scattering angles included in each individual is the same as the number of different scattering angle regions of the scattering screen, for example: dividing the scattering screen into 16 areas, and determining the scattering angles of the 16 areas, wherein each individual comprises the scattering angle information of the 16 areas; another example is: the scattering screen is divided into 24 areas, the scattering angles of the 24 areas need to be determined, and then the scattering angle information of the 24 areas is included in each individual. The number of individuals in the population can be set as desired to strike a balance between ensuring accuracy and reducing the number of calculations as much as possible. In the embodiment of the present invention, the number of individuals in a population is 150 for example.
In genetic algorithms, scattering angle information in an individual needs to be encoded, and a binary encoding method, a floating point encoding method or a symbol encoding method can be adopted in encoding. In the embodiment of the present invention, binary coding is taken as an example for description.
Assuming that the optimized range of the scattering angle of the scattering screen is 0.6 to 1.5 °, if each angle has an 8-bit code length, the optimized range of the angle of 0.6 to 1.5 ° can be divided into 256, and the code length corresponding to the scattering angle of 16 regions is 128(8 × 16 — 128). And (2) randomly initializing the code of each individual, namely randomly initializing each individual into a binary number of 128 bits, wherein the number of the individuals in the population is 150, generating 150 binary numbers of 128 bits after random initialization, namely generating 150 individuals, and the chromosome length of each individual is 128 bits.
In the embodiment of the present invention, the cost function is a function about a similarity variable or a fringe spacing variable. And calculating a cost function corresponding to each individual according to the scattering angle information of each individual.
And step 403, judging whether a preset condition for stopping iterative computation is met.
In an embodiment of the present invention, the condition for stopping the iterative computation is at least one of the following: the times of the optimized calculation reach the set times; or the average value of the cost functions of the M individuals meets a preset condition; or the cost function of at least one of the M individuals meets a preset condition. If yes, go to step 404, otherwise go to step 405.
The preset conditions can be set according to the result of optimization required. For example, assuming that the cost function is similarity S, when the cost function is optimized, the cost function needs to be optimized to a maximum value, and the preset condition may be set that an average value of the cost functions of the M individuals is greater than or equal to a preset threshold; for another example, assuming that the cost function is (1-S) and the cost function needs to be optimized to the minimum value, the preset condition may be set that the average value of the cost functions of the M individuals is smaller than or equal to a preset threshold.
And step 404, determining extreme values of the cost functions of the M individuals, and determining the optimized scattering angle according to the extreme values of the cost functions. And obtaining N scattering angles in the individuals corresponding to the extreme values as the optimized scattering angles.
And 405, iterating the M individuals according to a preset optimization algorithm to generate a next generation population. And then returns to continue to perform step 402.
Next, iteration of the population will be described still taking the genetic algorithm as an example. Then iterating the M individuals according to a genetic algorithm includes the following steps, as shown in fig. 5.
Then, step 502 is executed, and individual selection copying is performed according to the adaptive value and the preset selection algorithm of each individual; in embodiments of the invention, individuals may be selected using Roulette Wheel Selection (Roulette Wheel Selection), and the probability that each individual is selected to remain is
Wherein f isiAn adaptation value for each individual. Then, a population of the same number of individuals is generated according to the selection method. In other embodiments, the preset Selection algorithm may also use random competitive Selection (stored competition), optimal reservation Selection (optimal Value Selection), expected Value Selection (expected Value Selection), and the like, which is not limited in this disclosure.
And 503, carrying out cross variation on the reselected M individuals to generate a next generation population. The chromosomes of each individual have been described in the foregoing examples. When cross mutation is carried out, two individuals are exchanged by binary chromosomes with random lengths at corresponding positions according to a certain probability, namely chromosome crossing is realized; and inverting the chromosome of the individual with a certain probability, namely changing 0 into 1 and changing 1 into 0, so as to realize chromosome mutation.
As shown in fig. 6, a comparison graph of light field display effects before and after the scattering angle optimization method in the embodiment of the present invention is adopted; wherein, the left side is the three-dimensional model to be displayed, and the middle is the image seen by the observer when the scattering screen has a uniform scattering angle. As shown on the right, the resulting image is seen by the viewer under non-uniform scattering angles using the optimization procedure described above. As can be seen from fig. 6, when the scattering screen with uniform scattering angle is used, the images seen by the observer have gaps or overlap, and the images obtained by using the optimized scattering screen with non-uniform scattering angle can be approximately perfectly stitched. In the optimization process, assuming that the horizontal size of the picture projected by the projector is 200mm, and the diffusion screen is divided into 11 regions in the horizontal direction, the diffusion angles corresponding to the 11 regions at different positions after optimization are shown in table 1.
TABLE 1
Based on the same inventive concept, the embodiment of the invention further provides a scattering screen, which is applied to the light field display device, the light field display device further comprises a projector array, light rays emitted by the projector array enter human eyes after being scattered by the scattering screen, the scattering screen comprises N areas, and scattering angles of the N areas are set according to the scattering screen parameter optimization method in the embodiment. Various changes and specific examples in the foregoing method for optimizing the parameters of the diffuser screen in the embodiments of fig. 2 to 6 are also applicable to the diffuser screen in this embodiment, and those skilled in the art can clearly know the implementation method of the diffuser screen in this embodiment through the foregoing detailed description of the method for optimizing the parameters of the diffuser screen, so that the detailed description is omitted here for brevity of the description.
In the embodiment of the present invention, two possible diffuser screen configurations are explained. In light field display, the scattering screen is required to have horizontal small-angle scattering and vertical large-angle scattering. In practical application, the function can be realized by one scattering screen or two scattering screens.
As shown in fig. 7, the diffuser screen is a microlens structure. Each micro lens on the scattering screen scatters light emitted by the projector and emitted by one pixel point.
As shown in fig. 8, the diffuser is a diffuser formed by two cylindrical lens arrays, the left lens realizes large-angle vertical scattering, and the right lens realizes small-angle horizontal scattering. The scattering angle of the lens unit is calculated by the following formula:
wherein f is the focal length of the lens, and D is the diameter of the cylindrical surface.
According to the scattering angle and the position of the lens unit in the table 1, a corresponding small-angle directional scattering screen can be designed to realize small-angle scattering in the horizontal direction. For the vertical scattering with large angle, in order to ensure that the observer can see the complete picture when squatting down or standing upright, the vertical scattering angle is generally a large fixed angle, for example, the vertical scattering angle can be set to 60 °, and similarly, the corresponding structural parameters can be obtained according to the above formula.
An embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the processor is caused to execute the method in the foregoing embodiment.
The embodiment of the invention also provides a light field display method, which is applied to light field display equipment, wherein the light field display equipment comprises a projector array and a scattering screen, light rays emitted by the projector array enter human eyes after being scattered by the scattering screen, and the method comprises the following steps:
emitting light corresponding to the image to be projected through the projector array;
when the light rays are incident to different areas of the scattering screen, the light rays are subjected to non-uniform scattering through the different areas of the scattering screen; wherein the diffuser screen is divided into N regions having non-uniform scattering angles, N being a positive integer.
Various changes and specific examples in the foregoing method for optimizing parameters of a diffuser in the embodiments of fig. 2 to 8 are also applicable to the method for displaying a light field in this embodiment, and those skilled in the art can clearly know the method for implementing the method for displaying a light field in this embodiment through the foregoing detailed description of the method for optimizing parameters of a diffuser, so that the detailed description is omitted here for brevity of the description.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
in the scheme of the embodiment of the invention, the scattering angles of N areas are set as non-uniform scattering angles, a cost function related to a similarity variable or a fringe spacing variable is constructed, the cost function is optimized according to a preset optimization algorithm, an extreme value of the cost function is determined, then N scattering angles corresponding to the extreme value are determined as optimized scattering angles, as the similarity variable or the fringe spacing variable can reflect the splicing quality, the higher the similarity is and the smaller the fringe spacing is, the better the splicing quality is, therefore, a group of scattering angle parameters (namely N scattering angles) which can enable the fringes emitted by each projector to be spliced approximately and perfectly at a target view point are found by optimizing the cost function, then the group of scattering angle parameters are set as the scattering angles of each area of the scattering screen, so that the problem existing in the prior art is solved that after light emitted by the projector passes through the directional scattering screen, the technical problem that the light field display effect is poor due to the fact that the pictures at the target view point cannot be well spliced and slits or overlapping exists, and the technical effect of improving the splicing quality of each projector at the target view point is achieved.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
Any feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.
The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.
Claims (12)
1. A scattering screen parameter optimization method is applied to light field display, and equipment for realizing the light field display comprises a projector array and a scattering screen, wherein light rays emitted by the projector array enter human eyes after being scattered by the scattering screen; the method comprises the following steps:
constructing a cost function related to a similarity variable or a fringe spacing variable; the similarity variable is used for indicating the similarity between an actual projection picture which can be received by human eyes at the target viewpoint and an ideal projection picture; the fringe spacing variable is used to indicate the sum of adjacent projector fringe spacings receivable by the human eye at the target viewpoint; the similarity variable and the fringe spacing variable are both related to N scattering angles of the N regions;
optimizing the cost function according to a preset optimization algorithm, and determining an extreme value of the cost function;
determining an optimized scattering angle according to the extreme value of the cost function; and the N scattering angles corresponding to the extreme values are the optimized scattering angles.
2. The method of claim 1, wherein the method of calculating the similarity between the actual projection picture receivable by the human eye at the target viewpoint and the ideal projection picture comprises:
calculating the similarity between the actual projection picture and the ideal projection picture according to a structural similarity algorithm SSIM; wherein the target viewpoint refers to the position of human eyes; the number of the target viewpoints is one or more; when a plurality of target viewpoints are provided, taking the sum of the sub cost functions corresponding to the plurality of target viewpoints as the cost function; the actual projection picture is a picture obtained by calculation according to a three-dimensional object image and a preset projector stripe calculation method; the ideal projection picture refers to a picture corresponding to the target viewpoint in the three-dimensional object image.
3. The method of claim 2, wherein the preset projector stripe calculation method comprises:
aiming at each pixel point emitted by a projector, calculating the spot position and spot size of the pixel point projected on the scattering screen; calculating a light ray scattering angle of the light spot in a preset direction according to the size of the light spot and a scattering angle of an area where the light spot is located, wherein the preset direction is a horizontal direction or a vertical direction; judging whether the light of the light spot of the pixel point scattered by the scattering screen can enter human eyes positioned at the target viewpoint or not according to the light scattering angle and the position of the target viewpoint;
calculating all pixel points which are emitted by each projector and can be received by human eyes at the target viewpoint;
obtaining projector stripes which are emitted by the projector and can be received by human eyes at the target viewpoint according to all the pixel points;
and calculating all projector stripes emitted by the projectors in the projector array and capable of being received by human eyes, and generating the actual projection picture according to all the projector stripes.
4. The method of claim 1, wherein the method of calculating the sum of adjacent projector fringe spacings receivable by the human eye at the target viewpoint comprises:
aiming at each pixel point emitted by a projector, calculating the spot position and spot size of the pixel point projected on the scattering screen; calculating a light ray scattering angle of the light spot in a preset direction according to the size of the light spot and a scattering angle of an area where the light spot is located, wherein the preset direction is a horizontal direction or a vertical direction; judging whether the light of the light spot of the pixel point scattered by the scattering screen can enter human eyes positioned at the target viewpoint or not according to the light scattering angle and the position of the target viewpoint;
calculating all pixel points which are emitted by each projector and can be received by human eyes at the target viewpoint;
obtaining projector stripes which are emitted by the projector and can be received by human eyes at the target viewpoint according to all the pixel points;
calculating all projector stripes emitted by projectors in the projector array and capable of being received by human eyes;
calculating the sum of the intervals between the adjacent projector stripes in all the projector stripes as the sum of the projector stripe intervals; when two adjacent projector stripes overlap, the overlapping width is used as the interval between the two adjacent projector stripes.
5. The method of any one of claims 1-4, wherein the pre-set optimization algorithm is one of a genetic algorithm, a particle swarm algorithm, or a steepest descent method.
6. The method of claim 5, wherein optimizing the cost function according to a predetermined optimization algorithm comprises:
initializing a population, wherein the population comprises M individuals, the information of each individual is used for indicating the respective scattering angle of the N areas, and M is a positive integer;
calculating a cost function for each of the individuals;
judging whether a preset condition for stopping optimization calculation is met;
if yes, determining an extreme value of the cost functions of the M individuals;
if not, iterating the M individuals according to the preset optimization algorithm.
7. The method of claim 6, wherein the condition to stop the optimization computation is at least one of:
the times of the optimized calculation reach the set times;
the average value of the cost functions of the M individuals meets a preset condition;
the cost function of at least one of the M individuals meets a preset condition.
8. The method of claim 6, wherein when the preset optimization algorithm is a genetic algorithm, iterating the M individuals according to the preset optimization algorithm comprises:
calculating an adaptation value for each of the individuals; wherein the adaptive value of the individual refers to a value of a cost function of the individual;
reselecting M individuals from the population based on the adaptive value of each individual and a preset selection algorithm;
and carrying out cross variation on the reselected M individuals to generate a next generation of population.
9. A scattering screen is applied to light field display equipment, the light field display equipment further comprises a projector array, light rays emitted by the projector array enter human eyes after being scattered by the scattering screen, the scattering screen is characterized by comprising N areas, the N areas are set to be non-uniform scattering angles, and N is a positive integer.
10. A diffuser screen according to claim 9 wherein the diffuser screen is a microlens array; or the diffuser screen comprises a horizontal cylindrical lens array and a vertical cylindrical lens array.
11. A computer-readable storage medium, having stored thereon a computer program which, when executed by a processor, causes the processor to perform the method of any one of claims 1-8.
12. A light field display method is applied to a light field display device, the light field display device comprises a projector array and a scattering screen, and light rays emitted by the projector array enter human eyes after being scattered by the scattering screen, and the method comprises the following steps:
emitting light corresponding to the image to be projected through the projector array;
when the light rays are incident to different areas of the scattering screen, the light rays are subjected to non-uniform scattering through the different areas of the scattering screen; wherein the diffuser screen is divided into N regions having non-uniform scattering angles, N being a positive integer.
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