JPH0632046B2 - Object image synthesizer - Google Patents

Description

The present invention relates to an object image compositing apparatus for compositing images for displaying an object.

[Conventional technology]

As a method of synthesizing digital images for displaying an object, there is a method called a ray search method. In this method, the path of the light ray from the light source to the viewpoint is traced in the opposite direction,
The intersection determination process between the light ray and the object is performed, and the brightness of each pixel forming the image is calculated based on the result. An example of this ray search method is the IPSJ journal, Vol. 25, No. 6.
No., Hiroshi Deguchi, Hitoshi Nishimura, Hiroshi Yoshimura, Toru Kawada, Isao Shirakawa, Koichi Omura, Paper "Computer Graphics System"
LINKS-1 for speeding up image generation ".

In order to perform image generation by such a ray search method at high speed, the space in which an object is defined is divided into a plurality of areas, each area is assigned to one computer, and each computer is assigned. Methods have been proposed for processing rays that pass through a region. For more information on this method, see Computer Graph.
ics), Volume 18, Issue 3, Mark Dippe
ppe), John Swensen, "Unadaptive Subdivision Algorithm and Parallel Architecture Fore"
Realistic Image Synthesis (An Adaptive
Subdivision Algorithm and Parallel Architecture fo
r Realistic Image Synthesis) ”.

In the above method, the space is first divided into a plurality of rectangular parallelepiped areas, and each area is assigned to one computer. Next, the data of the object included in the assigned rectangular parallelepiped region is stored in each computer. Then, in each computer, intersection determination processing between a light ray passing through the assigned area and an object is performed. By this intersection determination processing, when an object intersects a light ray, reflection and transmission processing on the surface of the object is performed. Information about rays that do not intersect the object in that area is transferred to the computer assigned to the adjacent area.

When such processing is performed, there is a possibility that the processing amount of each computer may vary considerably. That is, the processing amount of the computer assigned with the area containing many objects is very large, and the computer assigned with the area containing no object may hardly perform the processing.

In order to reduce such a variation in load between computers, a method has been proposed in which the vertices of a region divided into a rectangular parallelepiped are arbitrarily moved to change the volume or shape of the region. That is, by moving the vertex, the processing amount of the computer assigned to the area whose volume is reduced is reduced. Then, the computer assigned to the area whose volume has increased due to the movement of the apex is responsible for the processing. In this way, the load is redistributed among the computers.

[Problems to be solved by the invention]

In such a conventional load redistribution method, the shape of the region is variously changed because the apex of the region is moved to redistribute the load. That is, since the deformation is caused by the movement of the vertices, the shape of the area is maintained as a hexahedron, but the orientation and shape of each boundary surface of the area are arbitrary. Therefore, the following problems occur.

When transmitting light ray information from the first divided area to an adjacent area, the area to be transferred is determined by determining the intersection between the boundary surface of the area and the light ray. However, since the direction and shape of each boundary surface of the region are arbitrary, the processing amount of this intersection determination processing becomes very large. For this reason, there is a problem that the entire processing time is delayed.

Second, when the shape of the area is changed, the information on the objects included in the area must be changed. That is, in the case of a region where the volume is reduced, there is a possibility that some of the objects included in the region before the change are not included in the region after the change. Further, in the case of a region where the volume is increased, a new object may be included in that region. Even when such object information is changed, there is a problem that the amount of processing and the processing time required to determine an object included in the area become very large because the shape of the area varies.

As described above, in the conventional method of moving the apexes of the area to redistribute the load, there is a problem that the amount of processing required for the redistributing is very large and the effect of the redistributing cannot be sufficiently obtained.

According to the present invention, by simplifying the area shape change information for load redistribution, the information associated with the area shape change can be reduced, and the effect of redistribution can be sufficiently enhanced. It is an object to provide a synthesizer.

[Means for solving problems]

The object image synthesizing device of the present invention includes an initial light ray generation unit that generates information about a plurality of light rays that pass through each pixel from a viewpoint, an object information setting unit that sets information about the object, and a space in which the object is defined. Of a plurality of areas generated by dividing the area into a plurality of areas, and calculating the brightness of the pixel by performing intersection determination processing between a ray passing through this area and an object included in the area And an image storage unit that stores the brightness calculated by the brightness calculation unit as an image, and the brightness calculation unit generates the object definition space by dividing the object definition space on a plane perpendicular to the coordinate axis. Area information storage means for storing the range of the area in charge of the brightness calculation portion of the plurality of areas to be stored, load determination means for determining the load of the brightness calculation portion, and the load in the direction parallel to each coordinate axis. The load on the adjacent brightness calculation unit that handles the area adjacent to this area and the mutual communication unit that performs mutual communication between the brightness calculation unit and the adjacent brightness calculation unit obtained via the mutual communication unit is maximized. A direction determining unit that determines the direction of the area in charge of the adjacent brightness calculation unit as the expansion direction of the area in charge of the brightness calculation unit and the load of the adjacent brightness calculation unit and the load of the brightness calculation unit that maximizes the load are compared. Then, in the direction determined by the direction determining means based on the determination of the enlargement determining means for determining whether to expand the area in charge of the brightness calculation unit in the direction determined by the direction determining means, and the direction determined by the direction determining means. Area expansion means for changing the range of the area in charge stored in the area information storage means in order to expand the area in charge is provided. [Operation] A method of redistributing the load of the brightness calculation unit in the present invention will be described. One area of a plurality of areas generated by dividing the object definition space on a plane perpendicular to the coordinate axis is assigned to each brightness calculation section as the area in charge of the brightness calculation section. The range of the assigned area is stored in the area information storage unit provided in the brightness calculation unit.

Here, among the areas adjacent to the area in charge of this brightness calculation section, the six brightness calculation sections in charge of the areas in the direction parallel to each coordinate axis (x, y, z axis) are called adjacent brightness calculation sections. .

The load of each brightness calculation unit is determined by the load determination unit and transferred to the six adjacent brightness calculation units via the mutual communication unit. Then, the direction determining means selects the maximum load from the loads of the six adjacent brightness calculation sections obtained via the mutual communication means, and the connection direction of the adjacent brightness calculation section having the maximum load is expanded in the area in charge. Determine as the direction. Then, the direction determining means outputs the maximum load to the expansion determining means, and outputs the determined direction to the area expanding means.

Next, the enlargement determining unit compares the load determined by the load determining unit with the maximum load of the adjacent luminance calculation unit output from the direction determining unit. Based on the comparison result, it is determined whether or not to expand the area in charge of the brightness calculation unit in the direction of the area in charge of the adjacent brightness calculation unit where the load is maximum.

Finally, the area expansion means changes the range of the area in charge stored in the area information storage means according to the determination of the expansion determination means,
Expand the area of responsibility.

In this way, by expanding the assigned area based on the load comparison result, the load is redistributed between the brightness calculation unit and the adjacent brightness calculation unit.

〔Example〕

1 (a) and 1 (b) are configuration diagrams showing an object image synthesizing apparatus as one embodiment of the present invention, and FIG.
FIG. 1 is an overall configuration diagram showing the entire object image synthesizing device, and FIG. 1 (b) is a configuration diagram showing a detailed configuration of the brightness calculation unit shown in FIG. 1 (a). As shown in FIG. 1A, the present embodiment is provided with an initial light ray generation unit 1 that generates information on a plurality of light rays passing through each pixel of an image to be combined from a preset viewpoint. .

Further, an object information setting unit 2 for setting the information of the displayed object is provided.

Furthermore, one of a plurality of regions generated by dividing the defined space of the object is in charge, and a ray passing through this region and an object included in the in-charge region (referred to as region 5) A plurality of brightness calculation units 3 that calculate the brightness of each pixel by performing the intersection determination process are provided.
An image storage unit 4 for storing the brightness calculated by the brightness calculation unit 3 as an image is provided. This image storage unit 4
Sets the brightness of all pixels to 0 before performing image composition.

Then, these initial light ray generation unit 1 and object information setting unit 2
And a connection line 5 for transmitting information between the plurality of brightness calculation units 3 and the image storage unit 4. This connection line 5
An information input unit 6 is provided for inputting information from a keyboard, for example.

As shown in FIG. 1 (b), the brightness calculation section 3 is provided with another brightness calculation section 3 in charge of areas adjacent in the six directions and mutual communication means 31 for mutual communication. Further, a communication means 32 for communicating via the connection line 5 is provided. Further, a connection line 101 for transmitting information in the brightness calculation section 3 is provided.

FIG. 2 is an explanatory diagram showing a method of calculating the brightness I of the pixel p (i, j), in which the light source L, the objects O and O ′, and the point E are arranged as shown in the figure. As shown in FIG. 2, in the ray search method, the path of the ray from the light source L through the pixel p (i, j) to the viewpoint E is traced in the opposite direction, and the pixel p (i, j
j) The brightness is calculated. Where pixel p (i, j)
Will be referred to as the brightness of the light ray R generated in the opposite direction from the viewpoint E through the pixel p (i, j). In FIG. 2 and the following description, R, R ′, _{RL and the} like represent light rays, Corresponds to the direction, the direction corresponds to the direction of the ray R, and so on. The brightness I of the light ray R means the pixel p (i,
It is the intensity I of the light that enters the viewpoint E through j). The brightness I of the ray R is calculated by the following equation. (* Indicates multiplication) ref: the reflection coefficient of the object O dif: diffusion coefficient of the object O I ':' intensities of light incident from the direction I _L: incident light intensity from the light source L: unit normal vector of the surface of the object O ': the direction of specular reflection Direction vector These two incident light intensity I ', in order to determine the I _L,
Starting from the intersection CP of the ray R and the object O, the direction is Two light rays R ′ and _RL are generated. In addition, the coefficients of I ′ and I _L for obtaining the brightness I are represented by light rays R ′ and R _L.
The attenuation rates G ′ and G _L of That is, the ray R
Is attenuated by the collision of the object O with the ray R ′,
R _L is generated. These attenuation factors G ′, G _L
Is G: The attenuation rate of the light ray R (= 1). By using these attenuation factors G ′ and G _L , the brightness I of the light ray R, that is, the brightness I of the pixel p (i, j)
Is calculated as follows.

I = G ′ * I ′ + G _L * I _{L When} the new rays R ′ and _RL are thus generated, the information of the ray R becomes unnecessary.

Further, as shown in FIG. 2, when the ray R ′ intersects the object O ′, rays R ″ and _RL ′ are similarly generated.
These attenuation factors G ″ and G _L ′ are similarly calculated by the following equations.

ref ': reflection coefficient of the object O'dif': diffusion coefficient of the object O '': unit normal vector of the surface of the object O ' In this way, the damping rate G ', _GL ' is multiplied by the damping rate G '.

However, the processing of the ray R _L is different from the processing of the rays R and R ′.
When the ray R _L intersects the object, the intersection CP becomes a shadow of the object and cannot receive the illumination light of the light source L. Therefore, the brightness I _L of the light ray R _L becomes zero. If the ray R _L does not intersect any object, the intensity I _L of the ray R _{L is} the intensity of the light source L. Thus, light rays R towards the object, the handle is a ray R _L where R 'and directed to the light source L are different, it is necessary to distinguish between the type of light. Therefore,
A type C for distinguishing the type of the light ray is set to the light ray R. This type C is 0 when the ray R is directed to the object,
A value of 1 is given when going to the light source.

As shown in FIG. 2, a ray of light directed to the object generates a ray of light directed to a new object each time it collides with the object. Therefore, in order to calculate the brightness I of one pixel p, a large number of light rays need to be processed. But,
Since the light ray is attenuated each time it collides with an object, the influence of the light ray on the luminance I becomes almost negligible as the number of collisions increases.

Therefore, in order to limit the number of collisions of the light ray R, the number of times T is set for the light ray R. This number T indicates the number of possible collisions of the light ray R. If a ray R having a number of times T strikes an object and a ray R'to the object is generated, the number T'of rays R'is set to (T-1). If the ray R of which the number T is 0 collides with the object, the ray R'to the object is not generated but only the ray R _L to the light source L is generated.

Although there is only one light source L in FIG. 2, if there are a plurality of light sources L _i (i = 1, 2, ...), light rays traveling to all the light sources L _i must be generated. I won't. By the way, in the case of the light ray R _L directed to the light source, a new light ray is not generated even if it intersects with the object as described above, so the number T of times as the information of the light source R _L has no meaning.
Therefore, when there are a plurality of light sources L _i , the light ray R
_As the number of times T of _L , the light source number i to which the ray R _L is directed
(The number i of the light source for the light ray R _L is set so as to correspond to the setting of the number of times T for the light rays R and R ′ in the processing of the computer). By setting the number i of the light source L _i instead of the thus rays R _L to the number of times T, even when a plurality of light sources L _i exists, the number i of the light source L _i of each light beam R _L is directed You know, so you can do it right.

For simplicity, only reflection on the surface of the object is considered here. If the transmission of the object is also taken into consideration, a ray in the transmission direction may be generated at the intersection of the object and the ray R. However, the type of this light ray is a light ray traveling toward the object, and if it is processed in the same manner as the above-mentioned light ray R ', the transmission of the object can be correctly expressed.

FIG. 3 is an explanatory diagram showing information on the light ray R to be set when the light ray R is generated. As shown in FIG. 3, when the light ray R is generated, as the information of the light ray R, the starting point position coordinates (S _x , S _y , S _z ) of the half line indicating the light ray R and the direction (d _x ,
d _y , d _z ) are set. The position (i, j) of the pixel p (i, j) affected by the brightness of the ray R is also set as the information of the ray R. Further, the attenuation rate G of the light ray R, the number T of the light ray R, and the type C of the light ray R are also set as the information of the light ray R.

FIG. 4 is an explanatory diagram for explaining the operation of the initial light beam generator 1. As shown in FIG. 4, in the initial light ray generation unit 1, a light ray R is generated with the viewpoint E as a starting point and an extension of a half line passing through each pixel p (i, j) forming the image P.

Therefore, in the initial ray generator 1 of FIG. 1 (a), the position coordinate (E _x , E _y , E of the viewpoint E is set by the information input unit 6.
_z ) is input. Also, as information defining the image P to be combined, parameters indicating the plane and range of the image P are
It is input from the information input unit 6. In the initial ray generator 1,
Information on the ray R is generated based on these parameters. An example of the method of obtaining the half line indicating the ray R is described in T. Whitted, Communication of A.C.
CM), Vol. 23, No. 6, pp. 343-349, Paper "Unimproved Illumination Model"
For Shaded Display (An Improved
Illumination Model for Shaded Display) ”.

Next, of the intersections of the half line and the object definition space, the position coordinates ( _Sx , _Sy , _Sz ) of the intersection closest to the viewpoint are obtained. The position coordinates _{(S x, S y, S} z) is the starting point position coordinates of the ray _{R (S x, S y,} S z) becomes. That is,
The position where the ray R first enters the object definition space is the ray R
Becomes the starting point. The direction from the viewpoint E toward the pixel p is the direction (d _x , d _y , d _z ) of the light ray R. Further, the position (i, j) of the pixel p (i, j) is set as the pixel position (i, j) of the ray R.

In the initial light ray generation unit 1, the attenuation rate G of the generated light ray R is set to 1, that is, a state in which the light ray R is not attenuated at all. Further, as the number of times T, a constant value preset in the initial light ray generation unit 1 is given from the information input unit 6. Furthermore, as the type C, a value of 0 indicating a light ray toward the object is given.

The initial ray generator 1 has a ray R having such information.
Are generated corresponding to all the pixels p (i, j) of the image P and are transferred to the luminance calculation unit 3.

FIG. 5 is an explanatory diagram showing the information of the object set in the object information setting unit 2. For simplicity of explanation, the displayed object is limited to a sphere, but the same can be applied to the case of displaying an object such as a polyhedron or a free-form surface.

As shown in FIG. 5, object information is input from the information input unit 6 and set in the object information setting unit 2. Information of the object _{O i} is set, the object _{O i} object number for distinguishing the _{n i,} spherical center coordinates as the object _{(x i, y i, z} i)
A radius r _i , a diffusion coefficient dif _i indicating the material of the object, and a reflection coefficient ref _i . Furthermore, as the information indicating the circumscribed area of the object O _i, the minimum rectangular parallelepiped range including the object is set.

FIG. 6 is an explanatory diagram showing a circumscribing region of a sphere as an object. As shown in FIG. 6, the circumscribed area of the object O _i is the range in the x direction (x _i− , x _{i +} ), the range in the y direction (y _i− ,
y _{i +} ), and a rectangular parallelepiped indicated by a range (z _i− , z _{i +} ) in the z direction. These values are calculated by the following formula.

x _i− = x _i −r _i x _{i +} = x _i + r _i y _i −− y _i −r _i y _{i +} = y _i + r _i z _i − = z _i −r _i z _{i +} = z _i + r _i 7th The figure is an explanatory view showing the information of the light source set in the object information setting unit 2. For the sake of simplicity, the description is limited to the point light source only, but the same can be applied to the case of handling various types of illumination light such as parallel rays and spot lights. Information on the light source as the illumination of the object is input from the information input unit 6 and set in the object information setting unit 2 as shown in FIG. The information on the light source to be set is the point light source L
position coordinates of the _i a _{(x i, y i, z} i), the light source luminance I _Li. The brightness I _Li is a real value from 0 to 1. The value of the brightness I _Li indicates the brightness of the light source, and the value of 1 is the brightest, and the value of 0 is the darkest light source.

The object information and the light source information set in this manner are transmitted from the object information setting unit 2 to the brightness calculation unit 3 via the connection line 5.

FIG. 8 is an explanatory diagram showing a method of connecting a plurality of brightness calculation units 3 in a three-dimensional array. As shown in FIG. 8, the brightness calculation section 3 is connected in a three-dimensional array through the mutual communication means 31 provided in the brightness calculation section 3. That is, each brightness calculation unit 3 is connected to the brightness calculation units 3 on both sides in the x, y, and z directions, and the brightness calculation units 3 are connected.
And can mutually communicate information. Where x,
The a, b, and c-th luminance calculation units 3 in the y and z directions are set to (a,
(b, c) When called as the brightness calculation unit 3, (a, b,
c) The brightness calculation unit 3 calculates (a-1, b, c), (a + 1,
b, c), (a, b-1, c), (a, b + 1, c),
(A, b, c-1), (a, b, c + 1) luminance calculation unit 3
Connected with.

Further, the brightness calculation units 3 are arranged in the x, y, and z directions in the figure by A, B, and C, respectively, and the total number D of the brightness calculation units 3 is D = A * B * C.

FIG. 9 is an explanatory diagram showing a method of dividing the space defining the object into the assigned areas S assigned to the respective brightness calculation units 3. As shown in FIG. 9, the object definition space is divided into a plurality of rectangular parallelepiped regions by planes that are respectively perpendicular to one of the x, y, and z coordinate axes. In this case, the division is performed so that the number of regions in the x direction is A, the number of regions in the y direction is B, and the number of regions in the z direction is C. And (a, b,
c) The a-th area in the x direction, the b-th area in the y-direction, and the c-th area in the z-direction are assigned to the brightness calculation section 3. As a result, all the divided areas can be assigned to one brightness calculation section 3.

Further, by performing such allocation, the brightness calculation units 3 connected via the mutual communication means 31 are in charge of the respective adjacent areas.

10 and 11 are explanatory diagrams showing the content of the area information indicating the area S in charge of the brightness calculation section 3. As shown in FIG. 10, area information storage means 33 provided in the brightness calculation section 3
In the area, area information indicating the area S in charge of the brightness calculation unit 3 is stored. As the area information, the values of (a, b, c) indicating the number in the x, y, z directions and the range (x, y, z) of the area S in charge as shown in FIG. 11 (x _- ,
_{x +), (y -,} y +), (z -, z +) and are stored.

Further, in the brightness calculating section 3 existing on the outer periphery of the three-dimensional array, the brightness calculating section 3 may not be connected by the mutual communication means 31. Therefore, whether or not the brightness calculation unit 3 is actually connected in each direction connected by the mutual communication unit 31 is stored in the area information storage unit 33 as information on presence / absence.

These area information is input from the information input means 6,
It is transmitted to each brightness calculation unit 3.

FIG. 12 is an explanatory diagram showing a process of transferring the information of the ray R from the initial ray generator 1 to the brightness calculator 3. The information of all the rays R generated by the initial ray generator 1 is the connection line 5
Are transmitted all at once to all luminance calculation units 3. Then, as shown in FIG. 12, the information of the light ray R transferred from the initial light ray generating section 1 is inputted to the light ray information judging means 37 provided in each luminance calculating section 3 via the communication means 32. It At the same time, the information on the area S in charge stored in the area information storage unit 33 is read by the light ray information determination means 37. The starting point position coordinates (S _x ,
S _y , S _z ) are set at positions where the light ray R first enters the object definition space. Therefore, if the starting point position coordinates (S _x , S _y , S _z ) are included in the assigned area S, the light ray R first passes through the assigned area S.

Therefore, in the light ray information determination means 37, the starting point position coordinates (S _x , S _y , S _z ) of the light ray R and the range (x ₋ ,
_{x +), (y -,} y +), (z -), Z +) and but is compared.

When all three conditional expressions of x ₋ ≦ S _x <x ₊ y ₋ ≦ S _y <y ₊ z ₋ ≦ S _z <z ₊ are satisfied, the starting point position coordinates (S _x , S _y , S _z ) are The ray R is included in the area S in charge and passes through the area S in charge first. In this case, the information of the light ray R is transferred from the light ray information determination means 37 to the light ray information storage means 34 and stored therein.

If any of these conditional expressions does not hold, the light ray R is first incident on the other area S'in charge. Therefore, the information of the light ray R is not stored in the brightness calculation unit 3.

Through the above processing, the information of the light ray R generated by the initial light ray generation unit 1 is stored in the light ray information storage unit 34 of the brightness calculation unit 3 which is in charge of the first incident area.

FIG. 13 is an explanatory diagram showing information that causes the object information storage unit 35 and the light source information storage unit 36 provided in the brightness calculation unit 3 to store the object information and the light source information from the object information setting unit 2. All the object information and the light source information stored in the object information setting unit 2 are simultaneously transferred to all the brightness calculation units 3 via the connection line 5. Then, as shown in FIG. 13, the light source information storage means 36 provided in the brightness calculation section 3 is provided.
Stores all the light source information transferred via the communication means 32. Then, the object information storage unit 35 provided in the brightness calculation unit 3 stores all the object information transferred via the communication unit 32.

FIG. 14 is an explanatory diagram showing the enlargement processing of the area S in charge of the brightness calculation unit 3. The enlargement processing of the assigned area S is performed by moving the boundary surface of the assigned area S perpendicular to the specific coordinate axis in a direction parallel to the coordinate axis.

As shown in FIG. 14, the load determining unit 43 provided in the brightness calculating unit 3 obtains the number of the light rays R stored in the light beam information storing unit 37 as the load F of the brightness calculating unit 3. Although the load determination method is described here for the sake of simplicity, various load determination methods are possible in addition to this. Even if a method other than this is adopted, the same processing can be performed. For example, in the load determining means 43, the time during which each brightness calculation unit 3 is actually processing and the time during which the information of the ray R is waited are measured, and the load of each brightness calculation unit 3 is calculated from these values. You may decide.

The load F determined by the load determining unit 43 in this manner is x ₋ , x ₊ , y of the brightness calculating unit 3 via the mutual communication unit 31.
_The luminance calculation unit 3 connected in the ₋ , y ₊ , z ₋ , and z ₊ directions
(X ₋ ), (x ₊ ), (y ₋ ), (y ₊ ), (z ₋ ),
(Z ₊ ) respectively. (The brightness calculation unit 3 connected in the x ₋ direction is referred to as the brightness calculation unit 3 (x ₋ ), and the same applies to other directions). And the direction determining means 44
Are brightness calculation units 3 (x ₋ ), (x ₊ ), (y ₋ ), (y
₊ ), (Z ₋ ), (z ₊ ) and loads F (x ₋ ), F (x ₊ ), F transmitted via the mutual communication means 31.
Among (y ₋ ), F (y ₊ ), F (z ₋ ), and F (z ₊ ), (the load of the brightness calculation unit 3 (x ₋ ) is referred to as F (x ₋ ), and is connected in the other direction. The same applies to the load on the brightness calculation unit 3),
Select only the maximum one. Then, the value D indicating the direction is output. This value D is an integer from 1 to 6, and x ₋ , x ₊ , y ₋ , in order from 1 respectively.
The y ₊ , z ₋ , and z ₊ directions are shown. In this way, the value D indicating the direction determined by the direction determining means 44 is output to the area expanding means 46 as the expansion direction of the area S in charge. At the same time, the maximum value F _max of the load obtained by the direction determining means 44 is output to the enlargement determining means 45.

Then, the enlargement determining unit 45 outputs the following result dF by comparing the maximum value F _max of the load of each adjacent brightness calculation unit 3 with the load F of the brightness calculation unit 3, and determines whether to expand the area S in charge. Is determined as follows.

When F _max -F> TH dF = 1 otherwise dF = 0 TH: Positive threshold value set in advance through the information input unit 6 As a result, when dF is 1, the assigned area S is indicated by the value D. Expand in the direction indicated. When the result dF is 0, the area S in charge is not expanded.

In response to the result dF of the area S in charge determined in this way, when the value is 1, the area expansion means 46 expands the range of the area S in charge. The area enlarging means 46 first reads the area a in the direction indicated by the value D of the area S in charge from the area information storage means 33 and stores it according to the value D indicating the expanding direction determined by the direction determining means 44. For example, the value D is 1
In the case of 2, the range x ₋ shown in FIG. 10 is read as the range a, and in the case of 2, x ₊ is read. Next, a new range a is obtained as shown below.

When D = 1, 3, 5 a ′ = a−dS When D = 2, 4, 6 a ′ = a + dS dS: Positive expansion amount preset through the information input unit 6 Range obtained in this way a'is the area information storage means 33
The range of the area S in charge is expanded by writing in the part storing the range of the corresponding direction.

By performing such an expansion process of the area S in charge,
The number of objects included in each assigned area S and the number of passing light rays can be increased, and the calculation amount of each luminance calculation unit 3 can be increased. At the same time, it is possible to reduce the load on the adjacent luminance calculation unit 3 which is in charge of the area adjacent in the direction indicated by the value D. Therefore, it is possible to redistribute the load appropriately by averaging the entire calculation amount.

FIGS. 15A and 15B are explanatory diagrams showing the transfer direction of the information of the light ray R between the brightness calculation units 3. The areas in charge of the brightness calculation units 3a to 3e shown in FIG.
Areas of responsibility Sa to Se shown in FIG.
Enlargement processing has been performed on a, Sb, and Sd. As shown in FIG. 15A, the change of the area S in charge causes the boundary surfaces of the areas to overlap. Further, as shown in FIG. 15 (b), the connection between the brightness calculation units 3 via the mutual communication means is fixed. Therefore, in the case as shown in FIGS. 15 (a) and 15 (b), the information of the light ray R incident from the area Sa in charge to the area Sb in charge is transferred from the brightness calculation unit 3a to the mutual communication means 31.
Cannot be directly transferred to the brightness calculation unit 3b via the.

Therefore, such information of the light ray R is transmitted from the brightness calculating section 3a through the mutual communication means 31 to the brightness calculating section 3e.
Transferred to. The information of the transferred light ray R is once stored in the light ray information storage means 34 of the brightness calculation section 3e,
Then, it is transferred to the brightness calculation unit 3c.

In order to perform such a transfer process, the information of the light ray R stored in the light ray information storage means 34 of each brightness calculation section 3 is first read out by the light ray information determination means 37. The light ray information determination means 37 determines the starting point position coordinates (S _x , S _y , S) of the light ray R.
and _z), the range of coverage area S read from the area information storage unit _{33 (x -, x +)} , (y -, y +), (z -, z
₊ ) And perform the following processing. However, the starting point position coordinates (S _x , S _y , S _z ) of the ray R have been updated to the intersection of the ray R and the boundary surface of the area S in charge by the intersection determination process described later.

When S _x <x ₋ , the information of the light ray R is transferred to the brightness calculation section 3 connected in the x ₋ direction via the mutual communication means 31, and the procedure is ended.

When S _x ≧ x ₊ The information of the light ray R is transferred to the luminance calculation unit 3 connected in the x ₊ direction via the mutual communication means 31.

When S _y <y ₋ , the information of the light ray R is transferred to the luminance calculation unit 3 connected in the y ₋ direction via the mutual communication means 31.

When S _y ≧ y ₊ The information of the light ray R is transferred to the luminance calculation unit 3 connected in the y ₊ direction via the mutual communication means 31.

S z _{<z -} via the mutual communication means 31, the information of the ray R z _- to be transferred is connected to the direction to the luminance calculation unit 3.

When S _z ≧ z ₊ , the information of the light ray R is transferred to the luminance calculation unit 3 connected in the z ₊ direction via the mutual communication means 31.

End By thus transferring the information of the light ray R between the brightness calculation units 3, the correct brightness calculation unit 3 can process the information of the light ray R.

FIG. 16 is an explanatory diagram showing a method of calculating the brightness of each pixel by the intersection determination processing between the light ray and the object in the brightness calculation unit 3. As shown in FIG. 16, the information of the light ray R stored in the light ray information storage means 34 is first read out by the light ray information determination means 37. As a result of the determination processing by the light ray information determination means 37, the information of the light ray R that has not been transferred to the adjacent brightness calculation section 3 is sent to the intersection determination means 39. The intersection determining means 39 is configured to detect the object R and the ray R included in the area S in charge.
Perform intersection determination processing with.

For that purpose, the object information determination means 38 has ranges (x ₋ , x ₊ ), (y ₋ , y) of the area S in charge from the area information storage means 33.
₊ ), (Z ₋ , z ₊ ) and the range (x _i− , x _{i +} ), (y _i− , y _{i +} ), (z _i− , z _{i +} ) of the circumscribed region of each object O _i. Then, a determination process of whether or not each object O _i is included in the area S in charge is performed.

17 (a) and 17 (b) are areas S in charge of the brightness calculation unit 3.
FIG. 7 is an explanatory diagram showing a process of comparing the object information with the circumscribed region. As shown in FIGS. 17A and 17B, the area S in charge
And the circumscribed area have no common part, at least one of the following conditional expressions is satisfied.

x ₋ ≧ x _{i +} x ₊ ≦ x _i- y ₋ ≧ y _{i +} y ₊ ≦ y _i- z ₋ ≧ z _{i +} z ₊ ≦ z _i- Therefore, the object information determination means 38 evaluates these conditional expressions. , It is required to determine whether the area S in charge and the circumscribed area have a common part. As a result, when there is a common part, it is determined that the object O _i is included in the area S in charge, and the information of the object O _i is transferred to the intersection determination unit 39. If there is no common part, it is not transferred.

Through the above processing, of the object information stored in the object information storage means 35, only the object information included in the area S in charge is transferred from the object information determination means 38 to the intersection determination means 39. Then, the intersection determination unit 39 performs an intersection determination process between the object O _i and the light ray R transferred from the object information determination unit 38.

As a result, for the ray R that does not intersect the object, the intersection point between the ray R and the boundary surface of the area S in charge is first obtained. From this intersection, the adjacent area S'where the ray R is next incident is determined, and the direction in which the information of the ray R should be transferred is determined. The information of the light ray R is transferred to the luminance calculation unit 3 in the determined direction via the mutual communication means 31.

At this time, the starting point position coordinates of the ray R are changed to the position coordinates of the obtained intersection. As a result, the starting point position coordinates of the light ray R are included in the region to be incident next.

The information of the light ray R thus transferred is the mutual communication means 31.
And is stored in the light beam information storage means 34.

Moreover, when the ray R intersects the object and a new ray R ′ or ray RL is generated from the ray R, information on the ray R ′ and the ray RL is stored in the ray information storage means 34. Remembered.

Such intersection determination processing is shown in the above-mentioned papers and FIG.

When the brightness I of the light ray R is determined by this processing, the brightness I is added to the pixel p (i, j) of the image storage unit 4 indicated by the information of the light ray R via the communication unit 32. It

By the intersection determination process described above, the synthesis of the image P is completed when all the information of the light ray R stored in the light ray information storage unit 34 of each brightness calculation unit 3 is processed.

〔The invention's effect〕

In the object image synthesizing apparatus of the present invention, the shape of the area in charge of each brightness calculation unit is a rectangular parallelepiped, and each surface of the rectangular parallelepiped is perpendicular to the coordinate axis. Therefore, it is very easy to determine the intersection between the boundary surface of the area in charge and the ray. Therefore, when a ray passes through the area in charge, it is possible to determine the area to which the information of this ray should be transferred with a processing amount much smaller than that in the conventional case.

Further, the shape of the assigned area is changed by moving the boundary surface perpendicular to each coordinate axis in a direction parallel to the coordinate axis. Therefore, even if the shape of the area in charge is changed, the area in charge is kept in a rectangular parallelepiped, and the above-mentioned effect is not impaired.

As described above, since the processing amount when changing the shape of the area in charge is small, it is possible to sufficiently obtain the effect of redistributing the load of each brightness calculation unit by changing the shape of the area in charge.

[Brief description of drawings]

1 (a) and 1 (b) are a block diagram showing the entire configuration of an object image synthesizing apparatus according to an embodiment of the present invention and a block diagram showing the detailed configuration of a brightness calculation section, respectively. FIG. Explanatory diagram showing a method of calculating the brightness I of (i, j),
FIG. 3 is a diagram showing the information of the light ray R to be set when the light ray R is generated, FIG. 4 is an explanatory view for explaining the operation of the initial light ray generation unit 1, and FIG. 5 is an object information setting unit 2 FIG. 6 is a diagram showing the information of the object set in FIG. 6, FIG. 6 is an explanatory diagram showing the circumscribing area of the sphere as the object, FIG. 7 is a diagram showing the information of the light source set in the object information setting unit 2, and FIG. Is an explanatory view showing a method of combining a plurality of brightness calculation units 3 in a three-dimensional array, and FIG. 9 is a view showing a method of dividing a space defining an object into assigned areas S assigned to each brightness calculation unit 3, 10 and 1
FIG. 1 is a diagram of region information showing a region S in charge of the brightness calculation unit 3 and an explanatory diagram showing it in a three-dimensional manner. FIG. 12 shows a transfer process of information of a light beam R from the initial light beam generation unit 1 to the brightness calculation unit 3. FIG. 13 is a block diagram showing the process of storing the object information and the light source information from the object information setting unit 2 in the object information storage unit 35 and the light source information storage unit 36 provided in the brightness calculation unit 3. FIG. 14 is a block diagram showing the enlargement processing of the area S in charge of the brightness calculation unit 3, and FIGS. 15 (a) and 15 (b) are explanatory diagrams showing a method of transferring the information of the ray R between the brightness calculation units 3. 16 is a block diagram showing a method of calculating the brightness of each pixel by the intersection determination processing between the light ray and the object in the brightness calculation section 3, and FIGS. 17A and 17B show the area S in charge of the brightness calculation section 3 and the object information. It is an explanatory view showing the comparison processing with the circumscribed area, It is a case where the coverage area S and circumscribing region has no the case with common parts. 1 ... Initial ray generation unit, 2 ... Object information setting unit, 3,3
a, 3b, 3c, 3d ... Luminance calculation section, 4 ... Image storage section, 5 ... Connection line, 6 ... Information input section, 31 ... Mutual communication means, 32 ... Communication means, 33 ... Area Information storage means, 34 ... Ray information storage means, 35 ... Object information storage means, 36 ... Light source information storage means, 37 ... Ray information determination means, 38 ... Object information determination means, 39 ... Crossing determination means , 43 ... load determining means, 44 ... direction determining means,
45 ... Expansion determination means, 46 ... Area expansion means.

Claims (1)

[Claims] 1. Ray tracing for tracing the path of a ray from the light source to the viewpoint in the opposite direction to perform intersection determination processing between the object and the ray, and calculating the brightness of each pixel forming an image for displaying the object. In an object image synthesizing device based on the method, an initial light ray generation unit that generates information of a plurality of light rays that pass through each pixel from the viewpoint, an object information setting unit that sets information of the object, and each defines the object. Is assigned to one of a plurality of regions generated by dividing the defined space by a plane perpendicular to the coordinate axis, and intersection determination processing of a ray passing through the assigned region and the object included in the assigned region is performed. A plurality of brightness calculation units that calculate the brightness of the pixel by performing the calculation, and a pixel storage unit that stores the brightness calculated by the brightness calculation unit as the pixels. An area information storage unit that stores a surrounding area, a load determination unit that determines each load, and an adjacent brightness calculation unit that is the brightness calculation unit that handles the region adjacent to the region in charge in a direction parallel to each of the coordinate axes. The direction of the area in which the one having the largest load among the adjacent luminance calculation units obtained via the mutual communication means and the mutual communication means performing the mutual communication is determined as the expansion direction of the area in charge. Direction determining means, and if the result of subtracting the load of the brightness calculating section from the load of the adjacent brightness calculating section where the load is maximum is larger than a predetermined threshold value, the direction is determined in the direction determined by the direction determining means. Expansion determining means for determining to expand the area in charge, and the area for expanding the area in charge in the direction determined by the direction determining means based on the determination by the expansion determining means. An object image synthesizing apparatus, comprising: an area expanding unit that changes a range of the area in charge stored in the information storage unit.