JPH0632044B2 - Object image synthesizer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object image synthesizing apparatus for synthesizing images for displaying an object.

(Prior Art) As a method of synthesizing a digital image for displaying an object, there is a method called a ray tracing 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 tracing method is described in Reference 1: IPSJ Transactions, No. 25.
Vol. 6, No. 6, Hiroshi Deguchi, Hitoshi Nishimura, Hiroshi Yoshimura, Toru Kawada, Isao Shirakawa, Koichi Omura, Paper "Speeding up Image Generation in Computer Graphics System LINKS-1".

In order to perform image generation by such a ray tracing method at high speed, the space in which the object is defined is divided into a plurality of regions, and one computer is assigned to each region, and each computer is assigned. A parallel processing method has been proposed in which a light beam that passes through an area is processed. For more information on this method, see Document 2: Computer Graphics, Volume 18, Issue 3, Mark Dippe, John Swensen.
n Swensen), `` An Adaptive Subdivision Algorithm and Paralle
l Architecture for 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, each computer performs an intersection determination process between a ray passing through the assigned area and an object included in the area. By this intersection determination processing,
When the object and the light beam intersect, reflection and transmission processing is performed on the surface of the object. Information about rays that do not intersect the object in that area is transferred to the computer assigned to the adjacent area.

In this way, each ray is determined to intersect only with an object included in the area through which the ray passes. Therefore, compared with the case where each ray is processed for intersection determination with all objects, the total processing amount is much smaller.

In addition, such intersection determination processing is executed in parallel in each computer. By adding this parallel processing effect, it is possible to combine images at a very high speed.

(Problems to be Solved by the Invention) In such a conventional image synthesizing method, each computer performs intersection determination processing between a ray passing through an assigned area and an object included in the area. The amount of processing required for this is much smaller than the case where the intersection determination processing is performed for all objects, but it is also a huge amount of processing. Therefore, by the simple process of determining the intersection of the area where the object exists and the ray, only the objects that may intersect with this ray are selected in advance, and the conventional intersection determination process is performed only with these objects. There is a method.
An example of this method is document 3: Pixel (PIXEL), 37th.
Issue, Akimoto Akira, "Rapid Tracing Acceleration Techniques-Prior Techniques and ARTS Techniques". In this method, the array of unit cubes through which the ray passes is 3
It occurs as a dimensional digital straight line. By using this three-dimensional digital straight line, the intersection of the region where the object exists and the light ray is determined at high speed.

However, in such a conventional method, an area in which an object exists is represented by storing an object included in the unit cube for each unit cube. Therefore, there is a problem that the amount of data required to represent the area where the object exists becomes enormous.

In order to solve such a problem, the present invention can represent a range in which an object exists with a very small amount of data, and can use this to perform high-speed intersection determination processing. The purpose is to provide.

(Means for Solving Problems) An object image synthesizing apparatus according to 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, and an object information setting unit that sets information about an object. , Performing one of a plurality of regions generated by dividing the space defined by the object, and performing intersection determination processing between a ray passing through the region and an object included in the region in charge. With a plurality of brightness calculation unit for calculating the brightness of the pixel by, and an image storage unit that stores the brightness calculated by this brightness calculation unit as the image, in the brightness calculation,
A straight line generating means for generating, as a three-dimensional digital straight line, a row of unit cubes through which the ray passes among a plurality of unit cubes generated by dividing the object definition space by a plurality of planes that are perpendicular to the coordinate axes and are equally spaced. , One of a plurality of regions generated by dividing the object definition space on a part or all of the plurality of planes is set as a corresponding region of the brightness calculation unit, and the range of the assigned region is stored. Area information storage means, existence range determination means for determining the existence range of an object included in the charge area in the charge area, existence range storage means for storing the existence range, and straight line generation means. A column of unit cubes is compared with the existence range of the object stored in the existence range storage means, and an object in which the light rays may intersect is selected from among the objects included in the assigned area. An object selection unit that, the intersection determination means for performing intersection determination processing with the selected object and the light beam by the object selecting means is provided.

(Operation) A method of determining an intersection between an object and a ray in the object image synthesizing apparatus of the present invention will be described.

A plurality of cubes generated by dividing the object definition space by a plurality of planes that are perpendicular to the coordinate axes and are equally spaced apart are called unit cubes.
Further, the object definition space is divided by a part or all of the plurality of planes to generate a plurality of regions. The region thus generated is a rectangular parallelepiped formed of one or a plurality of unit cubes, and each boundary surface of this rectangular parallelepiped is perpendicular to each coordinate axis. One of the plurality of areas is assigned as the area in charge of one brightness calculation unit. The range of the assigned area is stored in the area information storage unit provided in the brightness calculation unit.

Further, the existence range determination means provided in each brightness calculation unit is
The existence range of the object included in the assigned area in the assigned area is determined. Then, the determined existence range is stored in the existence range storage means.

Further, the straight line generation means provided in each brightness calculation unit sequentially generates a row of unit cubes through which a light ray passes as a three-dimensional digital straight line. Then, the object selection means reads the existence range of the object included in the assigned area from the existence range storage means, and compares the existence range of the object with the unit cubes sequentially generated. By this comparison, when the generated unit cube is included in this existence range, it is determined that the light ray may intersect with the object, and this object is selected as the target of the intersection determination process.

Then, the intersection determination means performs intersection determination processing between the object and the ray selected by the object selection means.

(Embodiment) FIGS. 1 (a) and 1 (b) are configuration diagrams showing an object image synthesizing apparatus as an embodiment of the present invention. FIG. 1 (a) shows the entire object image synthesizing apparatus. The entire configuration diagram shown in FIG. 1 (b) is a configuration diagram showing a detailed configuration of the brightness calculation unit. Fig. 1
As shown in (a), an initial light ray generation unit 1 that generates information about a plurality of light rays that pass through each pixel of an image to be combined from a preset viewpoint is provided.

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

Furthermore, one of the plurality of regions generated by dividing the space in which the object is defined is assigned to perform an intersection determination process between a ray passing through this region and an object included in the assigned region. Therefore, a plurality of brightness calculation units 3 for calculating the brightness of each pixel are provided. This brightness calculation unit 3
The image storage unit 4 that stores the brightness calculated in
Is provided. The image storage unit 4 sets all the luminances to 0 before the images are combined.

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

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

FIG. 2 is an explanatory diagram showing a method of calculating the brightness I of the pixel p (i, j). As shown in FIG. 2, in the ray tracing method, the path of the ray from the light source L to the viewpoint E through the pixel p (i, j) is traced in the reverse direction, and the luminance of the pixel p (i, j) is calculated. Calculate. Here, the brightness I of the pixel p (i, j) is changed from the viewpoint E to the pixel p
It is called the brightness of the light ray R generated in the opposite direction through (i, j). The brightness I of the light ray R is the intensity I of the light that enters the viewpoint E through the pixel p (i, j). The brightness I of the ray R is calculated by the following equation.

In order to obtain these two incident light intensities I ′, _RL , the direction from the intersection point CP as the starting point Two light rays R'and _RL are generated. Also, I for obtaining the luminance I ', the coefficient of I _L, light R', the attenuation rate of R _L G ', is set as G _L. That is, the light ray R is attenuated by colliding with the object O, and the light rays R'and _RL are generated. These damping factors G ′ and G _L are Becomes 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 obtained 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'crosses the object 0 ', rays R "and _RL ' are similarly generated. These attenuation rates G" and _GL 'are also Similarly, it is calculated by the following formula.

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 will be 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 types of light rays is set for the light ray R. This type C is 0 when the light ray R goes to the object, and I when it goes to the light source.
Is given.

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. The number of times T indicates the number of possible collisions of the light ray R. When a ray R having a number of times T strikes an object and a ray R'to the object is generated, the ray R '
The number of times T'of is set to (T-1). If the ray R having the number T of 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 ray L in FIG. 2, if there are a plurality of light sources L _i (i = 1, 2, ...), light rays traveling to all light sources L _i must be generated. I won't. By the way, in the case of the light ray R _L heading for the light source, a new light ray is not generated even if it intersects with the object as described above.
The number of times T as the information of R _L has no meaning. Therefore, when there are a plurality of light sources L _i as the number T of the ray R _L, the ray R _L
Set the number i of the light source to which

By setting the number T of the light rays R _{L in} this way, even when there are a plurality of light sources L _i , the light sources to which the respective light rays R _L go
Since the number i of L _i is known, the processing can be performed correctly.

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 directions (d _x , d _x , d _z ) and are set. Also, the pixels affected by the brightness of the ray R
The position (i, j) of p (i, j) 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 showing information set in the light ray R in order to generate a row of unit cubes through which the light ray R passes as a three-dimensional digital straight line. Here, a plurality of cubes generated by dividing the object definition space by a plurality of planes that are perpendicular to the x, y, and z coordinate axes and are equally spaced apart are called unit cubes. Fourth
As shown in the figure, the position ( _Tx , _Ty , _Tz ) of the last unit cube among the unit cubes sequentially generated as a three-dimensional digital straight line is set as the information of the ray R. It That is, this position ( _Tx , _Ty , _Tz ) indicates the current position of the ray R, and is updated as the ray R passes through the object definition space. Further, the error information ER for sequentially generating the three-dimensional digital straight line is also set as the information of the light ray R. A three-dimensional digital straight line can be generated at high speed by adding the error information ER and making a determination. The meaning and calculation method of this error information ER is described in detail in Reference 3.

FIG. 5 is a diagram for explaining the operation of the initial light ray generation unit 1.
FIG. As shown in FIG. 5, the initial light beam generation unit 1
At, a ray R is generated as a half line passing through each pixel p (i, j) forming the image P, starting from the viewpoint E.

Therefore, the position coordinate (E _x , E _y , E _z ) of the viewpoint E is input to the initial ray generation unit 1 by the information input unit 6. In addition, as information defining the image P to be combined, parameters indicating the plane and range of the image P are input from the information input unit 6. The initial ray generator 1 generates information on the ray R based on these parameters. An example of a method for obtaining the half line indicating the ray R is described in Reference 4: T. Whitted, Communication of ACM, Volume 23,
No. 6, pp. 343 to 349, Paper "An Improved Illumination Model for For Shaded Display
Shaded Display) ".

Next, the position coordinates (E _x , E
_y , E _z ) as the starting point position coordinates (S _x , S _y , S _z ) of the ray R, and the direction from the viewpoint E toward the pixel p is the direction of the ray R (d _x , d _y , d _z). ). Also, the position of pixel p (i, j)
(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.

Further, among the intersections of the ray R generated in this way and the object definition space, the position coordinates (t _x , t _y ,
t _z ). The position coordinates (t _x , t _y , t _z ) are converted into an integer, a unit cube including this intersection is obtained, and this is a ray R
It is set as the position (T _x , T _y , T _z ) as the information of. This position (T _x , T _y , T _z ) indicates a unit cube at which the ray R first enters the object definition space. Then, with this unit cube as the first unit cube, a row of unit cubes through which the ray R passes in the object definition space is generated in each luminance calculation unit 3 as a three-dimensional digital straight line.

In the subsequent processing, when the light ray R passes through the area S and is incident on the area S ′, the information of the light ray R is obtained by the luminance calculation unit 3
Transferred between. At that time, the current position ( _Tx , _Ty , _Tz ) of the three-dimensional digital straight line as the information of the ray R is updated to the position of the unit cube including the intersection of the new area S'and the ray R. .

Further, in the initial ray generation unit 1, the initial value of the error information ER for sequentially generating the three-dimensional digital straight line is calculated and set as the error information ER of the ray R. The method of calculating this initial value is described in detail in Document 3 as described above.

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. 6 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. 6, object information is input from the information input unit 6 and set in the object information setting unit 2. The information of the object i to be set is the object number n _i for distinguishing the object _i ,
The center coordinates (x _i , y _i , z _i ) of the sphere as the object, the radius r _i , the diffusion coefficient difi _i indicating the material of the object, and the reflection coefficient ref _i . Further, information indicating the circumscribed area of the object i and the minimum rectangular parallelepiped range including the object are set.

FIG. 7 is an explanatory diagram showing a circumscribing region of a sphere as an object. As shown in FIG. 7, the circumscribed area of the object i is a range in the x direction (x _i- , x _{i +} ), a range in the y direction (y _i- , y _{i +} ), z
It is a rectangular parallelepiped consisting of multiple unit cubes, which is indicated by the range of directions (z _i- , z _{i +} ). These values are integer values and are calculated by the following formula.

x _i- ＝ floor (x _i -r _i ) x _{i +} ＝ ceil (x _i + r _i ) y _i- ＝ floor (y _i -r _i ) y _{i +} ＝ ceil (y _i + r _i ) z _i- ＝ floor (z _i -r _i ) z _{i +} = ceil (z _i + r _i ) floor (a): maximum integer value not greater than a ceil (a): minimum integer value not less than a It is an explanatory view showing the information on 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. As shown in FIG. 8, the information of 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. The information on the light source to be set is the position coordinates (x _i , y _i , z _i ) of the point light source i and the brightness I _Li of the light source.
This brightness I _Li is a real value from 0 to 1. This brightness I _Li
The value of indicates the brightness of the light source, where 1 is the brightest and 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. 9 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. 9, the brightness calculation section 3 is an intercommunication means provided in the brightness calculation section 3.
It is connected through 31 through a three-dimensional array. 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 referred to as the brightness calculation unit 3, the (a, b, c) 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) connected to the brightness calculation unit 3.

In addition, the brightness calculation unit 3 uses A, B, and C in the x, y, and z directions in the figure, respectively.
They are arranged one by one, and the number D of all the brightness calculation units 3 is D = A * B * C.

FIG. 10 shows a method of dividing the space defining the object into the assigned areas S assigned to the respective brightness calculation sections 3. FIG. As shown in FIG. 10, the object definition space is divided into a plurality of rectangular parallelepiped-shaped regions by some or all of the plurality of planes serving as the boundary surface of the unit cube. By performing such division, each region can be configured by a manufacturing unit or one unit cube.

Further, 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. Then, the (a, b, c) luminance calculation unit 3 displays a in the x direction.
The numbered area, the b-th area in the y direction, and the c-th area in the z direction are allocated. 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 adjacent regions.

11 and 12 are explanatory diagrams showing the contents of the area information indicating the area S in charge in the brightness calculation section 3. As shown in FIG. 11, the area information storage means 33 provided in the brightness calculation section 3 stores area information indicating the area S in charge of the brightness calculation section 3. As the area information, the value of (a, b, c) indicating the number in the x, y, z direction and the range in the x, y, z direction of the area S in charge as shown in FIG. 12 ( _{x -, x +), (} y -, y +), (z -,
z ₊ ) and are memorized. Since each area is composed of a plurality of or one unit cube, the value indicating these ranges is an integer value.

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

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

FIG. 13 is an explanatory diagram showing a process of transferring the information of the light ray R from the initial light ray generating section 1 to the luminance calculating section 3. As shown in FIG. 13, all rays R generated by the initial ray generator 1
The information of 1 is simultaneously transferred to all the brightness calculation units 3 via the connection line 5. Then, the information of the light ray R transferred from the initial light ray generation section 1 is input to the initial information determination means 38 provided in each luminance calculation section 3 via the communication means 32. At the same time, the information of the area S in charge stored in the area information storage unit 33 is read by the initial information determination means 38.

The position (T _x , T _y , T _z ) of the ray R input in this way is set to the position where the ray R first enters the object definition space. Therefore, if this position (T _x , T _y , T _z ) is the area S in charge
, The light ray R first passes through the area S in charge.

Therefore, the initial information determination means 38 determines the position (T _x , T _y ,
T _z ) and the ranges (x ₋ , x ₊ ), (y ₋ , y ₊ ), (z ₋ , z ₊ ) of the area S in charge are compared.

If all three conditional expressions x _- ≤ T _x <x ₊ y _- ≤ T _y <y ₊ z _- ≤ T _z <z ₊ are satisfied, the position (T _x , T
_y , T _z ) is included in the area S in charge, and the light ray R first passes through the area S in charge. In this case, the information of the light ray R is transferred from the initial information determination means 38 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. 14 is an object information storage means provided in the brightness calculation section 3.
It is explanatory drawing which shows the process which memorize | stores object information and light source information from the object information setting part 2 in 35 and the light source information storage means 36. As shown in FIG. 14, 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. Luminance calculator 3
The light source information storage means 36 provided in the memory stores all the light source information transferred via the communication means 32.

In addition, the initial information determination means 38 provided in the brightness calculation unit 3
First receives the object information transferred via the communication means 32. Next, the range of the area S in charge of the brightness calculation unit 3 is read from the area information storage unit 33. Range of this area S (x
_{-, x +), (y} -, y +), (z -, the range of the circumscribed area of z ₊₎ and object information (x
_i- , x _{i +} ), (y _i- , y _{i +} ), (z _i- , z _{i +} ) are compared.

FIGS. 15 (a) and 15 (b) are explanatory views showing the comparison processing of the area S in charge of the brightness calculation unit 3 and the circumscribed area of the object information. First
As shown in FIGS. 15A and 15B, when the area S in charge and the circumscribed area do not have a 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 +} x ₊ ≤ z _i- Therefore, the initial 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, if there is a common part, it is determined that the object i is included in the area S in charge, and all the information of the object i is stored in the object information storage means 35. If there is no common part, it is not stored.

Through the above processing, of the object information stored in the object information setting unit 2, only the object information included in the area S in charge is stored in the object information storage unit 35 provided in the brightness calculation unit 3.

16 (a) and 16 (b) are explanatory views showing a method of determining the existence range of an object in the existence range determination means 40 provided in the brightness calculation section 3. As shown in FIG. 16 (a), first, the existence range determination means 40 reads out the object information stored in the object information storage means 35 and the range of the assigned area S stored in the area information storage means 33. The scope of the circumscribed area of the object i as object information _{(x -, x +),} (y -, y +), (z -, z +) and in charge area S
Of the range (x _i- , x _{i +} ), (y _i- , y _{i +} ), (z _i- , z _{i +} ),
Existence range (x ′ _i− ,
x ′ _{i +} ), (y ′ _i− , y ′ _{i +} ) and (z ′ _i− , z ′ _{i +} ) are determined as follows.

x _- ≧ x _i- if _{x 'i- = x - x -} <x i- if _{x' i- = x i- x +} ≦ x i + if _{x 'i + = x + x} +> if x _{i +} if _{x 'i + = x i +} y - ≧ y i- if _{y' i- = y - y -} <y i- if _{y 'i- = y i- y +} ≦ y i + if y' _{i +} = y ₊ y _+> y _{i +} if _{y 'i + = y i +} z - ≧ z i- if _{z' i- = z - z -} <z i- if _{z 'i- = z i- z +} ≦ z i + Then, if z ′ _{i +} = z ₊ z ₊ > z _{i +,} then z ′ _{i +} = z _{i +} Here, for simplification, the common part between the circumscribed area of the object i and the area S in charge is defined as the existence area of the object i. Were determined. However, if the existence range of the object i can be represented by a smaller rectangular parallelepiped as shown in FIG. 16 (b), this may be determined as the existence range.

The existence range determining means 40 existence range of the object i determined in this way _{(x 'i-, x' i} +), (y 'i-, y' i +),
(Z ′ _i− , z ′ _{i +} ) is stored in the existence range storage means 41.

FIG. 17 is an explanatory diagram showing a method of processing the information of the light ray R in the brightness calculation section 3. As shown in FIG. 17, the information of the light ray R stored in the light ray information storage means 34 is first read out and stored in the intersection determination means 39. This intersection determination means
Reference numeral 39 denotes the information of the light ray R based on the object selecting means 42 and the straight line generating means 43.
Communicate to. Receiving the information of the transmitted light ray R, the object selecting means 42 first uses the existence range storing means 41 to detect each object i.
_Existing range (x ′ _i− , x ′ _{i +} ), (y ′ _i− , y ′ _{i +} ),
(Z ′ _i− , z ′ _{i +} ) is read and stored. Then, the flag F _i corresponding to each object i is set to 0. The flag F _i is provided inside the object selecting means 42 and is set to 0 every time the information of the light ray R is received.

Further, the object selecting means 42 selects the position of the light ray R (T _x , T _y , T _z ) as the information of the light ray R and the object i of each of the objects i in order to select the object i in which the light ray R may intersect. Existence range (x ′ _i− , x ′ _{i +} ), (y ′ _i− , y ′ _{i +} ), (z ′ _i− ,
z'i ₊ ). However, when the value of the flag F _i corresponding to the object i is 1, the intersection determination process for this object i has already been performed, and therefore the comparison is not performed. If all three conditions of x ′ _i− ≦ T _x <x ′ _{i +} y ′ _i− ≦ T _y <y ′ _{i +} z ′ _i− ≦ T _z <z ′ _{i +} are satisfied, the ray R passes through. The unit cube to be included is included in the existence range of the object i. Therefore, this object i may intersect the ray R. Therefore, the number i of the object i is transferred to the intersection determination means 39. At the same time, the flag F _i is set to 1. In this way, the information of the object _i whose flag F _i is set to 1 is not compared in the subsequent processing. By this operation, it is possible to prevent the number i of the same object i from being repeatedly transferred to the intersection determination means 39 for one ray R.

After performing such processing for each object i, the object selecting means 42 sends the control information to the straight line generating means 43. Upon receiving this control information, the straight line generating means 43 generates the next unit cube through which the light ray R passes.

18 (a) and 18 (b) are explanatory views showing a straight line generating method in the straight line generating means 43. FIG. As shown in FIGS. 18 (a) and 18 (b), first, the straight line generation means 43 determines the information of the light ray R by the intersection determination means.
Remember this information, received from 39. Then, each time the control information from the object selecting means 42 is received, one unit cube through which the light ray R passes is generated by the addition determination processing of the error information ER which is the information of the stored light ray R.

In order to generate such a unit cube, straight line generating means
43 first performs an addition determination process of the error information ER, and updates the error information ER based on the result. Next, the straight line generating means 43 selects and determines the coordinate axis for generating the unit cube from the x, y, z coordinate axes based on the result of the addition determination processing, and determines the selection information SEL. This selection information SEL
Has a value of 0, 1 or 2, and these values respectively indicate x, y and z coordinate axes. At the same time, the straight line generating means 43 also determines the direction DIR of the generated unit cube. The value of this direction DIR is 1 or -1. The method for determining these values is shown in Document 3 as described above.

For example, as shown in FIG. 18 (a), a unit cube (T _x , T _y ,
Straight line generating means when generating the next unit cube of T _z ).
When the selection information SEL is determined to be 0 and the direction DIR is determined to be 1 by the addition determination processing of the error information ER of the light ray R in 43, the straight line generation means 43 determines the unit cube (T _x +1, T _y , T _z ).
To occur. Also, the selection information SEL is set to 0 and the direction DIR is set to -1.
If it is determined to be, the straight line generating means 43 generates a unit cube ( _Tx- 1, _Ty , _Tz ).

Then, the straight line generation means 43 uses the newly generated unit cube (T _x ′, T _y ′, T _z ′) at the position (T _x , T _y , T _z ) in the stored information of the light ray R. ). By doing this, the position (T _x , T _y , T _z ) of the ray R is updated, and this position (T _x , T _y , T _z ) is the last of the column of the unit cube as a three-dimensional digital straight line. It comes to show a unit cube.

The straight line generating means 43 also determines the selected selection information SEL and the direction DIR.
Based on and, it is determined whether the position (T _x , T _y , T _z ) of the new ray R is within the range of the assigned area S or outside the range. When it is determined that the light ray R is out of the range, the passing direction of the light ray R is determined, and the information of the light ray R and the passing direction are sent to the light ray information transfer means 44.

For example, as shown in FIG. 18 (b), when the generated unit cube is outside the range of the area S in charge, the direction in which the unit cube is generated becomes the passage direction of the light ray R.

In order to make such a determination, the straight line generation means 43 reads the value of the range of the assigned area S indicated by the selection information SEL and the direction DIR from the area information storage means 33. Then, by comparing this value with the value indicated by the selection information SEL of the positions (T _x , T _y , T _z ), it is determined whether the generated unit cube is within or outside the area S in charge. .

For example, as shown in FIG. 18 (a), the selection information SEL is 0 and the direction is
When DIR is 1, the value of x _{+ in} the range is read. This value x
Value indicated by selection information SEL between ₊ and position (T _x , T _y , T _z ).
It is compared with T _x and judged as follows.

When T _x > x ₊ Out of range When T _x ≦ x _{+ In} range When the selection information SEL is 0 and the direction DIR is −1, the value of x _{− in} the range is read. This value x _- a position _{(T x, T y, T} z) is compared with the value T _x indicated by the selection information SEL of the judges as follows.

When T _x <x ₋ is out of range When T _x ≧ x ₋ is in range In this way, when the straight line generation means 43 determines that the position (T _x , T _y , T _z ) is within the range, the updated ray is updated. Position of R (T _x , T _y ,
T _z ) to the object selection means 42. Upon receiving this, the object selecting means 42 compares the new position (T _x , T _y , T _z ) with the existence range of each object i, and the number of the object i that may intersect the ray R. i is sent to the intersection determination means 39.

Similarly, when it is determined that the value is out of the range, control information indicating that the value is out of the range is sent to the object selecting means 42. At the same time, the information of the ray R, the selection information SEL and the direction DIR are sent to the ray information transfer means 44. Upon receiving this, the object selecting means 42 sends control information indicating the end to the intersection determining means 39.

Through the above processing, the object selecting means 42 selects the number i of all the objects i that may intersect the ray R among the objects i included in the area S in charge, and the intersection determining means. Can be sent to 39. Then, the intersection determination means 39 reads the information of the object i selected by the object selection means 42 from the object information storage means 35, and performs the intersection determination processing with the light ray R.

As a result of this intersection determination processing, when the ray R intersects the object, a new ray R ′ or ray R _L is generated from the ray R, and information on these rays R ′ and ray R _L is It is stored in the information storage means 34. However, when the number of times T as information of the ray R is 0, a new ray R'is not generated as described above. Such intersection determination processing is shown in the above-mentioned documents and FIG.

As described above, when the light ray R intersects the object in the area S in charge, it is not necessary to transfer the information of the light ray R to the adjacent brightness calculation unit 3. Therefore, the intersection determination means 39 sends control information indicating that the light ray R intersects the object to the light ray information transfer means 44. Upon receiving this control information, the light beam information transfer means
Reference numeral 44 erases the information of the ray R, the selection information SEL and the direction DIR already sent from the straight line generating means 43.

As a result of the intersection determination processing in the intersection determination means 39, the information of the light ray R that does not intersect with the object is the adjacent brightness calculation unit 3
Must be transferred to. Therefore, the intersection determination means 39
Sends to the ray information transfer means 44 control information indicating that the ray R does not intersect the object. Upon receiving this control information, the light ray information transfer means 44, based on the selection information SEL and the direction DIR already sent from the straight line generation means 43, also outputs the information of the light ray R already sent from the straight line generation means 43. Transfer processing. In order to perform this transfer processing, the light beam information transfer means
Reference numeral 44 indicates information on whether or not the brightness calculation unit 3 is connected in the direction indicated by the selection information SEL and the direction DIR,
It is read from the area information storage means 33.

If the brightness calculation unit 3 is connected in this direction, the information of the light ray R is transmitted to the brightness calculation unit 3 connected in the direction indicated by the selection information SEL and the direction DIR via the mutual communication means 31. To transfer.

For example, when the selection information SEL output from the straight line generating means 43 is 0 and the direction DIR is 1, the information of the light ray R is transferred to the brightness calculation unit 3 connected in the x ₊ direction. Similarly, the selection information SEL output from the straight line generating / viewing means 43 is 0 and the direction DIR is −.
In the case of 1, the information of the ray R is transferred to the brightness calculation unit 3 connected in the x _- direction. The information of the light ray R thus transferred is read from the mutual communication means 31 in the adjacent brightness calculation section 33 and stored in the light ray information storage means 34.

If the brightness calculation unit 3 is not connected in the direction indicated by the selection information SEL and the direction DIR sent from the straight line generation means 43, the ray R will go out of the object definition space. Therefore, it can be seen that this ray R does not intersect the object in all object definition spaces.

Therefore, the light ray information transfer means 44 outputs this light ray R to the luminance determination means 37 as information. The brightness determining means 37 checks the type C of the light ray R as the information of the light ray R, and determines the light ray R
Is a light beam directed to the light source L, the light source information storage means
The information of the light source is read from 36, and the brightness I of the light ray R is determined. However, when there are a plurality of light sources L _i , the light source number i indicated by the number T of the light sources R is referred to, the information of the light source L _i of that number is read, and the brightness I is determined. This determination process is as shown in the above-mentioned documents and FIG. Then, the brightness I is added to the pixel p (i, j) of the image storage unit 4 indicated by the information of the light source R via the communication unit 32.

Also, if this ray is a ray going to the object,
Since the brightness I of the light ray R becomes 0, the information of the light ray R is erased without performing the addition processing of the brightness I.

By the intersection determination process described above, the synthesis of the image P is completed at the time 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.

(Effect of the Invention) In the object image synthesizing apparatus of the present invention, a three-dimensional digital straight line is used to select an object that may intersect with a light ray. Since this three-dimensional digital straight line can be generated at a very high speed, the object selection processing, which has conventionally required a large amount of processing, can be significantly speeded up.

At the same time, when the images are combined by the ray tracing method by the parallel processing for dividing the space, the intersection determination processing may be performed only for the objects included in the area in charge that may intersect the rays. Therefore, the effect of the intersection determination process can be sufficiently speeded up.

In addition, since it is possible to effectively select an object based on information having a small amount of data, that is, the existence range of the object, it is possible to significantly reduce the amount of data required as compared with the related art.

[Brief description of drawings]

FIG. 1 (a) is an overall block diagram showing the entire object image synthesizing apparatus, FIG. 1 (b) is a block diagram showing the detailed configuration of the brightness calculation unit, and FIG. , j) is an explanatory view showing a method of calculating the brightness I, FIG. 3 is an explanatory view showing information of the light ray R to be set when the light ray R is generated, and FIG. 4 is a unit cube through which the light ray R passes. Explanatory diagram showing the information set in the ray R in order to generate the columns of as a three-dimensional digital straight line,
FIG. 6 is an explanatory diagram for explaining the operation of the initial light ray generation unit I, FIG. 6 is an explanatory diagram showing the information of the object set in the object information setting unit 2, and FIG. 7 is a sphere of the object. FIG. 8 is an explanatory view showing a circumscribing area, FIG. 8 is an explanatory view showing information on a light source set in the object information setting unit 2, and FIG. 9 shows a method of combining a plurality of brightness calculation units 3 in a three-dimensional array. Explanatory drawing which shows, 10th
FIG. 11 is an explanatory diagram showing a method of dividing a space defining an object into areas S in charge assigned to each luminance calculation unit 3,
FIG. 12 and FIG. 12 are explanatory diagrams showing the content of the area information indicating the area S in charge of the brightness calculation section 3, and FIG. 13 is the transfer processing of the information of the light ray R from the initial light ray generation section 1 to the brightness calculation section 3. FIG. 14 is an explanatory diagram showing a 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. 15 (a) and 15 (b) show an area S in charge of the brightness calculation section 3,
Explanatory drawing showing a comparison process with the circumscribed area of the object information, 16th
FIG. 17 is an explanatory diagram showing a method of determining the existence range of an object in the existence range determination means 40 provided in the brightness calculation unit 3, and FIG. 17 is an explanatory view showing a method of processing information of the light ray R in the brightness calculation unit 3. 18 (a) and 18 (b) are explanatory views showing a straight line generating method in the straight line generating means 43. FIG. In the figure, 1 ... initial light ray generation section, 2 ... object information setting section, 3 ... brightness 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 ... Luminance determination means, 38 ... Initial information determination means,
39 …… Intersection judging means, 40 …… Existence range determining means, 41 ……
Existence range storage means, 42 ... Object selection means, 43 ... Straight line generation means, 44 ... Ray information transfer means.

Claims (1)

[Claims] 1. A ray tracing for tracing the path of a light ray from a light source to a viewpoint in the opposite direction to perform intersection determination processing between an object and a light ray, and calculating the brightness of each pixel constituting an image for displaying the object. In order to synthesize the image by the method, an initial light ray generation unit that generates information of a plurality of light rays that pass through the pixels from the viewpoint, an object information setting unit that sets information of the object, and an object information setting unit of the object. Of a ray passing through this area, which is in charge of one area of a plurality of areas generated by dividing the defined space, and an object included in the area in charge, which is one area of the plurality of areas. In an object image synthesizing device configured by a plurality of brightness calculation units that calculate the brightness of the pixel by performing intersection determination processing, and an image storage unit that stores the brightness calculated by the brightness calculation unit as the image, the above In the degree calculation unit, a row of unit cubes through which the ray passes among a plurality of unit cubes generated by dividing the object definition space by a plurality of planes that are perpendicular to the coordinate axes and are equally spaced are generated as a three-dimensional digital straight line. The straight line generating means and one of a plurality of regions generated by dividing the object definition space by some or all of the plurality of planes are assigned to the brightness calculation unit as a responsible region. Area information storage means for storing the range of the area, existence range determination means for determining the existence range that is a common part of the circumscribing area of the object and the area in charge, existence range storage means for storing the existence range, and There is a possibility that the light beams may intersect in the objects included in the area in charge by comparing the unit cube row generated by the straight line generation means with the existence range of the object stored in the existence range storage means. And object selection means for selecting an object, characterized in that is provided with a cross judging means for performing intersection determination processing and has been the object and the light beam selected by the object selection means, the object image synthesizer.