JPH07146953A - Image generating method by intersection tracking method - Google Patents

Abstract

PURPOSE:To provide the method which can increase the quality of a display image. CONSTITUTION:All bodies shown with read image information are classified into rigid bodies having distinctive external shapes and nonrigid bodies having indistinctive external shapes and the respective nonrigid bodies are represented in simple shapes of minimum size including the bodies (step 100); and light beam vectors are set, pixel by pixel, and bodies that the respective light beam vectors cross are retrieved (step 102). Then the bodies retrieved as to the same light beam vector are arrayed in the direction of the vector progress (step 104). Sections partitioned with the intersections of the arrayed bodies and light beams are determined by the light beam vectors and the representation formats of the bodies present in the sections are registered in the array order of the bodies as to the respective sections (step 106); while an object section is changed in the direction of the vector progress by the light beam vectors, color values corresponding to the representation formats of the bodies are integrated in the registration order of the representation formats to find color values of respective pixels (step 108).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating an image by an intersection tracing method (ray tracing method).

In the field of computer graphics such as CAD, a display image is generated by using a ray tracing method, a Z buffer method, a scan line method, etc. Particularly, according to the ray tracing method, a shadow portion or a light reflection portion of an object is generated. Can be expressed more realistically.

[0003]

2. Description of the Related Art In the ray tracing method, in addition to an object expressed using a plane or a quadric surface (for example, a sphere or an ellipsoid), voxels (a group of minute objects such as fog), metaballs (density) The object that is expressed by using (for example, that gradually changes) is also the target of processing.

However, since the method of calculating the intersection point with the normal line or the ray vector differs depending on the representation form of the object, in the case of an image in which objects of different representation forms coexist on the same ray vector, those calculations are unified. Difficult to handle.

For example, in the case of an image in which a part of a spherical object (represented by a quadric surface) is covered with a fog-like object (voxel expression), ray vectors intersect at the pixel portion where the spherical object is exposed from the fog-like object. The point is calculated, the closest one from the viewpoint is selected from the calculated intersections, and the processing of the content that sets the color of each pixel as the object color at the selected intersection is performed.

In the pixel portion where the spherical object is hidden by the mist-like object, the colors of the respective minute objects forming the mist-like object are sequentially added from the viewpoint side, and the addition result is added to that of the spherical object to obtain the pixel. Color is required.

Therefore, conventionally, the color of each pixel is calculated after the expression form of all objects is approximated to a set of triangles and unified.

[0008]

However, in the prior art, since the representation form of the object is approximately converted into a set of triangles when the pixel colors are integrated, a conversion error occurs at that time,
Therefore, the quality of the generated display image is deteriorated.

The present invention has been made in view of the above conventional circumstances, and an object thereof is to provide a method capable of generating a higher quality display image by a ray tracing method.

[0010]

FIG. 1 shows a first invention and a second invention.
The method of the invention is described. In the figure, the first invention classifies all the objects indicated by the read information into rigid objects whose contours are clear and non-rigid objects whose contours are unclear. An object is represented by a minimum simple shape including the object (step 100), a ray vector is set for each pixel, and an object where the ray vectors intersect is searched (step 10).
2) Arrange the objects searched for the same ray vector along the direction of vector progression (step 104),
For each ray vector, a section partitioned by the intersection of the arranged object and the light ray is defined, and the expression form of the objects existing in the section is registered for each section in the object arrangement order (step 1
06), while changing the target section in the vector progression direction for each ray vector, the color values corresponding to the expression format of the object are integrated in the registration order of the expression format to obtain the color value of each pixel (step 108). Is characterized by.

The second invention reads object information, classifies all the objects indicated by the information into a rigid object having a clear outer shape and an indistinct non-rigid object, and each non-rigid object is included in the object. All rigid objects and non-rigid objects are stored in the memory after being represented by the minimum simple shape as shown in step 10
0), a ray vector is set for each pixel, and an object where the ray vectors intersect is searched in the memory (step 10).
2) The objects searched for the same ray vector are arranged along the direction of vector progression and stored in a buffer provided for each ray vector, and when a rigid object and a non-rigid object compete with each other, a rigid object Is prioritized for the non-rigid object in the order of arrangement (step 104), the sections partitioned by the points where the arranged objects and the rays intersect are defined for each ray vector, and the objects within the sections are arranged in the order of arrangement for each section. (Step 106), the other buffers are accessed for each light ray vector in the array order of the object, and the registered contents including the expression format and the color value of the object are read out in order and indicated by the read information. The color values are integrated according to the representation format of the object, and the final integration result obtained for each ray vector is output as color information regarding the corresponding pixel (step 10). ), It is characterized in that.

[0012]

[Function] An object represented by a plane or a quadric surface and an object represented by voxels or metaballs are classified into a rigid object with a clear outer shape and an unclear non-rigid object, and a non-rigid object Is represented by a simple shape with the smallest dimension that includes this (for this, a plane or a quadric surface model is used).

Then, for each pixel, an object in which the ray vector intersects is searched and arranged in the direction of vector progression, and a section through which the ray vector penetrates each object is set to correspond to the representation form of the object existing in the section. The obtained color values are sequentially integrated from the vector base point side to obtain the pixel color value.

As described above, an object (non-rigid object) represented by voxels or metaballs is regarded as an object having a simple shape, and is treated in the same manner as an ordinary object (rigid object) having a clear outer shape. Need not be converted, and therefore the deterioration of the quality of the displayed image can be avoided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 2, an object information input process is described with reference to a flow chart. First, the object information is sequentially read (step 200).

Then, every time the object information is read, a process is performed to judge whether the object indicated by this information is a rigid object with a clear outline or a non-rigid object with an unclear outline (step 20).
2) In the case of a rigid object (for example, a sphere or an ellipsoid), its information is immediately stored in the memory (step 204).

When the object indicated by the read information is a non-rigid object with an unclear outline (for example, voxels or metaballs), the non-rigid object is the smallest simple shape in which the object is included ( For example, after being represented by a sphere or a box (step 206), the information of this non-rigid object is stored in the memory (step 204).

In FIG. 3, the pixel color output process is described with reference to a flow chart, in which the ray vector (the ray passes through the pixel from the viewpoint) is sequentially set for all pixels (step 302), and the ray vector is set. Each time a beam is traced, a ray tracing process (step 302) is performed.

In this ray tracing process (step 302), a value indicating the color of the pixel is obtained, and when the ray tracing process is performed, the pixel color value obtained in the same process is output ( Step 304).

In FIG. 4, the ray tracing process is described with reference to a flowchart. In this process, the process of detecting all objects intersecting the ray vector (step 400) is first performed.

In FIG. 5, the process of detecting all objects intersecting the ray vector (step 400) is described by using a flowchart, and all the processes of determining whether the object is a rigid object or a non-rigid object (step 500). Is repeated for the object.

Then, each time the object is confirmed to be a rigid object, its type is determined (step 502), and it is determined whether or not the ray vector intersects the same object (step 504).

Also, when it is confirmed that the object is a non-rigid object (boundary object), the type of the object is discriminated each time (step 506) and whether or not the ray vector intersects the same object. It is determined (step 508).

Furthermore, in the case of an object whose ray vectors intersect, the same object is registered in the ray buffer (step 51).
0), and finally, the type of the same object is additionally registered (step 512).

In FIG. 4, when the process of detecting an object intersecting the ray vector (step 400) is performed, the number of the object is checked (step 402), and if it is not 0, the process of rearranging the objects is started (step 400). Step 40
4).

In FIG. 6, this rearrangement process is described using a flowchart, and the process of retrieving the object closest to the viewpoint position from the objects registered in the ray buffer and moving it to the front side of the ray buffer is repeated. (Step 6
00, 602, 604, 606, 608).

As a result, the objects registered in the ray buffer are arranged in the order closest to the position of the viewpoint from the buffer head side (objects moved to the ray buffer head side are excluded from the search target).

However, when the rigid object and the non-rigid object have the same distance, the arrangement order of the rigid objects is given priority over the non-rigid object, and the simple shape is used for the distance calculation of the non-rigid object. .

When the respective objects are rearranged in this way, the process of storing the sections partitioned by the points where the ray vectors intersect these objects in the section buffer from the point closer to the viewpoint in FIG. 4 (step 406). ) Is performed.

Further, the object is registered in the secondary buffer of the section light source (step 408) and the color is determined (step 410).
The process is repeated for all the sections (step 412).

The section light source secondary buffer is described in FIG. 7, and in FIG. 7A, three objects 70 are arranged on the ray vector 701 extracted from the viewpoint 700 side.
2B, 702A, and 702C are arranged in order,
In the sections t0 and t1, the objects 702A, 702B, 7
02C overlaps.

In this case, as shown in FIG.
The objects 702B, 702 to the section light source secondary buffer at t1
Information of A and 702C (pointer indicating the substance) is stored in the order of arrangement of the objects 702B, 702A, and 702C.

In FIG. 8, the color determination processing is described using a flowchart, and this processing proceeds from the head section closest to the viewpoint to the tail section while changing the target section light source secondary buffer.

Then, the objects (information of the objects) are sequentially extracted from the head of the secondary light source for the section light source to be processed (steps 800, 802, 814) and it is determined whether the extracted objects are rigid objects or non-rigid objects. (Step 804,
806), color value integration processing (steps 808, 810, 812) is performed according to the determination result (the finally obtained integration value is output as a value indicating the color of the pixel.
.., FIG. 3_step 304).

FIG. 9 shows a structure used in this embodiment for storing object information. The object type (expression form) and its structure are shown in the first structure member and the next structure member. The color (the value of the color) is stored as information common to each object.

That is, the information common to each object is stored in the member portion offset from the head address of the structure by a certain amount, and therefore, other object information (coordinates of vertices, radius, etc.) is stored in the following members. Even if the size of the structure is different for each object, the processing for determining the type of the object expression format (FIG. 6_step 604, FIG. 8_step 804, 806) is simplified to further speed up the processing. Is possible.

As the variable for storing the expression form of the object, the 4-byte length shown in FIG. 10A is used. As shown in FIG. 10B, the expression form of the object is By setting the bit corresponding to, it is possible to handle 32 types of objects collectively with a 4-byte variable.

As described above, in this embodiment, a non-rigid object represented by voxels or metaballs is regarded as an object having a simple shape, and is treated in the same manner as an ordinary rigid object having a clear outer shape. Therefore, even if these objects with different representations are on the same ray vector,
There is no need to convert and unify the expression form of the object,
Therefore, the quality of the image can be improved.

Further, since the object information common to all objects is collected at the head side of the structure storing the information of each object (see FIG. 9), the expression format of each object is efficiently determined and its processing speed is increased. It becomes possible to raise.

Further, since it is possible to handle 32 kinds of objects simultaneously with the 4-byte variable (see FIG. 10), it is possible to efficiently use the memory resource.

[0041]

As described above, according to the present invention, an object having a voxel expression or a metaball expression has a simple shape and is regarded as another normal object. Even if there is, it is possible to omit the process of converting and unifying the expression form of the object, and thus it is possible to improve the quality of the display image.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the invention.

FIG. 2 is a flowchart illustrating an input process of object information.

FIG. 3 is a flowchart illustrating a pixel color output process.

FIG. 4 is a flowchart illustrating a light source tracking process.

FIG. 5 is a flowchart illustrating a process of detecting an intersecting object.

FIG. 6 is a flowchart illustrating an object rearrangement process.

FIG. 7 is an explanatory diagram of a secondary buffer.

FIG. 8 is a flowchart illustrating a color determination process.

FIG. 9 is a diagram illustrating the structure of object information.

FIG. 10 is an explanatory diagram of a data structure in an object expression format.

[Explanation of symbols]

 700 viewpoint 701 ray vector 702A, 702B, 702C object

Claims (2)

[Claims] 1. A simple shape of a minimum size in which all the objects indicated by the read information are classified into a rigid object having a clear outer shape and a non-rigid object having an unclear outer shape, and each non-rigid object is included in the object. Is represented by (step 100), a ray vector is set for each pixel, and an object where each ray vector intersects is searched (step 102). Objects searched for the same ray vector are arranged along the direction of vector progression. Then, the section partitioned by the point where the arranged object and the ray intersect is defined for each ray vector, and the expression form of the object existing in the section is registered for each section in the object arrangement order (step 104). 1
06), while changing the target section in the vector progression direction for each ray vector, the color values corresponding to the object representation format are integrated in the registration order of the representation format to obtain the color value of each pixel (step 1
08), An image generation method by an intersection tracking method characterized by the following. 2. Object information is read, all the objects indicated by the information are classified into a rigid object having a clear outer shape and a non-rigid object having an unclear outer shape, and each non-rigid object is included in the minimum dimension. Then, all objects are stored in the memory (step 100), a ray vector is set for each pixel, and an object intersecting each ray vector is searched in the memory (step 102). The objects searched for the ray vector are stored in the buffer provided for each ray vector by arranging them along the direction of vector progression, and when the rigid object and the non-rigid object compete, the rigid object is converted to the non-rigid object. The order of arrangement is prioritized (step 104), the sections partitioned by the points where the arranged objects and the rays intersect are defined for each ray vector, and the objects in the sections for each section are arranged in the other order in the arrangement order. Register to the buffer (step 106), access other buffers for each ray vector in the array order of the object, read the registered contents including the expression format and color value of the object in order, and display the object indicated by the read information. According to the intersection point tracing method, the color value is integrated according to the expression format of, and the final integrated result obtained for each ray vector is output as color information about the corresponding pixel (step 108). Image generation method.