Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
1998-09-04
2001-02-20
Zimmerman, Mark (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
C345S426000
Reexamination Certificate
active
06191789
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ray casting method using hardware.
2. Description of the Prior Art
Ray casting is known as a method of rendering using CG. In this technique, an object formed by a voxel is first arranged in a virtual three-dimensional space defined in a memory space. Internal information of the object is given as a plurality of voxel values to each voxel. A plurality of unit rays are virtually radiated from a view point present at a predetermined position in the virtual three-dimensional space. Each pixel value on a display plane is calculated based on the voxel values of the voxels present on each unit ray.
According to such a ray casting method, various internal information of the object can freely be visualized to satisfy requirements. Therefore, attention has recently been paid to the ray casting method as a new visualization technique (volume visualization) for a three-dimensional object including an organism.
However, it is necessary to calculate a path for a ray radiated from a view point and voxels on the path in real time. This is difficult to realize using hardware. Conventionally, software has mainly been used for implementation, and a lot of processing time is required. In a case where the view point and the object are moved in the virtual three-dimensional space, it is difficult to generate images reflecting their movement in real time.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above-mentioned problems, and its object is to provide an image synthesizing apparatus and method capable of performing high speed image processing using hardware.
In order to solve the above-mentioned problems, a first aspect of the present invention is directed to an image processor which casts a number of unit rays onto a virtual three-dimensional object formed with a three-dimensional array of a voxels, generates visualization information for each ray path based on voxel information assigned to at least one voxel on the ray path, and generates an image related to the visualization object based on the visualization information, comprising storing means for previously storing pattern information representing a pattern of ray paths, and ray path determining means for determining the ray path for generating the visualization information based on the pattern information.
According to the first aspect of the present invention, the visualization object is formed with the three-dimensional array of voxels. The ray casting is performed and the visualization information is generated for each unit ray path based on the voxel information given to the at least one voxel on the ray path. The image related to the visualization object is generated based on the visualization information.
In the present invention, particularly, the pattern information representing the pattern of the ray paths is previously stored in the storing means. When the visualization information is to be generated for each unit ray path, the ray path for the ray casting is determined based on the pattern information stored in the storing means. Thus, hardware can be used more easily than in the prior art in which each ray path is generated based on a numeric operation. As a result, it is possible to generate the image related to the visualization object at a high speed.
A second aspect of the present invention is directed to an image processor wherein the pattern information specifies the voxels on each ray path.
According to the second aspect of the present invention, at least one voxel on each ray path is specified by the pattern information. The visualization object according to the present invention is formed with the three-dimensional array of voxels. Therefore, information specifying the voxel on each ray path, for example, discrete numeric information, is set as the pattern information so that the pattern of the ray paths can be recorded in the storing means with sufficient required information.
A third aspect of the present invention is directed to the image processor wherein the pattern information represents a pattern of ray paths passing through a two-dimensional array of the voxels.
According to the third aspect of the present invention, the ray path determining means can determine a necessary ray path for casting onto the three-dimensional array of the voxels by placing the pattern information in the voxel space vertically and horizontally or inverting the same. When the pattern information is to be stored in the storing means, memory capacity can be reduced.
A fourth aspect of the present invention is directed to an image synthesizing apparatus wherein the pattern information includes information specifying a voxel position where the plurality of ray paths branch away from each other.
According to the fourth aspect of the present invention, the visualization object is formed with the three-dimensional array of the voxels. Therefore, if a large number of rays are to be considered in image processing, each ray which penetrates the visualization object shares some voxels to be penetrated with some other rays, and branches from any of the voxels. According to this aspect of the present invention, information specifying a branch position is stored as the pattern information in the storing means so that the pattern of the ray path can preferably be stored.
A fifth aspect of the present invention is directed to an image synthesizing apparatus comprising voxel information storing means for storing voxel information given to voxels forming a visualization object, pattern information storing means for storing pattern information representing a pattern of voxel trace paths which is used for reading the voxel information from the voxel information storing means, voxel information reading means for reading the voxel information from the voxel information storing means based on the pattern information stored in the pattern information storing means, and image generating means for generating an image related to the visualization object based on the voxel information read by the voxel information reading means.
According to the fifth aspect of the present invention, the voxel information given to the voxels forming the visualization object is stored in the voxel information storing means. The pattern information representing the pattern of the voxel trace paths which is used for reading the voxel information from the voxel information storing means is stored in the pattern information storing means. The voxel information reading means reads the pattern information from the pattern information storing means, and reads the voxel information from the voxel information storing means based on the pattern information. An image related to the visualization object is generated based on the voxel information read by the voxel information reading means. Thus, image generation can be performed more quickly than in a conventional technique in which a reading path is generated by numerical operation in real time.
A sixth aspect of the present invention is directed to an image synthesizing apparatus wherein the pattern information specifies the voxels on each voxel trace path.
According to the sixth aspect of the present invention, the voxels on the path are specified by the pattern information. The visualization object according to the present invention is formed by the voxel. Therefore, the information specifying the voxels on the path from which the voxel information is read is set as the pattern information so that the pattern of the reading can be recorded in the storing means with required sufficient information.
A seventh aspect of the present invention is directed to the image synthesizing apparatus wherein the pattern information represents a pattern of reading paths for a two-dimensional array of voxels.
According to the seventh aspect of the present invention, the voxel information reading means can acquire a necessary path by placing the pattern represented by the pattern information in the voxel space vertically and ho
Ishikawa Masashi
Sutou Yuki
Toeda Kengo
Tomita Masaharu
Yamane Daisaku
Japan Radio Co. Ltd.
Nguyen Kimbinh T.
Oliff & Berridg,e PLC
Zimmerman Mark
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