Method and apparatus for mapping texture on an object displayed at a varying view angle from an observer

• US 5,786,822 A
• Filed: 06/13/1997
• Issued: 07/28/1998
• Est. Priority Date: 01/26/1994
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sakaibara, Toru, Kuwana, Toshiyuki, Kawasaki, Toshiharu
• Primary Examiner(s): Feild, Joseph H.
• Assistant Examiner(s): BUCHEL JR, RUDOLPH JOHN
• Application Number:
  US08/874,954
• Time in Patent Office: 410 Days
• Field of Search: 345/426, 345/427, 345/428, 345/429, 345/430, 345/418, 434/38, 434/63, 463/30-34
• US Class Current: 345/582
• CPC Class Codes: G06T 15/04 Texture mapping

Abstract

A plurality of texture data of a surface of an object to be displayed as viewed from a plurality of assumed directions are stored in a texture memory. When a CPU sends to a graphic processor information specifying a shape of the surface, a direction to view the surface and a texture in the texture memory as a command, a geometric operation unit produces read information of the texture memory based on the input information. A triangle generator reads the texture data corresponding to the view direction of the surface of the object by the read information for texture mapping. An image of the texture mapped image of the surface of the object is stored in a frame memory and displayed on a monitor. When there is no texture data corresponding to the view direction, a plurality of texture data closest thereto are read from the texture memory and interpolated to produce an appropriate texture data.

Claims

1. A texture mapping method for mapping texture data on each of a plurality of polygons constituting a displayed polyhedron on a display screen, after conducting coordinate transformation for a plurality of vertexes on each of the polygons based on modeling data for geometrically defining the polyhedron, texture data for expressing a surface detail of each said polygon, and parameters including a view position and a view direction given by a virtual camera, comprising the steps of:

predetermining a plurality of view directions from said virtual camera for each said polygon;

presetting texture data for each said polygon for said plurality of predetermined view directions;

selecting the preset texture data for one of the predetermined view directions corresponding to an actual view direction for each said polygon being actually displayed; and

mapping the preset texture data on each said polygon being actually displayed.

2. The texture mapping method according to claim 1, further comprising the steps of:

selecting the preset texture data for predetermined view directions closer to the actual view direction of each said polygon being actually displayed where there is no preset texture data corresponding to said actual view direction;

interpolating the selected preset texture data in accordance with an error between said actual view direction and the predetermined view directions closer to said actual view direction to obtain texture data of each said polygon being actually displayed; and

mapping the texture data thus obtained on each said polygon being actually displayed.

3. A texture mapping apparatus for mapping texture data on each of a plurality of polygons constituting a displayed polyhedron on a display screen, after conducting coordinate transformation on a plurality of vertexes for each said polygon based on modeling data for geometrically defining said polyhedron, texture data for expressing a surface detail of each said polygon, and parameters including a view position and a view direction given by a virtual camera, comprising:

a memory for storing, for each said polygon, texture data for each of a plurality of predetermined view directions from said virtual camera;

a selection unit for selecting the stored texture data for one of the predetermined view directions corresponding to an actual view direction of each said polygon being actually displayed; and

graphic image generation means for generating an image of said polyhedron by mapping said preset texture data on each said polygon being actually displayed.

4. The texture mapping apparatus according to claim 3, further comprising:

an interpolator for selecting the preset texture data for predetermined view directions closer to the actual view direction of each said polygon being actually displayed where there is no preset texture data corresponding to said actual view direction, the interpolator interpolating the selected preset texture data in accordance with an error between said actual view direction and the predetermined view directions closer to said actual view direction to obtain interpolated texture data for each said polygon being actually displayed;

wherein said graphic image generation means generates an image of said polyhedron by mapping the interpolated texture data thus obtained for each said polygon being actually displayed.

5. A texture mapping apparatus for mapping texture data on each of a plurality of polygons constituting a displayed polyhedron on a display screen, after conducting coordinate transformation on a plurality of vertexes of each said polygon based on modeling data for geometrically defining said polyhedron, texture data for expressing a surface detail of each said polygon, and parameters including a view position and a view direction given by a virtual camera, comprising:

a first memory for storing texture data for each of a plurality of predetermined view directions from said virtual camera for each said polygon;

a second memory for storing plural sets of mapping data, each set of mapping data including the texture data stored in the first memory, for the predetermined view directions, and an interpolation coefficient therebetween; and

graphic image generating means for receiving a value corresponding to an actual view direction of each said polygon being actually displayed, the graphic image generating means reading a set of mapping data corresponding to said value from the second memory and conducting an interpolating process based on said set thus read to obtain interpolated texture data for each said polygon being actually displayed;

wherein said graphic image generation means generates an image of said polyhedron by mapping the interpolated texture data thus obtained on each said polygon being actually displayed.

6. A texture mapping method for mapping texture data on each of a plurality of polygons constituting a displayed polyhedron on a display screen, after conducting coordinate transformation on a plurality of vertexes of each said polygon based on modeling data for geometrically defining said polyhedron, texture data for expressing a surface detail of each said polygon, and parameters including a view position and a view direction given by a virtual camera, comprising the steps of:

predetermining a plurality of view directions from said virtual camera for each of the polygons;

pre-storing, in a texture memory, texture data for each of the polygons for said plurality of predetermined view directions;

determining, by a central processing unit (CPU), an actual view direction for each said polygon based on information inputted to said CPU, and sending a command indicating the actual view direction thus determined from said CPU to a graphic processor;

selecting, by said graphic processor, at least one pertinent texture data from the texture data pre-stored in said texture memory on a basis of the command received from said CPU; and

mapping the texture data thus selected on each said polygon being actually displayed.

7. The texture mapping method according to claim 6, wherein the graphic processor includes a texture data management table for storing relationships between each of a plurality of displacement values representing a view direction of said virtual camera and one texture data corresponding thereto, and the texture mapping step includes:

supplying, by the graphic processor, one of the displacement values to the texture data management table;

reading, by the graphic processor, one texture data from the texture memory by using an output of the texture data management table; and

mapping, by the graphic processor, the texture data thus read on each said polygon being actually displayed.

8. The texture mapping method according to claim 6, wherein the graphic processor includes a texture data management table for storing relationships between each of a plurality of displacement values representing a view direction of said virtual camera and a plurality of texture data corresponding thereto, and the texture mapping step includes:

supplying, by the graphic processor, one of the displacement values to the texture data management table;

reading, by the graphic processor, a plurality of texture data from the texture memory by using an output of the texture data management table;

interpolating, by the graphic processor, the plurality of texture data thus read to obtain new texture data; and

mapping, by the graphic processor, the new texture data thus obtained on each said polygon being actually displayed.

9. The texture mapping method according to claim 6, wherein a texture data management table stores a relationship between each of a plurality of displacement values representing a view direction of said virtual camera, a plurality of texture data corresponding thereto and an interpolation coefficient between texture data corresponding thereto, the texture data management table being included in the graphic processor, and the texture mapping step includes:

supplying, by the graphic processor, one of the displacement values to said texture data management table;

reading, by the graphic processor, a plurality of texture data and the corresponding interpolation coefficient from said texture memory by using an output of said texture data management table;

interpolating, by the graphic processor, said plurality of texture data thus read to obtain new texture data by using the interpolation coefficient thus read; and

mapping, by the graphic processor, the new texture data on each said polygon being actually displayed.

10. A texture mapping apparatus for mapping texture data on each of a plurality of polygons constituting a displayed polyhedron on a display screen, after conducting coordinate transformation on a plurality of vertexes of each of the polygons based on modeling data for geometrically defining said polyhedron, texture data for expressing a surface detail of each said polygon, and parameters including a view position and a view direction given by a virtual camera, comprising:

a texture memory for pre-storing texture data for each of a plurality of predetermined view directions from said virtual camera for each of the polygons;

a central processing unit (CPU) for determining a view direction of each polygon based on information inputted to said CPU, and sending a command indicating the view direction thus determined to a graphic processor; and

said graphic processor for selecting at least one pertinent texture data from the texture data stored in said texture memory based on the command received from said CPU, and mapping the texture data thus selected on each said polygon being actually displayed.

11. The texture mapping apparatus according to claim 10, wherein:

said graphic processor includes a texture data management table for storing a relationship between each of a plurality of displacement values representing a view direction of said virtual camera and one texture data corresponding thereto; and

said graphic processor supplies one of the displacement values to said texture data management table, reads one texture data from said texture memory by using an output of said texture data management table, and maps the texture data thus read on each said polygon being actually displayed.

12. The texture mapping apparatus according to claim 10, wherein:

said graphic processor includes a texture data management table for storing a relationship between each of a plurality of displacement values representing a view direction of said virtual camera and a plurality of texture data corresponding thereto; and

said graphic processor supplies one of the displacement values to said texture data management table, reads a plurality of texture data from said texture memory by using an output of said texture data management table, interpolates said plurality of texture data thus read to obtain new texture data, and maps the new texture data thus obtained for each polygon being actually displayed.

13. The texture mapping apparatus according to claim 10, wherein:

said texture data management table stores a relationship between each of a plurality of displacement values representing a view direction of said virtual camera, a plurality of texture data corresponding thereto, and an interpolation coefficient between texture data corresponding thereto; and

said graphic processor supplies a displacement value to said texture data management table, reads a plurality of texture data and a corresponding interpolation coefficient from said texture memory by using an output of said texture data management table, interpolates said plurality of texture data thus read to obtain new texture data by using the interpolation coefficient thus read, and maps the new texture data on each said polygon being actually displayed.

14. A driving simulator machine for displaying a simulated polyhedron constituted by a plurality of polygons, by mapping texture data on each of the polygons, after conducting coordinate transformation on vertexes of each said polygon based on modeling data for geometrically defining said polyhedron, texture data for expressing a surface detail of each of the polygons, and parameters including a view position and a view direction given by a virtual camera, comprising:

a display device having a display screen;

an input device for receiving input information representing at least steering wheel manipulation, brake manipulation and accelerator manipulation for simulation by an operator, and generating a signal representing said input information;

a central processing unit (CPU) responsive to said signals from said input device, for determining a view direction of each polygon based on information inputted to said CPU, and sending a command indicating the view direction thus determined;

a texture memory for pre-storing texture data for each of a plurality of predetermined view directions from said virtual camera for each said polygon; and

a graphic processor connected to said CPU and responsive to said command from said CPU, for selecting at least one pertinent texture data from the texture data stored in said texture memory based on said command, and mapping the texture data thus selected on each said polygon being actually displayed.