Apparatus and method for generating an image for 3-dimensional computer graphics

• US 5,903,273 A
• Filed: 08/26/1997
• Issued: 05/11/1999
• Est. Priority Date: 12/28/1993
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Mochizuki, Yoshiyuki, Hirai, Makoto
• Primary Examiner(s): FETTING, ANTON W
• Application Number:
  US08/918,380
• Time in Patent Office: 623 Days
• Field of Search: 345/418-423, 345/425-427, 345/430, 345/424
• US Class Current: 345/423
• CPC Class Codes: G06T 15/04 Texture mapping

Abstract

An apparatus of the invention generates an image including a plurality of pixels by mapping a plurality of texture data onto a surface of an object. The apparatus includes: a geometrical transformation section for geometrically transforming a curved surface defined in a 3-dimensional space into a curved surface in a 2-dimensional screen space; a micro-polygon generating section for dividing the curved surface in the 2-dimensional screen space into a plurality of partial curved surfaces in accordance with the number of the plurality of texture data, and for generating a micro-polygon in accordance with each of the plurality of partial curved surfaces; an area contribution determining section for determining an area contribution of the micro-polygon to a pixel included in the image, based on a relative positional relationship between the micro-polygon and the pixel; a texture data acquiring section for acquiring texture data in accordance with the micro-polygon; and an intensity-value determining section for determining an intensity value of the pixel, based on the area contribution determined by the area contribution determining section and the texture data acquired by the texture data acquiring section.

Claims

1. An apparatus for generating an image by mapping texture data onto a surface of an object, and the apparatus comprising:

geometrical transformation means for calculating sample points on a curved surface defined in a 3-dimensional space and for geometrically transforming only said sample points to points in a 2-dimensional screen space;

micro-polygon generating means for calculating control parameters from said points in said 2-dimensional screen space and for generating micro-polygons by the calculation and using said control parameters and the size of texture data for mapping;

area contribution determining means for calculating an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

texture data acquiring means for acquiring said texture data corresponding to said each micro-polygon;

intensity-value determining means for calculating an intensity value at said each pixel from said area contribution and said texture data; and

back-face culling means for determining whether said micro-polygon is rendered or not by the direction of the normal vector of said micro-polygon and the information for the direction of the front face of the original curved surface generating said micro-polygon.

2. An apparatus for generating an image by mapping texture data onto a surface of an object, and the apparatus comprising:

geometrical transformation means for calculating sample points on a curved surface defined in a 3-dimensional space and for geometrically transforming only said sample points to points in a 2-dimensional screen space;

micro-polygon generating means for calculating control parameters from said points in said 2-dimensional screen space and for generating micro-polygons by the calculation and using said control parameters and the size of texture data for mapping;

area contribution determining means for calculating an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

texture data acquiring means for acquiring said texture data corresponding to said each micro-polygon;

intensity-value determining means for calculating an intensity value at said each pixel from said area contribution and said texture data;

means for changing the order of generating micro-polygons from a curved surface in accordance with each depth position of said micro-polygons; and

means for changing the order of access to texture data to correspond to the changed order of generating said micro-polygons.

3. An apparatus for generating an image by mapping texture data onto a surface of an object, and the apparatus comprising:

geometrical transformation means for calculating sample points on a curved surface defined in a 3-dimensional space and for geometrically transforming only said sample points to points in a 2-dimensional screen space;

micro-polygon generating means for calculating control parameters from said points in said 2-dimensional screen space and for generating micro-polygons by the calculation and using said control parameters and the size of texture data for mapping;

area contribution determining means for calculating an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

texture data acquiring means for acquiring said texture data corresponding to said each micro-polygon; and

intensity-value determining means for calculating an intensity value at said each pixel from said area contribution and said texture data;

wherein said area contribution determining means includes;

inside/outside determining means for determining whether the representative point of a sub-pixel generated by dividing a pixel in accordance with the accuracy of the calculation is positioned within a region defined by the micro-polygon or not;

counting means for counting the number of sub-pixels whose representative points are included within said region of the micro-polygon from the consequence of said inside/outside determining means; and

area contribution calculating means for calculating the area contribution of said micro-polygon for each pixel by multiplying the number counted by said counting means into the area of said sub-pixel.

4. A method for generating an image by mapping texture data onto a surface of an object, the method comprising the steps of:

(a) geometrically transforming sample points calculated on a curved surface defined in a 3-dimensional space to points in a 2-dimensional screen space;

(b) generating a micro-polygon by the calculation and using control parameters calculated from said points in said 2-dimensional screen space, and the size of texture data for mapping;

(c) determining an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

(d) acquiring said texture data corresponding to said each micro-polygon;

(e) determining an intensity value at said each pixel from said area contribution determined in said step (c) and said texture data acquired in said step (d); and

further comprising the step of determining whether said micro-polygon is rendered or not by the direction of the normal vector of said micro-polygon and the information for the direction of the front face of the original curved surface generating said micro-polygon.

5. A method for generating an image by mapping texture data onto a surface of an object, the method comprising the steps of:

(a) geometrically transforming sample points calculated on a curved surface defined in a 3-dimensional space to points in a 2-dimensional screen space;

(b) generating a micro-polygon by the calculation and using control parameters calculated from said points in said 2-dimensional screen space, and the size of texture data for mapping;

(c) determining an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

(d) acquiring said texture data corresponding to said each micro-polygon;

(e) determining an intensity value at said each pixel from said area contribution determined in said step (c) and said texture data acquired in said step (d); and

further comprising the steps of;

changing the order of generating micro-polygons from a curved surface in accordance with each depth position of said micro-polygons; and

changing the order of access to texture data to correspond to said changed order of generating said micro-polygons.

6. A method for generating an image by mapping texture data onto a surface of an object, the method comprising the steps of:

(a) geometrically transforming sample points calculated on a curved surface defined in a 3-dimensional space to points in a 2-dimensional screen space;

(b) generating a micro-polygon by the calculation and using control parameters calculated from said points in said 2-dimensional screen space, and the size of texture data for mapping;

(c) determining an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

(d) acquiring said texture data corresponding to said each micro-polygon; and

(e) determining an intensity value at said each pixel from said area contribution determined in said step (c) and said texture data acquired in said step (d);

wherein said step (c) includes the steps of;

(f) determining whether the representative point of a sub-pixel generated by dividing a pixel in accordance with the accuracy of the calculation is positioned within a region defined by the micro-polygon or not; and

(g) counting the number of sub-pixels whose representative points are included within said region of the micro-polygon from the consequence of said step (f).

7. A method for generating an image by mapping texture data onto a surface of an object, the method comprising the steps of:

(a) geometrically transforming sample points calculated on a curved surface defined in a 3-dimensional space to points in a 2-dimensional screen space;

(b) generating a micro-polygon by the calculation and using control parameters calculated from said points in said 2-dimensional screen space, and the size of texture data for mapping;

(c) determining an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

(d) acquiring said texture data corresponding to said each micro-polygon; and

(e) determining an intensity value at said each pixel from said area contribution determined in said step (c) and said texture data acquired in said step (d);

wherein said step (e) includes the step of;

calculating an intensity value at each pixel by multiplying the intensity value of texture data by the area contribution, only when a sum of said area contribution is smaller than 1.

8. A method for generating an image by mapping texture data onto a surface of an object, the method comprising the steps of:

(a) geometrically transforming sample points calculated on a curved surface defined in a 3-dimensional space to points in a 2-dimensional screen space;

(b) generating a micro-polygon by the calculation and using control parameters calculated from said points in said 2-dimensional screen space, and the size of texture data for mapping;

(c) determining an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

(d) acquiring said texture data corresponding to said each micro-polygon; and

(e) determining an intensity value at said each pixel from said area contribution determined in said step (c) and said texture data acquired in said step (d);

wherein the texture data contains an intensity value and an opacity, and said step (e) includes the step of;

calculating an intensity value at each pixel with a product of the intensity value of texture data, the opacity, and the area contribution, only when a sum of said area contribution is smaller than 1.

9. A method for generating an image by mapping texture data onto a surface of an object, the method comprising the steps of:

(a) geometrically transforming sample points calculated on a curved surface defined in a 3-dimensional space to points in a 2-dimensional screen space;

(b) generating a micro-polygon by the calculation and using control parameters calculated from said points in said 2-dimensional screen space, and the size of texture data for mapping;

(c) determining an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

(d) acquiring said texture data corresponding to said each micro-polygon; and

(e) determining an intensity value at said each pixel from said area contribution determined in said step (c) and said texture data acquired in said step (d);

wherein the texture data contains an intensity value and an opacity, and a pixel contribution is defined as a product of the area contribution and said opacity of said texture data, said step (e) including the step of;

calculating an intensity value at each pixel, with a product of the intensity value of texture data, the opacity, and the area contribution, only when a sum of said pixel contribution is smaller than 1.

10. A method for generating an image by mapping texture data onto a surface of an object, the method comprising the steps of:

(a) geometrically transforming sample points calculated on a curved surface defined in a 3-dimensional space to points in a 2-dimensional screen space;

(b) generating a micro-polygon by the calculation and using control parameters calculated from said points in said 2-dimensional screen space, and the size of texture data for mapping;

(c) determining an area contribution of said micro-polygon for each pixel defined on said 2-dimensional screen space;

(d) acquiring said texture data corresponding to said each micro-polygon; and

(e) determining an intensity value at said each pixel from said area contribution determined in said step (c) and said texture data acquired in said step (d);

wherein the texture data contains an intensity value and an opacity, and a pixel contribution is defined as a product of the area contribution and said opacity of said texture data, said step (e) including the step of;

calculating an intensity value at each pixel with a product of the intensity value of texture data, the opacity, and the area contribution, only when a sum of said area contribution is smaller than 1 and a sum of said pixel contribution is smaller than 1.