Method and apparatus for generating a texture mapped perspective view

• US 5,179,638 A
• Filed: 04/26/1990
• Issued: 01/12/1993
• Est. Priority Date: 04/26/1990
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Dawson, John F., Cousens, James A., Snodgrass, Thomas D.
• Primary Examiner(s): Harkcom, Gary V.
• Assistant Examiner(s): Zimmerman, Mark K.
• Application Number:
  US07/514,598
• Time in Patent Office: 992 Days
• Field of Search: 395/125, 395/126, 395/127, 395/130, 364/443, 364/723, 340/729
• US Class Current: 345/582
• CPC Class Codes: G06T 15/04 Texture mapping

Abstract

A method and apparatus for providing a texture mapped perspective view for digital map systems. The system includes apparatus for storing elevation data, apparatus for storing texture data, apparatus for scanning a projected view volume from the elevation data storing apparatus, apparatus for processing, apparatus for generating a plurality of planar polygons and apparatus for rendering images. The processing apparatus further includes apparatus for receiving the scanned projected view volume from the scanning apparatus, transforming the scanned projected view volume from object space to screen space, and computing surface normals at each vertex of each polygon so as to modulate texture space pixel intensity. The generating apparatus generates the plurality of planar polygons from the transformed vertices and supplies them to the rendering apparatus which then shades each of the planar polygons. In one alternate embodiment of the invention, the polygons are shaded by apparatus of the rendering apparatus assigning one color across the surface of each polygon. In yet another alternate embodiment of the invention, the rendering apparatus interpolates the intensities between the vertices of each polygon in a linear fashion as in Gouraud shading.

Claims

1. A system for providing a texture mapped perspective view for a digital map system wherein objects are transformed from texture space having U, V coordinates to screen space having X, Y coordinates comprising:

(a) a cache memory means for storing terrain data including elevation posts, wherein the cache memory means includes an output and an address bus;

(b) a shape address generator means for scanning cache memory having an ADDRESS SIGNAL coupled to the cache memory means address bus wherein the shape address generator means scans the elevation posts out of the cache memory means;

(c) a geometry engine coupled to the cache memory means output to receive the elevation posts scanned from the cache memory by the shape address generator means, the geometry engine including means for

i. transformation of the scanned elevation posts from object space to screen space so as to generate transformed vertices in screen coordinates for each elevation post, and

ii. generating three dimensional coordinates;

(d) a tilling engine coupled to the geometry engine for generating planar polygons from the generated three dimensional coordinates;

(e) a symbol generator to the geometry engine for transmitting a vertex list to the geometry engine wherein the geometry engine operates on the vertex list to transform the vertex list into screen space X, Y coordinates and passes the screen space X, Y coordinates to the tilling engine for generating planar polygons which form icons for display and processing information from the tilling engine into symbols,

(f) a texture engine means coupled to receive the ADDRESS SIGNAL from the shape address generator means including a texture memory and including a means for generating a texture vertex address to texture space correlated to an elevation post address and further including a means for generating a texture memory address for scanning the texture memory wherein the texture memory provides texture data on a texture memory data bus in response to being scanned by the texture memory address;

(g) a rendering engine having an input coupled to the tilling engine and the texture memory data bus for generating image data from the planar polygons; and

(h) a display memory for receiving image data from the rendering engine output wherein the display memory includes at least four first-in, first-out memory buffers.

2. The apparatus of claim 1 wherein each polygon has a surface and the rendering means assigns one color across the surface of each polygon.

3. The apparatus of claim 1 wherein the vertices of each polygon have an intensity and the rendering means interpolates the intensities between the vertices of each polygon in a linear fashion.

4. The apparatus of claim 1 wherein the rendering means further includes means for generating transparent polygons and passing the transparent polygon to the display memory.

5. A method for providing a texture mapped perspective view for a digital map system having a cache memory, a geometry engine coupled to the cache memory, a shape address generator coupled to the cache memory, a tiling engine coupled to the geometry engine, a symbol generator coupled to the geometry engine and the tiling engine, a texture engine coupled to the cache memory, a rendering engine coupled to the tiling engine and the texture engine, and a display memory coupled to the rendering engine, wherein objects are transformed from texture space having U, V coordinates to screen space having X, Y coordinates, the method comprising the steps of:

(a) storing terrain data, including elevation posts, in the cache memory;

(b) scanning the cache memory to retrieve the elevation posts;

(c) transforming the terrain data from elevation posts in object space to transformed vertices in screen space, and

(d) generating planar polygons from the generated three dimensional coordinates;

(e) transmitting a vertex list to the geometry engine, operating the geometry engine to transform the vertex list into screen space X, Y coordinates and passing the screen space X, Y coordinates to the tiling engine for generating planar polygons which form icons for display;

(f) tagging elevation posts with corresponding addresses in texture space;

(g) generating image data in the rendering engine from the planar polygons and the tagged elevation posts; and

(h) storing the generated image data in the display memory wherein the display memory comprises at least four first-in, first-out memory buffers and the step of storing the generated images includes storing the generated image data in the at least four First-in, First-out memory buffers.

6. The method of claim 5 wherein each polygon has a surface and wherein the step of generating image data further includes the steps of assigning one color across the surface of each polygon.

7. The method of claim 5 wherein the vertices of each polygon have an intensity and the step of generating image data further includes the step of interpolating the intensities between the vertices of each polygon in a linear fashion.

8. The method of claim 5 wherein the step of generating image data further includes the step of generating transparent polygons and passing the transparent polygons to the display memory.