Reprojecting map images using graphical techniques

1. A computer readable medium encoded with a computer program product for enabling a computer to re-project digital map images comprising:

software instructions for enabling the computer to perform predetermined operations; and

a computer readable medium bearing the software instructions;

the predetermined operations including the steps of:

receiving digital map data representative of a first map image in a first projection;

determining a number of rectangular sub-images to divide the digital map data into, wherein the number of rectangular sub-images is based on the size of the rectangular sub-images;

extracting each rectangular sub-image from the digital map data;

computing the geographic coordinates of each corner of each rectangular sub-image from first planar coordinates; and computing second planar coordinates of each corner of each rectangular sub-image using a second projection equation; and

supplying each rectangular sub-image and corresponding second planar coordinates to a texture mapping process for graphically mapping each rectangular sub-image into a second map image using a texture mapping graphical technique, wherein the computer re-projects map images.

2. The computer program of claim 1 , wherein the software instructions are configured to execute on a processor in an aircraft.

3. The computer program of claim 1 , wherein the software instructions are configured to execute on a processor for navigation.

4. A method for re-projecting a digital map image comprising:

receiving digital map data representative of a first map image in a first projection;

determining a number of rectangular sub-images to divide the digital map data into, wherein the number of rectangular sub-images is based on the size of the rectangular sub-images;

extracting each rectangular sub-image from the digital map data;

computing the geographic coordinates of each corner of each rectangular sub-image from first planar coordinates;

computing second planar coordinates of each corner of each rectangular sub-image using a second projection equation; and

supplying each rectangular sub-image and corresponding second planar coordinates to a texture mapping process for graphically mapping each rectangular sub-image into a second map image using a texture mapping graphical technique.

5. The method of claim 4 , further comprising the step of supplying each rectangular sub-image and corresponding second planar coordinates to a texture mapping accelerator for graphically mapping each rectangular sub-image into a second map image using a texture mapping graphical technique.

6. A system for re-projecting a digital map image comprising:

a processor for re-projecting the digital map image;

a memory coupled to the processor for storing a program, a first digital map image in a first projection, a second digital map image in a second projection, and sub-images of the first digital map image;

a program loaded into the memory comprising means for re-projecting the digital map image in the first projection into the second digital map image in the second projection; and

a graphics subsystem coupled to the processor comprising a texture mapping process,

wherein the means for re-projecting the digital map image comprises:

means for extracting one or more rectangular sub-images from the digital map data;

means for computing the geographic coordinates of each corner of each rectangular sub-image from first planar coordinates;

means for computing second planar coordinates of each corner of each rectangular sub-image using a second projection equation;

and means for supplying each rectangular sub-image and corresponding second planar coordinates to a texture mapping process for graphically mapping each rectangular sub-image into the second digital map image using a texture mapping graphical technique.

7. The system of claim 6 , wherein the texture mapping process comprises software.

8. The system of claim 6 , wherein the texture mapping process comprises a hardware texture mapping accelerator.

9. The system of claim 6 , wherein the texture mapping process comprises a combination of software and hardware texture mapping accelerators.

10. The system of claim 6 , wherein the system is adapted for installation in a vehicle.

11. The system of claim 10 , wherein the vehicle is an aircraft.

12. The system of claim 10 , wherein the vehicle is a boat.

13. The system of claim 10 , wherein the vehicle is a terrestrial vehicle.

14. The system of claim 10 , wherein the vehicle is a spacecraft.

15. A system for re-projecting a digital map image comprising: a processor; a first memory coupled to the processor for storing a digital map image in a first projection; a second memory coupled to the processor storing sub-images for use as textures; a computer readable medium encoded with a computer program that when executed causes a processor to re-project the digital map image in a first projection into a digital map image in a second projection; a graphics subsystem coupled to the processor comprising a texture mapping process, wherein the computer program is configured to determine a number of rectangular sub-images in which to divide the digital map image in a first projection, and wherein the number of rectangular sub-images is based on the size of the rectangular sub-images; and a means for displaying the digital map image in the second projection.

16. The system of claim 15 , further comprising a hardware texture mapping accelerator in communication with the processor.

17. The system of claim 15 , wherein the system is configured to be operated on a vehicle.

18. The system of claim 17 , wherein the vehicle is an aircraft.