Single pass rendering for head mounted displays

1. A method of rendering geometry of a 3D scene on a display, the method comprising:

projecting geometry of the 3D scene into a 2D projection plane, wherein image regions are defined in the projection plane;

defining a first set of transformations;

adjusting the first set of transformations to produce a set of adjusted transformations;

mapping the geometry from the projection plane into an image space using the set of adjusted transformations, wherein a respective adjusted transformation is defined for each image region; and

rendering the geometry in the image space to determine image values of an image to be displayed on the display.

2. The method of claim 1 , wherein the adjusted transformations are configured for mapping the geometry into the image space so as to counteract distortion.

3. The method of claim 2 , wherein the distortion is introduced by an optical arrangement associated with the display.

4. The method of claim 1 , wherein the adjusting provides motion compensation.

5. The method of claim 1 , wherein the transformations are adjusted by combining each transformation in the first set of transformations with a global transformation.

6. The method of claim 1 , wherein the image regions are tiles.

7. The method of claim 6 , wherein the image regions in the projection plane are distorted tiles, and wherein the respective transformation for each of the image regions maps the image region to an undistorted tile in the image space.

8. The method of claim 1 , wherein the image regions are half-tiles.

9. The method of claim 1 , further comprising outputting the determined image values of the image to a frame buffer.

10. The method of claim 1 , wherein projecting geometry of the 3D scene into said 2D projection plane comprises:

sub-dividing pixels in said image space into a plurality of image regions, each image region of said image space comprising a group of pixels.

11. The method of claim 1 , wherein mapping the geometry from the projection plane into an image space using transformations comprises:

applying, for each vertex in an image region, a linear transformation to map the vertex position from the image space to said projection plane.

12. The method of claim 11 , wherein applying, for each vertex in an image region, a linear transformation to map the vertex position from the image space to said projection plane comprises:

applying the linear transformation, for each vertex in an image region, to X and Y coordinates in the projection plane and leaving other vertex attributes unmodified.

13. A graphics processing system configured to render geometry of a 3D scene on a display, the graphics processing system comprising:

tiling logic arranged to project geometry of the 3D scene into a 2D projection plane, wherein image regions are defined in the projection plane; and

rendering logic arranged to map the geometry from the projection plane into an image space using transformations, wherein a respective transformation is defined for each image region so as to define a first set of transformations, adjust the first set of transformations to produce a set of adjusted transformations, wherein the geometry from the projection plane is mapped into said image space using the set of adjusted transformation, and render the geometry in the image space to determine image values of an image to be displayed on the display.

14. The graphics processing system of claim 13 , wherein the transformations are configured for mapping the geometry into the image space so as to counteract distortion.

15. The graphics processing system of claim 14 , wherein the distortion is introduced by an optical arrangement of the display.

16. The graphics processing system of claim 13 , wherein the image regions defined in the projection plane are tiles, the image regions in the projection plane are distorted tiles, and wherein the respective transformation for each of the image regions maps the image region to an undistorted tile in the image space.

17. The graphics processing system of claim 13 , further comprising a frame buffer and wherein the rendering logic is further arranged to output the determined image values of the image to the frame buffer.

18. The graphics processing system of claim 13 , further comprising:

a memory arranged to store a plurality of transformation parameters defining the transformations, each transformation being a linear transformation and being associated with a group of pixels in said image space and defining a transformation of the pixels between image space and a projection plane.

19. A non-transitory computer readable storage medium having stored thereon a computer readable dataset description of a graphics processing system that, when processed in an integrated circuit manufacturing system, causes the integrated circuit manufacturing system to manufacture an integrated circuit embodying the graphics processing system, including:

tiling logic arranged to project geometry of the 3D scene into a 2D projection plane, wherein image regions are defined in the projection plane; and

rendering logic arranged to map the geometry from the projection plane into an image space using transformations, wherein a respective transformation is defined for each image region so as to define a first set of transformations, adjust the first set of transformations to produce a set of adjusted transformations, wherein the geometry from the projection plane is mapped into said image space using the set of adjusted transformation, and render the geometry in the image space to determine image values of an image to be displayed on the display.