Volume rendering processing distribution in a graphics processing unit
An intersection of a cut plane with a proxy geometry representing a scan volume is determined with a processor. The intersection is simplified, such as identifying a quadrilateral or triangle most closely enclosing the intersection. The vertex processor of a GPU deforms a reference grid and determines Cartesian coordinates and the texture coordinates for grid points of the reference grid as a function of the input intersection. The vertex processor provides coordinates for data for subsets of cut planes. The fragment processor inputs the texture coordinates and retrieves the data from the texture memory. The data is blended. The blended subsets are then blended together in the frame buffer of the GPU.
1. A method for vertex processing in a graphics processing unit, the method comprising:
receiving a planar reference grid of a plurality of intersecting lines with line intersections corresponding to grid points, at least one grid point being on an interior of the planar reference grid and other grid points being at exterior corners of the planar reference grid, the received planar reference grid being invariant between different cut planes and separate from a layout of data to be rendered;
deforming the planar reference grid to fit a polygon representing a two-dimensional intersection of a first cut plane of the different cut planes with a three-dimensional geometry, the deforming comprising mapping the exterior corners of the planar reference grid to vertices of the polygon and computing coordinates of the grid points on the interior as a function of the mapping, the deforming being performed by a vertex processor of the graphics processing unit;
repeating the deforming for each of the different cut planes with the three-dimensional geometry, the repetition providing a plurality of deformed planar reference grids; and
rendering an image as a function of the deformed planar reference grids.
2. The method of claim 1 wherein deforming the planar reference grid comprises calculating texture coordinates of the grid points within the reference grid with the vertex processor.
3. The method of claim 2 wherein calculating texture coordinates comprises calculating texture coordinates in an acoustic domain as range, azimuth and elevation values.
4. The method of claim 2 wherein the planar reference grid comprises an N×M grid where N and M are both greater than 3 , and wherein calculating texture coordinates of grid points comprises calculating texture coordinates of all grid points within the reference grid.
5. The method of claim 1 wherein deforming the planar reference grid comprises calculating Cartesian coordinates of grid points within the planar reference grid with the vertex processor.
6. The method of claim 1 wherein receiving comprises the vertex processor receiving the planar reference grid and receiving coordinates of three or more vertices defining the intersection of the first cut plane with a proxy geometry.
7. The method of claim 6 wherein the three or more vertices are four or more vertices, the method further comprising:
identifying the four or more vertices of the intersection, the proxy geometry corresponding to data representing a volume; and
if a number of the vertices is greater than four, identifying the intersection as a quadrilateral enclosing the intersection with fewer sides than the number.
8. The method of claim 1 wherein deforming comprises deforming as a function of a shape of intersection of the first cut plane with a volume shape.
9. The method of claim 1 wherein repeating comprises:
identifying at least a second cut plane with the vertex processor as a function of the first cut plane; and
deforming the planar reference grid as a function of the second cut plane, the deforming being performed by the vertex processor of the graphics processing unit.
10. The method of claim 1 wherein said method is used for 3-dimensional cardiology or radiology.
11. The method of claim 1 wherein receiving comprises the vertex processor receiving the planar reference grid and receiving parameters defining the intersection of the first cut plane with a proxy geometry.
12. A computer readable storage medium having stored therein data representing instructions executable by a vertex processor of a graphics processing unit for vertex processing as part of volume rendering, the storage medium comprising instructions for:
receiving a planar reference grid of a plurality of intersecting lines with line intersections corresponding to grid points, at least one grid point being on an interior of the planar reference grid and other grid points being at exterior corners of the planar reference grid, the received planar reference grid being invariant between different cut planes and separate from a layout of data to be rendered;
receiving three or more vertices defining a two-dimensional intersection of a first cut plane of the different cut planes with a proxy geometry;
calculating with the vertex processor texture coordinates in an acoustic domain as range, azimuth and elevation values for grid points within the planar reference grid, wherein calculating comprises mapping the exterior corners of the planar reference grid to vertices of the polygon and computing coordinates of the grid points on the interior as a function of the mapping; and
repeating the receiving three or more vertices and calculating for each of the different cut planes with the proxy geometry, the repetition providing a plurality of deformed planar reference grids output for rendering an image as a function of the deformed planar reference grids.
13. The instructions of claim 12 wherein the planar reference grid comprises an N×M grid where N and M are both greater than 10, and wherein calculating texture coordinates of grid points comprises calculating texture coordinates of all grid points within the planar reference grid.
14. The instructions of claim 12 wherein calculating texture coordinates comprises deforming the planar reference grid as a function of a shape of intersection of the first cut plane with a proxy geometry of a volume.
15. The instructions of claim 12 further comprising:
identifying at least a second cut plane, of the different cut planes, with the vertex processor as a function of the first cut plane; and
deforming the planar reference grid as a function of a second cut plane, the deforming being performed by the vertex processor of the graphics processing unit.