Z-depth matting of particles in image rendering

1. A computer-implemented method of rendering a first image having a plurality of particles, comprising:

receiving a z-depth image that provides a z-value for each pixel in a background image;

generating in the same space as said plurality of particles a single pixel particle of an opaque transparency for each pixel in said z-depth image positioned at the same x-y position as said each pixel in said z-depth image and at a z-position indicated by said z-value;

generating an adjusted z-position by randomly adjusting the z-position of each particle in each temporal sample of a series of samples,

wherein the adjustments corresponding to each temporal sample are independent of the adjustments corresponding to the other samples in the series of samples;

for each temporal sample:

sorting said plurality of particles in the sample with a plurality of said generated single pixel particles in said first image based on said adjusted z-position of each particle in the sample, and based on the opacity of a layer of a plurality of layers of varying opacities associated with each pixel of said plurality of particles; and

rendering said sorted plurality of particles and single pixel particles based on the sorted order of the particles in the sample.

2. The method of claim 1 , further comprising

rendering objects and surfaces of said background image in said first image.

3. The method of claim 2 , further comprising

building said z-depth image based on the geometry of said objects and surfaces rendered in said first image.

4. The method of claim 2 , further comprising

compositing the rendered plurality of particles with the rendered objects and surfaces of said background image.

5. The method of claim 1 , wherein said opaque transparency includes a transparency level of opaqueness in RGB and alpha channels such that objects that are behind will be hidden.

6. A computer-implemented method of rendering a first image having a plurality of particles, comprising:

receiving a z-depth image that provides a z-value for each pixel in a background image;

providing information indicating the behavior of said plurality of particles;

randomly adjusting the original z-position of a particle over a series of samples;

generating in the same space as said plurality of particles a single pixel particle of an opaque transparency for each pixel in said z-depth image positioned at the same x-y position as said each pixel in said z-depth image and at a z-position indicated by said z-value;

generating an adjusted z-position by randomly adjusting the z-position of each particle in each temporal sample of a series of samples,

wherein the adjustments corresponding to each temporal sample are independent of the adjustments corresponding to the other samples in the series of samples;

for each temporal sample:

sorting said plurality of particles in the sample with a plurality of said generated single pixel particles in said first image based on said adjusted z-position of each particle in the sample, and based on the opacity of a layer, wherein the layer is one of a plurality of layers having varying opacities and associated with each pixel of said plurality of particles; and

rendering said sorted plurality of particles and single pixel particles based on the sorted order of the particles in the sample, but using the original z-position of each particle, to generate a resulting image.

7. The method of claim 6 , wherein said randomly adjusting the z-position of a particle includes adjusting the z-position of said particle in a pseudo-random pattern.

8. The method of claim 6 , further comprising

rendering objects and surfaces of said background image in said first image.

9. The method of claim 8 , further comprising

compositing the rendered plurality of particles with the rendered objects and surfaces of said background image.

10. A computer-implemented method of rendering a first image having a plurality of particles, comprising:

receiving a z-depth image that provides a z-value for each pixel in a background image;

comparing the z-position of each pixel of a particle to be rendered with said z-value of said z-depth image at the same x-y position as said each pixel of a particle;

generating in the same space as said plurality of particles a single pixel particle of an opaque transparency for each pixel in said z-depth image if said each pixel of a particle is determined to be behind said each pixel in said z-depth image;

generating an adjusted z-position by randomly adjusting the z-position of each particle in each temporal sample of a series of samples,

wherein the adjustments corresponding to each temporal sample are independent of the adjustments corresponding to the other samples in the series of samples;

for each temporal sample;

sorting said plurality of particles in the sample with a plurality of said generated single pixel particles in said first image based on said adjusted z-position of each particle in the sample, and based on the opacity of one layer of a plurality of layers of varying opacities, wherein each pixel of said plurality of generated single pixel particles has a plurality of layers of varying opacities; and

rendering said sorted plurality of particles and single pixel particles based on the sorted order of the particles in the sample.

11. The method of claim 10 , wherein determining that said each pixel of a particle is behind said each pixel in said z-depth image includes determining that the z-position of said each pixel of a particle is greater than the z-value for said pixel in said z-depth image at the same x-y position as said each pixel of a particle.

12. A computer-readable medium storing a computer program for rendering a first image having a plurality of particles, the program comprising executable instructions that cause a computer to:

receive a z-depth image that provides a z-value for each pixel in a background image;

generate in the same space as said plurality of particles a single pixel particle of an opaque transparency for each pixel in said z-depth image positioned at the same x-y position as said each pixel in said z-depth image and at a z-position indicated by said z-value;

generate an adjusted z-position by randomly adjusting the z-position of each particle in each temporal sample of a series of samples,

wherein the adjustments corresponding to each temporal sample are independent of the adjustments corresponding to the other samples in the series of samples;

for each temporal sample:

sort said plurality of particles in the sample with a plurality of said generated single pixel particles in said first image based on said adjusted z-position of each particle in the sample, and based on the opacity of a layer of a plurality of layers having varying opacities and associated with each pixel of said plurality of particles; and

render said sorted plurality of particles and single pixel particles based on the sorted order of the particles in the sample.

13. The computer-readable medium of claim 12 , further comprising executable instructions that cause a computer to render objects and surfaces of said background image in said first image.

14. The computer-readable medium of claim 13 , further comprising executable instructions that cause a computer to build said z-depth image based on the geometry of said objects and surfaces rendered in said first image.

15. The computer-readable medium of claim 13 , further comprising executable instructions that cause a computer to composite the rendered plurality of particles with the rendered objects and surfaces of said background image.

16. An apparatus for rendering a first image having a plurality of particles, comprising:

means for receiving a z-depth image that provides a z-value for each pixel in a background image;

means for generating in the same space as said plurality of particles a single pixel particle of an opaque transparency for each pixel in said z-depth image positioned at the same x-y position as said each pixel in said z-depth image and at a z-position indicated by said z-value;

means for generating an adjusted z-position by randomly adjusting the z-position of each particle in each temporal sample of a series of samples,

wherein the adjustments corresponding to each temporal sample are independent of the adjustments corresponding to the other samples in the series of samples;

means for sorting said plurality of particles in the sample with a plurality of said generated single pixel particles in said first image based on said adjusted z-position of each particle in the sample, and based on the opacity of a layer of a plurality of layers of varying opacities, wherein each pixel of said plurality of particles has a plurality of the layers of varying opacities; and

means for rendering said sorted plurality of particles and single pixel particles based on the sorted order of the particles in the sample.

17. The apparatus of claim 16 , further comprising

means for rendering objects and surfaces of said background image in said first image.

18. The apparatus of claim 17 , further comprising

means for building said z-depth image based on the geometry of said objects and surfaces rendered in said first image.

19. The apparatus of claim 17 , further comprising

means for compositing the rendered plurality of particles with the rendered objects and surfaces of said background image.

20. The method of claim 1 , further comprising

comparing layers of the plurality of layers based on opacity by separately obscuring the layers.