Angle-dependent anisotropic filtering

Patent metadata

Field	Value
Publication number	US-9619898-B2
Application number	US-201314142805-A
Country	US
Kind code	B2
Filing date	Dec 28, 2013
Priority date	Dec 28, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A method includes computing an anisotropic filter with a major-axis and a minor-axis for a pixel to be displayed on screen-space, wherein the anisotropic filter is to be applied to corresponding MIPs on a texture map. Additionally, the method includes varying the length of the major-axis of the anisotropic filter based on the angle of the major-axis of anisotropy with respect to the screen space. Further, the method includes determining a number of texels from the texture map that are to be sampled in the anisotropic filter based on the length of the modified major-axis. The color of the pixel may be determined based on the texels sampled in the anisotropic filter.

First claim

What is claimed is:

1. A method for angle dependent anisotropic filtering, comprising:
computing an anisotropic filter with a major-axis and a minor-axis of a texture map for a pixel to be displayed on screen-space via a processing unit;
modifying a length of a major-axis of the anisotropic filter via the processing unit based on a screen space angle, wherein the length of the major axis of the anisotropic filter is modified to decrease from an original computed length as the angle approaches 45°;
determining a number of texels from the texture map via the processing unit that are to be sampled in the anisotropic filter based on the length of the modified major-axis; and
determining a color of the pixel based on the texels sampled in the anisotropic filter via the processing unit.

2. The method of claim 1 , wherein a distortion from the pixel is below a threshold.

3. The method of claim 1 , wherein the length of the minor axis of the anisotropic filter is held constant independent of the angle.

4. The method of claim 1 , wherein the length of the major axis varies based on the position of the anisotropic major axis with respect to the screen-space axes.

5. The method of claim 1 , wherein the texels are sampled using a computed effective sampling interval.

6. The method of claim 1 , wherein the moiré in a rendered image at all screen space angle values is equal.

7. A system for anisotropic filtering, comprising:
a central processing unit (CPU);
a graphical processing unit (GPU) coupled to the CPU, the GPU to:
compute an anisotropic filter with a major-axis and a minor-axis for a pixel to be displayed on screen-space, where the anisotropic filter is applied to corresponding MIPs on a texture map;
vary a length of the major-axis of the anisotropic filter based on the angle of the major-axis with respect to the screen-space axes, wherein the length of the major axis of the anisotropic filter is modified to decrease from the original computed length as the angle approaches;
determine a number of texels from the texture map that are to be sampled in the anisotropic filter based on the length of the modified major-axis; and
determine the color of the pixel based on the texels sampled in the anisotropic filter.

8. The system of claim 7 , wherein a display screen is to display the pixel on the screen space.

9. The system of claim 7 , wherein a memory drive stores information corresponding to the texture.

10. The system of claim 7 , wherein the angle is measured between the major-axis of anisotropy and an axis of the screen-space.

11. The system of claim 7 , wherein the length of the minor axis of the anisotropic filter is held constant independent of the angle.

12. A tangible, non-transitory computer-readable medium for angle dependent anisotropic filtering, comprising instructions configured to direct a processor to:
vary a length of a major-axis of the anisotropic filter via a processing unit based on a screen space angle, wherein the length of the major axis of the anisotropic filter is modified to decrease from an original computer length as the angle approaches 45°;
determine a number of texels from the texture map via the processing unit that are to be sampled in the anisotropic filter based on the length of the modified major-axis;
compute an anisotropic filter with a major-axis and a minor-axis of a texture map for a pixel to be displayed on screen-space via the processing unit; and
determine a color of the pixel based on the texels sampled in the anisotropic filter via the processing unit.

Assignees

• Intel Corp

Inventors

• Chatterjee Prosun
• Seiler Larry
• Spangler Steven

Classifications

• G06T1/20

  Processor architectures; Processor configuration, e.g. pipelining · CPC title

• G06T15/04

  Texture mapping · CPC title

• G06T11/40

  Filling planar surfaces by adding surface attributes, e.g. adding colours or textures · CPC title

• G06T7/44 Primary

  using image operators, e.g. filters, edge density metrics or local histograms · CPC title

• G06T7/403 Primary

  Physics · mapped topic