Angle-dependent anisotropic filtering

Patent metadata

Field	Value
Publication number	US-10109069-B2
Application number	US-201715454125-A
Country	US
Kind code	B2
Filing date	Mar 9, 2017
Priority date	Dec 28, 2013
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

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, where 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 graphics processing unit for angle dependent anisotropic filtering, the graphics processing unit is coupled to a central processing unit and a storage device, the graphics processing unit comprising:
at least one bilinear low pass filter, wherein the bilinear low pass filter is configured to filter data for a first MIP map and a second MIP map, where data from each MIP map represents a two by two group of texels, wherein the two by two group of texels is nearest to a desired position on the first MIP map and the second MIP map, respectively;
at least one anisotropic low pass filter, wherein the anisotropic low pass filter is configured to adaptively filter sampled data from the bilinear low pass filter for the first MIP map and the second MIP map, and a length of a major-axis of the anisotropic low pass filter is varied based on a screen space angle;
at least one sampler unit, wherein the sampler unit is configured to sample the output of the bilinear low pass filter and the anisotropic low pass filter, wherein the at least one sampler unit includes a texture sampling component to determine texels from a texture map that are to be sampled in the anisotropic low pass filter based on length of a modified major-axis; and
a pixel coloration component to determine a color of a pixel based on the texels sampled in the anisotropic low pass filter, wherein the pixel is displayed on a screen-space.

2. The graphics processing unit of claim 1 , wherein the results of the anisotropic sampling on the first MIP map and the second MIP map are combined as a weighted sum based on a fractional part.

3. The graphics processing unit of claim 1 , wherein a width of the anisotropic low pass filter for each of the first MIP map and the second MIP map is twice the anisotropic ratio for that MIP.

4. The graphics processing unit of claim 1 , wherein the anisotropic low pass filter shape passes a minimum of higher frequency components beyond an ideal sampling cut-off frequency and a maximum of lower frequency components within the ideal sampling cut-off frequency.

5. The graphics processing unit of claim 1 , wherein the first MIP and the second MIP are filtered by the bilinear low pass filter and then sampled at a one-texel interval on each of the first MIP map and the second MIP map.

Assignees

• Intel Corp

Inventors

• Chatterjee Prosun
• Seiler Larry
• Spangler Steven

Classifications

• 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

• G06T1/20

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

• G06T15/04

  Texture mapping · CPC title