US 7,626,591 B2Granted

System and method for asynchronous continuous-level-of-detail texture mapping for large-scale terrain rendering

AssigneeD&S Consultants, Inc.

InventorsRoger Crawfis, Fredrick Kuck, Eric Noble, Eric Wagner

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Abstract

A multi-resolution texture mapping system suitable for large scale terrain rendering using commodity graphics processing units (GPU). The GPU vertex and fragment shaders are used to implement the clip-mapping functionality. The terrain texture is represented by a combination of a mip-map and a multi-level clip-map having independent origins and off-set values. The independent clip-map levels may be independently updated. The offset values allow the origins to be associated with a reference point in a scene to be rendered. The desired clip-map level to be used to render a particular fragment may be determined using the base 2 logarithm of the maximum screen-space derivative of the source texture required by the terrain geometry to be drawn. If the desired clip-map level is non-integer and lies between two clip-map levels, appropriate texel data is created by interpolating between the bounding clip-map levels. This interpolation allows a multi-resolution texture mapping to be displayed.

Claims12

Dependent claims

A method, executed in a computer having a computer-readable memory, for continuous-level-of-detail texture mapping, comprising the steps of:

storing a texture mip-map in said computer-readable memory, said mip-map comprising texel data representing a source texture;
storing a texture clip-map in said computer-readable memory, said clip-map comprising a first-level clip-map having texel data representing a first level of detail of said source texture, a first origin and a first offset value associating said first offset value with a reference point of a scene to be rendered, and a second-level clip-map having texel data representing a second level of detail of said source texture, a second origin and a second offset value associating said second offset value with said reference point;
and
determining a desired level clip-map for a fragment of a texture image, and, if said desired level is between said first and second level clip maps, creating texel data by interpolation of texel data from two of said first-level clip map and said second-level clip map.

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