Method and apparatus for constraint-based texture generation

Abstract

A method and apparatus for texture mapping a surface. The method is applicable to texture mapping either a two-dimensional representation (image) of a three-dimensional surface as well as a three-dimensional computer model of a three-dimensional surface, such as a triangular wire mesh model. In one embodiment, the texture mapping process involves user-specification of a plurality of constraints, including texture flow constraints, texture discontinuities, and surface underfolds. A triangular wire mesh model of the surface to be textured is generated. The mesh allows a continuous texture distribution to be specified as a linear interpolation of texture values at the triangular vertices. User-specified constraints are preserved as edges within the triangular mesh. The triangular mesh is used to compute a weighted energy functional expressed in terms of nodal texture values. The global value of this functional serves as a measure of how closely the user-specified and physics-based constraints are met by a particular texture distribution. The optimal texture distribution is found by determining the set of nodal values which minimizes this functional, through an iterative process that is recursively applied to each nodal value using the results of a previous iteration. In accordance with one aspect of the invention, the results of previous optimizations may be used as the starting point for subsequent refinements of the texture distribution, in the event that greater levels of photorealisim are necessary. During this recursive procedure the triangular mesh is progressively refined using an adaptive subdivision procedure which allows local texture variations to be more accurately expressed whilst optimizing the overall mesh density against calculational efficiency.

Description

NOTICE PURSUANT TO 37 C.F.R. § 1.184(2)[0001]The patent or application file contains at least one drawing executed in color. Copies of this patent or application publication with color drawings will be provided by the Office upon request and payment of the necessary fee.FIELD OF THE INVENTION[0002]The present invention relates generally to computer graphics, and more particular to a methodology for creating high-quality texture maps for photographic re-texturing.BACKGROUND OF THE INVENTION[0003]In the field of computer graphics and computer graphics rendering software, it is often desirable to apply a texture to a graphical image of a digitally-rendered object. Such functionality is often referred to as “texture mapping” or “texturing,” and numerous software tools for performing this function are known to those of ordinary skill in the art.[0004]As a general proposition, it is more difficult to map a photo-realistic texture to an object whose surface geometry and topology is complex...

AI Technical Summary

Benefits of technology

[0008]In one embodiment, the invention consists of a mathematical technique, and an associated software implementation thereof, for determining the most visually realistic distribution of texture over a specified surface. As used herein, the term “surface” may be used to refer either to an actual surface within a 3D computer model, or the projection of a physical surface within a 2D image such as a photograph. When used in conjunction with suitable rendering software, the calculated texture distribution allows regions of the treated image to be re-textured in a highly realistic way such that the casual viewer would imagine that the applied texture was present on the object when it was photographed or otherwise created.

[0009]In accordance with one aspect, the invention consists of the application of specific mathematical and computer software techniques to the problem of realistically re-texturing regions of 3D models or 2D images or photographs. The invention provides the ability to specify general constraints and hints in the form of free-form lines which are drawn over the surface to be re-textured. The invention then finds the texture distribution which optimally meets these constraints and hints whilst minimizing the overall stretching and compression of the fabric.

[0010]Advantageously, this combination of user-specified constraints and physics-based constraints allows the invention to be used to generate visually realistic texture distributions with a minimum of skill and effort. In addition, the invention enables a wide range of visually important features to be replicated in order to enhance the realism of the final effect. These features include:

[0016]The nature of the invention is such that the authoring process (i.e., the entire process of generating a good texture distribution) can be performed incrementally. This advantageously enables existing texture distributions to be improved at a later date to meet higher standards of realism.

[0017]It is contemplated that the invention has various commercial applications, including on-line sales and marketing of products for which texture and shape are important purchasing considerations. In addition, the invention may be applied in support of product design and design modification of products for which texture and shape are important design considerations. The invention facilitates the general communication of specifications and appearance of commercial products.

Problems solved by technology

The generation of a texture map for a graphical image is complicated further when the surface to be mapped includes such features as underfolds, where the continuous surface folds beneath and partially obscures itself, and discontinuities.

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