US 5,966,133 A · Geomorphs and variable resolution control of progressive meshes

Abstract

An efficient, lossless, continuous-resolution representation (the "PM representation") of highly detailed geometric models for computer graphics specifies a succession of progressively more detailed polygonal meshes (i.e., "progressive meshes") as a base polygonal mesh and a sequence of complete mesh refinement transformations (e.g., the vertex split transformation) that approximate the model at progressively finer levels of detail. Procedures for storing and transmitting geometric models using the PM representation address several practical problems in computer graphics: smooth geomorphing of level-of-detail approximations, progressive transmission, mesh compression, and selective refinement. An optimized mesh simplification procedure constructs the PM representation of a model from an arbitrary polygonal mesh, while preserving the geometry of the original mesh as well as its overall appearance as defined by its discrete and scalar appearance attributes such as material identifiers, color values, normals, and texture coordinates. In particular, the PM representation and these procedures preserve discontinuity curves such as creases and material boundaries of the geometric model.

Claims27

Dependent claims

A method of creating a smooth visual transition between any two meshes of a progressive resolution succession of meshes representing a multi-dimensional geometric object for computer graphics, comprising:

selecting a coarser mesh and a finer mesh from the progressive resolution succession of meshes specified by a base mesh and a sequence of vertex split transformations which yield the progressive resolution succession of meshes when applied in sequence beginning with the base mesh, each mesh in the progressive resolution succession being defined by a set of position coordinates and a connectivity of a plurality of vertices, the vertex split transformations each modifying a position coordinate of a split vertex in a current mesh in the progressive resolution succession to yield a new position coordinate of the split vertex and introduce a position coordinate of a new vertex in a next mesh in the progressive resolution succession such that each vertex of the finer mesh has a vertex position derived from a vertex position of an ancestor vertex in the coarser mesh;
and
defining a geomorph having a set of vertices with a connectivity of the finer mesh and a set of vertex positions, at least some of the vertex positions varying between position coordinates of vertices in the finer mesh and position coordinates of their ancestor vertices in the coarser mesh according to a blend parameter;
evaluating the geomorph at a plurality of values of the blend parameter;
and
displaying views of the geometric object based on the geomorph evaluated at the values of the blend parameter.

3 more elements

A computer readable data storage medium having encoded thereon a geomorph data structure for performing a smooth visual transition with computer graphics between a coarser mesh and a finer mesh selected from a progressive resolution succession of meshes representing a multi-dimensional object, the progressive resolution succession being defined by a base mesh and a sequence of vertex split transformations where the vertex split transformations refine a set of position coordinates and a connectivity of vertices in the finer mesh from a set of position coordinates and a connectivity of ancestor vertices in the coarser mesh, the geomorph data structure comprising:

a vertex positions table for specifying positions of a plurality of vertices of the geomorph as varying from the set of position coordinates of the ancestor vertices in the coarser mesh to the set of position coordinates of the vertices in the finer mesh according to an interpolating function of a blend parameter;
and
a simplicial complex table for specifying a connectivity of the vertices of the geomorph as equal to the connectivity of the vertices in the finer mesh.

A system for controlling display of computer graphics views of a multi-dimensional geometric object at a variable level of detail, comprising:

a computer readable data storage medium for storing a progressive resolution meshes representation of the multi-dimensional geometric object as a base mesh and a sequence of mesh refinement transformations, the mesh refinement transformations being complete, the progressive resolution meshes representation defining a succession of meshes at progressive levels of detail;
a detail user interface control for varying a value of a level-of-detail variable responsive to user input;
a level of detail approximator for extracting from the progressive resolution meshes a representation of the multi-dimensional geometric object at a level of detail related to the value of the level-of-detail variable;
and
an image rendering and display means for producing and displaying a computer graphics view from the representation of the multi-dimensional geometric object at the level of detail.

2 more elements

A method of controlling display of computer graphics views of a multi-dimensional geometric object at a variable level of detail, comprising:

storing a progressive resolution meshes representation of the multi-dimensional geometric object in a computer memory as a base mesh and a sequence of mesh refinement transformations, the mesh refinement transformations being complete, the progressive resolution meshes representation defining a succession of meshes at progressive levels of detail;
setting a value of a level-of-detail variable responsive to user input;
extracting from the progressive resolution meshes a representation of the multi-dimensional geometric object at a level of detail related to the value of the level-of-detail variable;
rendering a computer graphics view of the representation of the multi-dimensional geometric object at the level of detail;
and
visually displaying the computer graphics view.

3 more elements

Dependencies are inferred from the claim text.

Geomorphs and variable resolution control of progressive meshes

Life of this patent

Geomorphs and variable resolution control of progressive meshes

Life of this patent

Abstract

Claims27