Abstract: Methods, structures and systems for encoding and decoding isosurface data. An encoder process takes volume data and an isolevel as input and produces compressed isosurface data as output. The compressed isosurface data produced by an encoder process is composed of an occupancy image record, an optional intersection points record, and an optional normal vectors record. An occupancy image is compressed with a context-based arithmetic encoder. Compressed isosurface data can be stored in a data storage device or transmitted through a communication medium to a remote computer system, where the decoder process is executed. The decoder processes take compressed surface data as input and produce surface data as output. The decoder processes first reconstructs the occupancy image by decoding the occupancy image record. An in-core isosurface decoder process produces a polygon mesh as a surface representation. An out-of-core isosurface decoder process produces a set of oriented points as a surface representation.

Abstract: A method, system, and computer program product for adjusting a unit image area within an input image according to information importance within the unit area. An image receiver configured to receive the input image. An image warper is coupled to an importance map as is configured to generate a warped image such that regions of higher importance in the input image are expanded in the warped image and regions of lower importance in the input image are compressed in the warped image. The importance map is configured to delineate the regions of higher importance and the regions of lower importance in the input image. Texture coordinates may also be warped in a similar manner. Thus, the image is unwarped automatically by modern graphics adapters having texture mapping capabilities.

Abstract: Disclosed are methods and apparatus for obtaining the shape of an object by observing silhouettes of the object. At least one point light source is placed in front of the object, thereby casting a shadow of the object on a translucent panel that is placed behind the object. A camera, or other imaging device, captures an image of the shadow from behind the translucent panel. The object's full silhouette is obtained from the image of the shadow as the region of the shadow is substantially darker than the region outside of the shadow. The full silhouette thus obtained may be processed by any suitable shape from silhouette algorithm, and thus objects are not limited in topological type. A color image of the object can optionally be obtained simultaneously with the shadow image using a camera placed on the same side of the object as the light source.

Abstract: Disclosed are methods and apparatus for obtaining the shape of an object by observing silhouettes of the object. At least one point light source is placed in front of the object, thereby casting a shadow of the object on a translucent panel that is placed behind the object. A camera, or other imaging device, captures an image of the shadow from behind the translucent panel. The object's full silhouette is obtained from the image of the shadow as the region of the shadow is substantially darker than the region outside of the shadow. The full silhouette thus obtained may be processed by any suitable shape from silhouette algorithm, and thus objects are not limited in topological type. A color image of the object can optionally be obtained simultaneously with the shadow image using a camera placed on the same side of the object as the light source.

Abstract: A method for encoding a non-manifold polygonal mesh operates by converting an original (non-manifold) model to a manifold model, encoding the manifold model using a mesh compression technique, and clustering, or stitching together during a decompression process, vertices that were duplicated earlier to faithfully recover the original connectivity. By separating the connectivity from model geometry and properties, the method avoids encoding vertices (and properties bound to vertices) multiple times. This provides a reduction in the size of the bit-stream compared with encoding the model as a manifold.

Abstract: A data structure for representing a general n-dimensional polygonal mesh. The data structure includes a structure record and a data record for each three dimensional shape. The structural record contains polygonal model connectivity information and further includes a stitching record that defines corresponding polygonal (triangular) mesh edge pairs and a polygonal (triangular) tree record representing a polygon (triangle) tree. The stitching record includes a vertex tree and a set of jump edges. The data record includes at least three polygonal records, each corresponding to a polygon. Each polygonal record is associated with a face of said polygonal model and classifies its corresponding polygon as either a leaf polygon, a running polygon or a branching polygon. Polygonal shapes are encoded into the data structure by first building a spanning tree for the polygonal mesh. A set of cut edges are derived for the polygonal mesh. The stitching record is constructed for the set of cut edges.

Abstract: The visibility ordering of polyhedral cells is efficiently determined by building an ordering graph, comprising oriented edges between two cells. Each edge (A,B) corresponds to the fact that cell A has to be projected, or rendered, before B. A set of ordering relations and rules that can be shown to generate, if one exists, a global ordering of the polyhedral cell complex. Three different types of edges are used to accomplish this: MPVO, BSP and PPC edges. MPVO edges exist between two cells that share a face. To define the BSP edges, a BSP-tree of the boundary faces of the cell complex is constructed. During this construction, some of the boundary faces of the cells will be ‘cut’ by the BSP-tree ‘extended’ faces, into multiple pieces. If C is the boundary cell, and c′, c″, and so on, are the pieces of its boundary faces, the BSP_edge (c′, C) is defined to mean that cell C can only be projected after c′ has been projected by the BSP.

Abstract: A computer implemented method is disclosed for increasing the level of detail of a polygonal surface. A first step of the method provides data in a memory of a computer (50) for representing a polygonal surface that is defined at least by a plurality of vertices, triangles and edges. Further steps of the method include providing a list of marked edges; cutting through the marked edges thereby creating new boundary vertices; applying displacements to the new boundary vertices thereby generating at least one hole in the surface, the hole being bounded by the displaced new boundary vertices; and filling the at least one hole with a forest of triangles. The step of providing data for representing the polygonal surface preferably includes a step of appending artificial vertices and triangles to the polygonal surface to fill potential boundary holes; and then subsequently removing or ignoring the artificial vertices and triangles when rendering the surface for display.

Abstract: A computer implemented representation and a method for encoding and decoding sequences of changes of a manifold triangular mesh. The representation is composed of a base manifold triangular mesh and a succession of specialized mesh surgery operations that may be of a different type. The methods encode or decode any sequence of mark, move, cut, delete, close, fill, or add operations. The mark operation specifies a type of mark and a set of marked elements. The move operation determines a set of displaced vertices from a set of marked elements, and applies a set of vertex displacements to the set of displaced vertices. The cut operation cuts the changing mesh through a set of marked edges. The close operation is applied to one or more boundaries that are determined when the type of mark is a boundary type, and the one or more boundaries are determined by a marked elements variable.

Abstract: Disclosed is a representation and file format for a multi-level progressive transmission or display of a triangular mesh, referred to as a Progressive Multi-Level Representation (PMR). Methods are disclosed for generating the PMR, for progressively building a triangular mesh from a PMR representation, and for extracting a particular level of detail of a triangular mesh from the PMR representation.

Abstract: A is a computer implemented method for converting a non-manifold surface to a manifold surface. The method includes the steps of (a) providing data in a memory of a computer for representing a non-manifold polyhedral surface comprised of a plurality of triangles each bounded by edges and having vertices; (b) analyzing the data to determine and record singular edges and singular vertices; and (c) cutting through the singular edges and singular vertices, and optionally other edges and vertices, to provide a plurality of connected polygonal surfaces that are free of singularities. The step of analyzing may include the initial steps of analyzing the data to remove isolated vertices and repeated triangles. The step of cutting operates in accordance with one of a local cutting method or a global cutting method, and may further include a step of stitching the cut surface along boundary edges.

Abstract: A computer system progressively stores and transmits compressed clustered multi-resolution polygonal models. The computer uses a data structure that represents a clustered multi-resolution polygonal model in n-dimensional space. The data structure has a connectivity record which encodes the connectivity information of the highest level of detail. The data structure also has a clustering record which encodes how the vertices of each level of detal are clustered to obtain the vertices of the next lower level of detail. The clustering record is organized in decreasing order of level of detail. The data structure also has a data record with information describing the vertex positions of the levels of detail, and optionally the corresponding properties. The fields of the data record are organized in increasing order of level of detail.

Abstract: A method and system for obtaining and processing acquired images of an object to extract a small scale geometry (a bump map) of the object that is independent of object curvature.

Abstract: A computer system stores and transmits compressed triangular meshes. The computer uses a data structure that represents a triangular mesh in n-dimensional space. The data structure has a table of vertex runs, a table of triangle runs, zero or more marching records, which provide the connectivity information of the triangular mesh. The data structure also has zero or more associated data records that include the geometric information of the triangular mesh. The table of triangle runs and the marching record have information that describes how to construct a triangular mesh (therefore, the polygon vertices and the boundary edges). The table of vertex runs describes a vertex spanning tree that provides additional connectivity information to construct the triangular mesh from the polygon. The associated data record determines the exact position of the triangular mesh in space.

Abstract: A computer system stores and transmits compressed simple triangular meshes. The computer uses a data structure that represents a simple triangular mesh in n-dimensional space. The data structure has a table of vertex runs, a table of triangle runs, zero or more marching records, which provide the connectivity information of the triangular mesh. The data structure also has zero or more associated data records that include the geometric information of the triangular mesh. The table of triangle runs and the marching record have information that describes how to construct a triangular mesh (therefore, the polygon vertices and the boundary edges). The table of vertex runs describes a vertex spanning tree that provides additional connectivity information to construct the triangular mesh from the polygon. The associated data record determines the exact position of the triangular mesh in space.

Abstract: An image processing system segments an object from the background of a scene by controlling a light source to illuminate the object more in one scene image than in another scene image. The two scene images are captured by an image input device and are then compared. The part of the image that experienced an increase in intensity is segmented as corresponding to the object. The image input device and the light source can also be placed in an opaque enclosure with an opening through which the input device can view and the light can illuminate the object. By placing the enclosure the correct distance away from the object, the effects of ambient light on the image are removed. Object glare is removed by a polarizing filter system.

Abstract: The present system and apparatus uses image processing to recognize objects within a scene. The system includes an illumination source for illuminating the scene. By controlling the illumination source, an image processing system can take a first digitize image of the scene with the object illuminated a higher level and a second digitized image with the object illuminated at a lower level. Using an algorithm, the object(s) image is segmented from a background image of the scene by a comparison of the two digitized images taken. A processed image (that can be used to characterize features) of the object(s) is then compared to stored reference images. The object is recognized when a match occurs. The system can recognize objects independent of size and number and can be trained to recognize objects that is was not originally programmed to recognize.

Abstract: The present invention smooths piece-wise linear shapes by defining neighborhoods of vertices around vertices of the shape. One or more vectors is defined between the vertex and each of its neighbors. Vector sums are alternately multiplied by one of two scale factors. The scale factors are opposite in sign with the negative scale factor of larger magnitude. The vertices of the shape are displaced by the multiplied vector sums to attain new positions. The process is repeated with the vertices moving back and forth approximately through their final position until the shape is smoothed without shrinkage.