Computer graphics systems and methods generating smooth feature lines for subdivision surfaces

Abstract

Computer graphics systems and methods are provided for generating a representation of a feature in a surface defined by a mesh representation, the mesh comprising at a selected level a plurality of points including at least one point connected to a plurality of neighboring points by respective edges, the feature being defined in connection with the vertex and at least one of the neighboring points and the edge interconnecting the vertex and the at least one of the neighboring points in the mesh representation. The feature generating arrangement comprises a weight vector generator module and a feature representation generator module.

1 . An arrangement for generating a representation of a feature in a surface defined by a mesh representation, the mesh comprising at a selected level a plurality of points including at least one point connected to a plurality of neighboring points by respective edges, the feature being defined in connection with the vertex and at least one of the neighboring points and the edge interconnecting the vertex and the at least one of the neighboring points in the mesh representation, the feature generating arrangement comprising:
 A. a weight vector generator module configured to generate at least one weight vector based on a parameterized subdivision rule defined at a plurality of levels, for which a value of at least one parameter differs at least two levels in the mesh; and   B. a feature representation generator module configured to use the at least one weight vector and positions of the vertex and the neighboring points to generate the representation of the feature.   
   
   
       2 . An arrangement as defined in  claim 1  in which weight vector generator module is configured to make use of values of the at least one parameter that differ at least two levels are related by a selected mathematical function. 
   
   
       3 . An arrangement as defined in  claim 1  in which the feature is a smooth feature line. 
   
   
       4 . An arrangement as defined in  claim 3  in which the smooth feature line is defined in connection with the vertex and two neighboring points and edges interconnecting the vertex and the respective neighboring points, the weight vector generator module being configured to make use of parameterized subdivision rule having a parameter value associated with each of the edges along which the smooth feature line is defined. 
   
   
       5 . An arrangement as defined in  claim 4  in which the weight vector generator module is configured to make use of parameters associated with the edges along which the smooth feature line is defined whose values are the same. 
   
   
       6 . A computer program product for use in connection with a computer to provide an arrangement for generating a representation of a feature in a surface defined by a mesh representation, the mesh comprising at a selected level a plurality of points including at least one point connected to a plurality of neighboring points by respective edges, the feature being defined in connection with the vertex and at least one of the neighboring points and the edge interconnecting the vertex and the at least one of the neighboring points in the mesh representation, the computer program product comprising:
 A. a weight vector generator module configured to enable the computer to generate at least one weight vector based on a, parameterized subdivision rule defined at a plurality of levels, for which a value of at least one parameter differs at least two levels in the mesh; and   B. a feature representation generator module configured to enable the computer to use the at least one weight vector and positions of the vertex and the neighboring points to generate the representation of the feature.   
   
   
       7 . A computer program product as defined in  claim 6  in which weight vector generator module is configured to enable the computer to make use of values of the at least one parameter that differ at least two levels are related by a selected mathematical function. 
   
   
       8 . A computer program product as defined in  claim 6  in which the feature is a smooth feature line. 
   
   
       9 . A computer program product as defined in  claim 8  in which the smooth feature line is defined in connection with the vertex and two neighboring points and edges interconnecting the vertex and the respective neighboring points, the weight vector generator module being configured to enable the computer to make use of parameterized subdivision rule having a parameter value associated with each of the edges along which the smooth feature line is defined. 
   
   
       10 . A computer program product as defined in  claim 9  in which the weight vector generator module is configured to enable the computer to make use of parameters associated with the edges along which the smooth feature line is defined whose values are the same. 
   
   
       11 . A method for generating a representation of a feature in a surface defined by a mesh representation, the mesh comprising at a selected level a plurality of points including at least one point connected to a plurality of neighboring points by respective edges, the feature being defined in connection with the vertex and at least one of the neighboring points and the edge interconnecting the vertex and the at least one of the neighboring points in the mesh representation, the method comprising:
 A. a weight vector generator step configured to generate at least one weight vector based on a parameterized subdivision rule defined at a plurality of levels, for which a value of at least one parameter differs at least two levels in the mesh; and   B. a feature representation generator step configured to use the at least one weight vector and positions of the vertex and the neighboring points to generate the representation of the feature.   
   
   
       12 . A method as defined in  claim 11  in which weight vector generator step includes the step of making use of values of the at least one parameter that differ at least two levels are related by a selected mathematical function. 
   
   
       13 . A method as defined in  claim 11  in which the feature is a smooth feature line. 
   
   
       14 . A method as defined in  claim 13  in which the smooth feature line is defined in connection with the vertex and two neighboring points and edges interconnecting the vertex and the respective neighboring points, the weight vector generator step includes the step of making use of parameterized subdivision rule having a parameter value associated with each of the edges along which the smooth feature line is defined. 
   
   
       15 . A method as defined in  claim 14  in which the weight vector generator step includes the step of making use of parameters associated with the edges along which the smooth feature line is defined whose values are the same.