Statistical dynamic modeling method and apparatus

Abstract

A method for animating soft body characters has a preparation phase followed by an animation phase. In the preparation phase, the skin deformation of the character model is determined for a set of basis poses. The skin deformation from posing is compactly represented in terms of the set of basis poses. In the animation phase, the set of basis poses and the skin mode response are used to create a final posed character. A desired character pose is projected onto the basis set to determine a set of basis weights. The basis weights are applied to the set of skin responses to create a skin pose response, and the skin pose responses is projected onto the basis set to create the posed character model.

What is claimed is:  
     
         1 . A method for creating a posed character model, the method comprising: 
 determining a basis set from a set of sample character positions;    determining a set of skin responses for the character model, wherein each skin response corresponds with one of the basis set;    projecting a first character pose onto the basis set to determine a set of basis weights in a first reference frame;    applying the set of basis weights to the set of skin responses to create a first skin pose response; and    constructing a posed character model from the first skin pose response and the basis set.    
     
     
         2 . The method of  claim 1 , further comprising: 
 repeating for a second reference frame the steps of projecting a character pose and applying the set of basis weights to create a second skin pose response; and    constructing the posed character model from the first skin pose response, the second skin pose response, and the basis set.    
     
     
         3 . The method of  claim 2 , wherein constructing includes combining the first and second skin pose responses according to a set of frame weights associated with the first and second reference frames.  
     
     
         4 . The method of  claim 3 , further comprising determining a set of frame weights by diffusing an initial set of frame weight values through the character model.  
     
     
         5 . The method of  claim 3 , further comprising determining a set of frame weights by comparing the set of skin responses with a corresponding set of non-linear solutions.  
     
     
         6 . The method of  claim 3 , further comprising setting at least a portion of the set of frame weights to values received from a user.  
     
     
         7 . The method of  claim 1 , further comprising: 
 repeating for a second character pose the steps of projecting a character pose, applying the set of basis weights, and projecting the set of skin responses to create a second posed character model.    
     
     
         8 . The method of  claim 1 , wherein the set of sample character positions comprises a training set of character poses.  
     
     
         9 . The method of  claim 1 , wherein the set of sample character positions comprises at least one dynamically created pose.  
     
     
         10 . The method of  claim 1 , wherein an armature is used to define the set of sample character positions and the first character pose.  
     
     
         11 . The method of  claim 1 , wherein the first character pose is at least partially defined according to an animation variable.  
     
     
         12 . The method of  claim 1 , wherein determining a set of skin responses comprises, for each basis of the basis set, applying a set of displacements from one of the basis set to a portion of the character model and minimizing a function of the displacement over the entire character model.  
     
     
         13 . The method of  claim 12 , wherein the function is a material energy function.  
     
     
         14 . The method of  claim 12 , further comprising: 
 discretizing the character model into a three-dimensional field of sample points, applying the set of displacements to a portion of the sample points, and minimizing the function at every sample point associated with the character model.    
     
     
         15 . The method of  claim 14 , wherein the field is a Cartesian grid.  
     
     
         16 . The method of  claim 14 , wherein the field is a set of vertices of tetrahedral volume elements.  
     
     
         17 . The method of  claim 1 , wherein each of the set of skin responses is defined as the linear combination of the elements of the basis set.  
     
     
         18 . A method for creating a posed character model, comprising: 
 transforming a character pose into a set of reference frames associated with a character model;    for each reference frame, creating a skin pose response of the character model in response to the character pose; and    constructing a composite skin response of the character model from the skin pose responses of each reference frame.    
     
     
         19 . The method of  claim 18 , wherein constructing a composite skin response comprises combining a portion of the skin response of a first reference frame with a portion of the skin response of a second reference frame.  
     
     
         20 . The method of  claim 19 , wherein the portion of the skin response of the first reference frame and the portion of the skin response of the second reference frame correspond to two, at least partially overlapping regions of the character model.  
     
     
         21 . The method of  claim 20 , wherein the portion of the skin response of the first reference frame and the portion of the skin response of the second reference frame correspond to two identical regions of the character model.  
     
     
         22 . The method of  claim 19 , wherein the portion of the skin response of the first reference frame and the portion of the skin response of the second reference frame correspond to two different regions of the character model.  
     
     
         23 . The method of  claim 19 , wherein the portion of the skin response of a first reference frame and the portion of the skin response of the second reference frame are combined according to a set of frame weights defining the influence of the skin responses of the first and second reference frames on the composite skin response.  
     
     
         24 . The method of  claim 18 , further comprising: 
 determining a set of frame weights associated with the set of reference frames, the set of frame weights defining the influence of each reference frame on the composite skin response.    
     
     
         25 . The method of  claim 24 , wherein determining a set of frame weights comprises diffusing an initial set of frame weight values through the character model.  
     
     
         26 . The method of  claim 25 , wherein diffusing comprises: 
 discretizing a character model into a field of three dimensional sample points;    assigning initial frame weight values to sample points adjacent to the origin of each reference frame; and    determining a set of frame weight values for a plurality of sample points from a diffusion of the initial frame weight values.    
     
     
         27 . The method of  claim 24 , further comprising determining a set of frame weights by comparing the set of skin responses with a corresponding set of non-linear solutions.  
     
     
         28 . The method of  claim 24 , further comprising setting at least a portion of the set of frame weights to values received from a user.  
     
     
         29 . An information storage medium having a plurality of instructions adapted to direct an information processing device to perform an operation comprising the steps of: 
 determining a basis set from a set of sample character positions;    determining a set of skin responses for the character model, wherein each skin response corresponds with one of the basis set;    projecting a first character pose onto the basis set to determine a set of basis weights in a first reference frame;    applying the set of basis weights to the set of skin responses to create a first skin pose response; and    constructing a posed character model from the first skin pose response and the basis set.    
     
     
         30 . The information storage medium of  claim 29 , further comprising: 
 repeating for a second reference frame the steps of projecting a character pose and applying the set of basis weights to create a second skin pose response; and    constructing the posed character model from the first skin pose response, the second skin pose response, and the basis set.    
     
     
         31 . The information storage medium of  claim 29 , wherein the first character pose is at least partially defined according to an animation variable.  
     
     
         32 . The information storage medium of  claim 29 , wherein determining a set of skin responses comprises, for each basis of the basis set, applying a set of displacements from one of the basis set to a portion of the character model and minimizing a function of the displacement over the entire character model.  
     
     
         33 . An information storage medium having a plurality of instructions adapted to direct an information processing device to perform an operation comprising the steps of: 
 transforming a character pose into a set of reference frames associated with a character model;    for each reference frame, creating a skin pose response of the character model in response to the character pose; and    constructing a composite skin response from the skin pose responses of each reference frame.    
     
     
         34 . The information storage medium of  claim 33 , wherein constructing a composite skin response comprises combining a portion of the skin response of a first reference frame with a portion of the skin response of a second reference frame.  
     
     
         35 . The information storage medium of  claim 34 , wherein the portion of the skin response of a first reference frame and the portion of the skin response of the second reference frame are combined according to a set of frame weights defining the influence of the skin responses of the first and second reference frames on the composite skin response.  
     
     
         36 . The information storage medium of  claim 35 , wherein the operation further comprises the step of determining a set of frame weights associated with the set of reference frames, the set of frame weights defining the influence of each reference frame on the composite skin response.  
     
     
         37 . A tangible media including a first image having a character model in a first pose and a consecutive image having a character model in a second pose, wherein the appearance of the character model in the second pose is independent of the appearance of the character model in the first pose and wherein the character in the first and second poses are created according to the method of  claim 1 .  
     
     
         38 . A tangible media including a first image having a character model in a first pose and a consecutive image having a character model in a second pose, wherein the appearance of the character model in the second pose is independent of the appearance of the character model in the first pose and wherein the character in the first and second poses are created according to the method of  claim 18.