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Spring 2014 CS274: Automatic Rigging
Zhinan Xu, Tianyuan Qin, Yue Liu Motivation Algorithm Overview
Primary 3D Silhouette Detection
global search, local search Curve Skeleton Extraction
triangulation, pruning, joint detection Animation Skeleton
Generation decomposition, refinement Skin Attachment skeleton
hierarchical movement skin transformation interpolation Primary 3D
Silhouette Detection
Global Search: Project all points to a 2D plane Find the 2D
silhouette using a process similar to Jarvis March for convex hull
computation Local Search: Connect all vertices according to the
connectivity of the original 3D mesh model. Curve Skeleton
Extraction
Triangulation Perform constrained Delaunay triangulation on 2D
silhouette. Extract the 2D medial axes. Generate 3D medial axes
from the 2D medial axes coupled with depth information which is
interpolated from the 3D silhouette. Triangle Pruning Prune &
Joint detection
Terminal Prune (cryan line) iteration Junction Prune BFS Joint
Detection(red point) local minimal Branch Connection straight
skeleton Curve Skeleton Extraction
Decomposition Medial axes generated from the previous step are
separated to different branches. Assign vertices on the mesh to
different groups base on their distance to each branches. Each
branch now has a group of vertices belongs to it. Curve Skeleton
Extraction
Curve Skeleton Refinement Depth information of the branches is not
accurate. For each part, find a second projection plane that is
perpendicular to the first projection plane. Construct another 3D
silhouette based on the second projection. Adjust the depth of the
branch base on it distance to the second silhouette Smooth the
branches to get the curve skeleton Animation Skeleton
Generation
Generate Skeleton Hierarchy Refined joint position Connection
information Calculate the mass center joint as root Generate
hierarchy starting from root with DFS Father Child Grandchild
Rotate Hierarchy Skin Attachment Linear Blend Skinning
Find joints related to the skin vertices with weight Interpolate
the joint transformations as vertices transformation Control them
with UI Result by demo Implemenetation Language: C++ Libraries:
OpenGL, OpenMesh, Face2D, Qt. Future Work Algorithm Limitations
Future Work
Models need to be fully extended Algorithm is too sensitive to the
occlusion Linear blend skinning causes lots of artifact Future Work
Instead of forward kinematics, implement inverse kinematics
Implement dual quaternion skinning Questions??? Thank you!!!