Techniques for interactive 3D manipulation of articulated objects in cluttered environments should be geometricallyaware, going beyond basic inverse or forward kinematics to allow contact while preventing interpenetration. This paper describes a general purpose interactive object manipulation technique using nonlinear optimization. The method converts geometry awareness into sets of inequality constraints and handles nonlinear equality and inequality constraints e ciently without restricting object topology. Our iterative algorithm has a quadratic convergence rate and each iteration can be solved in O(nnz(L)), where nnz(L) is the number of non-zeros in L, a Cholesky factor of a sparse matrix. To promote additional speedup, symbolic factorization is separated from numerical computation. Our approach provides a framework for using optimization techniques in interactive tools for building and manipulating models in constrained, cluttered environments.
Min-Hyung Choi, James F. Cremer