Characteristics
- - Hierarchical representation
-
- All children follow the transformation of the parent
- Need to define a root: usually at the hips/pelvis
- - Convenient to express relative transformation with respect to the parent frame
-
- ex. Ankle is at 20\(^{\circ}\) w/r knee
Converting local to global frames/joint coordinates
- With 4x4 matrices \(M\)
- \(M^i_{global} = M^{p(i)}_{global}\;M^{i}_{local}\)
- \(R^i_{global} = R^{p(i)}_{global}\;R^{i}_{local}\)
- \(t^i_{global} = t^{p(i)}_{global}+ R^{p(i)}_{global}\,t^{i}_{local}\)
