Rotation representation: Matrix

\( \left\{ \begin{array}{l} \mathrm{R}= \left( \begin{array}{ccc} r_{00} & r_{01} & r_{02} \\ r_{10} & r_{11} & r_{12} \\ r_{20} & r_{21} & r_{22} \\ \end{array} \right) \\ \\ \mathrm{R}^T\,\mathrm{R}= \mathrm{Id} \end{array} \right. \)
Pro.
  • - Standard structure (storage,manipulate)
  • - Simple application to vector: \(v'=\mathrm{R}v\)
  • - Composition b/w rotations: \(\mathrm{R} = \mathrm{R}_1\,\mathrm{R}_2\)
Cons.
  • - Large redundancy (9 coefficients for 3 dof).
  • - Rotation parameters don't appear explicitely
  • - Unclear interpolation
    • - Linear interpolation doesn't work well for large angles
    • ex. \(\mathrm{M}=(1-\alpha)\,\mathrm{R_1}+\alpha \mathrm{R}_2\)
    • => \(\mathrm{M}\) is not a rotation anymore (not a vectorial space)
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