On 15 Dec 2013 21:50, "Stephen Mather" <step...@smathermather.com> wrote: > > Hmm, I know so little about Euler, strike, dip and rake. What are the advantages?
Euler angles are very well known, and have a wide range of applications[1]. Strike, dip and rake[2,3] are familiar to any geology student, and also have a wide range of applications in the earth sciences. They are similar to Euler angles. I still need to think this one through. Both of these advanced 3d rotations can be described as affine transformation parameters. Their advantages are to perform a rigid body transform using well known angles. I think the XYZ rotation technique you are describing requires calculations of the X and Y rotation components (unless the rotation happens to align with the grid, i.e. orthogonal). > What I do know is that it's easy now to construct a 3 axis rotation function (which also might be better handled with ST_Affine). Easy, yes, but I'm not convinced they are useful, or even being used by othets due to their orthogonal limitations. -Mike [1] https://en.wikipedia.org/wiki/Euler_angles [2] https://en.wikipedia.org/wiki/Strike_and_dip [3] https://en.wikipedia.org/wiki/Rake_(geology)
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