[postgis-users] ST_RotateX with pointOrigin!

[Mike Toews]

On 15 Dec 2013 21:50, "Stephen Mather" <stephen at 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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