Precision in translation+rotation

[Möller]

I occasionally use CloudCompare to transform point clouds from world coordinates to project local coordinates. World coordinates can look like North 65 000 000, East 150 000 (in meters) while project coordinates are much smaller, with origo close to where the cloud is.

Transforming involves a move (translation) in North and East as well as a rotation. These numbers are know, generally with very high precision.

My workflow is:
-load e57 into CC
-Change suggested Global shift to my known coordinate move. Unclick "Preserve on save" to make the shift permanent.
-Rotate the cloud with Apply transformation using my known rotation angle in degrees.
-Export the cloud

This works, but perhaps there's a better method? I'm a bit annoyed by the destruction of precision - when entering shift coordinates I can only use 2 decimals, meaning centimetre precision.

[daniel]

Ah that definitely works.

Maybe another solution is to apply the default shift, then use the 'Edit > Apply transformation' method (with the total shift that you want to apply). Normally, since it's a big shift, CC will suggest to apply this shift to the Global Shift (without any loss of precision or anything). You don't need to drop the global shift normally (at export time, the cloud should end in your local coordinate system).

And anyway, with your actual workflow, you can also use the 'Edit > Apply transformation' tool to shift the cloud with the last remaining digits.

[Möller]

Okey, thanks! I'll make a note of this.