height grid generation with true Z

[d.elodie]

Hello,

I generate a height grid with my point cloud which is shifted because coordinates are too big and the height grid values display on the scale are the shift values but i need the original values.
Will it has a way to display the original values ​​? Or do I have to charge my point cloud without shift and perhaps lose some information on coordinates ?

Thank you,

elodie

[Dimitri]

Hi Elodie,

with the last version of Cloudcompare, there's no shift applied to the Z coordinate (you can check by looking at the properties at Global Shift, the third value sould be 0). Hence, the elevation of the new grid should be the true one.

Now for the coordinates, if you select a point with the "point picking tool" you'll have the local coordinate ("shifted" within cloudcompare) and the true one ("original" without the shift). When you'll export the data, the global shift will be reapplied so that you have not lost precision.

Dimitri

[daniel]

Well, as Dimitri pointed out older versions of CC suggested to shift the data in all dimensions even if the Z values were not so big. So the easiest thing is this case is to set 0 as global shift for the Z dimension (directly at loading time).

In the case your Z values are very big, you can apply the shift then use a little trick:
- export the Z coordinate as scalar field
- create a new constant scalar field ('Edit > Scalar Fields > Add constant SF') wit the Z shift as unique value
- then call the 'Edit > Scalar Fields > Arithmetic' method and generate a new scalar field corresponding to 'Coord. Z' plus 'Constant' (see constant)

cc_arithmetic.png (10.41 KiB) Viewed 3402 times

This will result in the creation of a new scalar field with the right height values (hopefully).