3D Deviation Problem

[servetgunday]

Hi guys,

I have 2 point cloud and i did analysis Meas beetween ref.
DevX=+ DevY=+ DevZ=+ but 3D= -
who explain this pls ? I cannot tell to my customer.

[Scott.Warren]

UCS and coordinate systems is my guess.

When you make an analysis, label something, export stuff, it looks at the active UCS for direction. If you have a world UCS on a typical coord system, your labels will be too. If you make a UCS of the wall (for example), with Z being the same as the world coord, and the X-Y origin the same as where the wall begins, you will have labels that make more relative sense.

[servetgunday]

UCS and coordinate systems is my guess.

When you make an analysis, label something, export stuff, it looks at the active UCS for direction. If you have a world UCS on a typical coord system, your labels will be too. If you make a UCS of the wall (for example), with Z being the same as the world coord, and the X-Y origin the same as where the wall begins, you will have labels that make more relative sense.

Hi Scott, i tried with local ucs and again analyse but result is not changed. dX, dY, dZ are pozitive, 3D deviation is negatif. Measurement is okey true but we dont understand whats mean negative or pozitive

[Nicolas L]

Hello

The sign of an inspection also depends on the reference cloud selected first. I remind that in the cloud/cloud inspection, the colored object is the one which is projected (the second selected or the measured one).

Each point is projected in the direction of the local normal of the cloud on a local plane. In other words, the "distance" is not the closest distance to a point of the target cloud, but the closest distance to a local plane of the target cloud.

That being said, we will also check on our side.

Regards

Nicolas L

[Scott.Warren]

UCS and coordinate systems is my guess.

When you make an analysis, label something, export stuff, it looks at the active UCS for direction. If you have a world UCS on a typical coord system, your labels will be too. If you make a UCS of the wall (for example), with Z being the same as the world coord, and the X-Y origin the same as where the wall begins, you will have labels that make more relative sense.

Hi Scott, i tried with local ucs and again analyse but result is not changed. dX, dY, dZ are pozitive, 3D deviation is negatif. Measurement is okey true but we dont understand whats mean negative or pozitive

I think the local UCS has to be enabled prior to analysis of a selected cloud. If i didn't have the local UCS made to represent the plane of the wall, the labels would use the UCS that was enabled prior to the creation of the inspection cloud. This seems to line up with what Nicholas is saying about the local plane, which is the one that is enabled prior. ( I don't work for Lieca and could be way off)

I would use the Wall-Wall UCS tool, make a new UCS of the wall, and while that UCS was enabled, started to select a cloud section for inspection. I found the labels I created were great as long as the local enabled UCS matched the coordinate system before using the analysis tools.

Food for thought, happy to learn if I'm missing something.

[servetgunday]

same axis and same protrusion but diffrent value, i try wall+wall ucs still colors diffrent. help pls.

[Nicolas L]

Hello
Sorry for the delay of my answer but I did not receive a notification.
The deviation sign between two point clouds is properly defined if each point cloud has scanning direction information. You can check that in their properties: Scanning direction on all points: Yes or No
Was it the case?
If not, the normal direction of the local plane used to compute the deviation between two point clouds may be unsuitable. Consequently, the distance is well computed but the sign may be reversed.
If your point clouds have no scanning direction, one way consist in creating a mesh from one of the two and compute the comparison between the mesh and the point cloud.

Regards
Nicolas L