Revopoint generated mesh coordinate system

What is the coordinate system that the mesh generated by Revopoint is in ?

Millimeters

@bau-3d.ch I meant not the units of the vertices but what is the coordinate system these vertices are in ?

Do you mean the coordinates of the origin ?

@PUTV I mean the coordinate system of the mesh when I export it from Revopoint as an obj. Also, is there a way to control this export to define what coordinate system I want it in ?

It’s a Cartesian coordinate system.

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Thanks @oliva . @PUTV And also what about the coordinates of the Origin where is it situated in the mesh?

OBJ coordinates have no units, but OBJ files can contain scale information in a comment line.
The origin of a mesh starts with the first frame the scanner captures on the specific scanner position and it happening on the hardware and the rest of the frames is aligned to that position in automatic process .

I know what you looking for , but this information at this moment is not shared by the software , neither can be exported and used .

The scanned model has the correct size if interpreted as mm. The file is saved as Y-up. The origin of all my scans is outside the object. All my scans have a weird ~45° rotation. And none of the exported scans can be imported in my main 3D-program because of a normals-issue in the exported .obj-file.
So my standard workflow is importing it to Blender and exporting it again so I can use it. Then I move the origin to the object’s base and tweak the rotation. Doing all that just takes a couple of minutes…

@oliva @PUTV thank you for your detailed reply. it all makes sense now.

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Hi @oliva

The obj is exported in rich format including also color per vertex that maybe why your 3D program have issues with reading it correctly .

The normals are ok as all my 3D programs reading it correctly , as long it support and can read rich format OBJ .

If u mean the orientation, I have already started a suggestion about that and wrote a tool to align Meshes correctly: Align to Coordinate System Using Surface Approximation in RevoScan

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I don’t understand why it needs to write vertex color information in a file that contains pure geometry (a meshed scan). The beauty of the .obj-format is it’s simplicity and compatibility. Approaches like this (saving unsupported data channels) breaks it’s usefulness completely.

All software I use has no issues with the rich format and I’m using a lots of software. You might consider trying.ply mesh export instead of .obj in most cad software.ply works better. Or use cloudcompare and convert the files

So I should use a format that supports vertex colors to save an object without vertex colors because the file format that usually does not support vertex colors is misused to save them? That’s… odd.
And could you please provide me a link to this “rich obj” file format’s specifications? I haven’t found anything.

In addition to geometry data, OBJ files can also store material information and group definitions and color per vertex, allowing for the organization and visualization of complex 3D models. These features make OBJ files a comprehensive format for representing 3D scenes and objects, providing a rich set of data to work with for 3D artists and developers.

And I use it for the last 25 years as my most favorite format .
OBJ is not only reserved to support geometry data .

You want a stripped geometry data only ? Use STL .

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That is not accurate statement regarding OBJ format .
You want pure geometry? Use STL

You are using a 3D scanning software that include not only color per vertex but also UV coordinates and textures .
Color per vertex is very usable in modeling in various situations , it can be converted into color textures , guide the alignments of 2 scans and many other great stuff .

If OBJ support only pure geometry , CGI would never exist .

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