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I'm trying to create an outline of a building on top of a point cloud that is georeferenced.

Because it's georeferenced, the object needs to be far away from the world origin (about 500000m). There, weird stuff begins happening. The mesh gets a "ghost" effect and the exported mesh is completely ruined in the sense that faces appear and disappear seemingly at random. This also appears once the object is exported. For example, I exported some geometry in FBX format and opened it in Maya and in MeshLab to find the same errors with the mesh as in Blender (the only difference is that there's no ghosting in other software packages).

enter image description here

Here is an example of a cube with a wireframe modifier with this problem. Notice the uneven edges and lack of visible faces.

Any help would be greatly appreciated.

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This is most likely because of memory limit on the numbers, aka a “precision error.” Try telling someone to give you three thousand four hundred and seventy-eight tons and two ounces. Most likely, they will forget the two ounces, and computers are the same way, unless you specifically tell them not to.

But anyhow, why does the object need to be offset from the world origin so far? Surely you can adjust the georefrencing somehow?

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  • $\begingroup$ I probably could but it's not my decision to make because the client uses this measurement. I exported the object at the world origin and manually set the transformation in another program. This worked but I would still like to find the solution for such cases for future projects $\endgroup$
    – Jernej Kalin
    Commented Apr 12, 2021 at 17:31
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    $\begingroup$ @JernejKalin There is no solution to this problem. You have to use transforms that are relatively close to the origin of the world in Blender, otherwise you won't have deterministic precision due to floating point precision error $\endgroup$
    – Gorgious
    Commented Apr 13, 2021 at 10:15

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