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I have an object (an eggshell fragment) that I want to scale to its real size to get a volume calculation. I pulled the mesh as an STL file from another software and the scale is completely wrong, but I assume that the proportions should be the same. I have tried changing the unit scale to match millimeters and for some reason, the size is still wrong. When I use the measure tool the object is off by about 4 mm. Also, the dimensions say it is over 5000 m in size. Where did I mess up, and how do I fix it? The volume calculations are for research purposes so I want to be as accurate as possible.enter image description here

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  • $\begingroup$ I'd say there is a bug when setting the unit scale to 10^-6. I usually use 10^-3 as most STLs I've seen assume 1unit = 1mm. You seem to be using 1unit=1µm. Not sure, but it could be a problem with floating point representations. Perhaps you could scale your model by a factor of 1,000 then work in mm instead of µm? $\endgroup$
    – Ron Jensen
    Oct 19, 2021 at 4:53
  • $\begingroup$ I tried changing it to a factor of 1,000 but am running into a similar issue. The dimensions still don't make sense. In the original program where I rendered the object the top of the eggshell should be about 7 mm across, so I'm confused as to why it isn't matching. $\endgroup$
    – Ash
    Oct 19, 2021 at 7:45
  • $\begingroup$ Can you share the stl? $\endgroup$
    – Ron Jensen
    Oct 19, 2021 at 12:52
  • $\begingroup$ Sure, I could do that. I poked around a little more and noticed that the same thing happened with ZBrush. $\endgroup$
    – Ash
    Oct 20, 2021 at 4:48

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