Hi guys,

For the past 2 weeks I'm trying to scan a part on my bike, kind of circle of 360mm diameter. I cannot scan it in one shot so i pan the scanner around following the circumference of the circle. But whatever i do, i end up with a mesh that has defect, i can see the circumference of the circle from one scan to the next does not mesh nicely, it's off by 1 or 2 mm. I tried to align the point clouds myself using Meshlab, it's a little better but still off by more than 1 mm.

I was thinking tonight that maybe the scanner does not read the surface properly. So i devised a simple test to check this. Results are below, the scan can be off by as much as 6 mm in some places !!!

Here is the test I've done:

- put the scanner in front of a perfectly flat white table, vertically standing, about 50 cm away.
- i checked that the scanner is leveled, and the table is vertical
- i made sure the scanner is focused, the distance i find with the sharpest cross is 50cm
- i scan the table, i should normally get a perfectly flat mesh, within 0.1mm.

But this is not what i get. The image below shows the deviation compared to a plane. I used Cloudcompare for this. I cannot get the scale to show on the right side. But i measured the worst deviation (red) at around 6-7 mm. You see the worst is in the upper left and bottom left corners.

You don't have to use any software to do this test, just scan a flat surface and check the result in Einscan. If you look at the scan from the side, you should be able to see if it's straight or not.

Would appreciate if someone can do the test so we can compare our results. Maybe it has to do with calibration. Well, hopefully. Because if all my scans are like this, this is not so good.

Maybe a workaround is to always delete these 2 corners at the end of each scan.

I tried to see if the problem gets worst when scanning at an angle, but i could not see difference, the same 2 corners are off. I wish there is a way to remove this defect by some kind of calibration.

Hope someone at Shining 3d reads this post.

plane_test.jpg