This "seams" wrong.....

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dcacioppo
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This "seams" wrong.....

Post by dcacioppo »

I have noticed mismatches in my x330 scanner start/stop locations. Anyone else seeing this? Using Scene 2022.0.0. The scanner was sent in for calibration due to this, but came back with the same issue and an invoice......
I attached the planar view that clearly shows the mismatch. I also included a picture of the scan point data showing the overlap with mismatched points. The scan data a single scan, not multiple scans registered together.

Any thoughts?
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landmeterbeuckx
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Re: This "seams" wrong.....

Post by landmeterbeuckx »

This is not uncommon. Just measure a point left and right from the line which have to have a certain z-value.

Points visual at different heights should give the same z
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Re: This "seams" wrong.....

Post by Ioannis »

Wrong calibration! :o
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Re: This "seams" wrong.....

Post by Leandre Robitaille »

This could maybe be fixed with a on site calibration but this being the older X series you can't do that and need to send the unit in for calibration.
This is your tipical out of calibration error, could result from a bunch of things, faro units loose calibration easily.
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Re: This "seams" wrong.....

Post by Mike Annear »

I agree with Lieven,
Measure the pointcloud, don't go by the image in faro Scene, I vaguely remember seeing this issue before.
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Re: This "seams" wrong.....

Post by VXGrid »

dcacioppo wrote: Sat Aug 13, 2022 2:11 pm I have noticed mismatches in my x330 scanner start/stop locations. Anyone else seeing this? Using Scene 2022.0.0. The scanner was sent in for calibration due to this, but came back with the same issue and an invoice......
I attached the planar view that clearly shows the mismatch. I also included a picture of the scan point data showing the overlap with mismatched points. The scan data a single scan, not multiple scans registered together.

Any thoughts?
landmeterbeuckx wrote: Sat Aug 13, 2022 2:28 pm This is not uncommon. Just measure a point left and right from the line which have to have a certain z-value.

Points visual at different heights should give the same z

What Liven said, but in addition: Same points should have the same X, Y and Z.
Perhaps you never noticed before or the gap was smaller.

Explanation: The scanner measures not 360° in one face, but 2 * 180° in 2 faces. When measuring a little bit more, like 181°, you get two areas which are doubled, the start - end and in the middle is another overlap area.

This was done by a FARO Focus:
overlapArea.png
It is not harmful at all, if one wants to remove this a complete resample might be necessary.
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Re: This "seams" wrong.....

Post by Tanguy Nédélec »

There is an easy way to test this: do a scan in front of a wall, and select a thin rectangle across the start/end overlap in quick view. Right-click the selection -> 3D view, and switch to a top view. If you see no "double wall", then all is good!
Do the same with the ceiling, floor, and test a few different spots (high/low, near/far).

You might have sent it to calibration unnecessarily...
1.png
2.png
3.png
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Re: This "seams" wrong.....

Post by TommyMaddox »

tengui wrote: Wed Aug 17, 2022 8:03 am There is an easy way to test this: do a scan in front of a wall, and select a thin rectangle across the start/end overlap in quick view. Right-click the selection -> 3D view, and switch to a top view. If you see no "double wall", then all is good!
Do the same with the ceiling, floor, and test a few different spots (high/low, near/far).

You might have sent it to calibration unnecessarily...

1.png
2.png
3.png
You're much more likely to see a seamline mismatch on a strip belonging to the floor and/or ceiling than on a surface normal to the mirror, you'd primarily be looking at a ranging error with that selection if it is at the same height as the scanner mirror/origin. Someone with a better understanding of photonics/scanner operation can correct me if I'm mistaken here.
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Re: This "seams" wrong.....

Post by Tanguy Nédélec »

TommyMaddox wrote: Wed Aug 17, 2022 7:08 pm You're much more likely to see a seamline mismatch on a strip belonging to the floor and/or ceiling than on a surface normal to the mirror
I think so too, if you have error on the vertical axis, or on the vertical circle (vertical index). I don't know how likely these are to occur on a Faro, however I've seen ranging errors personally, and if I remember well, described on this forum too.
So in conclusion: do check both the ceiling/floor and the wall in front 🙂.
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Re: This "seams" wrong.....

Post by john-newbegin »

I have had this problem many times before, but doesnt usually affect the 3d points at all just an image thing, same suggestion grab selection that covers both sides and look at a 3d view of it in camera or perspective and you can see if its fine or messed up, I freaked out over this for a while also but same thing I sent in for calibration and still did this from time to time.

I dont know but I thought it had to do with when it does the inclometer spinning back and forth after scanning before doing photos I thought it came from there..

Same thing can happen if someone bumps the scanner but that will show really messed up like 2 different surfaces in the 3d view.

John
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