Focus X330 360 degree scan misalignment

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BrendanM
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Focus X330 360 degree scan misalignment

Post by BrendanM » Thu Feb 15, 2018 1:38 pm

Hi All, wonder if anyone can shed some light on an issue we keep having with our X330 scanner. The unit is roof-mounted upsidedown (approx. 3.5m) above our research tank in which we conduct experiments looking at the interaction between water flows & sediment. We generally scan the resulting surface (usually quartz sand) once it has developed some morphology after each experimental run (and once it has sufficiently dewatered). The scanner is set-up to measure 0.0 to 360.0 horizontally and -60.0 to 90.0 vertically and we use a range of resolution & quality settings.

We have noticed this 'mismatch artefact' (see attached images) in the majority of our scans. Our scanner has recently been back to Faro for recalibartion & service but this issue occured in scans both before and after servicing. Any help would be appreciated. Thanks.
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Re: Focus X330 360 degree scan misalignment

Post by tbwester » Thu Feb 15, 2018 5:45 pm

its hard to tell what im looking at. Is it is a misalignment between the overlapping portions of the scan? It looks like something else.

Could you color in elevation to show the offset better?

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Phil Marsh
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Re: Focus X330 360 degree scan misalignment

Post by Phil Marsh » Thu Feb 15, 2018 6:02 pm

It could be the scanner out of calibration slightly so giving more of a height difference on the overlap.

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Re: Focus X330 360 degree scan misalignment

Post by jcparks » Thu Feb 15, 2018 6:09 pm

This was a few years ago - We had some scans that had different but strange defects and we contacted Faro. They had us upload the problem scans and they sent us back with a calibration file that made those scans better. Perhaps if you find the right technician, they could do the same?

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Re: Focus X330 360 degree scan misalignment

Post by BrendanM » Fri Feb 16, 2018 10:03 am

Thx for replies. The issue does not appear to effect elevation/height values but rather it seems to be a misalignment in the horizontal when undertaking a 360 degree scan. There seems to be a lack of data points on one side of the scan and a duplication on the other side (although this is more difficult to discern).

I have attached some additional images to try and more clearly illustrate the issue.

We had this problem before we sent the scanner for servicing/recalibration, we had hoped that the servicing/recal would sort this out but it is still occuring.
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Re: Focus X330 360 degree scan misalignment

Post by tbwester » Sat Feb 17, 2018 2:59 am

its funny. Im looking at a scan right now from our 330 and it has the exact same problem. I never noticed it!

Its a gap between the overlapping scan lines. Its not a calibration error as mine is accurate in the Z and Horizontal, just a small angled void.

maybe just change the angle of your scanner so the zenith is not within the area of interest? (just thinking of a simple fix). The only effect it would have is a void space, I dont think (at least on my data) will effect the accuracy.

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Re: Focus X330 360 degree scan misalignment

Post by Scott » Sat Feb 17, 2018 3:17 am

I've had it show in the scans since 2012, but it hasn't been a accuracy problem (though I wish the artifacts weren't there at times). It only shows up in the first batch of registration scans and is subsequently filtered out.
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Re: Focus X330 360 degree scan misalignment

Post by BrendanM » Mon Feb 19, 2018 10:22 am

tbwester wrote:
Sat Feb 17, 2018 2:59 am
its funny. Im looking at a scan right now from our 330 and it has the exact same problem. I never noticed it!

Its a gap between the overlapping scan lines. Its not a calibration error as mine is accurate in the Z and Horizontal, just a small angled void.

maybe just change the angle of your scanner so the zenith is not within the area of interest? (just thinking of a simple fix). The only effect it would have is a void space, I dont think (at least on my data) will effect the accuracy.
Hi Thad (and Scott), Thanks for your replies. We have taken the pragrmatic view and realigned the scanner such that the void artefact falls into an area we are not interested in on this occasion. This is OK for this set of experiments but it might not be an easy option in others.

I would welcome a response from Faro explaining why this artefact occurs..........(but I'm not holding my breath on this score!!).

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