Faro Users - What am I looking at?

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Dedken
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Re: Faro Users - What am I looking at?

Post by Dedken »

It really is bizarre. The scanner doesn't even seem to be mounted concentrically on the tripod.
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Re: Faro Users - What am I looking at?

Post by jedfrechette »

jcoco3 wrote:Looking at that bracket more it appears to be a heavy duty dual camera head, and you can almost make out the faint outline of a label on the right side of the center.
Maybe this one?
http://www.gitzo.com/double-platform
It looks to be about the right size judging from the shadow and since they appear to be using a Gitzo panohead and tripod...
richard_m wrote:Now you mention it the tribrach thingy could easy be a camera mount, the scans are color, maybe rotating the whole bracket 180deg around its centre point puts the camera on the nodal point of the scanner?
That could be an interesting setup, but since you can see the Gitzo panohead in the photos/data wouldn't that suggest the scanner's internal camera was used rather than an external one mounted on that head?
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Re: Faro Users - What am I looking at?

Post by Andrej »

Hi

my input to the mystery would be

They used the assumption that the Faro scanner starts from the same position every time. They orientated the unknowns tripod set up 90degrees to the previous scan station. This would give them a orientation for the scanner (I would use the internal compass). For the position they surveyed the target mounted under the scanner.

You could easily check if the scans are rotated to each other but the centre position has the right distance - assumptions are that they surveyed every scan position (1300 quite a lot).

All the best.
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Re: Faro Users - What am I looking at?

Post by richard_m »

Hi all, thanks for the replies.

Sincere thanks must go to jcoco3 for his forensic data snooping, with his help it looks like a methodology is emerging..

They appear to have used the double camera bracket only so that they can mount a TS target directly under the scanner, with a known vertical offset they can position every single scan position, there’s almost always a TS in the scan. Using the on-board compass they know an approximate orientation such that they can use a C-C constraint to “fine-tune” the orientation between scans with a bundle adjustment. When I say "fine" in mean in the barn-door and not swiss-watch sense..

For this project all they needed to produce was a relatively low accuracy registration that could be converted into an LFM database for pipe-modeling and not serious engineering so if they’re 10cm out its not the end of the world. I kinda like seeing people inventing custom workflows that are optimized for a particular application and happily this makes up a large part of my job. In this case the results are, to be honest, patchy as some areas are pretty accurate and in others I’ve found 30cm misalignments. Their biggest problem as I see it is that they’ve not made enough scans, this means their reg (based largely on C-C constraints) is rough as they’ve little overlap in most places and for the point of view of modeling, the very purpose of the project, they just don’t have enough data on the pipework. We're doing double their number of scans. I’m being a bit careful not to be too critical as there’s some clever thinking here, its just executed badly.

Does this sound plausible to Faro/scene users in particular?

Richard
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Re: Faro Users - What am I looking at?

Post by Ccctucker »

I know this is old, but no conclusive answer has been delivered, so I will add my thoughts..

Maybe they just removed the other camera while doing the scans. Since the target objects were not low enough to be obstructed by the mount, they just accepted the object being in the scans.
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