Mounting Scanner for Interior Tank Scan

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berdindc
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Mounting Scanner for Interior Tank Scan

Post by berdindc »

Trying to come up with a method for scanning the interior of a 30' diameter tank. The only access points are small hatches, see image. I am envisioning a piece of tube steel or angle that we mount the scanner on and then feed inside the tank. End of the angle/tube is then anchored via clamp of some sort. Scanner activated remotely.

Will only be one scan so no need for targeting. This is a one-off thing but it's a bit tricky and nerve-wracking to place the scanner in an untried position! Scanner is a FARO.
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Re: Mounting Scanner for Interior Tank Scan

Post by Stephen.Strand »

How about a jib crane? Do you have to close the door while scanning?
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Re: Mounting Scanner for Interior Tank Scan

Post by NOVAMECH »

What is the purpose of the scan.? What accuracy is required..I will post some images of something like this scanned with a DPi-8 with like system.
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Re: Mounting Scanner for Interior Tank Scan

Post by Stephen.Strand »

This is my idea for using the jib.
tank-scan-with-jib.jpg
Here is the link to the jib we have, you could probably make it yourself, or at least something similar, if you have access to the materials.

http://ezfx.com/

I could definitely see it being of good use for this project. Also, is the downcone going to be a problem? You may need to run two scans to get complete coverage (1 - scanner upright, 2 - scanner inverted), depending on how high you are planning on running the scan, or if you need the floor or not.

Hope this helps!
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Re: Mounting Scanner for Interior Tank Scan

Post by jcoco3 »

I might be missing something here, but is there a reason you need to extend it far out into the vessel? I would think that you would be fine with just sticking it in a couple of feet. Getting close to the center will only make the void circle bigger, but maybe you are concerned about uniform density of the data? If that is the case then why not just scan at a high res then spatial filter later? Vibration will also have less of an effect if you keep things short.

Anyway there are a million ways to do this, and if you can just fold up the legs of the tripod and shove it in there with the back end stabilized somehow then go for it. I have done that with a gitzo tripod so many times I get sick thinking about it, but the gitzo has never failed me.

I can't say enough about telestrut (perforated tubing), you can buy it almost anywhere and while it is ugly, it is strong and easy to adjust. I have probably posted these on this forum before, but here are a few examples anyway.

We had to sledge a hole in the side of the elevator because the elevator guy said they don't even make keys for elevators that old anymore:
20151029_103207.jpg
20151029_103217.jpg

A little more complex, but made on fly that morning:
Resized_20160622_131105.jpg
Resized_20160622_131117.jpg

2" EMT conduit:
selfie2.PNG
sketchy.jpg
Edit:

One other thing...if you get it out on a pole and are worried about whether or not it is moving, you can try to observe the scanner through the magnified scope of a transit, total station or even a camera from a fixed position(that is not also vibrating). Sometimes you can see the motion if you are zoomed in.

Another cool option if you want to get real nerdy: https://lambda.qrilab.com/site/
and an example I did with my mobile phone recording at 60fps:
https://www.youtube.com/watch?v=WUqaVq6 ... e=youtu.be


youtu.be/WUqaVq6a4_g
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Re: Mounting Scanner for Interior Tank Scan

Post by berdindc »

Not too concerned about the bottom of the tank. Main concern is near top, where tank starts to taper. They propose cutting off the "lid" at this point and popping on a new one. Plan is to use the scan data to pre-fab the new "lid". Idea is to get a good as-built of the circumference so the new "lid" can be butt-welded to the tank with minimal field rework.

If I turn the scanner sideways, obviously the inclinometer is worthless. But I could orient Z to axis of best fit tank cylinder and that would work. I assume the FARO has no problem rotating when held sideways?

Telestrut looks promising. I want to put it out 6 feet or so.. Any closer and I lose the angle to the top. I think accuracy needs to be tight, so not sure about the handheld DPi8
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Re: Mounting Scanner for Interior Tank Scan

Post by jcoco3 »

If I turn the scanner sideways, obviously the inclinometer is worthless. But I could orient Z to axis of best fit tank cylinder and that would work. I assume the FARO has no problem rotating when held sideways?
It is not completely worthless, as typically it will still get the scan in the upright position, just not the best sense of level. You can certainly rotate the scans on any axis after the fact in Scene. If you can perform another scan outside the opening looking in, then you can use its inclinometer to level the first scan through registration. Just turn of the inclinometer of the first scan in Scene prior to placing scans. Of course "level" may not be what is desired by the fabricator anyway, so you might be better off manually rotating or asking the fabricator what they want.

If you use a piece of 1", 1.25" and 1.5" telestrut you can get out to about 9 feet, but the platform better be very stable, because it has some flex to it at that point. Probably better off using something heavier like 4" box tube or pipe to get out 9 feet. I know 3" telestrut exist, as I have seen it being used for traffic control signage, but I have not looked for a supplier. If all you really need is 6', then at least make sure you capture a few scans for redundancy. If one had a bad vibration or movement during the scan then you can throw it away and try one of the "back-up" scans.

Some other things to maybe think about. Obviously this is to avoid a confined space entry or perhaps there is no floor or only coils/trays to step on. If there is a floor you could use a volunteer that has the confined space training to place the scanner for you. Are you certain there are no obstructions inside? The few dryers I have been in have had tubes hanging from the ceiling which blocked line of sight to the walls. Also if there is a floor maybe place the scanner on a wheeled tripod and push it to the center with a long pole.

Just throwing out ideas hoping that it will help :)
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Re: Mounting Scanner for Interior Tank Scan

Post by john-newbegin »

Nice with the unistrut, can I see an up close of how you mounted the scanner on that, did you make a custom mount or what did you do there?

I really want to scan in some manholes and we have a 5 story mechanical duct that doesn't have any openings, like you elevator shaft but we could pull an AC duct out and stick the scanner in I just haven't dared to yet because the cost and all.. don't quite trust it upsidown or sideways yet.. but I guess I could?

Thanks
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Re: Mounting Scanner for Interior Tank Scan

Post by jcoco3 »

I don't have any image up close of the end mount, but it is simple a piece of angle bracket from lowes or home depot with one leg chopped off and a 3/8-16" bolt going into the scanner. About as unsophisticated as you can get. Will try to get you an image tomorrow.
don't quite trust it upsidown or sideways yet.. but I guess I could?
If I only knew how many scans we have done upside down or sideways :o I used to think that it was special or difficult, but I am to the point where I wish there was another dimension to position the scanner in just to get an interesting thrill again. Please let it be known that it is ok to scan sideways or upside down :lol: The Faro scanners can handle this condition...furthermore we have entire projects that are upside down or sideways with no upright scans.
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Re: Mounting Scanner for Interior Tank Scan

Post by dhirota »

Jonathan

Another great thread by you.

Our friends at Leica support said that the BLK360 can be successfully run in any orientation like you have proposed using chop sticks to other extended metal rods as long as they have a 1/4X20 inch male screw some where attached to your $100 BLK360 Tripod Adapter.
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