Experience with spherical targets

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chrisg.cmg
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Experience with spherical targets

Post by chrisg.cmg »

We've been using black and white targets for ages but are considering getting some spherical targets to compliment these. Have people found that spheres are easier to pick up at a greater range, especially if being passively acquired (we're using P-series so can do target scans if need be)?

What has been the experience with the success of the 'find spherical targets' option on import of the raw data?

My hope is that since you need fewer points on them to define the sphere vs BW, you can get away with picking them up in lower resolution scans/from further away/without doing a target scan.
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Leandre Robitaille
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Re: Experience with spherical targets

Post by Leandre Robitaille »

In short ;
Long distance for most scanners a checkerboard will have better results (the bigger the better)
Spheres are useful for convenience.

I run multiple scanners and spheres are easier to have, don't need to rotate them(risk of error here) since they can be captures on both sides I usually run 2 scanners on site. I am maybe a bit biased because I use faro scanners. I have 6 small spheres (145mm) and 6 big spheres (200mm) per scanner we own (5)
We do rent P40 scanners every now and then and I still like using spheres with them that I use close range for those fast black and white scans in shorter range areas (20-50m zones). Dealing with spheres is a little bit harder with Leica scanners so I only carry one size of sphere on site when using leica (either only 145mm or only 200mm) I do carry a few leica checkerboard tough for long distance shots for added accuracy when scanning in larger areas. For TS control I use ''sticker'' checkerboard. Easier for me to simply concentrate on scanning and come back later with the TS for controls (or I can do a TS run first then scan).
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Re: Experience with spherical targets

Post by fobos8 »

Leandre Robitaille wrote: Sat Oct 23, 2021 2:00 am For TS control I use ''sticker'' checkerboard. Easier for me to simply concentrate on scanning and come back later with the TS for controls (or I can do a TS run first then scan).
Hi Leandre
Which "sticker" checkerboard do you use. Do they stick to rendered/painted walls
Regards
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Re: Experience with spherical targets

Post by sim.herrod »

fobos8 wrote: Sat Oct 23, 2021 1:19 pm Which "sticker" checkerboard do you use. Do they stick to rendered/painted walls
Regards
We use these...
https://shop.laserscanning-europe.com/C ... e-as-a-set

...and these...
https://shop.laserscanning-europe.com/c ... e-as-a-set

...depending on circumstances. Never had one fall off.
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Re: Experience with spherical targets

Post by fobos8 »

chrisg.cmg wrote: Fri Oct 22, 2021 5:48 pm We've been using black and white targets for ages but are considering getting some spherical targets to compliment these. Have people found that spheres are easier to pick up at a greater range, especially if being passively acquired (we're using P-series so can do target scans if need be)?

What has been the experience with the success of the 'find spherical targets' option on import of the raw data?

My hope is that since you need fewer points on them to define the sphere vs BW, you can get away with picking them up in lower resolution scans/from further away/without doing a target scan.
I use spheres a lot these days externally. If you get Scene to find them when processing it will find other things similar to spheres but you'll find you won't get many correspondences between these non-sphere spheres. I use 145mm spheres at 1/4 res and 2× quality i get brilliant results. Up to 25 -30 metres i use 1/2 res.

I'd think for longer distances you'd be better with 200mm spheres.
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Re: Experience with spherical targets

Post by Leandre Robitaille »

fobos8 wrote: Sat Oct 23, 2021 1:19 pm
Leandre Robitaille wrote: Sat Oct 23, 2021 2:00 am For TS control I use ''sticker'' checkerboard. Easier for me to simply concentrate on scanning and come back later with the TS for controls (or I can do a TS run first then scan).
Hi Leandre
Which "sticker" checkerboard do you use. Do they stick to rendered/painted walls
Regards
Damn I wish I was sponsored for this lol
We use these ; https://tdr360.com/produit/cible-carree ... permanent/
And we ask TDR to add our logo instead on the stickers. We order thousands of those. They are a company local to where I live so its supporting local economy. Plus they make really good stickers.I either use clear silicone for moderate adhesion for temporary scans (1-2month use) or I use PL glue on some surfaces to make them more permanent(2-3years). They stick good on their own but need a little help for concrete plus they are numbered unlike the laserscanning europe shop ones. I just did a project that they wanted permanent checkerboards for future scanning(from anyone), easy to share their coordinates by having a clear number on them
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Re: Experience with spherical targets

Post by chrisg.cmg »

Leandre Robitaille wrote: Sat Oct 23, 2021 2:00 am In short ;
Long distance for most scanners a checkerboard will have better results (the bigger the better)
Spheres are useful for convenience.

I run multiple scanners and spheres are easier to have, don't need to rotate them(risk of error here) since they can be captures on both sides I usually run 2 scanners on site. I am maybe a bit biased because I use faro scanners. I have 6 small spheres (145mm) and 6 big spheres (200mm) per scanner we own (5)
We do rent P40 scanners every now and then and I still like using spheres with them that I use close range for those fast black and white scans in shorter range areas (20-50m zones). Dealing with spheres is a little bit harder with Leica scanners so I only carry one size of sphere on site when using leica (either only 145mm or only 200mm) I do carry a few leica checkerboard tough for long distance shots for added accuracy when scanning in larger areas. For TS control I use ''sticker'' checkerboard. Easier for me to simply concentrate on scanning and come back later with the TS for controls (or I can do a TS run first then scan).
I'm hoping that Cyclone will have luck auto detecting spheres even if there isn't a ton of resolution on them (ie. at long range). Doing target scans is always an option but slows things down. It will likely be possible to manually pick out the spheres as well. Has anyone noticed a difference in accuracy of identifying the sphere center with a low number of points vs with black and white/sticker targets?
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Re: Experience with spherical targets

Post by MajorDomo »

chrisg.cmg wrote: Mon Oct 25, 2021 8:23 pm I'm hoping that Cyclone will have luck auto detecting spheres even if there isn't a ton of resolution on them (ie. at long range). Doing target scans is always an option but slows things down. It will likely be possible to manually pick out the spheres as well. Has anyone noticed a difference in accuracy of identifying the sphere center with a low number of points vs with black and white/sticker targets?
Spheres lose out against a checkerboard target that is angled towards the scanner, whenever the distance went past 20 meters or so, it became twice as bad, and doubled every 20 meters or so.
So that means mor distance = more resolution = slower.
We just got extra-large black and white tilt and turns.
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Re: Experience with spherical targets

Post by chrisg.cmg »

MajorDomo wrote: Mon Oct 25, 2021 8:43 pm
chrisg.cmg wrote: Mon Oct 25, 2021 8:23 pm I'm hoping that Cyclone will have luck auto detecting spheres even if there isn't a ton of resolution on them (ie. at long range). Doing target scans is always an option but slows things down. It will likely be possible to manually pick out the spheres as well. Has anyone noticed a difference in accuracy of identifying the sphere center with a low number of points vs with black and white/sticker targets?
Spheres lose out against a checkerboard target that is angled towards the scanner, whenever the distance went past 20 meters or so, it became twice as bad, and doubled every 20 meters or so.
So that means mor distance = more resolution = slower.
We just got extra-large black and white tilt and turns.
Ok good to know, very interesting.
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Re: Experience with spherical targets

Post by Justin Richards »

We use the KOPPA spheres. We have 3 of the 250mm and 18 150mm plus some small ones that hardly get used.

PROS
-easy to move around
-can be scanned at any angle
-less mistakes when auto registering
-Koppa spheres are pretty strong. The aluminum ones are not.
-they can be used on control marks to align scan with Revit model etc.

CONS
-on busy construction sites they are prone to being kicked when on the floor and I've had people grab them when attached with magnets.
-when they get slightly moved it can cause issues with the scan.
-harder to transport
-expensive

I use them almost every job but I keep targets on hand, especially for stairs.
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