100mm vs 230mm sphere targets vs flat targets

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MomentEng
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100mm vs 230mm sphere targets vs flat targets

Post by MomentEng » Tue Feb 12, 2019 2:01 am

All,

I'm in need of sphere targets so I need some advice from experience users...It makes that the larger targets will provide more range out of the registration, but my scanner is limited to 70m. Will the larger targets provide better registration at shorter distances or will the benefits be negligible. Also would like the groups opinion on the flat targets. If you haven't noticed by my questions, I'm new to scanning and need things explained from the basics. I have done lots of reading, but its not a replacement for experience.

trinibears
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Re: 100mm vs 230mm sphere targets vs flat targets

Post by trinibears » Tue Feb 12, 2019 3:19 am

Hello Fellow Noob,

Im suggesting you specify the scanner and software you are using and also the end result quality/use of the scan data you collect.

I use A Faro M70 and Scene, 25% overlap, without Targets and get great results for As-Building.
in my opinion Flat paper targets only help where there is featureless or highly repetitive features in my scans.

I currently dont use spheres at all......unless youre doing outdoor open space scanning (waste of $$ IMO).

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tadol
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Re: 100mm vs 230mm sphere targets vs flat targets

Post by tadol » Tue Feb 12, 2019 3:59 am

Spherical targets are far less necessary than they were - I know many people who are getting by without them, but I also know more than a few who either won’t scan without them, or find themselves wishing they had them for some jobs.

Personally, I’m biased - I think everyone should have at least one set of targets, even if they don’t do scanning.

The size of targets is only one variable - you also need to think about the amount of detail you need to collect, the amount of time you want to spend on the site, and how many scans you really need to do to collect all the data. A few large targets can help tie together a smaller number of high resolution scans, a bunch of smaller targets can help tie together lots of very quick scans. And the targets can help act as references to tie in known data points, and can make the registration process faster and possibly easier.

I do not recommend targets as small as 100mm - 150mm is a good minimum size for most applications, and 200mm are good for larger or outdoor work. Of course, at this point I need to put in all the usual disclaimers, since I also make 80mm targets (mostly for trajectory analysis, but also used for other applications) and I make 250mm targets and 380mm targets - both of which I mostly recommend for more specific work, which it doesn’t sound like you are probably doing.

If you are interested, feel free to email me directly, and I would be glad to try and help - I always offer discounts to LSF members -

Tad
http://www.KoppaTargets.com
Inexpensive Laser Scanning Targets & Accessories
for Architecture, Engineering, & Forensics
Now Available thru the FARO product catalog

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Re: 100mm vs 230mm sphere targets vs flat targets

Post by LPaulCook » Tue Feb 12, 2019 6:22 am

What Ted said is correct. He makes the best targets too!
L. Paul Cook, PLS
www.LPC3D.com

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Re: 100mm vs 230mm sphere targets vs flat targets

Post by SAttaya » Tue Feb 12, 2019 2:23 pm

tadol wrote:
Tue Feb 12, 2019 3:59 am
...
Personally, I’m biased - I think everyone should have at least one set of targets, even if they don’t do scanning.
...
Tad
If you don't do scanning, I guess you put:
* sphere targets on your Christmas tree, and
* quadrant targets are used for archery practice

right? ;)

Apologies in advance.

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Re: 100mm vs 230mm sphere targets vs flat targets

Post by MomentEng » Tue Feb 12, 2019 4:06 pm

tadol wrote:
Tue Feb 12, 2019 3:59 am


If you are interested, feel free to email me directly, and I would be glad to try and help - I always offer discounts to LSF members -

Tad
Thanks, I'm definitely interested...i scanned a project that I was not able to get enough overlap in the scans and the registration was not as good as I wanted it to be...fortunately it will likely not be a key part of the work but if it would have been, I would be in a bind.

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Re: 100mm vs 230mm sphere targets vs flat targets

Post by MalteHC » Wed Feb 13, 2019 8:20 am

It depends if you point out your targets on your scanner on field or if you point them out in your registrationsoftware. If you do it in your registrationsoftware, the needed size of your target is equal to your density of your pointcloud.

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Re: 100mm vs 230mm sphere targets vs flat targets

Post by max72 » Wed Feb 13, 2019 5:24 pm

There were some discussions about sphere range here:

viewtopic.php?t=9603

https://www.laserscanningforum.com/foru ... 1&start=60

Massimo
ing. Massimo De Marchi - +39 347 32 17 049 - www.studiodemarchi.net

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Re: 100mm vs 230mm sphere targets vs flat targets

Post by Oxbow » Thu Feb 14, 2019 7:05 pm

Hi,

In general, you extend about 1.5 times one's reference point range and thus have stable results. You probably have a FARO S70. With our spheres with the standard diameter of 145 mm you can see the spheres at 1/4 between 20 and max. 25 meters (outside and inside). So you can measure about 30 to 35 meters safely. If you want to continue longer range, you should use 200mm spheres. They go up to 40 meters in detection and then you are almost at the maximum range. Indoors this is not recommended, however, since these are too tricky to handle. Checkerboard detection is more critical, if you are not looking straight on it. Then you have less accuarcies.

Important are also, how you measure. If you have connection between different scan positions and same reference, a good registration software will be able to calculate adjustments about it. This make your global registration better.

Also with new scene and faro scanner update, you can make long range detail scanning. There is a option to scan to reference more longer. A combination of longe range target and short range targets make probality sense to get better registration result, but we did not try it out yet. Maybe we will do this soon.

..Eric

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