sphere size

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sphere size

Post by LPaulCook » Sun Nov 29, 2015 6:43 am

Anyone know? What is the range difference to hit a 200mm sphere vs a 140mm sphere at 4x?
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Re: sphere size

Post by kiloweb » Sun Nov 29, 2015 1:23 pm

Paul,

Based on some of my testing, it does not seem that quality (3x, 4x, etc) has much of an effect on sphere detection in Scene. I'd say what matters most is the resolution. With that said, with a 200mm sphere, you can expect to get "green" lights in Scene with the following (numbers are approximate):

1/2 resolution - 93 feet
1/4 resolution - 76 feet
1/5 resolution - 45 feet
1/8 resolution - 35 feet

With a 140mm sphere, we will get green lights at:
1/2 resolution - 85 feet
1/4 resolution - 58 feet
1/5 resolution - 38 feet
1/8 resolution - 25 feet

This data has been gathered using Spheres created by Koppa Targets, which seemed to give consistent and reliable data.
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Re: sphere size

Post by tadol » Sun Nov 29, 2015 5:46 pm

And if you need more range, we offer 250mm and 400mm targets -

or 80mm, if you can get by with less -

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Re: sphere size

Post by max72 » Sun Nov 29, 2015 5:53 pm

I posted some data here:
https://www.laserscanningforum.com/foru ... 1&start=60

there are 80, 145, 200 and 300 1/4 and 1/2.
The results are more or less the same unless you scan at the range limits (for instance 1X has a range of about 30m...)

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Re: sphere size

Post by SAttaya » Mon Nov 30, 2015 5:17 pm

max72 wrote:there are 80, 145, 200 and 300 1/4 and 1/2.
The results are more or less the same unless you scan at the range limits (for instance 1X has a range of about 30m...)

Massimo
Would someone with some knowledge of how there are range limits based on QUALITY?

This is the first I've heard of range being limited by quality (nX).

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Re: sphere size

Post by max72 » Mon Nov 30, 2015 8:56 pm

From my tests with faro the quality is directly related to the range.
Roughly if you increase the quality the scan takes more time and gets acceptable data for further points.
My rule of thumb is you multiply your quality by 30 to get an estimate of the scanner range. It works up to 4x. After that you start averaging, but this is another story.
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Re: sphere size

Post by LPaulCook » Mon Nov 30, 2015 10:26 pm

I have to say that the small range gain 200mm gives over 140mm according to Philips tests hardly makes it worth buying and transporting the 200mm around. I think I will be better off with just more 140mm spheres.

I shot my last site at 1/4 and 6x which in my opinion didn't help pick up the longer shots and the scan took 32 minutes instead of 11.5. Better to make more scan stations in my opinion.

Thanks for all the input. It's very helpful and appreciated.

Paul
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Re: sphere size

Post by IngSayyad » Tue Dec 01, 2015 10:38 am

@kiloweb and @max72
Thanks to share your findings.
@max72
Can you post your results/findings in a tabular form.
Dr.-Ing. Shahzad Sayyad

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Re: sphere size

Post by max72 » Tue Dec 01, 2015 12:39 pm

Please find attached the openoffice spreadsheet with the data collected.
For every run you have distance scanner-sphere (plotted on X), and on the Y you have the numbers of points detected by scene.
Consider also that excluding the 145mm sphere all the others are home made, so paint might not be excactly state of the art...
If you have questions please let me know.
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Re: sphere size

Post by LPaulCook » Tue Dec 01, 2015 3:51 pm

Thank you Massimo,

Just one question: Are your distances in feet or meter? Since you are in Italy I am assuming meters.

Thanks again. This is very interesting and helpful.

Paul
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