BLK 360 Calibration Issue

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James Hall
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Re: BLK 360 Calibration Issue

Post by James Hall » Thu Aug 09, 2018 11:32 pm

Phill wrote:
Thu Aug 09, 2018 10:27 pm
James

I cant see the measurements in those photos. Are you saying that the scanner is changing the distance the further from the scanner you get (kind of like a scale factor), or is it the beam is not level. You seem to indicate it is bending the beam when it should be straight? Is that correct? And this only happen out to a certain distance, after which if comes good. If it was me I'd be getting the targets out, putting the BLK side by side with the C10 and place targets out at series of distances from the two scanners.

Can you place a beam in the two scans aligned to the cloud and then show the centre of the beam in orthogonal view, so we can see the deviation.

The other point here (to do with the height) is the BLK is well known not to have a great level sensor, and there are some post around the forum about it not applying the level readings at all, so maybe you need to toggle levelled off in the registration and rely on the C10 to level up your data.

Cheers

Phill
Hello Phill,

"Are you saying that the scanner is changing the distance the further from the scanner you get"
Yes, scaling of sorts. It looks like the scanner is reporting good angels but the distance measurement is off.

If you open the Images in Paint you can zoom in. I don't know how to control there display size on the forum but they to have enough resolution to read the numbers.

I'll set up and post an orthogonal view tomorrow.

The C-10 data has a constant height that matches the known values for the steel parts and the BLK shows a decrees in measurements the closer you get to the scanner.

I have not tested the data from 12 to 30 feet to see if the point cloud is scaled there as well. (Next test)

The data seams to indicate the error is not a constant scale factor, X,Y but a radial scaling from the scanner position. Starting at around 12 feet from the scanner the distortion is diverging from the C-10 data closer you get to the BLK scanner position where the measurement are significantly smaller then the known value.

The BLK360 data was un-leveled and registered C2C to a C-10 scan. The images show only one scan each to eliminate alignment error.

I had already planed to setup targets at a few different distances to test side by sided with the C-10, a Total station and the BLK 360.
This will have to wait a bit wile I get job delivered.

At this point the only thing I'm using the BLK360 for its Images.

James,

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James Hall
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Re: BLK 360 Calibration Issue

Post by James Hall » Mon Aug 13, 2018 8:19 pm

I don't know why but the images i posted are at a lower resolution then the originals.
So is cropped out enough to show an example you can read.
BLK360 Steel beam test 1a.jpg
BLK360 Steel beam test 2a.jpg
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James Hall
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Re: BLK 360 Calibration Issue

Post by James Hall » Thu Dec 06, 2018 6:40 pm

I have been supper busy at work, sorry for the long time in posting results.
The Pictures, when I posted them the forum derezzed the images.
Conducted a test back at the office October 15. I placed 12 black and white targets around our office and scanned them in with our C-10, BLK360 and a Total station.
The total station and the C-10 where comparable, the BLK360 was always scaled down when compared to the other data sets.

Row 2 is total station Coordinate Value.
In my excel sheet I show only the worst two C-10 scans in rows 4 though 9 as a comparison.
Rows 10 through 41 are BLK 360 data.

Column A is the name of the setup, Column B is the distance to closet object.
For Column C,G,K,O and so one is the Target point name.

Column BA and BB are distance measurement between points 103 and 110 / 104 and 111.
The row beneath the measurement is the difference compared to the total station measurement.
BLK360 TEST CONTROL.xlsx
The worst BLK360 measurement between points 103 and 110 was -0.0334 smaller than the total station measurement.
This measurement was 17.9128 feet per the total station. The scan was 0.186% smaller than the other two instruments.
The average measurement was 0.0246 different than the total station measurement. The measurement distances were between 1.5 feet and 35 feet.

Results
Scanworlds from our BLK360 scanner were smaller than the C-10.
If we were to scan the outside of a building with only the BLK360 the Registration would report good cloud to cloud results but any control placed in the seen would show a scaling difference between the scan and the control file.

The listed a accuracy is 4mm at 10M and 7mm at 20M
Or
0.0131 feet at 32.81 feet and 0.0230 feet at 65.6168

We exceed the 0.0230 feet tolerance at a range of within 30 feet with 9 out of the 11 scans I did in my test.

I am forwarding my data to Leica.

James,
Last edited by James Hall on Fri Dec 07, 2018 2:02 pm, edited 1 time in total.

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Felix_the_Cat
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Re: BLK 360 Calibration Issue

Post by Felix_the_Cat » Fri Dec 07, 2018 4:33 am

Well I didn't go to all that trouble but have what appears to be a similar experience.

In trying to find a way to make these things even slightly useful we attempted to use them to fill in holes or to do less important areas that didn't relate directly to the task at hand.

What we found was that for anything spanning more than two or three scans maximum the BLK cloud was unregisterable with data from Faros as the scale was off (too small usually) enough to make for a misaligned overlap on one side or the other. Confirmed via surphaser. Also the garish pastel color palate imparted by register360 is horrendous but I digress.

I'm pretty much down to using the things to scan people during dog and pony demos. People think they are "cute". And the flip phone crowd love to see themselves instascanned.

Anyhoo

Please keep us up to date on your findings and whatever Leica has to say


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James Hall
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Re: BLK 360 Calibration Issue

Post by James Hall » Sat Dec 08, 2018 1:44 pm

Felix_the_Cat wrote:
Fri Dec 07, 2018 4:33 am
I'm pretty much down to using the things to scan people during dog and pony demos. People think they are "cute". And the flip phone crowd love to see themselves instascanned.
I have found the BLK360 useful doing inverted scans of electric and telecom vaults. We have also done complicated underground storm drain structures with it.
Its faster to dip most manholes. But, it makes sense to use a BLK360 to avoid confined space entry. We can get 2 to 4 vaults per hour with it. Slower then dipping the invert but faster and cheaper then a maned entry.

James

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