Using Cyclone core for this, but I'm more proficient with realworks.
Suppose you've just gotten a brand new scanner and know nothing about it, what processes do you undertake to judge the quality of a scan and/or registration?
Previously what I've done in the past is scan a flat surface such as a whiteboard, granite surface, or a finished precast wall, and then take a horizontal cross section and look and the range of the bands of points. Ie i would expect in a 50mm thick cross section there would be <3mm variation of points (depending on distance), with the mean being the correct value.
I would see what the direct fit of an observation of 3 BW targets against the same 3 targets measured with a total station.
I would also inspect the .fls images from the instrument perspective to see if there is any obvious tearing.
To compare the accuracy of the overall registration, i would colour each scan by the station, then look at the overlap of the scan data to see if there is a strong correlation.
I'm sure there are other tricks; feel free to write yours below.
What processes do you do to judge the quality of the scan/scanner?
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Re: What processes do you do to judge the quality of the scan/scanner?
In addition to the above I'd also consider the following (coming from a roads and topo background);
- Ideally, compare scans of the same area with results from other scanners, example here; https://www.linkedin.com/pulse/first-lo ... claughlin/
- Check a level surface (as opposed to a flat one that may not be level) to check the compensator
- Check sharpness of intensity returns, coloring by intensity and looking at something like road markings
- Compare relative position of a road marking when coloring by intensity versus coloring by RGB to check camera alignment
- Check noise levels on dark matt surfaces and dark shiny surfaces, some scanners struggle here
- Check how easy it is to adopt external control
- For mobile mapping, check the density and pattern of scan points, preferring parallel even spacing over scattergun patterns.
- Check field to finish time, from starting to scan to having a clean, registered point cloud
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Re: What processes do you do to judge the quality of the scan/scanner?
Thanks Shane, this was very informative