Point clouds quality+Coordinate systems

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Sainsbury's
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Point clouds quality+Coordinate systems

Post by Sainsbury's » Wed Jun 05, 2019 3:42 pm

Hi there,
I just started using Cyclone software, I have two questions

1) Can you please explain to me the steps for transferring the coordinate system of point clouds from local coordinate system (Terrestrail Laser Scanning system) to OSGB36 (GPS system)?
I have GCPs are collected by GPS in a different day of scanning. These GCPs are placed over the same location of TLS targets. Is it fine if I used these GCPs although they were measured in a different day.
2) How can I estimate the horizontal and vertical data quality of a specific number of point clouds (e.g., 30 point) in this software? Does Cyclone software able to determine the point clouds quality? if not, which software you recommend me to use?

Thanks in advance,
Lilianna

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Matt Young
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Re: Point clouds quality+Coordinate systems

Post by Matt Young » Thu Jun 06, 2019 8:06 am

Hi Lilianna,

The simplest way to do this is to pick two targets in the model space. And assign the GPS coordinates to them. When assigning coordinates you will need to give the coordinate of the first point and an angle from that point to the second point. To do this, select the two points (these can be target vertices) and from the drop down menu select 'View', 'Coordinate system', 'Set from points'. Then check some of the other GPS points and check that the coordinates match what they should be.

It's worth bearing in mind that you may have large differences between the terrestrial scan (Flat grid) and the GPS (Curved grid). Using the above method you will be accurate to one point (the first one chosen) and off on the others.

Another way to do this is to create a control text file with the GPS points. And number them as per the target vertices from the terrestrial scan in the control space. You can then create a new registration and register the terrestrial scan to the GPS. You may still have errors, but they will be spread across the the whole network.

Matt
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