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How to determine point cloud density when scanning

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fattiretom
(@fattiretom)
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Anyone have any tips for determining good point cloud density at X distance for doing things like roadway/curb topo or general urban scanning? Or any general advice about usable distances/densities?

I'm pretty new to scanning (have an MS50) and I'm trying to find that good balance where I can get a good picture to draft from with as little setup time as possible.

Thanks!


 
Posted : July 29, 2014 3:49 pm
Mapman
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With point clouds you need enough points to be able to visualize what is being captured. On our Leica C10 I usually use a medium resolution when my scans overlap by 30% or better. The medium res is described as - @ 100', points will be located on a .1' grid. This is a good balance between cloud size and file size for most projects. There are times when a higher res is needed, but for most applications medium is sufficient.

At that density it is fairly easy to determine your culture for topo. If your scanner (MS50) can color the points using a picture then it gets much easier to see painted stripes, etc. The Intensity and Grayscale modes will also provide a good indication of the culture and how well it was shot.

Usually, I setup control first if possible. This helps to register your scans together later back at the office. Control for hard surfaces are typically set like doing any other topo. For roadway projects I will use a 300' to 400'(max.) separation between points to assure the best vertical returns. For building scans it can be much more.

Since you are using a Leica product I assume you have Cyclone software to process with. The learning curve is pretty steep, but well worth learning.

Here is a video I did of a scan along a roadway that is failing near the 405 freeway. There are a total of 3 videos in my channel, but this one has the linework derived from the clouds.

Good luck and hope that helps.


 
Posted : July 30, 2014 8:24 am
fattiretom
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Thank you! that is very helpfull for me to start experimenting with. We will be using MultiWorks. I may go for Cyclone down the road if we find ourselves doing a lot more scanning.

Thanks
Tom


 
Posted : July 30, 2014 10:30 am