Digital terrain model from pointcloud - how to smoothen / make model more workable without losing definition

[evariste]

Hi everyone,

I have a pointcloud from a site survey and want to use it to make a digital terrain model (DTM). I can figure out how to make the DTM no problem, but I run into problems the following way:
- When I use a lot of points the DTM retains all the definition from the site but is very slow.
- When I use few points the model is a lot smoother and easily workable but loses all of the definition of the road etc.

The pointcloud has lots dense clusters of vegetation on the site that's unnecessary for the DTM.

Ideally I would have a less dense model with smoothed out grass while retaining the accurate slope and retaining the definition of the road etc.

How do I go about this? Can this be done inside of Vectorworks? Or do I need to look elsewhere?

Thank you in advance.

[Poot]

You could probably go about this in a few ways, but I might suggest grabbing the important info from the detailed model of the point cloud (e.g. road geometry) by using something like grade objects or stakes set to follow site model, and then copy those to use when creating the less detailed, but faster model.

There is a whole other profession that usually deals with this kind of task on the mapping/aerial surveying side of things because its a complicated task best suited to programming. You might be able to find/create a script that filters/evens out the peaks from selected areas of the point cloud.....but not sure if this exists.

[unearthed]

I normally thin (reduce closely proximate) points outside of VW in QGIS (free, FOSS, and constantly improving) using something like this or this. GIS is near instant (once you've learned the workflow) whereas this stuff will bog VW for hours ime.

 

A problem with this new (uncleaned data) is that it is too dense - it is collected at a finer detail than we would draw at), or even perceive - for the scales we present at.