Global Mapper v25.0

Forestry post-harvest visibility using LiDAR?


I'm new to Global Mapper (v18.0.3), so apologies in advance if this has been discussed in a thread that I did not discover.  We have large areas of LiDAR point cloud data that has been minimally filtered into 'Surface' and 'Other' classes, as well as overlapping Ortho imagery.  I've been able to make a DEM surface and a DSM surface, as well as add RGB code to a LAS tile.  I've looked at each in a 3D window.

I have been trying to figure out a workflow that would enable me to make a post-harvest 3D view, which shows me a scene with a forest harvest block removed from either the DSM or the Ortho point cloud, bringing that opening back down to the bare earth.  The objective is to model what is currently visible from specified viewpoints and compare this to what would result from harvest proposals.  Ideally the resulting scene would have the Ortho draped on while the new harvest would be coloured brown simulating clearcut.  I will assume that I'd be able to run a quick viewshed routine on that same "logged" surface so I can map out what the scene shows me.

My guess is that I'd have to make a grid of the logged opening shapefile and use it as a mask to convert the current LAS file into a Logged LAS file, where the 'Other' classified points are removed or masked out of the opening.  Then I expect I'd colour-code the points with ortho & brown, recreate the new view scene and viewshed.  It sounds logical in theory... I hope.  If anyone has worked out a methodology they'd be willing to share I would greatly appreciate some tips.

Part two relates to the viewpoint location in the 3D view.  Is there a way to lock in the viewer's position to an established coordinate or data point?



  • Have you had any luck in figuring out this process? I too would be interested in a similar process if it was somewhat efficient to do.