Create 3D polygon of airspace above terrain

Question

I have a LAS dataset of mainly vegetation and ground. I am looking to create 3D polygons in ArcGIS Pro that essentially fill in the space above the ground and flanked by the data (trees and bushes) to the left and right up to x height where x is the highest elevation along the walls. Preferably I would like to create multiple 3D polygons so that they are say up to 5' from the ground and the next stack be 10-15' etc. up to my height. But at this point I'll take one big polygon if I can get it. Almost like if the Grand Canyon filled with water - how to create a 3d polygon of that water space up to the top of the canyon if you have a LAS file of the Canyon. For this example the polygon would reach to a height of each point along the top of the canyon walls on the left and right with the head and foot of the polygon being bound by the start and ending of the las file bounding box.

Any ideas of what tool to use? I have looked around and haven't found exactly what I need to do this. I assume I need to make the LAS a TIN file which will be then the base and sides of the polygon then somehow create a polygon above the TIN.

Answer 1

Here is a workflow to get what I think you are asking for:

1. create a LAS Dataset to hold a reference to the LAS point files

2. convert the LAS points to a Raster using LAS Dataset To Raster

3. use Binary Thresholding on the resulting raster based on the Elevation attribute to find the surface constraints (the walls of the canyon)

4. convert the binary raster to polygon using Raster to Polygon

5. add a floating point number to the polygon featureclass

6. calculate it to be the height of the 1st fill-level of interest

7. convert that Polygon back to a Raster using Polygon to Raster

8. use the Raster Domain tool to create a 3D polygon representing the domain of the raster from step 7

Repeat steps 6-8: re-calculating the polygon elevation data, converting it to a raster, then using Raster Domain to get a new 3D polygon each time. (I couldn't find a convenient Polygon-to-3D Polygon conversion otherwise steps 7 and 8 could be replaced.)

Now you have a collection of 3D polygons with the same boundary and differing heights. You can assemble them all into a single 3D polygon featureclass, if desired, or incorporate the LAS, and 3D polygons all into a TIN Dataset.

It was unclear what the end-state of all of this would look like for you, so I leave the solution here, with options, for you to finalize.