Topgraphic Wetness Index using updated LiDAR

JoshuaBrengel — Mon, 15 Oct 2018 14:02:14 GMT

My ultimate goal is to do a step by step exact replication of a topographic wetness index workflow we've developed, but using a more recent LiDAR dataset (point cloud). I'm using ArcMap 10.4, windows 7 Pro and only have access to Spatial and 3D Analyst extensions.

I have a couple questions about my approach:

1) The base dataset was downloaded in bulk from NOAA in .laz format. I used lastools' "laszip.exe" to convert laz files to las files. These .las files don't show up in ArcMap when browsing in Catalog or when using Add Data option. From my research online, it seems ArcMap can't inherently load laz format, but why can't I see the las files?

Note:

- I'm able to load las files into LiDAR tool (LAS to Multipoint) without tool giving me an error.

2) Our workflow first generates DEM by converting the las points to a multipoint shapefile and then using IDW. Yet, I've encountered numerous errors (i.e. Error 010067- Error in executing grid expression) when running LAS to Multipoint tool. Or, after successfully generating the multipoint shapefile, the points in the shapefile don't have associated elevation data which results in IDW error. The base LiDAR data comes in tiles and there are many tiles of LiDAR point data covering the area of interest for TWI analysis- in this case, an entire county. There are over 9 billion points in total. What's the best approach to break up the dense LiDAR dataset and still exactly replicate our workflow (must minimize impact on DEM generation to be run in further steps)?

Note:

- In LAS to Multipoint, I'm only using classes associated with ground and water points.

- I've tried lasmerge to merge all lidar points into single file but that tool has 4 billion point limit. My research online suggests avoiding such a workflow anyways.

My apologies if this seems like a loaded question. Trying my best to condense my explanation. Thank you for your suggestions!

- Josh

topic Topgraphic Wetness Index using updated LiDAR in 3D Questions

Topgraphic Wetness Index using updated LiDAR