I am working with a set of LAS data which is irregularly shaped, picture a starfish as the point coverage, surrounding the starfish may be water on one side, may be more land elsewhere but no points were collected for it. In fact most of the areas around this starfish of points is land without points collected, and inside the starfish shape is a little lake.

I want to make a DEM of just the area where points were collected, and there are many ways of doing this, but most will interpolate all the no-point areas inbetween "arms" of the starfish data point pattern. Making the DEM by using a Terrain Dataset allows for the input of a bounding shape, to theoretically omit no-point areas from being interpolated and only geoprocessing inside of the boundary shape.

However, I have difficulty coming up with a precise bounding polygon of the outside edge of the starfish to use as my geoprocessing limiting extent.

I found a process online in a blog by Clayton Crawford which was picked up by Esri and used as their help file for the process of turning LAS to DEM's, but it involves downloading a custom VBA script and several steps which went a bit over my head.

Does anyone have a suggestion on how to get that starfish pattern of LAS datapoints inside a bounding starfish-shaped polygon, without the use of VBA, or alternatively if there's a way to go right from LAS to DEM raster with no-point areas end up as NoData?

I'm using ArcGIS 10.1 for Desktop.


3 Answers 3


How to create the Concave Hull around an irregular point cloud in Arc10:

  1. You have an input point cloud (for better performance > MULTIPOINT).

  2. Create a TIN: 3D Analyst > Data Management > TIN > Create TIN.

  3. Delineate TIN data area with a max_edge_length as parameter (this depends on the distance between your input points, e.g. I'm using 10m) and parameter "PERIMETER_ONLY": 3D Analyst > Data Management > TIN > Delineate TIN Data Area.

  4. Use the tool 3D Analyst > Conversion > From TIN > TIN Domain to save a polyline or polygon item outlining your TIN.


If you have an Advanced level license of ArcGIS for Desktop then you could try using the Feature Outline Mask tool as suggested in this posting by Ask A Cartographer in response to:

I have a point dataset with about 17,000 points. I'm looking to create a footprint of the outer most points. I see one can create a convex hull, but my points form an irregular shape and the convex hull doesn't follow the path of the outer most points. Is there a way to do this?


The solution for this in ArcMap 10.3+ (and ArcGIS Pro) is to add a Surface Constraint of type clip to the LAS Dataset.

Creating a boundary polygon that closely matches the actual extent of the input points is a bit of an exercise though, see Esri's Data area delineation from lidar points 6 step process.

  1. Rasterize the lidar points using the LAS Point Statistics As Raster
  2. Assign one value to all data cells using Con
  3. Fill small NoData areas using Expand
  4. Reduce the overall extent of data cells using Shrink
  5. Vectorize the raster with the Raster To Polygon
  6. Remove remaining small holes using Eliminate Polygon Part

To which I add:

  1. Manually edit the polygon as needed
  2. Generalize (weed redundant points)
  3. Create LAS Dataset using this polbygon as Surface Constraint, type: soft clip.
  4. Now finally use LAS Dataset to Raster.

For #9 it's a good idea to remove the LASD from ArcMap or Pro table of contents and re-add to force refreshing the dataset, else the new surface constraint might be present but not enabled. (Verify with r-click >> properties.)

If you're willing to step outside the Esri ecosystem How to create boundary polygons of the actual data area in LAS files? has information on how to do the same in fewer steps using and/or .

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