LAS Dataset - how to see multiple returns?

MichaelSmith1 — Fri, 31 Aug 2012 17:36:18 GMT

ArcGIS 10.1, ArcInfo license - 3D Analyst.

I am using the LAS Dataset tools and I have noticed that where in my LAS file I have multiple returns, I can only ever seem to see or Identify one of the returns. It's like ArcGIS choses one of returns to represent the point and suppresses all the others.

Workflow is this:

1) Load an LAS dataset and zoom in close to a forested area (where I know I will have multiple returns per point).
2) Use Identify and click on a few points until you find one where Number of Returns > 1. For example a point that is Return No. 1 out of Number of Returns = 2. So in this case this is the first of two returns. That is the point showing in the display.
3) Go into the layer properties and use the filters to show last returns only.
4) Now, in this case there were two returns, and you should see the second one (the last return) now, right? Yet it is not there.
5) Likewise if you do an LAS Dataset Profile View, and include a point with known multiple returns, the profile view shows only the return which "Identify" says is there. In this case it would only show the first return and not the second return.

This same behavior will occur if you use a different point as a test, for example one where it is Identified as return 2 of two. Then it will not show a first return at that location.

I tried this with two different collections - one from 2011 via PhotoScience and the other from 2012 via Woolpert.

Anybody else have this issue or know how to show the multiple returns? Or is this a bug and the software should show the returns?

Mike

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LAS Dataset - how to see multiple returns?