I've been working with TINs for years and have only ever been satisfied when using 3D polylines for breaklines.

I am currently transitioning to using terrains and after reading the documentation in ArcGIS, it seemed that I ought to be able to apply a polygon as a breakline.

Intrigued by the possibility, I decided to try it with a LiDAR data set I received from a project partner along with a 2D polygon feature class of wetted stream channel planform.

I specified the wetted channel polygon as a hard breakline, built the terrain, and ended up with two very deep (0 elevation) troughs along the extent of each bank.

See below:

Based on my reading the software should create nodes where the polygon perimeter intersects triangle edges and interpolate z-values along those edges, but that does not seem to be the case. Is this actually possible?

I am using ArcGIS 10.0 SP4 with an ArcInfo license and 3D Analyst and Spatial Analyst extensions.

  • Is it possible for you to zip up a small amount of your data (a bit of lidar and river polygon) for people to examine?
    – Hornbydd
    Commented Sep 2, 2013 at 13:59
  • From your description it seems like ArcGIS Desktop 10.0 SP4 is not working as documented. This would suggest a bug or maybe a documentation error/enhancement to address an undocumented software limitation. If it persists in the latest ArcGIS for Desktop version that you are using, then I would recommend that you submit this one to your local Esri Support so that it can be reproduced, and if confirmed, forwarded to the appropriate development team.
    – PolyGeo
    Commented Mar 25, 2014 at 10:54