Is anyone familiar with creating a TIN using ArcGIS9.3 and British Columbia DEM data (.GEN files)? I can't figure out how to get the breaklines to work during the creation of the TIN. Using Workstation/AML it works perfectly. I can provide more details if anyone's familiar with the problem I'm encountering. See the images below.


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  • It looks like the breaklines were not added to the TIN. Can you please describe the process of adding the breaklines to the TIN? Have you tried editing the TIN after the fact and adding the breaklines as hardlines? Nov 19, 2011 at 0:57

1 Answer 1


Looking at the image, I'd say the breaklines have been added. You can see this in the triangulation and the blue breakline lines. However, you need to specify what the breaklines will do.

I am guessing that your area represents some islands in a lake. In which case you may prefer to use hulls rather than hard breaklines (same dialog box, just a different option). You can also set the polygon type of the lake areas. Try using 'Replace Polygons' for the lakes. In my experience, water areas need some intervention like this. Check out the ArcGIS 9.3 help for TIMS here: http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=Creating%20TIN%20surface%20data%20from%20vector%20data

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