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I have Lidar data and I want to create a TIN from it, and then run the TIN Triangle tool to create a polygon shapefile of the triangles.

The only thing is that the Lidar data is in a UTM CS with Meters as the x,y and z coordinates. I want the result shapefile to be in a state plane CS with feet as the x,y and z units. So I have to convert the CS as some point.

At what point can I do that? The Project tool doesn't run on either Lidar data or on TINs as far as I can tell. Maybe I could do it as the last step, but does Project work on the Z coordinates of a 3D shapefile?

Thanks!

  • Out of curiosity - why do you want Z-values for TIN triangles? Each triangle face will actually cover a range of z-values from which you will only be able to calculate a max, min or centroid Z. You may be better off converting a raster grid to polygon so that you get discrete Z-values for each cell-sized polygon that you output. I can provide an answer for either approach, but there appear to be some issues with calculating converted Z-values for TIN triangle faces. I'll work on sorting that out. – JWallace Aug 5 '14 at 15:54
  • I intend to open the triangle face shapefile in a 3D CAD program, as a surface. I was thinking that each of the three triangle face vertices has an x, y, z coordinate, isn't that how it works? – kmack Aug 5 '14 at 16:22
  • Ahh - yes if you're going to end up in CAD, that makes more sense. Answer forthcoming. – JWallace Aug 5 '14 at 16:30
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The project tool will not convert your Z values, but you can project your polygon shapefile to your desired CS and then obtain the appropriate Z-values using the Data Management Tools - Features - Adjust 3D Z. This tool gives you the option to apply a manual conversion factor or choose from a set of predefined conversions (including meters to feet). enter image description here

Note that you are also given the option to add a Z conversion factor if you use the TIN Triangle tool to turn your faces into polygons. The only problem that I had with this was that output file doesn't understand that you have converted the Z units. The converted Z-values will be accurate, but your file will indicate that you are still using the original units. Not a huge problem, but a little confusing if you happen to forget what you did down the road.

  • This is great-- The Adjust 3D Z tool. I didn't know about it. Thanks! – kmack Aug 5 '14 at 16:55

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