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Up Topic Discussions / LiDAR Support / More coordinate conversion questions
- - By dpdacha Date 2013-04-08 20:28
I have also been having problems converting the contour data from UTM to a County system.  I have brought in the contour layer (I believe 2 foot contour interval), which is contained within the contour subset, within the gdb file.  I have tried the project command, but I keep getting an error message about having an undefined geographic transformation.  Have tried a lot of different geographic transformation combinations, but nothing seems to work.  Also, I noticed that when I look at the properties of the contour layer, the coordinate system is greyed out, and not selectable.  Thanks for the help

Tim
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Parent - - By Taylor Long Date 2013-04-10 21:01
I think I’ve gotten to the bottom of your projection issue. At first, I thought the problem might have something to do with the feature classes being stored within a feature dataset (all feature classes in a feature dataset must use the same projection). However, I found the real solution in a PowerPoint presentation on the MnGeo site under Education and Training called Accessing and Using Minnesota LiDAR Data Packets. To convert from NAD83 UTM Zone 15N to any given county coordinate system, you’ll need to make a custom transformation. This is because the county coordinate systems use a slightly different datum than the UTM projection does. Custom Transformations sound scary, but making this one is actually quite simple.

To create your custom transformation, open the Create Custom Geographic Transformation tool. You’ll name your transformation (something you’ll recognize later) and enter the Input Coordinate System (NAD_1983_UTM_Zone_15N) and the Output Coordinate System (in the case of Dakota County, it would be NAD_1983_HARN_Adj_MN_Dakota_Feet). Finally, under Custom Geographic Transformation > Method, select LONGITUDE_ROTATION. Click OK, and you’re ready to project.

Using the project tool this time around, when you enter your desired Output Coordinate System, your custom transformation should show up in the box under Geographic Transformation (optional). Save the Output Feature Class anywhere except the feature dataset that housed the original Contours feature class. The new feature class should be properly projected and ready to go.

I think that should solve your problem. If anyone else knows more about this than I do, feel free to chime in.
-Taylor
Parent - By LesEverett Date 2013-04-15 15:45
Make sure to do the custom transformation before opening the Project window, or the custom transformation won't show up when you try to do the re-projection.
Up Topic Discussions / LiDAR Support / More coordinate conversion questions

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