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Non Earth Projection

November 19 2008 | 0 comments
Categories: ArcGIS Methods, Map Data

I created a cross section of a river, and I'd like to project my data. Right now I am working with an unknown projection, but I can't map mycross  section like I wanted because I can't set the scale of my data frame.

Is there a way to create a "non-earth" projection in ArcView 9.2 in meters, regardless of the spheroid and datum because there is none?


Mapping Center Answer:

Interesting question and one that plagues anyone trying to integrate data produced via a graphics workflow into GIS.  I would guess there are a few steps.  First is finding a suitably generic coordinate system to use as a replacement for "Unkown".  But before you do that, make sure the coordinates for your data are within the realm, i.e., spatial extent, of the coordinate system you want to use.

With the Editor you can move your data so it overlaps, but you may also need to scale the data--In the customize dialog for the Editor, there is a tool called Scale--it works on the selected set of features and is incredibly handy for this kind of task.  Then use the Define Projection tool to set the coordinate system.

Last, the data likely does not match perfectly with data collected other ways.  To help with that, use the Spatial Adjustment tools to do heads-up rubbersheeting of your data.  To get exact matches, you can use the Reshape Editor task (scroll 1/3 or so down) to trace against or more closely mimic existing geometry.


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