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I'm working with in-situ data collected from several field sites that must be converted into points that lie within a separate layer of polygons. These polygons are the boundaries of the different study areas, in which the points, representing trees, must go. I've successfully converted the in-situ data to points, but I'm having a lot of trouble making those points fall within the necessary polygons.

The issue is that the point data does not have a traditional coordinate system. We based our coordinate measurements off of a 30x30m plot, and the points correlate to a 30x30m grid. As a result, even if I ensure that the coordinate system matches, the points are very spread out in ArcMap - to the point where I can't drag and drop them to the correct spot on the polygons because they're impossible to find unless I zoom to the layer.

Is there a way for me to define a lat/long extent for the point layer that matches the lat/long extent for the polygons so that I can make the points within the boundary of their respective polygons?

I'm relatively new to ArcGIS.

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  • @atxgis has a great idea. Otherwise, do any of the points have lat/lon coordinates? If so, you could try defining a custom "Local" coordinate system using the Local projection, and setting the center coordinates to that point. Local also supports an azimuth and scale, which you might have to use to get the data to fit properly. – mkennedy Apr 13 '17 at 20:40
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The points are spread out or dislocated? If I fully understand you, if the point shapefile and the grid match but it just seems spread/spaced out, it seems to me that your problem (the spacing-out) is most likely related to the symbology chosen for your point shapefile instead of it being inaccurate, because coordinate problems happen in a systemic way, meaning that all the points would be moved to a certain direction and/or the distance between them will different then it should be. To make sure that you are really facing a coordinate problem, I'd suggest you measure the distance between points and see if it's completely unreal (I'm assuming you have such information or, at least a distance notion precise enough). If the distances are accurate, then try changing the symbology and choose bigger dots to see if the spacing-out impression disappears.

Please note that dragging your data will remove the precision on which it was collected in every circumstance. It is always preferable to fix the problem on a different way.

Another thing that I should ask you is how this data was collected and what did you mean by unusual coordinate system. Arcmap converts the data you input on-the-fly and if you used a GPS, then I doubt the coordinate system is unknown to the software.

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