I've got attributes for a length that the Near tool calculated, and it gave them to me in decimal degrees. I need them in feet. Is it possible to do this with the Calculate Field tool? I tried reading the documentation in the ArcMap help, but it was really unhelpful. I'm willing to do it in python or VBScript or whatever it takes.

  • 4
    I think the easiest thing to do would be to reproject your data and rerun the near tool so you can get back some useful units. – crmackey Jun 3 '15 at 16:51
  • 3
    It is never possible to recover linear units from Cartesian distance of angular units. – Vince Jun 3 '15 at 16:57
  • But there do exist tools which can return great circle distances or even distance along ellipsoid. "Distance" function in SpatiaLite is one such gaia-gis.it/gaia-sins/spatialite-sql-latest.html. Naturally it needs start and end points in lat/lon as source data. – user30184 Jun 3 '15 at 17:28
  • 1
  • 1
    I suspect the problems you were running into with the Project tool (if the data was loaded in to the correct place relative to other data, as your comment about using the dataframe for export seems to indicate) is related to the choice of transformation or lack thereof. 2011 isn't just regular NAD83, so it's actually a different datum than the NAD83 of the state plane projection (unless you're using the updated datum for both sides). Without more specifics on your data and the Project settings you used, it's hard to say. Sounds like you got what you needed though. – Chris W Jun 4 '15 at 18:21

The near tool gives you the results in the linear unit of measurement of the layer's projection. Try choosing a different (appropriate for your dataset) projection that uses feet. Then re-run the near tool.

  • I've tried to reproject the data a number of times (going into a state plane system) but it's giving me all kinds of trouble. Ir's not reprojecting correctly so that's why I'm just trying to convert these values. – BlakeG Jun 3 '15 at 16:54
  • 4
    I would fix that problem first. Your distances are going to be more accurate if you're in the appropriate coordinate system. Trouble reprojecting your data may also be symptomatic of other issues. – MWrenn Jun 3 '15 at 16:57
  • I concur. Since a degree isn't a constant unit of measurement (deg of longitude is 69 miles at equator and 0 at the poles) conversion is a pain. Better to use a system that's in feet or meters from the get-go. – fdonnelly Jun 3 '15 at 16:58
  • Okay let's just say I'm not looking for accuracy. All my data points are in San Diego, so the variance in degree lengths is negligible. Is is at all possible to convert these values? – BlakeG Jun 3 '15 at 17:01
  • 2
    Remember that the length of degree is different from West to East and from South to North. Simple multiplication is not enough but you must know the angle of the distance as well. Gets complicated and I suggest to use a better method. – user30184 Jun 3 '15 at 17:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.