topic Re: NEAR Results? in Geoprocessing Questions

NEAR Results?

DougOuren — Thu, 05 Nov 2015 20:33:40 GMT

Hello:

I have am using two point data sets, one representing animal locations (AL) and one representing a landscape feature (LF). I used the NEAR function to try to get the distance to the nearest LF from each of the AL’s. It ran with no problems, quite fast actually (maybe a little to fast to believe) but the distance values (as shown below) don’t make any sense…projections are the same, thought maybe the distance values could be fractions of a kilometer but even then they don’t make sense. So I am probably just missing something simple but would certainly appreciate any insight. Thanks much

NEAR_FID	NEAR_DIST
143	0.012692458
38	0.012239339
38	0.00345468
142	0.003430614

Re: NEAR Results?

DarrenWiens2 — Thu, 05 Nov 2015 20:49:09 GMT

What projection are you using? I'm guessing those numbers are in units of decimal degrees.

Re: NEAR Results?

ChrisDonohue__GISP — Thu, 05 Nov 2015 20:56:21 GMT

I think Darren Wiens has a good guess. Check the input feature's coordinate system to see what the units are. It's probably a Geographic Coordinate System, so decimal degrees.

From the Near (Analysis) Tool Help:

NEAR_DIST—Stores the distance from the input feature to the nearest feature. The value of this field is in the linear unit of the input's coordinate system.

ArcGIS Help 10.1

Chris Donohue, GISP

Re: NEAR Results?

ChrisDonohue__GISP — Thu, 05 Nov 2015 21:00:47 GMT

If it turns out the input is indeed in a Geographic Coordinate System, the Near (Analysis) Tool Help offers this advice:

The distances calculated by this tool are in the unit of the coordinate system of the input features. If your input is in a geographic coordinate system and you want output distances to be measured in a linear unit (as opposed to decimal degrees), you must first project your input to a projected coordinate system using the Project tool. For best results, use an equidistant projection or a projection intended for your study area (UTM, for example).

ArcGIS Help 10.1

Chris Donohue, GISP

Re: NEAR Results?

DougOuren — Thu, 05 Nov 2015 21:31:39 GMT

Thanks all, looks like you hit the nail on the head. Also thanks for responding so quickly, for that you deserve at least a beer!

Re: NEAR Results?

ChrisDonohue__GISP — Thu, 05 Nov 2015 21:38:59 GMT

Send the beer to Darren Wiens - he responded with the essential issue identified first (though I am assuming he drinks beer, if not I will take it ).

Or at the very least, mark Darren's answer here as Correct so others who do a search on the same type of issue will know an answer was found.

Chris Donohue, GISP