Proximity Tool Problem (incorrect units)

[JessicaW]

Hello,

I am a total beginner to ArcGIS, I am just using it for a school project.

Question:  I loaded a list of longitudes/ latitudes (in decimal degrees) of several subjects in an excel file.  I created another excel with just one particular longitude/latitude (in decimal degrees).  I added both data excel files into arcgis.  I displayed xy coordinates and used the Geographic coordinate system.  All the points from both data sets appear on the map.

Goal:  I want to find the distance( meters) from all the points in the first excel file in relation to the one data point in the 2nd excel file I added.  So, I used the proximity tool, then point distance.  I set the first excel data points as my Input feature.  I set the data point from the second excel sheet as my Near feature.  I set the desired output value for meters.

Problem:  When I get the output table of all the distances, they are not in Meters.  They are in a decimal form.  Maybe because my data is in longitude/latitude decimal degrees?  Can someone explain how I can get my distance in Meters?

[IanMurray]

You will need to project your input data to an appropriate coordinate system that uses meters:

See (copy + paste the url).  http://resources.arcgis.com/en/help/main/10.2/index.html#//000800000048000000

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).

[JessicaW]

Thanks.  I was reading some other posts that said the same.  I was using GCS 1984 because the longitudes/lattitudes were obtained using GoogleMaps.

When I click Projected coordinate system, and then look under UTM, there are SO MANY options.  I randomly tried "NAD_1983_UTM_Zone_17N" but when displayed on the map, the points appear near South America.  Do you have any idea what specific system I would use if I'm in Tennessee, USA?

[IanMurray]

I would follow the instructions Darren has laid out for projecting your data.  As for which projection to use, I would use either an equidistant projection(keeps distance true), in this case try USA Contiguous Equidistant Conic, or a good local projection would be NAD 83 StatePlane Tennessee FIPS 4100.  There is a StatePlane for both units in feet and meters so which you pick is up to you(there is a search bar at the top when you are selecting output coordinate system, I typed all projections as they appear in the list, so they should turn up).  Incidentally, Tennessee is in UTM Zone 16N for future reference(fellow Tennesseean here).

[JessicaW]

Small world! I just moved to TN for school.  I'm just trying to make it through summer research.

Thanks for the suggestions.  Greatly appreciated

[IanMurray]

I'm in grad school at MTSU, where are you at?

[JessicaW]

I'm in medical school at Meharry, but I'm doing my summer research at Vanderbilt

[DarrenWiens2]

Use the Project tool to apply a projection to your layer. The projection will have a linear unit (e.g. metres) associated with it. When you rerun Point Distance, the units will be in the linear unit of the input feature class.

[JessicaW]

Thanks.  I'm using ArcGiS 10.2, I don't actually see a Project tool.  Once I've added my data, I just right click, hit display xy.  A window pops up and in that window I can change the coordinate system to what I want. 

Is this what you are referring to?

[DarrenWiens2]

No. The pop-up window is where you define the coordinate system of the original data. This can be a geographic or projected coordinate system, but it needs to be the coordinate system that corresponds to the data (e.g. if your data is lat/long coordinates, then you probably want to define a geographic coordinate system, as you've correctly done).

Once you've correctly defined the data, you are free to re-project it using the Project tool in the ArcToolbox section, under Data Management tools -> Projections and Transformations -> Project. Run this tool to translate your unprojected data to a projected coordinate system. ArcGIS will do the math to situate the data in the correct location, but now it will also be in a linear unit, like metres or feet.