3

I've got several GIS datasets for a national park in South Africa (elevation map, water points, elephant density and such). I have access to the full ArcGIS Desktop Advanced suite, but am no GIS expert at all.

I want to use this data as a source of information inside of a multi-agent simulation. Therefore I need the coordinates of the resulting map in ArcMap to be transformed to relative x,y coordinates with a 0,0 origin somewhere instead of degrees and arc seconds (because programming and visualizing with those coordinate sytems is not really intuitive to me and the tools I use).

Actually I am ok with dealing with different file formats like ShapeFiles and .asc raster data in my simulation (using SharpMap), but I need the coordinates of these files to be relative, cartesian coordinates.

Can somebody tell me how to do that? I already got lost in the ArcGIS documentation.

  • Your need to create your own coordinate system then if you don't like using the global lat and long. Directions in a previous questions: gis.stackexchange.com/questions/23155/… – jonathanw Nov 21 '14 at 15:11
  • What coordinate system are the datasets you have in? It sounds like they might be a geographic coordinate system if the units are degrees (note that the unit display on ArcMap in the lower right can be set differently than the actual data). It may not be necessary to use your own custom coordinate system. If your study area/that particular park falls within a single UTM zone, you could work from that since it uses meters for units. To convert your data you'll need to use the Project tool. – Chris W Nov 21 '14 at 19:58
  • @jonathanw : Thanks for the link! I will have a look! – chrishuen Nov 22 '14 at 8:34
  • @ChrisW : I think my data is WGS-84 (is that a coordinate system?). The park is the Kruger National Park. Where can I find out if it fits into a single UTM zone? If I use the Project Tool, how do I then export the datasets to one or more files which are "encoded" with my new coordinate system? – chrishuen Nov 22 '14 at 8:46
  • 1
    UTM ZONES of africa: upload.wikimedia.org/wikipedia/commons/8/85/… – jonathanw Nov 22 '14 at 17:17
1

WGS84 is a coordinate system, but it's a Geographic coordinate system, which means it's referenced to a sphere (or ellipsoid). Note that it's also a datum, so if the full name you see under the coordinate system properties is WGS84, that's GCS, but you may also see WGS84 as part of a coordinate system name. You want a Projected coordinate system, which is where that sphere is flattened out. UTM is one such system of projections. Based on the park name, looking at the map jonathanw linked to, and a quick search on 'park name utm zone', it looks like UTM Zone 36 South would work for you.

ArcGIS is capable of reprojecting on-the-fly, but if you want to use the data in other software and even for some tools in ArcGIS it's best to make sure everything is actually in the projection you want. That's what the Project tool is for. It takes an input file and reprojects it to a new output file using a different coordinate system you specify. You can find it by browsing through the toolboxes in the Catalog window or just typing Project into the Search window. Note that you want the Project tool, not the Define Projection tool - that's for when the projection isn't set correctly; it doesn't change any coordinate values.

If the datums are different between the two coordinate systems you use, you have to apply a transformation. There will usually be a warning about this. But if you use the same datum, you don't have to worry about a transformation. So you'll launch the Project tool, select your first file in the top box, type in the name of the output file or feature class in the third box (maybe you just tack UTM36S onto the end of the original filename to keep which is which straight, and make sure it stores it in the right path location - you may need to browse to where you want it with the button to the right), then click the button next to the Output Coordinate System box. In the resulting dialog you'll want to expand the Projected Coordinate Systems folder and drill down to UTM > WGS 1984 > Southern Hemisphere > WGS 1984 UTM Zone 36S. Since that's the same datum as your original data, you don't have to worry about the transformation box. Click Ok, and then repeat for all your other files.

  • Wow! Amazing answer! Thanks a lot! You saved me a ton of time! – chrishuen Nov 22 '14 at 22:59

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.