Importing GIS Data with Projections and/or Missing Coordinate Systems

Introduction

Terrain Navigator Pro can import a wide variety of GIS data as an Overlay to display over its vast library of maps and images. In order to properly place this information (commonly loaded from in the shapefile or DXF file formats) the Projection must be specified. However, neither .DXF nor .SHP files (on their own) contain the coordinate system projection that is needed.

Using a .PRJ File

In many cases, a .PRJ file will be supplied with the GIS data (shapefile or DXF) which will contain the necessary projection parameters. For example, if you have a GIS_DATA.SHP file, you should also have a GIS_DATA.PRJ file. Often times, these are contained in a single .ZIP archive; extract them into a folder, then open the Layers menu and choose Overlays to import the .SHP file into Terrain Navigator Pro. The .PRJ file, if present, will automatically be detected by TNP and used to place the data.

While not common, Terrain Navigator Pro will automatically detect .PRJ files that accompany .DXF files. As with shapefiles, ensure they share the same name as the data file, and are in the same directory. For example, if you have a GIS_DATA.DXF file, you could also have a GIS_DATA.DXF file that contains the projection parameters.

If a .PRJ file is not present in the same directory (and with the same name) as the base GIS data file, you will be prompted to select a Coordinate System...

Picking a Projection/Coordinate System

If a .PRJ file is not present in the same directory that matches the root portion of the .SHP or .DXF file, Terrain Navigator Pro will present a list of common map coordinate systems used in North America. Those using the NAD27 datum are presented first, followed by NAD83 and WGS84. State plane, UTM, and degree-based projections are all available.

Select the projection/coordinate system used by your GIS dataset, and Terrain Navigator Pro will properly place the GIS data on its maps. However, if the wrong coordinate system is specified, the data will not be placed properly. Check with the provider of the GIS data for more information about the necessary coordinate system.

My Projection is not shown on the list of available projections. How do I specify less-commonly used Coordinate Systems in Terrain Navigator Pro?
While Terrain Navigator Pro has a fair number of coordinate systems available, there are some that are not currently supported. Fortunately, .PRJ files specify all the necessary information for any projection. Thus, when importing GIS data (from either a .SHP or .DXF file) include a matching .PRJ file that supplies the necessary projection parameters.

.PRJ files for almost any projection/coordinate system can be found at:
http://www.spatialreference.org/ref/

For example, suppose you had a GIS_DATA.DXF file that was projected using the Alabama East coordinate system, in NAD83, feet. Visit the above link and search for Alabama. Locate the desired projection (ESRI:102629: NAD 1983 StatePlane Alabama East FIPS 0101 Feet) and download the 102629.PRJ file. Then copy the 102629.PRJ file into the same folder as GIS_DATA.DXF, and rename 102629.PRJ to GIS_DATA.PRJ. Finally use Layers, Overlays to import the GIS_DATA.DXF file from that folder, and the Alabama East coordinate system, in NAD83, feet (as defined by the downloaded 102629.PRJ file) will be used to properly place the GIS information onto TNP's maps.

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