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 or Custom Map (with the optional Sites Add-on) 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 (aka Coordinate System) must be specified. However, neither .DXF nor .SHP files (on their own) contain the coordinate system projection that is needed.Using a .PRJ (projection) 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 Terrain Navigator Pro 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.PRJ file that contains the projection parameters.
Using a .DC (calibration) File
In some cases (especially when used in conjunction with Trimble Business Center), a .DC calibration file will be supplied with the GIS data (usually DXF) which will contain the necessary projection parameters. For example, if you have a GIS_DATA.DXF file, you may also have a GIS_DATA.DC file. (Or a .DC file that references the entire dataset.) Open the Layers menu and choose Overlays to import the .DXF file into Terrain Navigator Pro. The .DC file can then be loaded by pressing "Load Projection/Calibration File" in the Choose Coordinate System window.Picking a Projection/Coordinate System
If a .PRJ (or .DC) 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.
Alternatively, use "Load Projection/Calibration File" in the Choose Coordinate System window to specify the .PRJ (or .DC) file that contains the projection used to reference the .SHP or .DXF file.
My Projection is in meters, but TNP only gives a US Feet option. How do I apply the correct coordinate system?
In the Choose Coordinate System window, select the US Feet option from the list of available Coordinate Systems, then in "Apply Additional Transformation" choose Feet to Meters. This will apply the correct conversion of units. This can also be used in rare cases where the units in the .DXF file are different than those in the .DC calibration file.
In the Choose Coordinate System window, select the US Feet option from the list of available Coordinate Systems, then in "Apply Additional Transformation" choose Feet to Meters. This will apply the correct conversion of units. This can also be used in rare cases where the units in the .DXF file are different than those in the .DC calibration file.
I am trying to import a .SHP ESRI Shapefile. Why am I being prompted to choose a coordinate system?
GIS data contained in an ESRI Shapefile is made up of several individual component files. One of those component files has the extension .SHP. However, for TNP to accurately import GIS data from an ESRI Shapefile, ALL component files must be included and present in the same directory. Thus, to import a particular GISDATA.SHP file, the matching GISDATA.PRJ, GISDATA.DBF, and GISDATA.SHX files must also be present in the same folder.
If one or more of those files are missing, TNP will do its best to import the .SHP data alone. If the .PRJ file is missing - you will need to supply the correct projection/coordinate system (see above). If the .DBF file is missing, no metadata will be included.
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