Strtrim idl
![strtrim idl strtrim idl](http://www.idlcoyote.com/graphics_tips/coloredline_1.png)
Almost everyone will set this projection up like this. It is much easier to recognize this map projection as a UTM projection that is in zone 13N. The center longitude error probably persists in the file because no one uses it. MapCoord = Obj_New('cgMap', 'Transverse Mercator', ELLIPSOID='GRS 1980', $įALSE_EASTING=500000.0D, FALSE_NORTHING=0.0D, CENTER_LONGITUDE=-105) This kind of error is not uncommon in shapefiles, so you have to be on your toes. It should be -105 to put the shape file in Colorado. Note, however, that the "Central Meridian", which we are going to call the "Center Longitude", is incorrectly written in the file. If you like, you can use all of this information to set up the map coordinate object. The projection is a Transverse Mercator projection with a number of parameters. Here we see that the spheroid (IDL calls this the "ellipsoid") used for the datum is the GRS 1980 ellipsoid. You want to pay attention the DATUM and PROJECTION information in this file. PROJCS, In your case, you have an projection file containing the information you are looking for. Sometimes there is a "projection" file (with a *.prj file extension) containing the information you need, and sometimes this information is included in an XML file (with a *.xml file extension) that is included with the shapefile collection. Order to correctly display the shape polygons on a map of your choosing.Ī "shapefile" is actually a collection of different files, containing various kinds of information. Going to have to know something about the map projection used to create the shapefile in In projected meter space, rather than latitude/longitude space.
![strtrim idl strtrim idl](https://www.l3harrisgeospatial.com/docs/html/images/imgwarp09.gif)
The values in the shapefile are not even in latitude and longitude! How in the world canĬolorado county shapefile as viewed with cgShapeInfo.ĪNSWER: You are right, the values in the shapefile are I opened the file with cgShapeInfo and it looks to me like I wish to display only a single county, Summit County, on a map. QUESTION: I have a shapefile containing Colorado counties. Transparent Polygon Shapes from Shapefiles Coyote's Guide to Traditional IDL Graphics.