How can I import my GPS Points into ENVI Classic?

GPS points are often obtained in the following format:

ID#, X, Y

and users would like to import these points into ENVI.

This type of GPS point file has three columns of data, consisting of the point ID number, the X location, and the Y location.

These points are usually an ASCII file; however, the File->Open External File->Generic Format->ASCII method in ENVI doesn't allow for the import of points in this format, because it is an ASCII raster reader and is not intended to read ASCII point data.

This Help Article discusses another method available to import these points into ENVI 5.0 Classic and ENVI 4.8.
 

If you have a GPS point file with the format of ID#, X, Y you can import these points into ENVI Classic using the Window->Point Collection utility.

Here is a sample GPS data file in this format:

1, -107.7840409, 44.28326903
2, -107.7764449, 44.28345405
3, -107.7688487, 44.28363857
4, -107.7612525, 44.28382258
5, -107.7536563, 44.28400609

This file has 5 GPS point locations, identified by the ID number in the first column. The second column of data is the longitude value and the third column is the latitude value. The file can be delimited by space, comma, or tab. The file can also contain any optional header information, provided that the header is commented out with a semicolon (;).

Here are the steps to import this file into ENVI Classic:

1. From ENVI Classic, select Window->Point Collection

2. In the Point Collection window, select File->Import Points from ASCII.

3. Select your saved GPS point text file.

4. In the Input ASCII file dialog box, verify that your desired file is shown as the input file.

5. Set the Latitude Column as column 3.

6. Set the Longitude Column as column 2. You can leave the other Column fields blank if your GPS point file only has the above three columns.

7. Select your Map Projection, Datum, and Units. In this example, the GPS point file's projection is in Geographic Lat/Lon, the datum is WGS-84, and the units are degrees.

8. Click OK.

9. The longitude and latitude from the points are imported into ENVI Classic and appear in the Point Collection dialog box.

You then are able to save these points as an ENVI vector (.evf) file.
To do so, please follow these steps:

10. From the Point Collection window select File->Save Points As->EVF Layer.

11. Select the layer name and either select the Output File Name or output to Memory.

12. Click OK.

13. The layer name then appears in the Available Vectors List. Select the layer name, then select "Load Selected".

14. The points appear in the new vector window.

You can now open an associated image and overlay these points on that image.

The resulting vector file is also the easiest way to bring the GPS points into ENVI 5.0.