Convert ASCII Coordinates

Use ASCII Coordinate Conversion to convert ASCII coordinates in one projection and datum to another. The input ASCII file must contain columns of x,y coordinates, and optional z values (elevations). If no elevations are included in the input coordinates, then ENVI assumes elevation values of 0 m. The output file will also contain two columns of x,y,(z) coordinates in the new selected projection. You can output the coordinates to an ENVI ground control points (GCP) file.

1. From the Toolbox, select Geometric Corrrection > ASCII Coordinate Conversion. The Enter Input Coordinate Filenames dialog appears.
2. Select the input ASCII coordinates file.
3. Click OK. The Convert Input Coordinate Files dialog appears.
• To add a file to the Selected Input Files list, click Input Additional File.
• To remove the file from the list, select a filename in the Selected Input Files list and click Delete.
4. Enter an output filename.
5. Click OK. The ASCII Coordinate Conversion dialog appears.
6. Select the input projection type from the Select Input Projection list.
7. Select the desired output projection type from the Select Output Projection list.
8. Enter Map X/Y Column values of the columns that contain the map information, Map Z Column elevation values (if any), and Image X/Y Column values (if your input file is in ENVI GCP format).
9. Select the numeric precision of the output data by entering a Precision value.
10. Select one of the following output options:
• To output your converted coordinates and all other unchanged input columns of data, click the Output toggle button to select All Input Columns.
• To output the converted coordinates and image values to an ENVI GCP (ground control points) file, click the Output toggle button to select ENVI GCP File.
11. Click OK. ENVI converts the coordinates and writes a new ASCII file containing the converted coordinates.