The file format to import tie points (Ground Control Point, Checkpoints) is a .csv or .txt file. It contains four or six columns per line and uses commas "," as column separators. The formats of tie points are described in the table below:
- GCPs in geographic coordinates.
- GCPs in geographic coordinates with accuracy values.
- GCPs in projected coordinates.
- GCPs in projected coordinates with accuracy values.
Note*: The order of coordinates in the input file needs to
follow the order of axes in the coordinate system definition chosen in the import dialog.
For example, if the coordinate system definition specifies that the first axis is X and the second is Y then the order of the coordinates in the GCP input file needs to be the same.
For more information see
How to check the order of the axes in the coordinate system definition section.
How to check the order of the axes in the coordinate system definition
To check the order of axes in the coordinate system definition:
- Open the EPSG Geodetic Parameter Registry website.
- Write the name or the EPSG code in the EPSG Dataset - Text search.
- Click GO and select the correct name in the results..
- Expand the COORDINATE SYSTEM section and check the order in the AXES subsection.
After checking the order of the axes in the coordinate system definition, modify the input file to follow the same order of coordinates.
Example: For the WGS 84 / UTM zone 32N (EPSG code 32632) the order of axes in the coordinate system definition is first
Easting and second
Northing. The GCPs file should be formatted as:
label, Easting [meter], Northing [meter], z [meter]