Tie points (GCPs, CPs) import format

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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:

 
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 axes is X and the second is Y then the order of the coordinates in the GCP input file needs to be the same.
GCPs in geographic coordinates

label, coordinate1* [decimal degrees], coordinate2* [decimal degrees], z [meter]

GCP0,46.23456,6.56114,299.931
GCP1,46.23234,6.56234,299.823

The latitude value is between -90° and 90°.
The longitude value is between -180° and 180°.

GCPs in geographic coordinates with accuracy values

label, coordinate1* [decimal degrees], coordinate2* [decimal degrees], z [meter],  Accuracy Horz [meter], Accuracy Vert [meter]

GCP0,46.23456,6.56114,299.931,0.02,0.02
GCP1,46.23234,6.56234,299.823,0.02,0.02

The latitude value is between -90° and 90°.
The longitude value is between -180° and 180°.

GCPs in projected coordinates

label, coordinate1* [units], coordinate2* [units], z [units]

GCP0,2532795.105,1152094.639,395.883
GCP1,2532728.805,1152079.825,396.619
GCPs in projected coordinates with accuracy values

label, coordinate1* [units], coordinate2* [units], z [units], Accuracy Horz [units], Accuracy Vert [units]

GCP0,2532795.105,1152094.639,395.883,0.02,0.02
GCP1,2532728.805,1152079.825,396.619,0.02,0.02

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 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]

EPSG_registry_Axes_order.jpg

Check the order of AXES on the EPSG website.

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