Georeference Tiepoints editor

Add Tiepoint

 

Adds a tiepoint, also called ground control point, to this georeference tiepoints, this georeference direct linear or this georeference orthophoto. A tiepoint establishes the relation between a Row Column number in a map and its real world XY- or XYZ-coordinate.

Dialog box:

Row Col:

The Row and Column numbers of the position that you clicked in the background image are shown.

X Y:

To obtain the XY-coordinate for this tiepoint, either:

  • read the XY-coordinate of this position from a paper map, and type these in the X Y boxes, or
  • click at the same position in a map window which already has correct coordinates (master/slave) and the X Y boxes are automatically filled out, or
  • digitize the same position on a map stuck on the digitizer and the X Y boxes are automatically filled out.

When you already have a (mathematically) sufficient number of tiepoints, and you add a new tiepoint, the dialog box comes up with a suggestion for the XY-coordinates for this point. The suggested XY-coordinate gives an indication of the quality of your existing tiepoints. You should never accept this suggestion but always look up the correct XY-coordinate from a paper map, a master, etc.

Z:

When adding a tiepoint to a georef direct linear or a georef orthophoto, select this check box when you want to fill out a Z (height) value for the inserted tiepoint; as a default, the Z-value found in the DTM is given.

Clear this check box when you want to use the height value found in the DTM.

When you click OK, the tiepoint will be added to the tiepoint table.

Tips:

See also: