Image Registration

Image registration takes an image like an aerial photograph or scanned map, and assigns coordinates to some points so that the computer can calculate the coordinates for every point.  If the process is complicated, the program might Reproject the data  so that it has a simple geometry.

In the simplest case, the coordinates for three points will define a translation and rotation.  This is an affine transformation.

The following conditions will limit the effectiveness of such registration, and require more complicated algorithms:

The term "rubbersheeting" refers to a stretching or warping of the image to bring it into the correct geometric location.

Triangulation registration maps points on one map to another, computes an optimal set of triangles, and then distorts the map to obtain a correct geometry. 

Database with image registration points

  • Image coordinates came from the location where the mouse was clicked.  The origin (0,0) is the upper left corner of the image, the computer graphics convention.  The user will not interact with these, other than not panic about their reference system.
  • Lat/long coordinates were entered from the keyboard.
  • UTM coordinates for the current zone, converted from the lat/long values entered.

Last revision 12/4/2017