Register Image Caveats

Affine image registration directions.

Full TM scene.  The swath width is about 185 km, and the orbit is broken in scenes that are approximately square.

The yellow arrow shows the satellite's path, which is a "polar" orbit with small inclination. 

The UTM map projection keeps the scene geometry, but it is rotated and there are triangular voids on all sides.

If you had the original imagery, with respect to the satellite, the scenes would be square, but would not line up with the UTM grid.

Airplanes could fly in any direction, so that in general you cannot expect north to be at the top of the image, except in a very general sense.  The same applies to a map that you would scan; unless you were very lucky, scanning would introduce an angular rotation because you would most likely not be able to place the map in the scanner exactly vertical.

Caveats on image registration, which might work if the simple World file options will not:

World file and grid types.

Delaunay triangulation registration is valid in a wider range of cases.

Last revision 12/3/2017