While testing the fix for T3732 we used the Symmetric Forces Demon Registration with the 3M3 Demo images. The results did not look like the results for the Demon Registration at all. Instead we got a mostly black picture, whith just one corner showing data. Adding screenshots in a bit.
With the 3M3 Demo images the Symmetric Forces Demon Registration does not work because the used images have different modalities. The Symmetric Forces Demon Registration works only with the "mean square difference" metric which is only usable for images with equal modalities. This is the reason why the registration result with different modalities is incorrect. We changed the documentation of the Registration Class and will close the Bug.