Register a photograph

Mark the same feature in both layers — a peak, a notch, a spur end. Each pair is one registration point. Drag either end to nudge it.

Paint the ridgelines on the photograph — a skyline, or terrain against terrain. Save, then Solve runs the ridge filter from the pose the earlier steps left. The fit is checked on the map: the photograph hangs where it was solved, and the blend compares.