Flying high with long lens, or low with wide lens gives the same 'footprint' on the ground, so for the same flight speed and pattern you get the same overlap and therefore cameras per point.
Trouble with wide lens is that only the 'middle' section of the fov is nadir facing, getting more oblique towards the edges. That means when 'point A' is at the top of the field of view in photo 1 you are looking at it from in front, straight down in photo 2, and from behind in photo 3 when it has reached the bottom of the frame, and in some cases the difference means that 'point A' isn't well matched, if at all, in the 3 consecutive images as its appearance is drastically different from the 3 different angles, particularly when there are complex surfaces such as trees to deal with.
Flying high with a long lens you are always looking straight down on 'point A' in all three photos so it is matched easily, because it always looks more or less the same.
The trouble with the long lens approach is it gives you good XY accuracy but more uncertainty in Z, but still great for orthophotos!
I don't have much experience with aerial either, but this is what I have picked up from the forum anyway!
Topic: Forcing the alignment (Read 3647 times)
