Tim Bsaid:
“So if you see 5m of the wall horizontally in your image, move 1m (20%) to the side. That’s your 80% overlap. Same thing for vertical”
Yes I was getting round to that - ‘same thing for vertical’. If the objective is for the same Feature to appear in at least three photos, four better, or even (in theory, with 80% overlap) five, then yes that’s what you get by stepping along the wall with 80% overlap.
Then Tim says ‘same for vertical’. I quite agree, that what goes for horizontal makes sense for vertical too. So not just a single horizontal pass, but a rectangular grid of camera positions (‘rectangular’ rather than ‘square’ because the photo format is 3:2 (or similar) wider horizontally than vertically).
In stepping along a wall horizontally, the camera is seeing both left and right hand side of objects - but objects have tops and undersides too - so stepping also up and down the wall vertically makes sense.
What I’m getting round to, is that this need not mean 2x or 3x as many photos. As long as a Feature appears in 3, 4 or 5 photos, RC doesn’t mind if these are all in a line, or a scattering from different horizontal and vertical angles (within 30o max, I’m saying). In other words, instead of 80% overlap in a horizontal line, you could do say 50% overlap horizontally and 50% vertically. Or 67% H x 67% V.
The 50% x 50% layout means that a Feature would appear in four photos - once in ea of the four quarters of four different photos (draw it out, to see!). The 67% x 67% layout would mean nine appearances for ea Feature! Unfortunately it’s kinda whole-number modular - 40% or 60% overlap (hoping to get 3 or 5 appearances) don’t work, leaving portions of the grid a little or a lot less overlapped.