[ptx] fine tuning

[Ph. Gac]

hi pablo and all,

I'm still working on my images trying to get the best of hugin

auto-finetune does quite a good job but I'm afraid integer rounding errors could in the end propagate into big effects.
I was able to better significantly a large pano (3x10 images) when setting some more precise values. Moreover, better
placed points means there can be fewer points, because they don't need to cancel each other their errors. It seems,
also, that these errors sometime prevent the optimizer to glide smoothly along a better situation.

on top of my wishlist is a 400% (or 800%) zoom to finetune manually some points in some difficult cases. Then,
auto-finetune would be disabled for such points, marked with a non-zero fractional part (123.0 would be changed to
123.01). Of course, a fractional auto-finetune would be better still...

such a zoom would be very useful since the circle mark at 200% zoom is really fatty... and the detail is often still
quite small, especially on a big screen (with high dpi). A one screen-pixel wide cross could help, with image pixels 4
times that wide.

BTW, the auto-update feature (for which there is no checkbox!) is rather hasty: when you change X in the text box, it
validates it immediatly and deselects the pair, which cannot be selected again by clicking or double-clicking in its
row, so you have to select another pair and then select again the former to change Y! One suggestion: only ENTER
validates (no mouse action, since anyway you have to use the keyborard to change these values).

Sometimes, the point circle mark is not cleared from the view buffer and you have to select another couple of images to
have it cleaned. It seems this happens when you create the first point of a pair and don't give one on the other side,
escaping the waiting state in some specific manner I didn't identified clearly.

BTW, the active circle is sometime difficult to distinguish among other reddish circles


regards, Philippe