Centering and cropping of large black areas [was: Re: [ptx] thoughts for hugin UI, post 0.5]

[Pablo d'Angelo]

Hi all,

douglas wilkins wrote:

> 
>>To do this you'll want to hit the "Center" and "Fit" buttons on the
>>preview pane, that should do exactly what you want, but there are a
>>few bugs with it that I'm aware of:
>>
>> - if the panorama is more than 180 degrees (i think), it stops working

Should work better with rc1. If it doesn't work in the way you expect 
it, please let us know. Remember that it only centeres horizontally, 
because only that makes sense for all projections.

>> - the horizon of the panorama is *always* mapped to be exactly on
>>that center line in the preview pane, so even if you use the
>>center/fit buttons, if your panorama's horizon is near the bottom of
>>the pano, then you'll end up with a big empty space at the bottom of
>>the panorama (eg, the horizon will be the middle of the output always,
>>so if the horizon is near the bottom of the photos, then the top half
>>of the output will be your pano, and the bottom half will be a blank
>>space, because the horizon is in the center). I hope that makes sense.
> 
> 
> It does to me :-) 
> Perhaps we need to add an "horizon offset" adjustment in the preview?

This is a different question. The center lines in the pano indicate the 
direction of the virtual "panorama camera". Actually, the position of 
the input images is changed, not that of the virtual camera, but the 
result is the same.

If the "virtual camera" is pointed up and down, "strange" distortions 
will appear to the image.

For example, when hugin is used to get nice verticals in architectural 
photography, the "virtual camera" is oriented perpendicular to the front 
of the building. If the camera points onto the middle of image, to 
minimize the black areas, typically it won't be oriented perpendicular
to the front anymore -> converging vertical will appear.

The "architectural projection" (I'm not sure about the name) tutorial
on the hugin site shows that.

What we really need is a "crop" function, build into the stitcher and 
preview window, that works just on the final pano image. This effect 
cannot be archived by rotating the virtual camera.

ciao
   Pablo