[ptx] Conserving verticals with many control points

[Damien Douxchamps]

Hi Rob,

On Fri, 2006-04-14 at 17:57 -0600, Rob Park wrote:
> On 4/14/06, Damien Douxchamps <ddouxcha at is.naist.jp> wrote:
> > - do we have to use both H and V intra control points to keep the
> > panorama straight (from a theoretical point of view)? Or can we afford
> > to use only one type? In my panorama no horizontal feature can be used;
> > this may lead to the ineffectiveness of the intra control points.
> 
> Generally, when I make a panorama, I let autopano-sift generate as
> many "inter" points as it likes, and then I add in 2 or 3 vertical
> "intra" points to straighten things out. If the panorama is less than

autopano-sift crashes on my computer so I do it manually. I should not
change much because the fit is almost perfect (.727 pixel average
discrepancy).

> 360 degrees, I'll put one vertical line in the leftmost image, one in
> the rightmost, and one in one of the central images (if it is 360
> degrees, then I just try to space them evenly throughout the full
> range). That usually straightens things out really nicely, and if it
> doesn't, I just wiggle the "intra" points until it comes out. I very
> rarely use the horizontal "intra" points, almost always vertical ones.

OK, good news I don't have to use the horizontal points too. I will try
to play with the vertical points to see if it fixes the problem. Maybe
some of them are not good (or not well characterised by hugin) and this
leads to the distorted horizon.

Thanks,

Damien


-- 
  _    Damien 'Takahara' Douxchamps, PhD
 ('-   Post-doctoral investigator
 //\   Image Processing Group, NAIST
 V_/_  http://chihara.aist-nara.ac.jp/