[photo-3d] Re: Algorithm wanted

[CanterMike@xxxxxxx]

In the continuing discussion it is written:

<< 
 > Now, in practical terms this problem has hunted me too.
 > Quite a few hyperstereos from Grand Canyon had a small 
 > rotation and shift. I was rotating one chip trying to 
 > see if this made things better and had hard time figuring 
 > it out.  That's because with small rotations the vertical 
 > displacements are very small.
 > 
 > Anyone who has tried to align such slightly misalignment
 > pairs will, no doubt, sympathize with me :)
 
 I do, and this is how the problem first occurred to me some months
 ago, with a pair of prints that seemed to both have "roll" from my
 hand held shifting, and unevenly trimmed prints that apparently
 were not run level through the processor.  The methods in my 3D
 books and online for checking rotation problems were not getting
 me quickly to an answer, and I began to realize how tricky the
 problem can be.  At least in that case I had some idea of "up",
 and of the depths of various parts of the scene.  Even then, it was
 a pain.
 
 I still think there must be a general solution that can be
 accomplished with regular common equipment, excluding computers.
  >>


This sometimes happens to me as well (except when I use my Kodak).  The 
"solution" that I resort to (and admittedly a quick and dirty one) is to 
superimpose one image over the other and match up the images.  Since it has 
been stipulated that we know which is left and which is right (easy for me as 
my photofinisher prints the frame number on the back of each print, and [for 
me] the lower number is always the right image), the image parallax quickly 
identifies the "up" vector.  Can't see through your prints?  Try a stronger 
light source (another untraditional use for your projector)...many prints are 
on light enough paper to let you see enough gross detail to get going....

Admittedly this is not an ideal solution, but it has allowed me to salvage 
portions of some images that were otherwise headed to the trash (or, almost 
as bad, the 'flat' album).  I wouldn't say that any (so far) are competition 
entries, but they are at least viewable.

Mike Canter