Stephen Irons wrote:
> Christopher Sawtell wrote:
>   
snip
>> With hugin you can assemble a mosaic of photographs into a complete 
>> panorama, 
>> stitch any series of overlapping pictures and much more.
>>
>> If so go here:-
>> http://hugin.sourceforge.net/
>> and here
>> http://panotools.sourceforge.net/
>>
>> Beautiful results claimed ( I havn't used the programs )
>>
>>     

>>   
>>     
> Thanks for the pointers: I was wondering if there was something like
> this available. I have a whole series of photos of the Waimak - Mingha -
> Bealey valleys taken from the ridge above the Bealey Hut that I have
> been trying to assemble into a big panorama using gimp, using the
> methods described in 'Beginning GIMP'. I was holding the camera by hand,
> however, so they are all rotated slightly.
>
> I can't wait to try it...
>
> Stephen
>
>   

I installed Hugin from the Ubuntu archives.

Operation is quite simple: you load up the photos you want to stitch
together, then on each pair of photos, you mark identifical points on
each of them: the corner of a window, a ship in the distance, anything
that has good contrast. After you have marked the first point of each
pair, you just have to mark a point on one of the other photos, and it
makes a very good guess at finding the corresponding point on the other
photo.

The next step is 'optimisation', where it works out how to adjust the
photos so that the points line up. It adjusts for lens common lens
distortions, rotates the photo in three dimensions, and probably more
transformations than I care about.

You can get a preview of the result at any time.

Finally, you stitch them together, producing either a single composite
image, or a multi-layer TIFF file. In a single image, the joins between
the photos are not straight lines: it uses some sort of spline to select
the best from each photo. This does not happen for the multi-layer TIFF
format, however; in this case, each transformed photo is a separate
layer with a transparent background. You can load it into GIMP and
create your own join paths.

The join is really amazing: I had to zoom in to pixel level to see an
misalignment.

One disappointing thing was the exposure and colour control. In my test,
the exposure in a few of the photos was very different from others (they
were taken with an old digital with no manual exposure control). Hugin
can use 'enblend' to correct for this, but there was no Ubuntu package
(although enblend source code is GPL, one of its libraries seems not to
be (or something)).

The other disappointing thing is that Hugin crashed when trying to use
an alternate stitching program PTstitcher (which apparently can do
exposure and colour tweaking).

Previously, I had spent hours trying to line up these very same images.
Yesterday, Hugin got the images lined up after about 30 minutes
(including installation and learning how to drive it). I did spend
another few hours trying to get the colours right, but...one thing at a
time...

There are alternative GPL command-line tools that Hugin can use instead
of the defaults, but I have not had time to try them.

Stephen


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