On Mon 08-Sep-2014 at 02:08 -0400, William Sherman wrote:
My first issue is that I'd like to find a way to constrain what
images are compared in the control-point search. I've taken a
range of panorams, and the largest are quite large -- over 1000
pictures. So I'd like to find a way to limit control point
analysis to say the 8 neighboring pictures of any one picture.
You can try different control point strategies in File ->
Preferences. The default CPFind detector tries to minimise the
number of comparisons by assuming you have taken photos in rows.
Alternatively if you can approximately arrange the photos using a
template, there is a 'prealigned' detector that only compares photos
that are nearby.
Okay, so now onto a 210 image shoot (42x5) using a Gigapan robot.
First, loading the images it put them horizontally, whereas they
were shot vertically, so it has a typical striation pattern from a
misalignment -- I know that at this stage that doesn't matter, but
would be nice if I could provide Hugin with the basic layout of
the images.
Hugin will read any EXIF orientation data from the camera to try and
get this right. If your photos don't have this data then you need
to used the advanced/expert interface to set the 'roll' of the
photos before alignment.
I then ran the "2. Align" step. And this took over 6 hours to
process. It was not fun waiting for that, and I dread what will
happen when I get to my "large" image collections! I did notice
that at times all the CPUs were going, and then other times just a
single CPU. Also, I'd be interested to know exactly what
"Optimizing Variables" were being optimized to get a sense for
where it is in the process.
Definitely you need to stop using the Assistant for such a big image
set. The Assistant will optimise all sorts of lens parameters by
default, whereas if you have already characterised your lens there
is only any need to optimise roll, pitch and yaw for the photos.
The optimiser is much quicker when optimising fewer parameters.
Eventually, it produced a result, and the pictures are in the
proper order.
With one huge problem -- the pictures wrap around past 360 to
about 400 degrees. In reality the shoot was about 270 degrees.
The angle of view parameter for your _photos_ is too high. Normally
the Assistant optimises this, but if your panorama doesn't cover
much of the sphere surface then there is no way of knowing how big
it is supposed to be - i.e. your panorama is too thin and incomplete
to be able to calculate lens angle of view.
You need to characterise the angle of view of your lens by aligning
a full 360°, then use this number from then on. You could
alternatively stitch a not-thin panorama, say 90x90°, this would
work for calculating lens angle of view too.
I looked and looked for a way to correct this -- tried using the
"Field of View" parameter under the "Projection" tab, and pressed
the "Fit" button, but that just did some processing, then returned
the horizontal FOV to 360, but shrunk the vertical FOV! But it
left all the pictures where they were, so there is still about 40
degrees of overlap.
This is adjusting the angle of view of the _output panorama_, which
can never be larger than 360°.
I figured I might as well see what happens
Segmentation fault (core dumped)
make: *** Deleting file `IMG_7374-IMG_7584_fused.tif'
I looked at the "stack_ldr" pictures, and as I expected the two
ends of the panoram are blended together.
Yes this is going to be a mess because you have overlapping photos
that shouldn't be.
I also noticed that the list of "exposure_layers" temporary images
was missing at least one in the sequence, so perhaps this could be
related to the seq-fault.
The segfault could be something else, possibly just running out of
memory.
One thing I notice is that for my small panoram, the Batch
Processor is informing me that a Cylindrical projection was chosen
for the output, and for the medium, a Mercator projection was
chosen.
You need to take control of the software. The Assistant will pick a
projection for you using heuristics, but you probably always want to
stitch these panoramas in equirectangular projection.
In general, Hugin has lots of options and widgets which can be
bewildering, the feature-matching, alignment and stitching process
also has some quirks which are logical but unexpected until you see
them in action - trying to learn all this with a large image set is
going to be extremely frustrating.
Is there a method by which I can process panorams consisting of
1600 images with Hugin? I sure hope so.
Yes though you need lots of memory for stitching.
--
Bruno
--
A list of frequently asked questions is available at:
http://wiki.panotools.org/Hugin_FAQ
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