On 11 Okt., 22:21, Bernd Hohmann <[email protected]> wrote:
> Hi,
>
> is there any switch to force autopano-sift-c to create a buch broader
> distriubution of the control points?

Probably not, but why use autopano-sift-c?
I reckon I am using the same lens as you (mine is called Walimex pro
fisheye, but I think it's the same as your Samyang) - and I do 6
around, 1 up 1 down and get good results using Panomatic and/or
Jenny's autopano. Often I combine the two, and the process is still
much faster than using autopano-sift-c. If you're on Windows, you can
just download the precompiled binaries from the relevant websites, if
you're on Linux, Panomatic sources compile with next to no effort
(have tried it), but you can't get autopano 103 sources. What system
are you on?
And, even if your CPs are concentrated in specific areas, if you use
the right lens parameters, this should not be a problem [you only
absolutely need an even distribution and many CPs when you calibrate
the lens]. You can calculate the lens parameters by creating a
panorama with many (like, 20) well-overlapping shots done with a pano
head, best indoors with lots of detail all around you (like, a
structured ceiling, not just wallpaper), and optimize for a,b,c,d and
e. This is done more quickly if you do not use full-size images but
scale them down to some 3 MP apiece. Don't forget to set the lens type
to stereographic (you need a recent hugin version for that), and there
you go [with earlier hugin versions, you can work with the full-frame
fisheye setting, but the Samyang really is stereographic!]. For your
actual panoramas you use that same lens ini file, never mind what
image size you have then, the important thing is a,b, and c; the d and
e you optimize again with your panorama since they vary every time. In
my experience, it's not a good idea to optimze for a,b and c again;
better to just use the lens ini from the accurate measurement.
The lens ini will shape your images just right, and then you don't
need that many CPs to get the panorama right, even only three per pair
should be enough. With my Walimex I got
v=98.2757
a=0.0153614
b=-0.0595849
c=0.00447485
(that's in portrait orientation, with lens type 'stereographic', and
using hugin 2010.2.0 - there's a bug with earlier versions of hugin
which calculates the hfov wrong with stereographic lenses)
You might try that as a starting point, maybe our lenses aren't too
different.
Do check panomatic out - if you only have 10 images a pano it's well
fast enough, even though it compares every pair - which, on the other
hand, is quite a good method to get the zenith and nadir right. And
Jenny's autopano is even faster, and usually spits out a fair number
of CPs, and if you have a few misses, just do the statistical cleanup.
with regards
KFJ

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