Doh! Sometimes I can't believe how dense I am!
Erik's comment that he never gets blending artifacts at the zenith got
me thinking. I had assumed they were endemic to enblend, since I get
them regularly, and I've seen others complain about them. So I've been
dutifully patching the zeniths of my panos, and more recently using
smartblend to minimize the problem. But if Erik never gets the
artifacts....
He mentioned that he uses a zenith shot. Well, so do I -- two of them,
in fact.
I use a Tokina 10-17 lens attached to a RebelXT on top of a NN3. The
FOV of the Tokina at 10mm is about 83 x 125. I normally shoot 5 images
around at -20 pitch (because I'm trying to get as close to the nadir as
possible; tilting past -20 puts the NN3 in the bottom of the frame).
This leaves a hole of about 95 degrees at the top, so I take two shots
of the zenith for full coverage, one at +90 pitch 0 yaw and the other at
+90 pitch +90 yaw.
These two images obviously overlap substantially at the zenith, and
therein lies the problem. Enblend doesn't know how to blend across the
zenith, so when it combines the two images it creates the artifacts.
The solution (so obvious in retrospect that I could kick myself!):
punch a hole in the middle of one of the zenith shots.
convert -size 2306x3466 xc:none -draw "circle 1153,1733 853,1433"
miff:- | composite -compose Dst_Out miff:- IMG_0154.tif -matte -depth 8
IMG_0154.tif
Then there's no overlap at the zenith, so there's nothing for enblend to
do and hence nothing it can mess up. Et voila, problem solved:
http://VictoriaVR.ca/test/enblend-zenith.jpg
http://VictoriaVR.ca/test/enblend-zenith-no-overlap.jpg
Cheers,
BBB
On Wed, 2008-09-24 at 00:31 +0200, Erik Krause wrote:
> On Monday, September 22, 2008 at 16:04, Bob Bright wrote:
>
> > I still get fewer blending artifacts around the zenith with smartblend
> > than with enblend, and using enblend's maximum number of blending levels
> > doesn't affect this. E.g., compare the following two zeniths, the first
> > created by enblend with -l 29, the second by smartblend at default
> > settings:
> >
> > http://VictoriaVR.ca/test/enblend-zenith.jpg
> > http://VictoriaVR.ca/test/smartblend-zenith.jpg
>
> Interesting. I never got anything alike with enblend, but of course I
> use a zenith shot.
>
> Did you try the --fine_mask option?
>
> best regards
> Erik Krause
> http://www.erik-krause.de
>
>
> >
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