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Pablo,<br>
<br>
Thanks for the test cases. As we discussed offline, these tests
illustrate that b=0 prevents optimization of b, but they do not
illustrate the "goes berserk" problem; b is optimized correctly if it
is optimized at all. My build of the optimizer handles these tests the
same as yours. <br>
<br>
It seems that b=0 prevents optimization in some cases but not in
others. I don't know exactly why that is. Maybe something to do with
relative scaling of various parameters in the depths of the
Levenberg-Marquardt algorithm. Anyway, the safest approach seems to be
always make a/b/c non-zero if you want to optimize them.<br>
<br>
Let me know if/when you want me to look at a test case where the
optimizer goes crazy. I suspect that it will turn out to be related to
control point placement, so I will need access to the images too.<br>
<br>
Thanks much,<br>
--Rik<br>
<br>
Pablo d'Angelo wrote:<br>
<blockquote type="cite" cite="mid20040718093745.GA1435@svalbart">
<pre wrap="">On Fri, 16 Jul 2004, Rik Littlefield wrote:
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">Ups, overlooked that. I'll take a look at it.. Strangely, the same thing
happens if I just use PTOptimizer on the script. If I set the initial b to
some number significantly different from 0 (0.1 or so), it works, but else
it fails on the command line as well. If I set it to a really small number,
like 0.0001, the b estimate goes berzerk and I get a rms error of ~144,
where
I don't remember the old optimizer did stuff like that, I'm using the new,
panotools 2.7a-2 rpm from bruno's site. Maybe its a bug somewhere inside
the improved optimisation?
</pre>
</blockquote>
<pre wrap="">Could always be a bug. But I just reran one of my standard test cases,
using pano12.dll built from 2.7.0.3 sources, under PTGui, optimizing
fov/a/b/c from starting a/b/c = 0, e-6, e-5, e-4, e-3, e-2, 0.1, 0.2,
0.5, and it converged stably in all those cases. It finally failed to
converge well starting at a/b/c = 1, no great surprise.
Could also be some subtle interaction with other parameters.
If this problem persists, send me the PTOptimizer script and I'll try it
in my environment.
</pre>
</blockquote>
<pre wrap=""><!---->
Here are some simple tests, I have made, Its just a 2 image pano with some
11 control points, maybe the control points are not set nicely for a,b,c
value estimation.
ciao
Pablo
</pre>
<br>
</blockquote>
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