From: Nick Hurlburt <nickhurlburt@ya...> - 2002-03-07 18:06:15
I wrote a bundle adjustment routine to solve an N-view reconstruction problem
using vnl_levenberg_marquardt. My vnl_least_squares subclass takes a vector
that is the serialization of the projection matrices and returns the vector
whose elements are geometric distances dist(PX, x), where X and x are world and
image points that are kept unchanged. There are about 20*N image points and N
is only 3 or 4 right now. I am not supplying a gradient. The initial guess is
Most of the time, the solver responds with something like:
vnl_levenberg_marquardt: too many iterations
vnl_levenberg_marquardt: 390 iterations, 14403 evaluations, 177 residuals. RMS
error start/end 1.8665/0.422231
and then fails.
From intermediate measurements I know the solution is converging, albeit slowly
and not strictly monotonically, but the solver cuts off and throws away the
incomplete but improved results. Can I change the convergence criteria or at
least recover the last parameter vector?
Also, if you see a way by which I can improve the general algorithm I've
described, I'd be interested. On the rare times it does terminate, the error
from external reprojection tests isn't always better, sometimes a little worse.
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From: Ian Scott <ian.scott@st...> - 2002-03-11 10:57:05
> Can I change the
> convergence criteria or at
> least recover the last parameter vector?
The base vnl_nonlinear_minimizer has functions such as set_f_tolerance(),
The call to minimize(x) should have left x with the best value it found. If
not, then that is a bug.
From: Nick Hurlburt <nickhurlburt@ya...> - 2002-04-29 19:10:51
I have some code that I would like to document using doxygen in the same style
as the VXL code (with the intention of maybe contributing some of it at some
point). The doxygen manual doesn't discuss the "\\:" format that seems to be
used. Could someone explain how I can use the same style, or maybe send me a
sample config file?
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