Hi,
The vertex state space is already restricted to the perpendicular
lines as you suggest. When the initial seam line bends, these state
space lines tend to intersect, which leads to geometrically
uninteresting solutions where the seam line doubles back on itself.
Addressing this issue would be a good start. One of the motivations
for choosing annealing was the ability to encode more complex
optimization criteria into the costfunction, like a penalty for seams
that have self-intersections, or are too straight, or too curvy, or
reduce the enclosed area of a closed contour by too much, etc. The
current implementation is very rudimentary, both in the costfunction
implementation and the annealer itself. I would put more time into it
if I had any to spare.
Andrew
On Thu, Jun 18, 2009 at 1:06 AM,
r.e.wolff<r.e.wo...@harddisk-recovery.nl> wrote:
>
> On Jun 14, 8:12 am, Andrew Mihal <andrewcmi...@gmail.com> wrote:
>> The seam line optimization uses a two-step approach influenced by
>> research on active contours. The overlap region between an image pair
>> is treated as a cost function. Areas of disagreement and areas outside
>> the intersection region have high cost. First, the result of the
>> nearest feature transform is vectorized into a polyline, and a
>> generalized deterministic annealing algorithm is used to adjust the
>> vertex positions to optimize the cost of the line. The line is
>> penalized for crossing areas of high cost and vertices are penalized
>> for moving far from their initial positions in the center of the
>> overlap region. Second, Dijkstra's shortest path algorithm is used to
>> fill in the exact seam line between polyline vertices.
>
> Hmm. I worked on "real time minimimum cost contour detection" in
> '92-'95. Why the annealing, there is an algorithm that will give you
> the
> exact minimum cost.
>
> I would take the initial seam line. take lines perpendicular to this
> line
> and along this line I'd sample the cost function. A parabolic function
> for "distance from the original seam", and some function for the
> difference
> between the two images. Preferably the number of points on those
> perpendicular lines are always the same. This gives a rectangular
> matrix
> of cost points. Now, for every point in the matrix, you have three
> options of getting there from the line above. diagonal from the left
> diagonal from the right, or straight down. If you move down the matrix
> this way, you'll find the minimum cost from top to bottom through the
> matrix, which transforms to a line more or less parallel to the
> initial
> seam.
> >
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"hugin and other free panoramic software" group.
A list of frequently asked questions is available at:
http://wiki.panotools.org/Hugin_FAQ
To post to this group, send email to hugin-ptx@googlegroups.com
To unsubscribe from this group, send email to
hugin-ptx-unsubscr...@googlegroups.com
For more options, visit this group at http://groups.google.com/group/hugin-ptx
-~----------~----~----~----~------~----~------~--~---
