[Insight-developers] ICP patent thoughts

[Miller, James V (Research)]

I thought about this further this weekend. I am really starting to like the
"bullets" and "gun" analogy.  
 
Iterative closest point is implemented in ITK as a metric.  All this metric
does is return a vector of the distances between the points in the moving
set to the fixed set. There is actually nothing "iterative" about the
metric.  It merely measures a set of distances and returns a vector of
distances (one distance for each point in the moving set). This class 
could be renamed "ClosestPointMetric" to make this even clearer.
 
(By the way, if a distance map is not being used, the metric should use some
sort of spatial search data structure (grids, kd-trees, etc.)  as opposed to
a linear search of the container.)
 
The output from the ClosestPointMetric can be used for a variety of
algorithms.  ICP is one. Collision detection for a surgical application is
another. So I think the metric is more general than ICP.
 
This being said, the examples/tests that put all the pieces together to form
an ICP algorithm may have to be modified.  This all hinges on the
interpretation of what if covered by the patent. The ICP examples/tests may
have to be moved into a patented directory. They may have to be removed if
we cannot obtain the appropriate permissions.
 
Again, we may be able to avoid almost all the issues with ICP, if the
ClosestPointMetric did not return euclidean distances but instead return
weighted euclidean distances using some robust weight function.
 
 

Jim Miller 
_____________________________________
Visualization & Computer Vision
GE Research
Bldg. KW, Room C218B
P.O. Box 8, Schenectady NY 12301

millerjv at research.ge.com <mailto:millerjv at research.ge.com> 

james.miller at research.ge.com
(518) 387-4005, Dial Comm: 8*833-4005, 
Cell: (518) 505-7065, Fax: (518) 387-6981 

 
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