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Re: Neighbourfinding at large angles [message #1312 is a reply to message #1311] 
Mon, 26 November 2007 12:30 
lima Messages: 47 Registered: May 2004 Location: DeKalb, IL, USA 



Hi Mat,
Thanks for looking into alternatives to improve the efficiency of neighborfindingbased clustering. The logic for nonprojective (NP) neighborfinding is based on the assumption that highenergy clusters point to the origin, which as you pointed out, is not true for some cases (like loopers). Note that this behavior mimics the original (projective) neighborfinding implementation.
A possible extension which could be useful would be a new method allowing the user to provide (theta,phi) for reference, rather than assuming the origin as reference. This is easy to implement for NP geometries, as most of the infrastructure is already there. However, an equivalent method (with same interface) should also be made available for the projective segmentations as well  Tony/Norman may want to comment on that.
Moreover, the clustering algorithm will have to provide the theta,phi reference as input to neighborfinding method, and this requires new clusterers (preferable) or changes to the existing clusterers.
Other alternatives could, for instance, be based on the cluster energy and/or position and/or shape + direction w.r.t. the origin. Then the neighborhood window could be expanded, say from (1,1,1) to (1,3,3) or more. Again, this should be managed by the clustering algorithm, not the neighborfinding method.
What do you think?
Guilherme



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