[ptx] Question on BBF used in Brown's paper.

Xianyong Fang FANGXIANYONG at CAD.ZJU.EDU.CN
Wed Mar 31 09:58:48 BST 2004


Hi,

	In Brown's paper:Recognising Panoramas, he used BBF algorihtm to search the KD tree. But when I check ANN(http://www.cs.umd.edu/~mount/ANN/), I find that there is another algorithm that seems to fulfil the same purpose. In ANN,that algorithm is called priority search which is based on Arya and Mount's paper:Approximate nearest neighbor queries in fixed dimensions.(In Proc. 4th ACM-SIAM Sympos. Discrete Algorithms,pp 271-280,1993). 
   
    In ANN's user manual, it writes:Whenever we arrive at a nonleaf node, we compute the distances from the query point to the cell of the two children. We enqueue the further child on a priority queue, sorted by distance, and then visit the closer child recursively. On arriving at a leaf node, we compute the distance to the points sorted in this node, and continue by dequeing the next item form the priority queue. 

    I also check the original paper on BBF algorithm. According to my understanding, I find that these two algorithm have the same idea. 

   So does anybody can tell me where i am wrong here? 

Xianyong






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