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/* |
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========================================================================= |
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k-nearest neighbour lookup routines for out-of-core octree data structure |
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Roland Schregle (roland.schregle@{hslu.ch, gmail.com}) |
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(c) Lucerne University of Applied Sciences and Arts, |
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supported by the Swiss National Science Foundation (SNSF, #147053) |
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========================================================================= |
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$Id: oocnn.h,v 1.14 2015/11/13 18:05:15 taschreg Exp taschreg $ |
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*/ |
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#ifndef OOC_SEARCH_H |
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#define OOC_SEARCH_H |
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#include "oococt.h" |
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/* Priority queue node for octree lookups */ |
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typedef struct { |
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float dist2; /* Record's *SQUARED* distance to query point */ |
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unsigned idx; /* Record's index in queue buffer */ |
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} OOC_SearchQueueNode; |
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/* Priority queue for octree lookups. Note that we explicitly store the |
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* NN candidates in a local in-core buffer nnRec for later retrieval |
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* without incurring additional disk I/O. */ |
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typedef struct { |
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OOC_SearchQueueNode *node; |
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unsigned len, tail, recSize; |
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void *nnRec; |
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} OOC_SearchQueue; |
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/* Filter for k-NN search; records are accepted for which func(rec, data) |
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* returns nonzero */ |
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typedef struct { |
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int (*func)(void *rec, void *data); |
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void *data; |
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} OOC_SearchFilter; |
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float OOC_FindNearest (OOC_Octree *oct, OOC_Node *node, |
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OOC_DataIdx dataIdx, const FVECT org, float size, |
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const FVECT key, const OOC_SearchFilter *filter, |
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OOC_SearchQueue *queue, float maxDist2); |
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/* Find k nearest neighbours (where k = queue -> len) within a maximum |
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* SQUARED distance of maxDist2 around key. Returns the corresponding |
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* data records with their SQUARED distances in the search queue |
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* (queue -> node [0] .. queue -> node [queue -> tail - 1]), with the |
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* furthest neighbour at the queue head and queue->tail <= queue->len. |
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* |
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* This is a recursive function requiring params for the current node: |
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* DataIdx is the data offset for records in the current node, which is |
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* necessary for implied addressing into the leaf file. Org and size are |
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* the origin and size of the current node's bounding box. |
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* |
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* An optional filter may be specified; if filter != NULL, filter->func() |
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* is called for each potential nearest neighbour along with additional |
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* data provided by the caller; see OOC_SearchFilter typedef above. |
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* |
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* Return value is the SQUARED distance to furthest neighbour on success, |
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* else -1 on failure. */ |
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float OOC_Find1Nearest (OOC_Octree *oct, OOC_Node *node, |
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OOC_DataIdx dataIdx, const FVECT org, float size, |
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const FVECT key, const OOC_SearchFilter *filter, |
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void *nnRec, float maxDist2); |
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/* Find single nearest neighbour within max SQUARED distance maxDist2 |
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* around key and copy corresponding record in nnRec. This is an |
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* optimised version of OOC_FindNearest() without a search queue */ |
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int OOC_InitNearest (OOC_SearchQueue *squeue, |
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unsigned len, unsigned recSize); |
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/* Initialise NN search queue of length len and local buffa for records |
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* of size recSize; precondition to calling OOC_FindNearest() */ |
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void *OOC_GetNearest (const OOC_SearchQueue *queue, unsigned idx); |
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/* Return pointer to record at pos idx in search queue after calling |
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* OOC_FindNearest() */ |
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#endif |
