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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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|
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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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|
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$Id: oocnn.c,v 1.30 2015/11/13 18:07:26 taschreg Exp taschreg $ |
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*/ |
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#include "oocnn.h" |
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#include "oocsort.h" |
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#include <stdlib.h> |
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#include <string.h> |
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#include <math.h> |
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|
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|
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#ifdef DEBUG_OOC_NN |
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static int OOC_SearchQueueCheck (OOC_SearchQueue *queue, const FVECT key, |
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RREAL *(*keyFunc)(const void*), |
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unsigned root) |
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/* Priority queue sanity check */ |
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{ |
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unsigned kid; |
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const OOC_SearchQueueNode *qn = queue -> node; |
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void *rec; |
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float d2; |
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|
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if (root < queue -> tail) { |
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rec = OOC_GetNearest(queue, qn [root].idx); |
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d2 = dist2(keyFunc(rec), key); |
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|
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if (qn [root].dist2 != d2) |
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return -1; |
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|
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if ((kid = (root << 1) + 1) < queue -> tail) { |
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if (qn [kid].dist2 > qn [root].dist2) |
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return -1; |
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else return OOC_SearchQueueCheck(queue, key, keyFunc, kid); |
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} |
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|
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if (++kid < queue -> tail) { |
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if (qn [kid].dist2 > qn [root].dist2) |
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return -1; |
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else return OOC_SearchQueueCheck(queue, key, keyFunc, kid); |
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} |
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} |
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|
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return 0; |
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} |
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#endif |
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|
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|
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static float OOC_PutNearest (OOC_SearchQueue *queue, float d2, void *rec) |
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/* Insert data record with SQUARED distance to query point into search |
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* priority queue, maintaining the most distant record at the queue head. |
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* If the queue is full, the new record is only inserted if it is closer |
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* than the queue head. |
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* Returns the new maximum SQUARED distance at the head if the queue is |
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* full. Otherwise returns -1, indicating a maximum for the entire queue is |
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* as yet undefined |
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* The data record is copied into the queue's local record buffa for |
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* post-search retrieval to minimise redundant disk access. Note that it |
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* suffices to only rearrange the corresponding indices in the queue nodes |
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* when restoring the priority queue after every insertion, rather than |
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* moving the actual records. */ |
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{ |
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OOC_SearchQueueNode *qn = queue -> node; |
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unsigned root, kid, kid2, rootIdx; |
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float d2max = -1; /* Undefined max distance ^2 */ |
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|
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/* The queue is represented as a linearised binary tree with the root |
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* corresponding to the queue head, and the tail corresponding to the |
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* last leaf */ |
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if (queue -> tail < queue -> len) { |
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/* Enlarge queue if not full, insert at tail and resort towards head */ |
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kid = queue -> tail++; |
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|
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while (kid) { |
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root = (kid - 1) >> 1; |
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|
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/* Compare with parent and swap if necessary, else terminate */ |
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if (d2 > qn [root].dist2) { |
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qn [kid].dist2 = qn [root].dist2; |
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qn [kid].idx = qn [root].idx; |
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kid = root; |
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} |
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else break; |
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} |
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|
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/* Assign tail position as linear index into record buffa |
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* queue -> nnRec and append record */ |
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qn [kid].dist2 = d2; |
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qn [kid].idx = queue -> tail - 1; |
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memcpy(OOC_GetNearest(queue, qn [kid].idx), rec, queue -> recSize); |
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} |
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else if (d2 < qn [0].dist2) { |
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/* Queue full and new record closer than maximum at head; replace head |
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* and resort towards tail */ |
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root = 0; |
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rootIdx = qn [root].idx; |
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|
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while ((kid = (root << 1) + 1) < queue -> tail) { |
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/* Compare with larger kid & swap if necessary, else terminate */ |
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if ((kid2 = (kid + 1)) < queue -> tail && |
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qn [kid2].dist2 > qn [kid].dist2) |
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kid = kid2; |
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|
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if (d2 < qn [kid].dist2) { |
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qn [root].dist2 = qn [kid].dist2; |
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qn [root].idx = qn [kid].idx; |
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} |
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else break; |
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|
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root = kid; |
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} |
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|
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/* Reassign head's previous buffa index and overwrite corresponding |
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* record */ |
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qn [root].dist2 = d2; |
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qn [root].idx = rootIdx; |
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memcpy(OOC_GetNearest(queue, qn [root].idx), rec, queue -> recSize); |
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|
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/* Update SQUARED maximum distance from head node */ |
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d2max = qn [0].dist2; |
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} |
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return d2max; |
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} |
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|
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|
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|
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int OOC_InitNearest (OOC_SearchQueue *squeue, |
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unsigned len, unsigned recSize) |
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{ |
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squeue -> len = len; |
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squeue -> recSize = recSize; |
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squeue -> node = calloc(len, sizeof(OOC_SearchQueueNode)); |
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squeue -> nnRec = calloc(len, recSize); |
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if (!squeue -> node || !squeue -> nnRec) { |
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perror("OOC_InitNearest: failed search queue allocation"); |
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return -1; |
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} |
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|
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return 0; |
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} |
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|
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|
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|
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void *OOC_GetNearest (const OOC_SearchQueue *squeue, unsigned idx) |
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{ |
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return squeue -> nnRec + idx * squeue -> recSize; |
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} |
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|
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|
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|
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static float OOC_BBoxDist2 (const FVECT bbOrg, RREAL bbSiz, const FVECT key) |
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/* Return minimum *SQUARED* distance between key and bounding box defined by |
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* bbOrg and bbSiz; a distance of 0 implies the key lies INSIDE the bbox */ |
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{ |
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/* Explicit comparison with bbox corners */ |
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int i; |
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FVECT d; |
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|
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for (i = 0; i < 3; i++) { |
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d [i] = key [i] - bbOrg [i]; |
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d [i] = d [i] < 0 ? -d [i] : d [i] - bbSiz; |
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|
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/* Set to 0 if inside bbox */ |
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if (d [i] < 0) |
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d [i] = 0; |
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} |
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return DOT(d, d); |
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} |
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|
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|
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float OOC_FindNearest (OOC_Octree *oct, OOC_Node *node, OOC_DataIdx dataIdx, |
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const FVECT org, float size, const FVECT key, |
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const OOC_SearchFilter *filter, |
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OOC_SearchQueue *queue, float maxDist2) |
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{ |
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const float kidSize = size * 0.5; |
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unsigned i, kid, kid0; |
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float d2; |
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char rec [oct -> recSize]; |
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FVECT kidOrg; |
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OOC_DataIdx kidDataIdx, recIdx; |
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OOC_Node *kidNode; |
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|
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/* Start with suboctant closest to key */ |
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for (kid0 = 0, i = 0; i < 3; i++) |
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kid0 |= (key [i] > org [i] + kidSize) << i; |
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|
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for (i = 0; i < 7; i++) { |
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kid = kid0 ^ i; |
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kidNode = node; |
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kidDataIdx = dataIdx + OOC_GetKid(oct, &kidNode, kid); |
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|
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/* Prune empty suboctant */ |
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if ((!kidNode && !OOC_ISLEAF(node)) || |
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(OOC_ISLEAF(node) && !node -> leaf.num [kid])) |
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continue; |
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|
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/* Set up suboctant */ |
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VCOPY(kidOrg, org); |
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OOC_OCTORIGIN(kidOrg, kid, kidSize); |
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|
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/* Prune suboctant if not overlapped by maxDist2 */ |
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if (OOC_BBoxDist2(kidOrg, kidSize, key) > maxDist2) |
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continue; |
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|
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if (kidNode) { |
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/* Internal node; recurse into non-empty suboctant */ |
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maxDist2 = OOC_FindNearest(oct, kidNode, kidDataIdx, kidOrg, |
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kidSize, key, filter, queue, maxDist2); |
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if (maxDist2 < 0) |
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/* Bail out on error */ |
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break; |
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} |
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else if (OOC_ISLEAF(node)) |
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/* Leaf node; do linear check of all records in suboctant */ |
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for (recIdx = kidDataIdx; |
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recIdx < kidDataIdx + node -> leaf.num [kid]; recIdx++) { |
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if (OOC_GetData(oct, recIdx, rec)) |
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return -1; |
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|
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if (!filter || filter -> func(rec, filter -> data)) |
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/* Insert record in search queue SQUARED dist to key below |
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* maxDist2 and passes filter */ |
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if ((d2 = dist2(key, oct -> key(rec))) < maxDist2) { |
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if ((d2 = OOC_PutNearest(queue, d2, rec)) >= 0) |
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/* Update maxDist2 if queue is full */ |
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maxDist2 = d2; |
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#ifdef DEBUG_OOC_NN |
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if (OOC_SearchQueueCheck(queue, key, oct -> key, 0)) { |
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fprintf(stderr, "OOC_SearchPush: priority queue " |
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"inconsistency\n"); |
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return -1; |
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} |
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#endif |
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} |
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} |
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} |
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|
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return maxDist2; |
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} |
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|
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|
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|
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float OOC_Find1Nearest (OOC_Octree *oct, OOC_Node *node, OOC_DataIdx dataIdx, |
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const FVECT org, float size, const FVECT key, |
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const OOC_SearchFilter *filter, void *nnRec, |
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float maxDist2) |
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{ |
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const float kidSize = size * 0.5; |
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unsigned i, kid, kid0; |
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float d2; |
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char rec [oct -> recSize]; |
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FVECT kidOrg; |
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OOC_DataIdx kidDataIdx, recIdx; |
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OOC_Node *kidNode; |
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|
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/* Start with suboctant closest to key */ |
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for (kid0 = 0, i = 0; i < 3; i++) |
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kid0 |= (key [i] > org [i] + kidSize) << i; |
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|
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for (i = 0; i < 7; i++) { |
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kid = kid0 ^ i; |
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kidNode = node; |
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kidDataIdx = dataIdx + OOC_GetKid(oct, &kidNode, kid); |
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|
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/* Prune empty suboctant */ |
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if ((!kidNode && !OOC_ISLEAF(node)) || |
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(OOC_ISLEAF(node) && !node -> leaf.num [kid])) |
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continue; |
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|
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/* Set up suboctant */ |
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VCOPY(kidOrg, org); |
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OOC_OCTORIGIN(kidOrg, kid, kidSize); |
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|
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/* Prune suboctant if not overlapped by maxDist2 */ |
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if (OOC_BBoxDist2(kidOrg, kidSize, key) > maxDist2) |
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continue; |
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|
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if (kidNode) { |
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/* Internal node; recurse into non-empty suboctant */ |
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maxDist2 = OOC_Find1Nearest(oct, kidNode, kidDataIdx, kidOrg, |
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kidSize, key, filter, nnRec, maxDist2); |
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if (maxDist2 < 0) |
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/* Bail out on error */ |
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break; |
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} |
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else if (OOC_ISLEAF(node)) |
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/* Leaf node; do linear check of all records in suboctant */ |
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for (recIdx = kidDataIdx; |
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recIdx < kidDataIdx + node -> leaf.num [kid]; recIdx++) { |
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if (OOC_GetData(oct, recIdx, rec)) |
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return -1; |
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|
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if (!filter || filter -> func(rec, filter -> data)) |
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/* Update closest record and max SQUARED dist to key if it |
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* passes filter */ |
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if ((d2 = dist2(key, oct -> key(rec))) < maxDist2) { |
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memcpy(nnRec, rec, oct -> recSize); |
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maxDist2 = d2; |
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} |
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} |
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} |
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|
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return maxDist2; |
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} |
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|
