# Accelerating kd-tree searches for all k-nearest neighbours

Merry, Bruce, James Gain and Patrick Marais (2013) Accelerating kd-tree searches for all k-nearest neighbours. Technical Report CS13-01-00, Department of Computer Science, University of Cape Town.

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## Abstract

Finding the k nearest neighbours of each point in a point cloud forms an integral part of many point-cloud processing tasks. One common approach is to build a kd-tree over the points and then iteratively query the k nearest neighbors of each point. We introduce a simple modification to these queries to exploit the coherence between successive points; no changes are required to the kd-tree data structure. The path from the root to the appropriate leaf is updated incrementally, and backtracking is done bottom-up. We show that this can reduce the time to compute the neighbourhood graph of a 3D point cloud by over 10%, and by up to 24% when k = 1. The gains scale with the depth of the kd-tree, and the method is suitable for parallel implementation.

EPrint Type: | Departmental Technical Report |
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Keywords: | kd-tree, all nearest neighbours |

Subjects: | I Computing Methodologies: I.3 COMPUTER GRAPHICS |

ID Code: | 847 |

Deposited By: | Merry, Bruce |

Deposited On: | 12 Febuary 2013 |