For two d-dimensional point sets A,B of size up to n, the Chamfer distance from A to B is defined as CH(A,B) = ∑_{a ∈ A} min_{b ∈ B} ‖a-b‖. The Chamfer distance is a widely used measure for quantifying dissimilarity between sets of points, used in many machine learning and computer vision applications. A recent work of Bakshi et al, NeuriPS'23, gave the first near-linear time (1+ε)-approximate algorithm, with a running time of 𝒪(nd log (n)/ε²). In this paper we improve the running time further, to 𝒪(nd(log log n+log1/(ε))/ε²)). When ε is a constant, this reduces the gap between the upper bound and the trivial Ω(dn) lower bound significantly, from 𝒪(log n) to 𝒪(log log n).
@InProceedings{feng_et_al:LIPIcs.ICALP.2025.76, author = {Feng, Ying and Indyk, Piotr}, title = {{Even Faster Algorithm for the Chamfer Distance}}, booktitle = {52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025)}, pages = {76:1--76:18}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-372-0}, ISSN = {1868-8969}, year = {2025}, volume = {334}, editor = {Censor-Hillel, Keren and Grandoni, Fabrizio and Ouaknine, Jo\"{e}l and Puppis, Gabriele}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2025.76}, URN = {urn:nbn:de:0030-drops-234531}, doi = {10.4230/LIPIcs.ICALP.2025.76}, annote = {Keywords: Chamfer distance} }
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