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Anchor CA #4
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@hogyun2 In fact we slice a point cloud into multiple levels and top (by area) CAs at some levels are anchors. As described in the paper (Sec V.B.3, complexity analysis), we select 3x6=18 anchors for each scan. |
@lewisjiang Thank you for your answer. |
@hogyun2 Actually each anchor has an associated retrieval key and a local graph/constellation connection, as is shown in Fig.3 of the paper. When revisiting, all the keys in the query scan will be used. |
@lewisjiang Thank you for your answer. |
@hogyun2 The number of comparison times is not definite, cuz at first the matching is a search with a maximum distance. The correlation value between query and candidate calculated from GMM optimization together with a given threshold jointly determines if a match is positive. |
@lewisjiang thank you in advance. |
@euncheolChoi Yes, "18 anchor-centered descriptors per scan" is roughly the idea. When comparing, we first search the DB and do discrete check on an anchor-to-anchor basis, and this will propose several possible transforms with several poses. We do not compare all possible combinations of descriptor pairs since one pair is enough to propose a good enough transform. It is possible that descriptors in two scans propose many transforms, and in that case we use some voting to select the most probable one. Note that the mission of CAC/key/descriptor is over when we obtain the intial guess of the transform. Following that, the GMM is done with (almost) all CAs in a batch from two scans for a given transform when calculating correlation. Hope this solves your question. |
@lewisjiang Thank you for your answer! |
Hello. Thank you very much for your good research.
I understood that one anchor is created for each frame of pointcloud by reading the paper and looking at the code. Then, what is the criteria for selecting one anchor among the various CA?
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