Low-latency Visual SLAM with Appearance-Enhanced Local Map Building
Low-latency Visual SLAM with Appearance-Enhanced Local Map Building
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DOI：
10.1109/icra.2019.8794046
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发表时间：
2019-05
期刊：
影响因子：
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通讯作者：
Yipu Zhao;Wenkai Ye;P. Vela
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文献类型：
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作者：
Yipu Zhao;Wenkai Ye;P. Vela
在现代视觉里程计/视觉同时定位与地图构建（VO/VSLAM）系统中，通常会实现一个局部地图模块，以改进数据关联和位姿估计。传统上，局部地图的内容由共视性决定。虽然共视性易于建立，但它利用的是相对较弱的时间先验（即以前见过，现在可能也会见到），因此局部地图中纳入的特征比实际需要的更多。本文描述了一种通过结合强外观先验对共视性局部地图构建的增强方法，这使得局部地图更紧凑，并减少了下游数据关联的延迟。从当前图像收集的外观先验会影响局部地图的内容：只有在视觉上与当前测量值相似的地图特征才可能对数据关联有用。为此，使用多索引哈希（MIH）对已映射的特征进行索引和查询。开发了一种在线哈希表选择算法，以进一步减少MIH的查询开销和局部地图的大小。所提出的基于外观的局部地图构建方法被集成到一个最先进的VO/VSLAM系统中。在两个公开基准测试中进行评估时，局部地图的大小以及VO/VSLAM中实时位姿跟踪的延迟都显著降低。同时，VO/VSLAM的平均性能得以保持或提高。
A local map module is often implemented in modern VO/VSLAM systems to improve data association and pose estimation. Conventionally, the local map contents are determined by co-visibility. While co-visibility is cheap to establish, it utilizes the relatively-weak temporal prior (i.e. seen before, likely to be seen now), therefore admitting more features into the local map than necessary. This paper describes an enhancement to co-visibility local map building by incorporating a strong appearance prior, which leads to a more compact local map and latency reduction in downstream data association. The appearance prior collected from the current image influences the local map contents: only the map features visually similar to the current measurements are potentially useful for data association. To that end, mapped features are indexed and queried with Multi-index Hashing (MIH). An online hash table selection algorithm is developed to further reduce the query overhead of MIH and the local map size. The proposed appearance-based local map building method is integrated into a state-of-the-art VO/VSLAM system. When evaluated on two public benchmarks, the size of the local map, as well as the latency of real-time pose tracking in VO/VSLAM are significantly reduced. Meanwhile, the VO/VSLAM mean performance is preserved or improves.