3D models are an essential part of many robotic applications. In applications where the environment is unknown a-priori, or where only a part of the environment is known, it is important that the 3D model can handle the unknown space efficiently. Path planning, exploration, and reconstruction all fall into this category. In this letter we present an extension to OctoMap which we call UFOMap. UFOMap uses an explicit representation of all three states in the map, i.e., unknown, free, and occupied. This gives, surprisingly, a more memory efficient representation. We provide methods that allow for significantly faster insertions into the octree. Furthermore, UFOMap supports fast queries based on occupancy state using so called indicators and based on location by exploiting the octree structure and bounding volumes. This enables real-time colored octree mapping at high resolution (below 1 cm). UFOMap is contributed as a C++ library that can be used standalone but is also integrated into ROS.

中文翻译：

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UFOMap：拥抱未知的高效概率 3D 映射框架

3D 模型是许多机器人应用程序的重要组成部分。在环境先验未知或仅部分环境已知的应用中，重要的是 3D 模型可以有效地处理未知空间。路径规划、探索和重建都属于这一类。在这封信中，我们介绍了 OctoMap 的扩展，我们称之为 UFOMap。UFOMap 使用地图中所有三种状态的显式表示，即未知、空闲和已占用。令人惊讶的是，这提供了更高效的内存表示。我们提供了允许显着更快地插入八叉树的方法。此外，UFOMap 通过利用八叉树结构和边界体积，支持基于占用状态使用所谓的指标和基于位置的快速查询。这可以实现高分辨率（低于 1 厘米）的实时彩色八叉树映射。UFOMap 是作为 C++ 库贡献的，可以独立使用，但也集成到 ROS 中。