Create 3-D occupancy map

The `occupancyMap3D`

class stores a 3-D map and map information.
The map is stored as probabilistic values in an octree data
structure. The class handles arbitrary environments and expands its size
dynamically based on observation inputs. You can add observations as point clouds or as
specific *xyz* locations. These observations update the probability
values. Probabilistic values represent the occupancy of locations. The octree data
structure trims data appropriately to remain efficient both in memory and on
disk.

creates an
empty 3-D occupancy map with no observations and default property
values.`omap`

= occupancyMap3D

specifies a map resolution in cells/meter and sets the
`omap`

= occupancyMap3D(`res`

)`Resolution`

property.

creates an object with additional options specified by one or more
`omap`

= occupancyMap3D(`res`

,Name,Value)`Name,Value`

pair arguments. For example,
`'FreeThreshold',0.25`

sets the threshold to consider
cells obstacle-free as a probability value of 0.25. Enclose each property
name in quotes.

`checkOccupancy` | Check if locations are free or occupied |

`getOccupancy` | Get occupancy probability of locations |

`inflate` | Inflate map |

`insertPointCloud` | Insert 3-D points or point cloud observation into map |

`rayIntersection` | Find intersection points of rays and occupied map cells |

`setOccupancy` | Set occupancy probability of locations |

`show` | Show occupancy map |

`updateOccupancy` | Update occupancy probability at locations |

[1] Hornung, Armin, Kai M. Wurm,
Maren Bennewitz, Cyrill Stachniss, and Wolfram Burgard. "OctoMap: an efficient
probabilistic 3D mapping framework based on octrees." *Autonomous
Robots*, Vol. 34, No. 3, 2013, pp. 189–206..
doi:10.1007/s10514-012-9321-0.