ROS Occupancy Grid
Open BetaOccupancy Grid is a map format for robots and autonomous navigation in ROS/ROS 2. Map as a raster image (PGM): each pixel is 'free', 'occupied', or 'unknown'. Used for SLAM, path planning, and Nav2.
Key Features
About ROS Grid Format
An occupancy grid is how a mobile robot sees the world: the territory is split into square cells, each marked as free, occupied or unknown. In ROS and ROS 2 such a map is stored as a pair of files — a raster .pgm and a .yaml description — served through map_server, and the Nav2 planners build a route on it.
Usually the robot builds such a map itself, driving around the territory with a scanner. A map from OpenStreetMap is needed where the robot has not driven yet: to model deliveries across a block, to test a planner on a real street and courtyard network, to prepare a scene for simulation, to give the robot an initial idea of the district.
What is inside: a ZIP with map.pgm (a black-and-white raster) and map.yaml with the resolution, the origin and the occupancy thresholds. Buildings, water and permanent barriers such as walls and fences become occupied cells; roads, sidewalks and parks become free ones; everything else stays unknown. The default resolution is 0.5 meters per pixel and can be set down to 0.1 meters; the raster side is capped at 10,000 pixels, so a large district has to be taken at a coarser resolution.
What Program Opens ROS Grid Files
The following programs and applications can open, edit, and work with ROS Occupancy Grid (.zip) files exported from OSM2CDR:
Format specifications
- Open standard
- 2D only
- Lossless (no quality loss)
- No attributes
- Output: 2 files in archive
- ROS occupancy grid map: .pgm raster + .yaml metadata (ZIP). For ROS / ROS 2 navigation stack (move_base, Nav2).
Who Uses ROS Grid Maps
How to Export ROS Grid
How to Open After Export
- ROS 1 — put both files next to each other and launch map_server with the path to map.yaml: the map will appear in the /map topic and in RViz.
- ROS 2 and Nav2 — the path to map.yaml is given in the nav2_map_server parameters inside the launch file, and from there the planner uses the map as is.
- RViz — Add > Map, topic /map: a quick way to make sure the walls and the passages are in place and the scale is right.
- Gazebo — the map works well as the base of a scene for simulating a drive before going out to a real test site.
- GIMP or any raster editor — the .pgm can be edited by hand: paint a closed zone black, a passage white, and leave gray for the unknown.
Popular maps in ROS Grid
Get ROS Occupancy Grid map exports
Download professional ROS Grid maps from OpenStreetMap. Instant generation, any area.