AutoCAD DXF (Drawing Exchange Format)

DXF was invented by Autodesk itself — as an open text companion to the closed DWG, so that drawings could be exchanged between different systems. Since then it has become the common language of CAD: it is read by AutoCAD, BricsCAD, NanoCAD, KOMPAS-3D, FreeCAD, LibreCAD, and along with them by GIS programs such as QGIS and by machine-tool CAM applications.

An OSM map is exported to DXF for the sake of a base plan and maximum compatibility: when it is not known which program the file will be opened in, DXF is the safest choice. The designer gets a ready context of the site (streets, buildings, water, greenery, boundaries) and does their work on top of it.

The output is a text DXF of version R2007 (AC1021): the map is laid out across named layers, colors and line types are preserved, and the layers you do not need are switched off with a single toggle. By default the drawing arrives in the metric Web Mercator projection, so it can be measured right after opening; at export you can pick a different coordinate system.

Two peculiarities are worth knowing in advance. If you explicitly chose a projection, the file will arrive as a ZIP archive: the format itself cannot store a coordinate system inside, so a .prj file is put next to it — as with a shapefile. And the larger the area, the stricter the internal limit on the number of objects: it keeps the drawing from growing to a state in which CAD stops opening it.