In order to be as non-destructive as possible the importer aims to map as many DXF types to Blender curves as possible. : Since Blender (v2.71) is pretty slow at adding objects the user might want to merge similar dxf geometry to one object. It is possible to merge geometry . The first produces one object per layer, if there is mesh, curve, lamp, text data on one layer one object per layer and per Blender object. The second not only differentiates between Blender data types but also DXF types, such as LWPOLYLINE and POLYLINE. As of version 0.8.6 (March 2016) two new options are available: ‘By Layer AND closed no-bulge polys’: closed polylines with no bulge, that is no curved edges, can be merged to one single mesh. This makes sense when the DXF polylines have an extrusion and/or an elevation attribute which basically describes a loc/rot/scale transformation. If this merge option is chosen, line thickness settings will be ignored/disabled. ‘By Layer AND DXF-Type AND Blocks’: for DXF files with a block being referenced MANY times, this option allows to insert the same block MANY times with one dupliface object instead of with one object for each time the block needs to be inserted. Unfortunately this works only for block inserts that are uniformly scaled. Non-uniformly scaled block inserts are being imported as defined in ‘Blocks As’. have an effect on line in z and x/y direction respectively. A straight line might be turned to a cube by its attributes for instance. Therefore in Blender these attributes are represented with curve extrusion, Bevel and Taper objects. : export NURBS 3D geometry (BODY, REGION, PLANESURFACE, SURFACE, 3DSOLID) to ACIS-Sat files, since this is the format AutoCAD stores NURBS to DXF. The user is being notified about the amount of stored .sat/.sab files. : center the imported geometry to the center of the scene, the offset information is stored as a custom property to the scene Geo Referencing Options: If a scene has a geo reference already, the scene SRID is set automatically and (when using pyproj) a DXF SRID MUST be set. Unit Scale is used to scale coordinates (e.g. centimeter to meter) : DXF files do not store any information about the coordinate system / spherical projection of its coordinates. Best practice is to know the coordinate system for your specific DXF file and enter this information in the DXF importer interface as follows: ) pyproj and copy it to your AppData/ApplicationSupport Folder/Blender/2.70/scripts/modules/. In case you need to compile your own binary refer to pyproj is a python wrapper to the proj library, a well known C library used to convert coordinates between different coordinate systems. Open source GIS libraries such as ‘proj’ are used directly or indirectly by many authorities and therefore can be considered to be well maintained. If pyproj is available the DXF importer shows a selection of national coordinate systems but lets the user also to enter a custom EPSG / SRID code. It also stores the SRID as a custom property to the blender scene. If a scene has already such a SRID property the coordinates are being converted from your DXF file to target coordinate system and therefore you MUST specify a SRID for the DXF file. If no SRID custom property is available the scene SRID is by default the same as the DXF SRID. : In case pyproj is not available the DXF importer will only use its built-in lat/lon to x/y converter. For the conversion we use the ‘transverse mercator’ projection that asks for a lat/lon coordinate to be used as the center of the projection. The lat/lon coordinate is being added to your scene as a custom property. Subsequent imports will convert any lat/lon coordinates to the same geo reference. Important: So far only lat/lon to x/y conversion is supported. If you have a DXF file with euclidean coordinates that refer to another lat/lon center the conversion is not (yet) supported. : if you have your data from openstreetmap or some similar GIS service website and exported it with QGIS or ArcGIS the coordinates are most likely in lat/lon –>, use WGS84 as your SRID with pyproj or ‘spherical’ if pyproj is not available. For other DXF vector maps it’s very likely that they use local / national coordinate systems. Open the DXF with a text editor (it has many thousands of lines) and make an educated guess looking at some coordinates. DXF works with ‘group codes’, a name AutoDesk invented for ‘key’ as in key/value pairs. x has group code 10, y has 20, z has 30. If you find a pattern like 10, newline, whitespace, whitespace, NUMBER, newline, 20, newline, whitespace, whitespace, NUMBER, newline, 30, newline, whitespace, whitespace, NUMBER then NUMBER will be most likely your coordinates. Probably you can tell from the format and/or the range of the coordinates which coordinate system it should be. Source.