Import your model from your Architecture drawing software

It is always a mess to know how put your work out of an app to another. Let review the best way to import your model to Blender from most used Architecture drawing software :

3D

 * Babel3D : an online 3D file translation service. You can upload your files and translate them to supported output formats. No software is required to be downloaded or installed. Input formats supported for translation are SketchUp, 3DS, DXF/DWG, STEP/IGES & OBJ files. Output formats supported are 3DS, OBJ, XAML (3D only) and PDF for 2D DWG/DXF files.
 * Archicad : Export your model in 3DS format from the 3D view. While in ArchiCAD 3D View window (Parallel Projection Settings) go to 'File > SaveAs... > Format > 3DStudio File' for the correct file type.  In the 'Save 3D as 3DStudio object' window, choose "by material" to have all materials linked, 'Set drawing unit to' 10 mm is suggested. In Blender, go to 'File > Import > 3D Studio (.3ds)' or import the file using the 3DS import script at 'User Preferences View > File > Import > 3D Studio (.3ds)'.  Navigate to your file and right-click to select it, then click on the tan 'Import 3DS' button which is located at the top right of the file list window.  Click on 'Image Search' and 'Transform Fix' in the new 'Import 3DS' window that appears and click 'OK'.  Scroll out to make sure to see the object and object's arrows.
 * Allplan :
 * 3DS - Export your model in 3DS format from the 3D rendered view. Import your file in Blender using the modified 3DS import script for Allplan
 * DAE - You can use very good Collada (ver 1.4.1 or 1.5.0) export from Allplan 2014 (very good import quality, but you must redefine materials for cycles)
 * IFC - good export from Allplan 2011-2014 (chaotic BIM data/objects structure and object names in Blender and you must redefine materials for cycles)
 * SketchUp : Save your file into the Google Earth 4 format (.kmz). Rename the .kmz file into .zip. Extract the .dae file within. It's a Collada file you can import with Blender's Collada 1.4 importer. The Collada import script only works with a full Python install.
 * AutoCad, AutoCad Architectural Desktop and Autodesk Architecture : There are many ways to do this and you should try them to see what works best for you.
 * DXF-Importer script ver.1.12 imports 2D and 3D geometry from DXF up to v2007. It has advanced functionality for on-the-fly transforming geometry data. For more details see the manual at:  http://wiki.blender.org/index.php/Scripts/Manual/Import/DXF-3D.
 * 3DS export from AutoCAD : This format is well supported by Blender. The command in the AutoCAD software family for exporting to 3ds is '3dsout'. If this gives you an error this might be because since 2007 3dsout must be manually installed. At the Autodesk website there is a 3dsout utility which will add this ability. If you need this function always available you'll need to run the command 'appload' and add the file 'Ac3Dsout.arx' to the Startup Utility. Read the README file for options to make the 3ds file as useful as possible.
 * DWG/DXF through SketchUp: SketchUp 6 can import DWG and DXF files up to v2007. You can use it to produce a Collada file more easy to import. (See SketchUp import above)

2D

 * Autocad :
 * DXF-Importer script ver.1.12 imports 2D and 3D geometry from DXF. (see above)
 * DXF built-in importer has very limited functionality: You must provide Autocad DXF version 12 files of the project. A file for each floor, for instance. Since the buildin DXF importer has some coordinates problems with large DXF files, the smaller the DXF file, the better. The CAD drawing to be positioned according with CAD program grid. Blocks and polylines must be exploded. All entities in layer 0. Basically only lines, points, circles and arcs will be accepted by the importer.
 * DXF -> SVG : Another way is to convert you DXF sketches into SVG through OpenOffice. Caution: You must restart Blender between each import to avoid a nasty bug. (Blender import your second file AND your first file again if you don't restart)
 * Import via SketchUp : SketchUp has a good DXF/DWG import up to v2007 Autocad files. Export from SketchUp to the Google Earth 4 format (.kmz). Rename the .kmz file into .zip. Extract the .dae file within. It's a Collada file you can then import with Blender's Collada 1.4 importer. The Collada import script only works with a full Python install.
 * Allplan : convert the 2D lines into 3D. Then export in DXF.