If you want to convert an autocad DXF file to the Collada format, download [Blender]. Install the [ColladaBlender] plugin using the [install directions].
Import the DXF into a clean scene.

Then export as a Collada 1.4.1.

The Development Blog of Tim Graupmann
If you want to convert an autocad DXF file to the Collada format, download [Blender]. Install the [ColladaBlender] plugin using the [install directions].
Import the DXF into a clean scene.

Then export as a Collada 1.4.1.
