Does anyone know of an accurate method for building a dwg file from a scan of a scaled drawing or plan. The dwg files will also be referenced for or made into 3d models so pulling the information straight into a modelling software would work too if possible.
It's not an easy task and according to my knowledge there is no way to do it fully automatic (I might be wrong of course).
You have options as follows: Read scans and
- recreate it manually in CAD application
- recreate it using digitizer (in the old days they had puck - kinda magnifier with crosslines to digitize from printouts/blueprints)
- create 3D object omitting 2D drawings
- convert bitmap to vectors in 2D app
- use scannig service like this (would be expensive)
Depending on complexity of your schemas, the easiest way, would be option 1 or 3. Option 4 is very doubtful (even if it's the most automatic way, it won't create useful data)
The most of CAD apps have option to import bitmap and then work on such "background". For example in AutoCAD use command Imageattach