How to quickly edit DXF from poor quality scans

If you've vectorized a poor quality scan and ended up with a messy DXF file you can still use it to quickly build up a drawing in CAD. Scan2CAD user Alan Darbyshire describes how.

"I use Scan2CAD on every contract drafting job I do. As I am supposed to be redrafting a drawing from scratch my customers expect 100% first quality but to save myself time I use Scan2CAD to do 80% of the work and I do the rest, thus ensuring that the final results are perfect.

"The problem is that 99% of the drawings I get are copies, not originals. When I scan these poor quality copies and convert them in Scan2CAD the results are not as good as if I was working from the original master drawing. Fortunately, I've developed a way around this problem which has proved very useful when I'm redrawing a very messy DXF file.

"Once Scan2CAD has created the DXF file I import this into the CAD software. In my case, it's AutoCAD. The method I use is as follows. I place the Scan2CAD DXF geometry onto a faint colored layer that I call 'S2C', dark gray if it's on a black background. Then I create another layer, which I call 'Trace' and make this white. Next, I change all of the perfect geometry from the 'S2C' layer onto 'Trace'. The easiest way to do this is to just select the 'S2C' entities, then pick the 'Trace' layer. This is a standard method of moving geometry form one layer to another in AutoCAD.

"Very quickly I am able to build up the detail required. Note that I am not drawing over the 'S2C' layer, simply changing it to the 'Trace' layer. I use AutoCAD's Offset and Fillet Zero commands to tidy up and modify the Scan2CAD DXF file, plus I am able to 'snap' to the Scan2CAD geometry to add or tidy any items as required. I don't have to start from a clean sheet in CAD. It is surprising how quickly I can build up the detail. Afterwards, I just delete the leftover entities on the 'S2C' layer using AutoCAD's Properties 'Funnel' to search for all the 'S2C' entities.

"This method allows me to complete the drawing in around half the time it takes to redraw it from scratch. The result is an accurate drawing that I can email to my customer who can carry out his amendments in turn.

"When the master drawing is good and I scan it correctly, I have a lot less work to do afterwards. If you have an architectural drawing it is of paramount importance that you scan it in straight as this will affect the results you get. Yes, you can rotate a skew drawing in Scan2CAD but if you scan it in straight in the first place it will save you an additional step in the tidying-up process later on.

"Scan2CAD has saved me a lot of time and given me a rapid payback on my investment. It really does help me get my work done more quickly!"

Return to main Hints and Tips page