Cypris’ lookout

Linux: AutoCAD DWG to SVG preview conversion.

Friday, July 18, 2008

Years ago I did a small utility to convert DWG or DXF files into a vector-graphic, zoomable, SVG preview. The Linux command-line utility was used in a larger drawing management application that I had built before I left that company for greener pastures.

The Linux server-based application would scan the vast (100,000s of CAD drawings) and, depending on their format, attempt to create thumbnails and extract textual information from them and populate a database so we could easily find related drawings through a simple web-interface.

The software would present thumbnails of the drawings; when the drawing was in DWG or DXF format, the thumbnail would be an SVG vector representation of the original drawing instead of an image. That made the preview much more useful as you could zoom in and still retain enough detail to ascertain if the drawings was actually what you were looking for.

Other file formats (TIFF, HPGL plots, etc) were transformed into PNG image previews that were saved into 2 size: a small thumbnail, good enough to be displayed in a list, and a larger one that would show more details.

The server software was written in Perl, with some of the converters in C. Every night, the server would go through the whole tree of drawings on the filesystem, looking for drawings it hadn’t seen before and it would pass them to the appropriate plug-in for extracting text -where possible- and create thumbnails.

Memories of fun projects…

Entry Filed under  :  Linux, Programming