Adobe's Portable Document Format (PDF) has become the de-facto standard for document exchange over the last few years, and has gained its popularity because the file remains visually identical to the original from which it was created. Even after sharing, PDF files will retain their appearance regardless of platform, operating system or local settings of the computers that they are opened on. This factor has inevitably caught the attention of the CAD community, where designers can be confident that the recipient will view the drawing exactly as intended, and will not have to rely on native translators to interpret the data.

Outputting drawing data as PDF files is an acceptable means of sharing information when there is no longer a need for the information to be edited, as once converted they are not easily editable, especially if you want to edit them layer-by-layer. If the original CAD data is not available and editing is required, conversion back into CAD is inevitable. Although there are many converters available that will automatically convert PDF’s back to DWG files, it is important to understand the limitations of performing software based conversions.

Inside a PDF file there is a set of drawing instructions that use geometrical mathematical equations to define every line, shape and object. These vector graphics provide scalable 2D versions of a drawing when the PDF has been created by a CAD application and do not get pixelated when zooming. Based on the quality of the source PDF, the conversion software will interpret the instruction set contained in the PDF and convert them to the closest match found in the DWG vector language. It is this mapping process that is the major flaw with automatic conversion, as vector graphics use geometrical primitives such as points, lines, curves and polygons, and do not support circles and ellipses.

When a PDF is created direct from a DWG file and circles and ellipses are detected, they are downgraded to curves and polygons. When these entities are converted back to the DWG vector language, they are mapped to curves and polygons based on the closest match. This behaviour can be verified in AutoCAD by clicking on a circle contained within a converted DWG file, and noticing that instead of grips being displayed at the centre and quadrant points, they are displayed at the tessellation points of a polygon. Another factor to remember when automatically converting is that an option in settings must be checked to keep text as text, as failure to do so will result in all text contained within a PDF also being converted to vector graphics.

If you have a requirement for a PDF to DWG conversion but are concerned with the time it will take then why not let RubiTech Design Services carry out the task for you. Conversions undertaken will be faithfully replicated in AutoCAD 2010 and will be fully compliant with your company’s layer protocol as these requirements will be agreed between us before the conversion process commences. Simply e-mail or post us your existing PDF documents and I will be happy to supply you with a quick lead-time and a cost effective price for carrying out your conversion.