Converting vector PDF files to CAD: |
Software solution: pdf2cad (one at a time) or pdfFLY (multiple files at a time)
Conversion service solution: Trix Systems Conversion Services
The vectors in vector PDF files are essentially stored in PostScript language. PostScript was originally designed as a printer input language, not a CAD format. Consequently the vector entities in PDFs do not necessarily map directly to equivalent vector entities in CAD. This means that even if a drawing was originally created in CAD, when it is converted to PDF some of the entity types will be changed.
So when the vectors in the PDF are converted back to DXF CAD vectors it won't, in most cases, have identical entities to the original. The lines will all be there, in the correct locations, but when you select one to edit it won't be quite the same.
This
screen shot shows some simple entities as created in AutoCAD.When converted
to PDF they appear to be identical:
However,
when the PDF file is converted to DXF, as in the illustration to the right,
all the curved shapes are actually interpreted as polylines.
This proliferation of points may seem like quite a hassle. But it beats redrawing.
Another consequence of the high number of points is that the DXF files created from PDFs are much larger than if they had originally been created in CAD.
How is text handled?
When you create text in a CAD application you create 'strings' of real text and you assign a font to the text. So, for example, a string
is recorded in the CAD file as one entity, a text string of real ASCII characters, using the font Arial Bold with a specified size.
If you type the same string Revised 03/21/04 in a word processor file and then used Adobe Acrobat to create a PDF from the word processor the full string would always be recorded. You could then do a Search for 'Revised' in Acrobat and it would find the string.
To create an equivalent text-searchable PDF file from a CAD application requires a PDF creation program that specifically can convert the CAD text strings into strings in the PDF. An example of such a program is Adobe Acrobat Professional which works directly inside AutoCAD (you need to convert from a Layout).
Unfortunately, from the point of view of converting PDF files back to CAD, most people don't use one of these specialist PDF creation programs. They use programs such as the Adobe Acrobat Standard. These create PDF files that are perfectly fine for viewing. However the text that you see in the PDF is saved not as true text in strings but as vector lines. When this is converted to DXF the 'text' is linework.
Layers
It is only relatively recently that it has become possible to capture layers from an AutoCAD drawing to a PDF using Adobe Acrobat Professional. Consequently most PDF files still do not contain layer data. pdfFLY software does not yet support conversion of layers back to DXF. All vector data is placed on a single DXF layer.
Converting Raster PDFs Converting Hybrid PDFs
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