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Working with DXF Files

DXF is an open CAD interchange format supported by most popular CAD and productivity applications as an import option using "load", "open" or "import". With DXF files generated by PDF FLY, you can:
  • Make modifications in AutoCAD
  • Overlay other GIS information in Microstation
  • View in, or plot from, your favorite CAD system
  • Feed into your CNC software
  • Merge with other project drawings
  • Test, measure, change, add, delete

    Before converting your PDF file, it is important to determine whether it is a suitable file for conversion. To do this, you must determine whether it is a vector or bitmap PDF fie. In general, any PDF file generated by another application will be a vector PDF while scaned drawings wil be bitmap PDF files. PDF FLY can convert all PDF files but can only generate editable text and objects from vector PDF files. Scanned or bitmap PDF files will simply be converted into equivalent DXF bitmap objects. For more on this, please see:
  • Will my PDF file convert well with pdf2cad?
  • Can I convert scanned CAD drawings into eitable CAD files?

    Bitmaps in DXF
    Sometimes, a DXF file will contain a combination of vectors and bitmaps. For eample, the drawing itself may be converted into text and editable objects but there may logos or watermarks which are bitmap images. These will be saved as separate files. In order for the DXF to render any referenced raster images, the corresponding TIFF and/or JPEG files must be in the same directory as the DXF file. 

    Text in DXF files
    If your PDF file contains ascii text, pdf2cad will convert it into the equivalent characters in the DXF file where they can be edited. Unfortuantely though, when saving a CAD file to PDF, the text is not always retained. Sometimes it is "plotted" or drawn as pen strokes which PDF FLY can only interpret as individual lines which looks like text when displayed. When this happens, the intelligence about what the characters was is lost and pdf2cad can only reproduce the curves. What looks like text in the original file is actually just an object that looks like a word. The rule of thumb is that if the text in your PDF file is represented as curves, the text will be saved as curves (=SPLINES entities) in the DXF file. If the text in the PDF-file contains actual textstrings, it will be mapped to MTEXT entities in the DXF file. 
    A complicated subject we have several tips to offer on treatment of text in DXF files:
  • To see if the text in your PDF drawing can be converted, open the PDF file in Acrobat Reader and use the Text Select tool. If you cannot highlight any words, the text has already been reduced to vector curves. 
  • If you have control over the creation of the PDF files, make sure to use TrueType fonts in the drawing and have your PS/PDF printer driver set to "keep text as text" instead of "convert text to curves". 
  • if your PDF files contain non-Roman font text (such as Chinese, Arabic or Cyrillic), or if the text looks garbled in the DXF output, try using the "Convert characters to curves" option in the General tab of the Options menu of pdf2cad. This outlines the text during conversion to ensure WYSIWYG rendering.
  • In order for fonts (the way the text looks) to be displayed properly, they must be available on the target system. If they are not, an automatic substitution will be made in favor of the closest available font. You can use font mapping to fine-tune this.

    Lines in DXF
    Line types in PDF and PostScript are often handled differently than those that are defined in a CAD application. This is due to file format differences. For example, PDF and PostScript represent circles and ellipses using splines or polyline segments, text may be composed of curves and fills may have been used to simulate cropping. PDF FLY can in many cases compensate for these differences using Intelligent filter options. In many cases, a little manual clean-up may be required to adapt the vector geometry to your CAD system.

    Tip
    Have a look at pdf2cad if you just need to convert PDF to DXF or HPGL. pdf2cad supports a subset of input/output formats of PDF FLY and is available at a lower cost. 


    WARNING:
    Inaccuracies in X/Y measurements may have been introduced during the creation of the PDF or PostScript file that you are converting to DXF. Visual Integrity is not responsible for the accuracy of the designs or other derivatives that you create using the DXF output of PDF FLY. PDF FLY reproduces the vector geometry from the source file as accurately as possible. It is up to the software user to make sure that the resulting CAD file meets engineering requirements.