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In
AEC and Manufacturing industries, people need to
collaborate during all phases of a project - design, build, operate.
Engineering information needs to be distributed up and down the supply chain
all the time. Drawings are an important part of this: designs, layouts,
schematics, maps, illustrations, artwork and more.
Customers, suppliers and partners for any
given project may use different applications and different platforms. This
leads to compatibility issues and productivity loss when native file
formats are used. Version control, accountability and intellectual property
are further reasons why companies do not distribute native CAD files. All
this has given rise to Adobe Acrobat PDF technology as an
application-independent platform to store, exchange, view and collaborate on
engineering drawings.
More and more, contractors and
other supply chain members receive drawings in PDF file format. And
often, they have a need to bring them into their engineering
environment for various purposes: viewing, plotting, editing,
measuring, testing, merging, profiling, cutting. In many cases, the
PDF files are part of an RFQ (Request For Quote) and the engineers
need to be able to work with the drawing geometry to make a good
proposal. The problem is that
most CAD/CAM/CNC systems do not support PDF as an input format. And there is
no easy way to extract the vector geometry from a PDF file to a CAD-oriented
file format. So, designers and operators have little choice but to redraw
the graphics from scratch, or use scanned printouts of the PDF to either
trace or apply raster-to-vector software on. The latter is generally
difficult to use, leads to wobbly lines that approximate the original at
best, and requires significant clean-up to be usable. Valuable time and
quality is lost. Few people realize
that if a PDF file was generated directly from the CAD/graphics application
where the drawing was created, the vector geometry is still alive. pdf2cad
can quickly and accurately convert such PDF files to the DXF file format,
saving the abovementioned valuable time and quality.
In a PDF file, drawings can be stored as
raster images (scans, screenshots, pictures, TIFF or JPEG files) or as
vector graphics. As raster images, they're nothing more than a digital
picture - a rectangular grid of tiny pixels, each with their own color,
together forming the image that you recognize as a CAD drawing. But it could
just as well be a picture of a sunset or your face. There is no intelligence
left in the PDF file. For such files, the only software solution to turn the
drawing (back) into an editable vector CAD file is to use a class of
software called raster-to-vector software. These programs try to recognize
lines, shapes and sometimes even text strings from patterns of pixels, and
turn them into geometry that tries to approximate those patterns. In our
experience, obtaining the best possible results takes lots of tweaking, and
those results are not usable without lots and lots of clean-up. If however a PDF file
was generated directly from the CAD/GIS/graphics application where the
drawing was created (using e.g. Acrobat Distiller, Bluebeam Pushbutton PDF
or CAD2PDF from Layton Graphics), the drawing will be stored as a vector
graphic - a set of drawing instructions that define every line, shape and
object using geometrical mathematical equations. Meaning, a scalable 2D
version of the CAD drawing, as it would be plotted to paper. (No, we're not
doing anything with 3D in PDF yet.) It is no longer
a CAD file, so you do not need to worry about your intellectual property
more than usual - for that, some key CAD-specific elements are
missing. And, the PDF is still a reference for what you sent out - taking
care of engineering accountability. But the
basic geometry is still there, possibly along with text strings and embedded
raster images. In short, a vector
PDF is less than a CAD file, but way more than a raster image.
More and more, as new product
lifecycles are started, companies adopt paperless workflows and
generate scalable vector-based PDF files. And it is this kind of PDF
file that pdf2cad was developed for.
Quite
simply (said, not done), pdf2cad interprets the drawing instructions in the
PDF file, and translates them to their equivalent in the DXF vector language. Line types used in
the PDF are reproduced in DXF. It is important to keep in mind that these
line types are not always what you hope them to be: PDF does not know
circles or ellipses, and can only represent them using curves or polyline
segments. Curves may already be downgraded to polyline segments in the PDF.
pdf2cad currently has little choice but to reproduce line types as it finds
them in the PDF. Watch this space though, as we are working on some highly
intelligent features to recognizes high level objects (e.g. curves forming a
circle) in the PDF drawing and represent them as such in the DXF.
A similar story goes for text. In many cases,
text in a drawing will already be outlined as vector paths in the PDF file.
Meaning, it is no longer 'live' text, just graphics that look like text.
pdf2cad again has little choice but to reproduce that in the DXF. If however
text is still 'alive' in the PDF file, often referred to as 'searchable'
PDF, then pdf2cad can in most cases reproduce it as searchable/editable text
(MTEXT) in the DXF. Click here for instructions to
create searchable PDF from AutoCAD. Finally, embedded
raster images are extracted to separate TIFF (for b&w) or JPEG (for color)
files, and referenced in the DXF. As long as you keep them with their DXF
parent, you will see them when you open the DXF file - assuming your target
application supports raster images, of course. If the drawing in your PDF
file is a raster image (or contains raster images), pdf2cad will warn you
after the conversion is completed. pdf2cad is a batch conversion tool,
so you don't need to open and re-save the PDF file. You just select
and convert the file. Its
intelligent architecture enables you to apply a number of filter options
during conversions, for example to emulate fonts, outline fills or rotate
the file. |
