Software review by Ralph Grabowski
PDF became the de facto exchange medium for drawings and documents because it is accurate (Adobe made sure of that when they first developed Acrobat), and because it is read-only: recipients can't modify the document. Even in the CAD industry PDF has taken over from other formats meant to be lightweight (don't contain all the baggage a drawing file normally carries) and meant to be read-only (can't be edited), such as Autodesk's DWF.
But people want what they can't have, and so third-party developers figured out how to reverse engineer the contents of PDF files. There now are a number of programs on the market, usually around $100, which will do the job for us. I happened to test PDF Converter Elite, because the Vancouver-based vendor approached me to write a review. (Disclosure: PDFConverter.com provided me with a license key, effectively giving me the software free.)
My interest was in converting PDF files of drawings back to DWG format. How good a job would the software do? I received excellent tech support as I worked my way through the simple-to-use program -- although maybe tech support was excellent because PDFconverter.com knew I was writing this review.
Opening PDFs
Starting PDF Converter Elite gives a blank slate, with dark interface, but logical toolbar. See Figure 1.
Figure 1
The initial user interface of PDF Converter Elite when it starts up
Click Open, choose a PDF file, and then choose the output format, such as Word or AutoCAD. To the right is a palette with options specific to the destination format.
My first problem occurred when I wanted to select a PDF to open. The preview screen was blank, except for an error message that referred to Windows Vista on my Windows 7 machine. Tech support quickly provided the solution to the problem, which was caused by the computer was running an older version of Acrobat Pro. I was told to hunt down the following registry key with RegEdit...
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Classes\CLSID\{DC6EFB56-9CFA-464D-8880-44885D7DC193}
and then change the AppID to {534A1E02-D58F-44f0-B58B-36CBED287C7C}. Now the preview worked. See figure 2.
Figure 2
Opening a PDF file made from an AutoCAD sample drawing
I decided to open a PDF made from one of AutoCAD's ancient sample drawings -- the complex airport.dwg floor plan. This way I would be able to compare the converted PDF with the original DWG file.
Converting PDFs to DWGs
PDF Converter Elite converts PDF files to these formats:
Destination Application File Format
AutoCAD DWG, DXF
Excel XLSX
Image JPG, PNG, BMP, GIF, TIFF
OpenOffice Calc ODS
OpenOffice Impress ODP
OpenOffice Writer ODT
PowerPoint PPTX
Publisher PUB
Web Browser HTML
Word DOCX
The program coverts a single page, all pages, or a selected area. It operates in manual and batch modes. In batch mode, we can select two or more PDF files to convert at a time.
Along the toolbar, I choose AutoCAD as the output option, and then reviewed the options listed on the right. See figure 3.
Figure 3
Conversion options for AutoCAD output
A few options puzzled me. For example, what is the difference between standard and RGB color palettes? So I clicked Help to see what it might mean. I was disappointed to see that the help for this consisted of a single sentence for all six options:
"On the dynamic sidebar, choose between AutoCAD Formats (DWG or DXF), Color Palettes (standard or RGB), Units (millimeters or inches), Polyline Width (from source document or zero), insertion point and scale."
With a bit more puzzling on my own, I decided I wanted these options:
Option Chosen
Select Select All Pages
AutoCAD Format DWG
Units Inches
Polyline Width Zero
Merge Connected Segments into Polylines Yes
Insertion Point 0,0
Scale 1
The output from PDF Converter Elite works with just about any CAD program that reads DWG files, not just AutoCAD, as well as any graphics program that reads DXF files. All entities are converted into polylines, with some exceptions. Keep the polyline width to 0, otherwise the result is sets of polylines that are too wide. Raster images in the PDF are not converted to vector lines, but retained as raster. Text is converted either to vectors or mtext; see below. OCR support is new with this release.
I clicked Convert, and conversion took about four seconds on my computer. The resulting DWG file opened in my default CAD program. I zoomed in for a closer look. See figure 4.
Figure 4
Converted PDF file open in BricsCAD; drawing credit Autodesk
For this old PDF file, all entities are converted to connected polylines, including text, hatch patterns, and blocks -- as you can see by the one entity that I selected. The conversion was not particularly accurate looking.
I asked tech support if a OCR (optical character recognition) module is available for converting the text to CAD text. There is, but it does not work with drawings in which the CAD program output the CAD fonts into vectors in the PDF, as had occurred for airport.pdf. More recent release of CAD programs, however, give the option of exporting text as actual text. To force the OCR option on, from the Edit menu I choose OCR Options > Convert Using OCR. When I tested it again with a more recent PDF file, the text was indeed converted to strings of MText.
The other advantage of PDF files generated from more recent releases of CAD programs is that layers are optionally preserved, and hatch is exported as hatch entities. See figure 5.
Figure 5
PDF converted to DWG showing layers (upper left), along with discrete mtext and hatch entities (upper right); drawing credit BCIT
Conclusion
PDF Converter Elite ($100) works with what it has: PDFs based on older vector-only drawings are converted into polyline of varying quality, while more modern ones give us cleaner text, hatch, layer, and vector results. I was pleased to see that conversion occur quickly.
http://www.pdfconverter.com
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