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File Formats for Sharing CAD Drawings - Part II

DWF, HPGL, WMF, or PDF?

Geoff Harrod

.......continued from Part 1

Members of Queensland CAD Users Group (Australia) have been exploring ways of sending AutoCAD work to clients and others - allowing the recipients to view and print the drawings without requiring AutoCAD or the ability to use it and such that the drawing data cannot be altered. This is the second part of the report on our investigations and recommendation.

PDF

That leaves PDF - Adobe Acrobat 'Portable Document Format'. Acrobat is usually thought of as a system for book-size documents of formatted text and graphics. But it can handle large format graphics including both vector and raster also. PDF is now the preferred method for sending data to printing companies, whether by internet or on CD. It is becoming increasingly popular for publishing technical drawings or sending them to clients. It is more widely applicable for that than DWF, which is geared to AutoCAD only. However, DWF does provide more CAD-type viewing controls such as layer selection.

Nearly everyone these days already has the free Acrobat Reader program. If not, it can be downloaded from Adobe at no charge. The Acrobat Reader provides for printing quite adequately, and has good zoom control. Several offices have found PDF a good solution to this drawing office requirement.

The trick is how to generate the PDF files. The official Adobe method is to use the full Acrobat package, which costs about A$600. The process involves printing from whatever source program you use to a Postscript printer driver, but directing the output to a file instead of a printer (which you probably don't have). It doesn't matter a lot what make and type of Postscript printer you install, but for CAD it would need to be a large format one, which could be a problem. Windows comes with several Postscript A4 and A3 printers in its driver library, but drivers for large format Postscript printers would usually only be available if you purchased a large format Postscript printer, such as an HP DesignJet or Encad NovaJet Graphic Arts model. Having generated a Postscript file you then run Adobe's Acrobat Distiller program from the full Acrobat package, which reads that file and generates the PDF equivalent.

PDF Generator Software

As well as the official Adobe tools, there are some PDF generators that operate as Windows printer drivers and so create a PDF file directly without going through the Postscript file intermediary. One that I use is the 'Zeon Docucom PDF Driver' from Taiwan. It costs about AU$70 and I have found it very good indeed for book size documents from various program sources. In fact, rather oddly, it works much better than Distiller from Microsoft Word when Arial fonts are used. However, when I tried it with data from AutoCAD it always produced PDF files that Acrobat Reader rejected as invalid, even when I printed from an A4 size paper-space Layout.

We searched around and found a direct PDF driver that does work well with large format AutoCAD output, and surprisingly, it is free! It is called 'FreePDF' on the web site where you download it, but when installed calls itself "5D PDF Creator". It is from a publication company in England that does various kinds of printing (books, posters, brochures, etc) and accepts data from clients via the Web. To assist clients they provide this PDF driver. The company is called 'CtrlP.com', presumably because Ctrl+P initiates printing from most Windows programs.

This 5D PDF Creator (or FreePDF) is a 6Mb download. As well as downloading it, you need to request an activation key from CtrlP.com, which is sent to you as an email, also free. You must register on-line by giving your name, email, address etc. Clearly they expect downloaders to use it for dealing with them for printing jobs, but they still make FreePDF available if you will not be doing so, as is almost certain if you are far away from the British Isles. CtrlP.com also offer FreePDF on a CD, but only for customers in UK and Europe.

Experiences with PDF

QCADUG member Viv Duncan comments on the use of PDF at his place of work: "Hatch (formerly BHP Engineering) use PDF files to distribute drawings to their engineers internally and to clients for review. No changes can be made by the engineers but they can print the drawing without having AutoCAD or other associated programs. Most people seem to have Adobe Acrobat reader and a printer. Line thickness etc is maintained and a very good copy can be made for reviewing." (I think Hatch use the Adobe Acrobat package to create the PDF files.)

Another member, Stephen Gye, reports on his tests of the FreePDF at Brown & Root: "We have toyed with the idea of using PDF files for AutoCAD drawings and other documents being distributed to clients. I am currently using that option on the project I am working on at the moment. It is basically an in-house operation but involving inter-city locations. It saves problems of worrying about external references and other things. We simply create the PDF file by plotting to the FreePDF printer driver device. FreePDF is very simple to operate. I have been using it at work for a while now and am very pleased with it. Using AutoCAD 2000i, it is just a matter of choosing the sheet set-up I want, changing the device from the plotter to the FreePDF driver, and sending it just as for plotting.

"I have found it best to print A1 size drawings at 1:2 (A3 reduction), simply because all our offices have A3 laser printers. I have tried it with page sizes from A4 to A1 and all came out great. (It goes up to A0.) Line-types are all good and line widths are scaled properly. No print looks either heavy or light. Since it is an installed printer device, you can print to it from any Windows program. I have created PDF files from AutoCAD before using the Adobe tools, and I believe that this is just as easy to use and outputs the same quality, but is a lot less expensive and occupies a lot less hard disk space."

Adobe's Acrobat Reader 4 has just been replaced by v5, so you may need to get the new version (a free download of approximately 6Mb) to ensure you are able to read PDF files that people may send you from here on. QCADUG member John Tacey reports: "Acrobat v5 is capable of multiple documents in the one PDF file, and each can be printed and viewed individually. It also has a host of markup features for document reviews. One file I saw recently contained an AutoCAD A0 size drawing, an A3 size Spreadsheet, and an A4 Bill of Materials."

Summary

The PDF medium appears to be the best solution to this requirement, and CtrlP's FreePDF appears to be the best tool to use with AutoCAD. The image quality that the PDF format provides with a large format drawing is excellent. You can zoom in however much you need to see fine detail and the line-work always remains crisp.

Geoff Harrod acknowledges the input of Alan Harbour, Viv Duncan, Stephen Gye, and John Tacey, members if the Queensland CAD Users Group, in researching and reporting the information published here.

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