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CAD on the Web

By Tom Riley

The Web is a much more powerful place if you can place all the drawings for the Golden Gate Bridge on the Web, have someone else pull them off, and build the bridge. Mechanical drawings have been a major means of communication and great means of self-expression for technical people since the beginning of the industrial revolution. In the last two decades this medium has moved from paper to computers in the form of Computer Aided Design (CAD). Now it is time to move it onto the Web.

This effort has been a background fight in the struggle for "Content" versus "Flash" on the Web. I, for one, am a passionate advocate for "Content". "Flash" does not last.

  1. What Woodware is Doing

    Let me explain explain briefly what we are doing at Woodware Designs and why it requires massive amounts of CAD on the Web.

    About four years ago we came up with the idea that if you could get together a good design, a person with physical challenges, and a woodworker, you could create the important community service of getting people the computer furniture they need. There many people with physical challenges such as Repetitive Strain Injury (RSI) and Multiple Sclerosis (MS) whose pain could be relived by simple improvements in their computer furniture. In fact, bad computer furniture is a real health hazard in our modern world.

    Furthermore, there are thousands of amateur woodworkers with many millions of dollars invested in woodworking equipment who would get great joy from doing the woodwork. They only need the plans and materials.

    There are plenty of designers available too. Some are students needing projects but many are professionals in unrelated design fields who would love to help. Design is a major means of self-expression, a great joy, and sometimes even a meditation.

    Can the Web close this circle?

    We take the stand that it can. The key limiting factors are making plans widely available and raising modest amounts of money for materials. Woodware Designs therefore sales plans for low-stress computer furniture to amateur woodworkers to support itself and raise the money for materials while providing free design and organization services to people with physical challenges.

    The last remaining key stone is then distributing the plans over the Web and that means many CAD drawings flying though hyper-space.

  2. A Brief History of CAD on the Web

    A computer graphic may be in one of two very different formats. It may be in the form of a bit map where the color of each dot or pixel on the screen is defined. There are many types of bit maps but the most common on the web are .GIF for drawings and .JPG for pictures. This type of file can be very large (and they compress very little). Size is especially a problem if the file contains a lot of detail and if it is larger than a computer screen. Most painting graphic manipulation programs produce this type of file.

    The second form is Vector graphics. Here each line is described as starting point, a direction, and a length. CAD programs generate this type of file. Circle, squares, and many other shapes are either given special codes or build up from many lines. The resultant files are efficient at holding large amounts of detail and are large files but compress very well.

    It is possible to convert vector graphics to bit maps but it is not possible to reverse the process. Programs to display bit maps on the Web are very common and the files are standardized but vector graphics have proved just the opposite on both counts. Vector graphic readers have been very slow in comming to the Web.

    Most CAD programs generate vector graphics files in propriety formats. This requires that both sender and receiver have copies of the specific expensive software. You cannot make such a drawing widely available.

    The first step forward was a standard vector file format called Drawing Exchange File (.DXF). Unfortunately it never was run as a true international standard controlled by an independent part so many incompatible versions of this 'standard" developed.

    Conversion of plans to huge bit maps was tried but the files were very large and therefor slow to transmit. Also the inexpensive conversion software simply did not work. Two major software company advertized that their graphic conversion software would do this job but the software simply would not do it. The companies also showed no interest in debugging their software. A complete rip off! -- twice.

    JAVA does support line color and you can make different line types appear as different colors if you are careful in making the drawing. No mater what you do with color it is not the international standard for hidden lines and you loose much information when it is printed out in black and white.

    Last fall a second .DWF reader became available. It is CADWriter. Its approach is to make the reader a relatively small JAVA Applet that automatically down-loads before the drawing in a few tens of seconds. The supplier of the drawing must buy $200 software to do this but the feature is free to the reader. Its major draw back is that it has the JAVA drawing type limitations.

    When is someone going to expand the JAVA class for "line"?

    Another approach has been available for about three years. Acrobat sells a well proven software program that converts all types of word processing files into one standard type (.PDF). This includes files with a mix of text and graphics. The results is shown on the screen exactly as it will appear on the printed page. It does not care if the page is text, a mix, or all graphics. Their $300 software package lets the provider send you drawings to a special .PDF printer file. These files come moderately compressed and transmit well.

    The receiver out on the Web must have down loaded the free Acrobat reader but this file is very handy to have for all kinds of word processing applications. It lets you view each page of the drawing and prints them out with great quality. It does not let you zoom in on small parts easily but most people print out our plans to take them to the shop anyway.

    You can now get a free reader for the Drawing Web Format (.DWF) Express Viewer form AutoDesk. This is a true vector format.

  3. Results of our December Survey

    Last December we at Woodware Designs ran a big test to determine which type of CAD drawing files our potential customers want most. Normally about half our plans are free and half are reasonably priced ($12.95). For all of last December, everything was free. (Aren't you sorry you missed it.)

    During that month we had about 3000 hits on our site and sent out about 200 sets of plans. Over %90 of the requests were for Acrobat .PDF files. The .DWF and .DXF files types ran a distant second and third. Nothing else was even in the race. Acrobat won hands down. As Acrobat's best feature is its printout, we took this result to mean that we are now about 100 years away from the paperless office (200 years from the paperless shop).


I believe that a Web that allows easy transfer of CAD graphics is a most powerful Web. It is a Web with greatly enhanced content and less subject to the criticism of "all flash".

We have come a long way in achieving this goal in the last two years but we are not there yet. We must get JAVA to support line type and we must get better free CAD readers.

Thanks for reading my article. I would appreciate feedback; please drop me an e-mail with your comments.

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