Floundering in formats: also remember that the best format doesn't necessarily become the most popular one

CADalyst, May, 2004 by Sara Ferris

IT'S HARD ENOUGH KEEPING the various CAD file formats straight, but now there's a whole new crop of TLAs (three-letter acronyms) that designate what we call publishing formats for CAD drawings. In short, these formats are portable--you can send them via e-mail or post on a Web site without causing too much grief on the receiving end--and secure, which means the recipient can't change the drawing or model.

The main use of such formats is communication: involving clients and suppliers in the design process, distributing finished plans and drawings, archiving projects for future reference, reusing CAD data in downstream tasks such as documentation, marketing, and maintenance. This month we look at the relatively staid world of 2D options: PDF, DWF, and CSF (p. 18). Later this year we'll tackle the 3D side, where it seems every few weeks we hear about another new format.

One 2D format that doesn't appear in our roundup this month is SVG, short for scalable vector graphics. This is a language that describes 2D graphics and graphical applications in XML. It's a text-based, open language similar to HTML, but the tags are familiar geometric elements such as , , and . SVG carries the blessing of the W3C, the consortium responsible for establishing Web standards. From a CAD perspective, the most obvious benefit is the ability to insert a scalable graphic directly into a Web page. Though you can, for example, make a PDF file available on a Web site, you can't incorporate it directly into a Web page, let alone in a way that makes it decipherable no matter what the screen resolution.

Because it's based on XML, SVG is extensible, which means you can embed metadata, even in proprietary formats. So a CAD program could export to SVG format but also include geometric data to aid in future editing. W3C is also working on a SVG Print specification for hard-copy output and archiving. Another SVG Tiny specification is designed to provide vector viewing on handheld devices and mobile phones.

Intel is spearheading a similar initiative on the 3D side, the U3D (universal 3D) format, via the 3D Industry Forum. Keep in mind that what ultimately makes a standard is not the imprimatur of an industry organization but the number of people who actually use it, and require it (what we call de facto standards to distinguish them from official standards). Also remember that the best format doesn't necessarily become the most popular one. Convenience and ease of use can trump elegant technology and nifty features. Sometimes all it takes is being there first.

As you weigh the benefits of a particular format, also look at what's being done to promote its use. What do recipients need to view the files? Is the viewer widely distributed and easy to download? Is it easy to use, even for someone who thinks a layer is part of a cake? Open formats tend to promote the development of more tools for creating them and also provide added assurance that your drawing data will remain accessible in the long term. With so many publishing options out there, you may even decide to adopt different formats for different purposes.

SARA FERRIS

Editor-In-Chief

sara.ferris@cadalyst.com