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MCAD Modeling Methods: Data Exchange Tips and Tricks
15 Sep, 2004 By: Don LaCourseWeb site collects advice for 3D CAD users.
This month's focus on data exchange provides an excellent opportunity to share some of the 3D modeling information I've collected for my new Web site: www.3DCADTips.com (figure 1). During my 25 years of experience, first as a 3D CAD designer and then as a writer, I've accumulated hundreds of technology tips. Some are useful regardless of what application you use. Others are specific to products such as Alias Studio Tools, Alibre Design, Pro/ENGINEER, Solid Edge, thinkdesign, and VX CAD/CAM.
I sponsor and help develop the site for the sole purpose of sharing this information with as many 3D CAD users as possible.
 Figure 1. 3DCADTips.com contains more than 270 tips on topics such as implementation, construction and editing techniques, performance issues, PDM, design collaboration, data exchange, and documentation. |
You can register and submit your own tips for the next update.
The site expands monthly, and I personally thank those of you who have contributed tips. So without further ado, let's get a little tip-sy.
 Figure 2. Each CAD system supports a subset of the IGES standard. The entity types supported by both systems are mapped from the sending system to the receiving system. Other entities within the subset may be ignored. |
How Data Loss Occurs
Neutral-format data exchange standards such as IGES and STEP are extensive in structure and scope. This is because they attempt to support a varied field of disciplines—mechanical design and AEC are only two among many. During the exchange process, a 3D model file is translated from one native CAD format (sending system) to an IGES or STEP file. This file is then translated into another native CAD format (receiving system). Product-Specific Tips |
Because of the size and scope of the standard, mechanical CAD systems support only a subset of the standard. While System A may support entities a, b, c, d, and e, System B may support only entities a, c, and e. So, you ask, what happens to entities b and d? System B ignores those entities because it doesn't support them. This is one way in which data can be lost (figure 2). See www.3DCADTips.com for more about data loss during 3D CAD data exchange.
Can Data Accuracy Change?
Accuracy can change in many ways. Starting from the native sending system, what you see on the screen isn't necessarily what's in the 3D database. 3D modeling kernels can force geometry to connect or treat elements as though they connect even though they don't. Neutral-format data exchange can expose these inconsistencies. DATA EXCHANGE CHECKLISTS |
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AutoCAD Tips!
Autodesk Technical Evangelist Lynn Allen guides you through a different AutoCAD feature in every edition of her popular "Circles and Lines" tutorial series. For even more AutoCAD how-to, check out Lynn's quick tips in the Cadalyst Video Gallery. Subscribe to Cadalyst's Tips & Tricks Tuesdays free e-newsletter and we'll notify you every time a new video tip is available. All exclusively from Cadalyst! |
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