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From CAD User Mechanical Magazine  Vol 18 No 10 - OCTOBER/NOVEMBER 2005

David Chadwick explains how Lattice3D manages to compress data files down to the absolute minimum using XVL technology, while still retaining 3D model detail - and then have free viewing of the models to boot

If you are in business to publish CAD data in the form of 3D models, the one thing that is guaranteed to annoy your customers more than anything else will be having to zap large files around the ether. Yes, I know there are a number of ways to get round this, such as incremental downloads, and simplifying the model structure to accommodate just the amount of detail required for the job, but the best solution would be to avoid all of this, and reduce the size of the model dramatically without losing any of the detail.

And, yes, there is a way to do this - XVL (eXtensible Viewing Language) technology - invented by Lattice Technology Japan, and sold and developed by the American company, Lattice3D, set up by LAJ's owner, Mitsui Corporation. Like Adobe PDF, Lattice3D charges for content creation but viewing is free.

The software incorporating the technology, XVL Studio, lies at the heart of a set of ancillary programmes that can embed 3D models in 2D Office documents, together with their geometry, parts lists and assembly instructionsor create 3D-aware documents and websites - but more of that later. The most interesting thing to establish first is how Lattice3D manages to compress its model files down to a minute fraction of their original size - typically 95%, and often up to 98% or 99%! It makes you wonder, first of all, at the extravagant waste of space that the native CAD models are responsible for.

3D models imported into the software are converted to XVL format, which resurfaces the entire model with the minimum number of NURBs that are needed to remodel the entire structure, without losing any detail. The amount of compression achieved depends on the geometry of the model - the more curved surfaces there are, the better the compression. This is easily explained. Flat surfaces contain few elements - tessellations of polygons - and these can only be replaced on a 1 to 1 basis, whereas curved surfaces allow lots of elements to be replaced by far fewer new tessellations. The compression technology also plays its part, and XVL, invented by Lattice Technology Japan, is, perhaps, the most powerful one available for such purposes.

There is another issue. Other 3D publishing technologies are based on polygon formatted surfaces - Autodesk's DWF, UGS's JT, Solidworks edrawings, etc. If you zoom in on one of these models, absolutely necessary if you want to pick up fine detail, such as the difference between a plain and spring washer in a complex assembly, at some stage in a polygon based model, you will run out of tessellations, and you will have to go back to the 3D model and set up a higher number of polygons to get at the detail - the model size rockets! XVL technology, on the other hand, allows users to zoom in ad infinitum, recreating the tessellations as it does so - the model doesn't get any bigger!

Another advantage of XVL is that it can publish models with different models of accuracy - an example of this could be a company like Lockheed could publish 3D models of its JSF (Joint Strike Fighter) with re-surfacing accuracies of 1 thousandth of a millimetre for its manufacturing partners, and restrict the accuracy to just 1mm for general dissemination of data - preventing competitive organisations (and countries) from picking up manufacturing quality data. The point is - the accuracy of the XVL model is user settable.

XVL Studio Pro
XVL Studio Pro - also available in Basic and Standard versions, which provide basic view, explode, section, measure and annotate functions - is used for the exploration and validation of designs, and is capable of dealing with very large data sets. The Pro version includes features for conducting automatic interference and clearance checking in complex assemblies, and can display the results in spreadsheets, integrating 2D and 3D cross/section views, and which can, of course, form the basis of reports that can be distributed to collaborators and sub-contractors.

All the Studio versions are also capable of assembling parts from multiple CAD systems, or files, after converting into ultra-compressed XVL - parts are easily snapped in using existing geometry - and it can be used to create interactive animations to provide assembly or disassembly instructions, digitally based maintenance manuals, on-line demos and so on - with multiple camera views, keyframe editing and automated process animation.

Assemblies can also be edited, renaming, regrouping or editing properties - a useful feature for matching CAD and BOM data. Users can also create intersection profiles, 2D profiles that can be updated in real time to resolve complex design issues - which can also be saved to design review reports.

Another useful feature that enhances model checking is the ability to offset surfaces, or shrink geometry, iterating designs for advanced interference and clearance checking, or for the simulation of design changes - and, a further refinement, sophisticated cross-section control, allowing users to track cross-sections along edges and output them as IGES or DXF files for inspection of digital mock-ups.

Publishing XVL files
XVL data can be published in a number of ways. It can be embedded in MS Office documents, PDFs or HTML files, or as 3D data inside dumb 2D files - where the files can be linked to the 3D data, but don't know much about the detail they contain.

Or, using the Composer utility, instead of Embed, users can create 3D-aware documents containing and interconnecting all 3D model information (geometry, assembly structure, parts list, comments and annotations, dimensions, materials and textures, lights and cameras and animation), and which can be emailed to collaborators, sub-contractors etc.

A model, for instance, can be delivered in a document with a table of parts, one of which is highlighted to expose a current issue, linked to the corresponding part in the 3D model - a means of ensuring absolute and unmistakeable communication of intent. Or, using the Publisher application, 3D webpages can be automatically generated - including automatic exploded parts views and disassembly animations, cross-referenced parts lists and assembly structures - all through standardised templates that can automate the whole process.

Publishing catalogues of products or spare parts used to involve the accumulation of thousands of static JPEGs - posted to a CD or a website. A German mechanical engineering company, Seidenader GmbH, was able to create a 3D parts catalogue, comprising 1000s of items, in a mere 6 days, which can be used by clients to zoom in, pan, section and measure 3D models - with the added benefit of each part being updated whenever the original art is updated.

The company had spent years drawing its parts in 3D form using SolidWorks, and Benno Macherhammer, managing director of the IT department of the pharmaceutical machinery maker, thought it was obvious that the same graphics should be used in the company's spare part catalogs. Instead of converting its existing 3D data into 2D technical drawings for a parts catalogue, it saw XVL technology in use in CATALOGCreator, a German-designed software tool which functions as a blank electronic template for product and spare parts catalogs using XVL, and decided that the technology answered their needs exactly. The compression technology of XVL enabled Seidenader to publish its SolidWorks designs directly into catalog CDs. The 3D CAD files, normally too massive to be reused outside the engineering department, truncated to just one percent of the original size when translated into a XVL 3D model.

XVL Availability and online demos VXL Studio Pro, and its ancillary utilities, are available form two companies in the UK - Virtalis, featured in earlier issues of CAD User, is one of the world's leading Virtual Reality (VR) and advanced visualization companies. Headquartered in Manchester, England, Virtalis systems and solutions offer the ability to understand information and data, to interact with it and to foster communication between designers, manufacturers, trainers, marketing and senior management.

Epitomy, based in Sheffield, provides online search and cataloging solutions throughout the UK and Europe to aid in sales and service networks for manufacturers. Download the free XVL viewer/player and try the Lattice3D online demos yourself. CU

www.lattice3d.com
www.virtalis.com
www.epitomy.com

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