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SOFTWARE review

Icame across a suite of programsat SolidWorks World that set methinking. They were designed totake solid models from some ofthe current range of modellers,

including SolidWorks, and convertthem so that they could be renderedwithin 3ds Max - the leading rendering,visualisation and animation software,producing the highest quality photore-alistic images. Nothing remarkable inthat - except that SolidWorks has itsown rendering engine and producesimages that, to most of us, appear tobe highly satisfactory.

The questions I asked myself werepretty basic; what is the differencebetween the quality of rendered mod-els produced in SolidWorks and thoseproduced by 3ds Max, and why wouldit need a separate piece of software toprepare the SolidWorks model for 3dsMax or VIZ?

The basic differences between thetwo boil down to the fact that, whilst

SolidWorks is a great tool for paramet-ric modelling, it doesn't have greattools for lighting, UVW mapping, tex-ture mapping, materials handling and,of course, rendering - all of which arepresent in 3ds Max/VIZ, which are spe-cially designed to handle such effects.The SolidWorks tessellation engine ismainly set up to display the model onthe screen as rapidly as possible, andto improve the modelling software'srendering performance they wouldhave to sacrifice some of the displayperformance.

Getting high quality photorealisticimages out of SolidWorks is difficult, asit hasn't got the best renderer (neitherdo any of the other solid modellingprogrammes, for that matter) nor is theadd-on rendering engine that’s avail-able able to match up to 3ds Max.They don't have the best lighting andmaterial libraries, a basic ingredient ofhigh quality rendering. 3ds Max, on theother hand, is perfect for setting up the

different types of realistic lightingrequired, applying materials to themodel, often in layered amounts, andsorting out a host of other renderingdetails.

The most important factor, though, isthat the tessellations required to rendera model efficiently must be of the high-est quality. SolidWorks' renderers andthose of most other software develop-ers, deal with polygons (although someof them will be converting to NURBsformats in the future). Long, skinnypolygons and other irregular polygons,produced with imperfect or inferiorMesh generation software, will causerendering artefacts - and the resultingimage will have flaws. For the highestquality images, the mesh has to beuniform.

All of this was explained to me byDavid Gill of nPower, developers ofPower Translators, including the Solid-WorksToMax translator. He explainedhow his company's software created

Rendered to the Max

SolidWorksToMax from nPower gives SolidWorksdesigners a rapid means of turning out ultra-highquality renderings of their models in 3ds Max.

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the best mesh for rendering in 3ds Max. There are other compa-nies that translate data for rendering in 3ds max, but they alltend to transfer the data as polygons, which means that they arestuck with the accuracy of the native tessellation engine. PowerSolidWorksToMax transfers SolidWorks data as precise NURBSbased surfaces and solids. This enables the user to retain con-trol over various parameters within the tessellation engine, sothat they can adjust the density of the mesh and the length ofthe profile edge and arc segments etc., ultimately producing anextremely high quality mesh that will provide the ultimate render.

Power SolidWorksToMax is part of the Design Visualisationsolutions of nPower Software - a range of Power Translators thatplug-in to 3ds Max for visualisations, animations and renderingCAD models. Capable of handling UGS, CATIA, Parasolid andRhino models, it can now also handle models and assembliesfrom SolidWorks. It doesn't yet do the same for Inventor - butthat's on its way.

What this means is that SolidWorks users attempting toimprove the quality of their rendered output no longer have tospend days or weeks translating their high quality solids intoimprecise polygonal models, with, perhaps, intermediate formatsbeing created along the way, and then struggle to produce highquality renderings. They can now transfer models directly into3ds Max using SolidWorksToMax/Viz to generate smooth, crack-free renderings wholly free of polygonal artefacts - and oncetransferred, use the Mesh and Polygon editing commands thatcome with the software, Max Editable Mesh and Editable Poly, totweak the mesh to produce the best results for each type of ren-dered image.

It does this by creating a precise NURBS-based 'Brep Object',which represents the precise geometry defined in the Solid-Works model files. The software can then be used to create amesh to user-defined tolerances, depending on the size of theobject in the image. Setting a tolerance of a half a pixel, forexample, will produce a very high quality image with verysmooth edges free from those infernal polygonal artefacts.

BrepObjects are subject to MAX Meshmodifiers such as twist,UVMap and so on, and can have materials applied at sub-objectlevel. The highest quality renderings build up the image usingseveral layers of materials and lighting effects. Other objectclean up tools enable users to sew together faces, flip face nor-mals, trim and un-trim surfaces by curve projections or surfaceintersections, project curves and apply materials to faces. PowerSolidWorksToMax comes with a range of model editing tools thatcan be used to clean up imported SolidWorks models beforethey are rendered, if the incoming data is found to be incorrect.

The software is not only able to dramatically improve productiv-ity on rendered models, it can also handle large assemblies.Furthermore, its batch mode for processing groups of modelscomes with automatic Mesh generation at the same time, oncethe mesh parameters and tolerances have been set up.

MISSION: POSSIBLE!Some of the most demanding tasks for modelling tools,and for subsequent ultra high quality rendering of thosemodels, is seen in the film industry, where digital cre-ations need to be produced very rapidly, and where therendering and animation of the models has to be as life-like as possible. Simon McGuire, a senior conceptdesigner within the film industry, working on high profilefilms such as Mission:Impossible 3, is very positive aboutthe impact the Power Translators have made; "This isactually the best software I have seen in a long time.Speed is very much the order of the day. And nPowersoftware has greatly increased my productivity. Even moreso with CNC machining becoming more and more preva-lent in the film industry, being available to export detailedmodels greatly increases the turn around, especially whenwe have often little more than a week from design to pre-sentation prototype." CUwww.nPowerSoftware.com

SOFTWARE review

April/May 2005 CAD User 25

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