Professional versus consumer graphics

Written by Greg Corke

Published Wed 16 Jul 2008

Many of you will be familiar with AutoCAD’s Performance Tuner and the warning sign that pops up to tell you your graphics card is not certified. Most of you probably ignore it too. But what exactly does a certified card mean and should you be bothered?

Autodesk, like most CAD vendors, currently certifies cards to help ensure that everything is displayed correctly and accurately on screen. It periodically tests out graphics cards and their associated drivers to give its ‘seal of approval’ to certain hardware configurations. By doing this it not only improves the customer experience, but hopefully reduces support calls.

Any ‘errors’ that are found are fed back to the graphics card manufacturers and are then (hopefully) ironed out in a new driver release. It’s a continual process and one that costs time and money. Historically, this cost has been passed on to the professional, and as a result many architects and engineers have opted for cheaper consumer graphics cards instead.

Consumer cards certainly do a job, and in many cases feature a virtually identical graphics chip, but their drivers are optimised for 3D games, which feature simplified geometry and hi-res textures to deliver realistic real time effects. 3D CAD applications, on the other hand, require complex and highly accurate geometry and as a result the drivers for professional cards are optimised in this manner. It’s also worth noting that anti-aliasing (a process designed to improve clarity by smoothing lines on screen) is typically a professional feature and isn’t supported in consumer cards.

In the scope of this article we took a closer look at the differences between a professional ‘Quadro’ card and a consumer ‘GeForce’ card from graphics card manufacturer Nvidia, both in terms of user experience and performance. We did this in Revit Architecture 2009 and AutoCAD 2009 with a Quadro FX 370 up against a similarly priced GeForce 8600GT. We tested in both OpenGL and Direct3D modes where applicable. N.B. OpenGL and Direct3D are the two main 3D graphics APIs. OpenGL has been the 3D standard since the origins of 3D CAD, but Direct3D is driven by Microsoft and has been gaining ground in recent years.

Revit Architecture 2009

Interestingly, Autodesk doesn’t have a certification process in place for Revit, so it doesn’t recommend specific drivers or cards. It’s also worth noting that while Autodesk advocates the use of professional graphics, consumer and professional cards are treated as equals when it comes to support.

Revit only supports OpenGL (not Direct3D) and you can turn this on and off. In our tests it automatically put both the Quadro FX 370 and GeForce 8600GT in OpenGL mode, but it gave a warning to turn OpenGL off if there were any problems. We found no difference in visual quality between any of the cards and OpenGL only gave slightly better performance than standard software acceleration (apart from when carrying out solar studies) which was surprising.

AutoCAD 2009

In 3D, AutoCAD features four graphics modes, wireframe, hidden line, conceptual, and realistic. It supports both OpenGL and Direct3D under Windows XP, but only Direct3D under Windows Vista. As anti aliasing is not supported in Direct3D, it’s important to note that AutoCAD does not support ‘smooth line’ mode in Vista.

With the consumer GeForce 8600GT, AutoCAD immediately flagged up that it was not certified, and that smooth lines mode was not available. 3D performance was good, as was the experience in most graphic modes but wireframe mode was nearly three times faster under Direct3D than OpenGL. There was a glitch with the View Cube (the new 3D navigation device) in so far as it disappeared momentarily when we moved the mouse cursor near.

We installed the Quadro FX 370 with the latest Nvidia driver but AutoCAD flagged up that the 3D device was not certified. This was because the driver hadn’t yet gone through certification. It automatically put us in Direct3D mode but we could change this manually to OpenGL.

After downloading and installing a certified driver, AutoCAD gave it the thumbs up and automatically put it in OpenGL mode. Smooth lines were off by default, but we could still turn these on. However, smooth lines slowed everything down considerably and we didn’t feel it actually improved the 3D experience that much, particularly for the trade off in performance. Interestingly we experienced the same problems with the disappearing View Cube and overall performance was on par with the GeForce card.

The real difference came when installing Nvidia’s dedicated AutoCAD driver, Powerdraft. In terms of performance it gave a clear advantage over the GeForce card. In OpenGL hidden line mode, performance was boosted by a factor of three and in conceptual mode by a factor of 1.5. The View Cube problems also disappeared.

Conclusion

With Revit there appears to be little difference when using a professional or a consumer card, either in terms of performance and quality. And when compared to applications like 3ds Max or Inventor, the 3D experience was not as good in terms of how smoothly models could be rotated. An overhaul of the graphics engine certainly wouldn’t go amiss.

With AutoCAD there are significant performance benefits when using a professional card, but this is limited to 3D hidden line and conceptual mode. However, this will make little to no difference for 2D users which are in the majority. The biggest lesson learnt is to make sure the right driver is used and then that the card is configured correctly. Unfortunately, for the inexperienced this is still a bit of a minefield.

While professional certification currently plays an important role in AutoCAD and other 3D applications, Autodesk is following a trend to have the standard setting organisation define the standards and perform the certification. A case in point is DirectX 10 and Autodesk expects to take advantage of this going forward. Where this will leave professional and consumer cards in the future remains to be seen.