When choosing a professional graphics card for SolidWorks bigger is not always better. It depends on the types of models you create, writes Greg Corke of Develop3D

Our first model, the digital camera assembly, is made up of relatively complex geometry and the more powerful graphics cards showed real benefit when RealView was turned on. This is because the model makes good use of complex VBOs so the full power of the card is able to be harnessed.

In terms of 3D graphics, SolidWorks is one of the most advanced mid-range CAD applications out there. Its RealView technology, which enables designers to work with realistic images when modelling, was one of the first examples of real time rendering in a mainstream CAD application. SolidWorks was also one of the first applications to feature Level of Detail (LoD) technology in its 3D graphics engine, which simplifies geometry when rotating, panning and zooming in order to maintain frame rates. And finally, it features a technology called VBOs (Vertex buffer Objects), which takes some of the load off the CPU (Central Processing Unit) and puts it onto the GPU (Graphics Processing Unit) to improve performance.

In the course of this article we will look at how these different technologies affect 3D performance by testing with a variety of models, display states, and a wide range of professional graphics cards, from the entry-level right up to the high-end. Before we do this though we need to explain a few things in a bit more detail.

Realview: This uses the Shader Model 3.0 capabilities of modern professional cards to give a more realistic visualisation of real world materials. By having this enhanced visual quality, however, an additional load is placed on the graphics card, which can greatly affect performance.

The technology was introduced in SolidWorks 2007 with basic set of around 100 shaders but for 2008 the whole technology was revamped and SolidWorks took the materials and textures from its rendering add-on, PhotoWorks, and implemented them in RealView.

Some users, particularly those involved in product design, like to use RealView all the time as they find it helps to model with realistic materials. Others, perhaps those in machine design, prefer to switch it off completely as they find it detracts from the modelling task at hand. Shading can also be used to communicate other information in the design. For example, colouring all the weld faces in an assembly in blue for clarity.

Large Assembly Mode: This was introduced to help prevent workstations grinding to a halt when working with sizeable models. It is automatically invoked when an assembly reaches a certain number of components. Large assembly mode automatically switches off RealView and sometimes edges, and when panning, zooming, rotating, or moving a component, decreases the Level of Detail seen in the model. Sometimes this can mean quite complex geometry is reduced to simple boxes.

Large assembly mode is optional. Some users prefer working with it on because they don’t like experiencing jerky graphics, which can happen with particularly large models. Others prefer not to use it because they want to see the full details of their designs at all times. Settings can be fine tuned for a balance between quality and performance.

Vertex Buffer Objects (VBO ): These allow 3D geometry to be loaded, stored and processed on the graphics card. When displaying a model, geometry data doesn’t have to be moved back and forth over the PCI Express bus, as has traditionally been the case. This helps minimise the instances when the GPU has to wait for the CPU (as it is often tied up with other tasks) and as a result can boost realtime 3D performance.

In SolidWorks, VBOs are built for every individual body in the model. Complex bodies that are made up of many faces benefit much more from VBOs than simple bodies with few faces. To put this in perspective, when VBOs are turned off in the relatively complex digital camera model 3D performance is about 2x slower. However, with a huge model made entirely out of cubes, VBOs would provide no benefit.