by L. Stephen Wolfe P.E.
On July 26, Bunkspeed released Shot, an application for making realistic renderings quickly. It’s the first end-user application of mental images Iray interactive realistic rendering technology. Mental images became a subsidiary of graphics-chip maker Nvidia in December 2007.
Bunkspeed Shot offers the first example of the use of Iray in an end-user application. Iray is able to employ the graphics processing units (GPUs) of Nvidia graphics cards to run race-tracing algorithms. Ray-tracing provides the only “physically correct” rendering according to mental images chief executive Rolf Herken. Other real-time rendering software employs shortcuts that reduce the time needed to generate an image at the expense of fidelity. According to Herken, only Iray can resolve to a correct image with absolutely no renderer-introduced artifacts.
Watching Bunkspeed Shot at work, the viewer sees a grainy image of the rendering almost immediately. As time passes, the granularity resolves itself into a true-to-life image. This process contrasts with earlier versions of mental images mental ray software that renders portions of an image in square tiles as it works. The advantage of the Iray approach is that users may be able to quickly see if colors or other settings are not right, stop the rendering process, and change them. In Shot, users can turn off ray tracing to move the model around, set the scene, etc. and then turn ray tracing back on to begin the render. This kind of interaction is harder to do if the rendering software displays the image in tiles.
Bunkspeed Shot enables artists to change rendering models quickly. By turning off the ray tracing to speed interactivity, users can copy and model paste model geometry, change the materials, change HDRI (high dynamic range image) backgrounds, and set Shot to rendering again. Imported model geometry also can be scaled within the rendering application.
Although Bunkspeed Shot is said to be interactive, it nevertheless seems slower than rendering software that uses less accurate techniques. Demonstrations at Siggraph took anywhere from a few seconds to several minutes to produce high quality images. These demonstrations were run on Nvidia’s highest performance desktop hardware: dual Quadro 6000 graphics processors that are expected to sell for almost $5,000 per board when they become available in October.
In contrast, less accurate renderers at competing booths seemed almost instantaneous. With less costly graphics processors, the performance difference between Shot and the competition is likely to become more pronounced. IRay is a CUDA-based application meaning that only Nvidia’s GPUs can be used for acceleration (GeForce or Quadro). Iray supports CPUs, GPUS, and has a hybrid option to allow users put both GPUs and CPUs to work on an image. Iray can leverage multiple central processor chips or cores to render images in the same fashion as the GPU.
Customers are likely to be confused for some time about which rendering application is best. Products such as Luxion Keyshot 2, Luxology’s Modo, Maxon’s Cinema 4D, Autodesk’s Showcase, and others may produce pretty pictures faster than Shot, especially on computers with ATI graphics cards. And because Shot is new, it may lack sophisticated features of the more mature programs.
Over time, however, the equivalent of today’s high-end Nvidia adapters is likely to fall to mainstream prices. When that happens, Bunkspeed’s software – if it continues to mature — should become more productive for customers who eventually want to produce very realistic renderings. Artists who use fast but less accurate rendering software may need to set up new models in ray-tracing applications to get the quality they need for final artwork. This extra labor will more than offset any time saved by getting an initial picture a few seconds quicker.
Bunkspeed Shot sells for $995. Current Hypershot customers can receive a free upgrade. Trial licenses are available. The software runs only on Microsoft Windows 32- and 64-bit versions. Apple computers are not currently supported.