Summer 2016

Issue link:

Contents of this Issue


Page 51 of 63

50 CINEMONTAGE / Q3 2016 50 CINEMONTAGE / Q3 2016 TECH TIPS by Joseph Herman I magine if the excruciatingly long time it took to render photo-realistic 3D images were reduced to practically no time at all. No, it's not a pipe dream, it's graphic processing unit (GPU) rendering, it's here right now, and it's one of the most exciting new developments in the field of CGI. The company leading the way in this area is the Los Angeles-based OTOY with its innovative GPU render engine, Octane Render. Let's start with a little background. There has long existed a bottleneck in creating 3D computer animation and visual effects for motion pictures, namely the final rendering — the last step before CGI frames are sent over for compositing and finishing. The process of 3D computer animation can roughly be summarized in five stages. First comes modeling (and rigging), in which you create the three- dimensional geometry (or polygonal meshes) that describes the underlying structure of the objects in your shot. Next comes the animation stage where you tell the system how everything moves. Materials, the third stage, describe how the surfaces of your objects appear; for example, their color, reflectivity, bumpiness and transparency. During the lighting stage, you illuminate your scene. Often high-dynamic-range (HDR) images are used for realistic lighting (a technique known as Image-Based Lighting). Last comes the final rendering of your images, when your computer calculates everything and renders the results into pixels. Unfortunately, this has traditionally been a very time-consuming process, one that relied on your computer's central processing unit (CPU). If you're working on a single image for a static ad or a poster, it isn't really a problem. After pressing the render button, it might not take much more than the length of a coffee break before it's done. The nice part of it is that your computer does all the work. In the case of motion pictures, however, it's a different story. Movies are comprised of hundreds of thousands of frames and each one must be rendered individually. RENDERING INSANITY The time it takes to render a single frame depends on several factors. Before GPU rendering, it could take anywhere from around a minute a frame to 20 minutes or more on your CPU. Let's choose an amount in between — say eight minutes for a moderately detailed Fill 'Er Up with High-Speed Octane for GPU Rendering Octane is a powerful unbiased renderer that works with MAXON's CINEMA 4D. A model of a Porsche, that is in the middle of being textured, is lit by an HDR image which also provides the reflections. Octane's Live Viewer window (bottom right) continuously displays a final-quality render of your scene, immediately updated every time a change is made.

Articles in this issue

Archives of this issue

view archives of CineMontage - Summer 2016