3.Mai
2013

Post-FMX: m4d/iray-FAQ

Know-How
Post-FMX: m4d/iray-FAQ
Even slightly silly renders can look good when rendered in m4d/iray.

After having some really interesting chats with users and developers at at² software’s FMX booth there were some questions concerning m4d / iray and GPU-rendering that seemed to pop up on a regular basis. Hope i can answer some of these questions here:

Q: Dude why iray? / Why should I care? A: ‚Cause it’s darn fast! And it offers you GI, Caustics, Soft shadows and all that computationally expensive stuff in a fratciotn of the time that other renderers would need to calculate an image. Additionally it comes with some neat little shaders that are missing in C4D. For example there’s diffractive glass (Glass that produces color fringing when you look through it), metallic flakes fory all you car-enthusiasts aout there and an extremely handy round corners shader (which gives you beveled edges without the need to model them by hand).

Q: Do I need a Tesla/Quadro? A: Definitely not! iray supports any Graphics Card that supports CUDA – hell it even renders on my historic GTS250!

Q: Which graphics card (GPU) should I buy? A: In general you’ll want a GPU that offers you lots of Memory as you’ll only fit so much polygons & textures in your GPU’s RAM. So likely candidates are:

  • – GTX 580 (3GB RAM)
  • – GTX 680 (4GB RAM)
  • – GTX TITAN (6GB RAM)

I’ve personally tested GTX580s and GTX680s and although I like the 680’s bigger RAM they’re computationally not as performant as the GTX580. So if your daily scenes don’t exceed 3GB of RAM I’d recommend buying a GTX580 as long as you can still get them (atm they’re around €380,- for the 3GB versions). My next best guess would be opting for a Titan. Massive amount of RAM paired with decent computational power.

Q: Does it render animations? A: Yes. Even Particles. Even hair if it’s converted to polygons first. Basically anything that you can convert to polygons.

Q: Does it do GI? A: Hell yeah! iray is what’s called an „unbiased path tracer“ unbiased meaning it automatically renders GI, Caustics, DOF, Motion Blur, Soft Shadows etc. pp.

Q: But if it always renders GI it’s slow as „!§$%, right? A: Nope. That’s where the beauty of GPU acceleration comes in. In my tests iray was always faster than C4D’s Advanced Renderer or Physical Renderer. Depending on the scene I’ve seen render times 5 – 20 times faster.

Q: Does GI flicker? A: Nope. If you set your render setting too low your rendering is gonna be noisy. Think of QMC-Sampling in C4D’s AR.

Q: What’s the limiting factor? A: Memory consumed by your scene. If you scene doesn’t fit in your GPU’s RAM iray is gonna render it purely on your CPU. It still renders yet this is definitely gonna be slower than with GPUs.

Q: How does iray compare to Octane? A: Octane is an unbiased path tracer just as iray. Octane however supports rendering on GPUs ONLY, meaning that if your scene doesn’t fit your GPU’s RAM it’s not gonna render. iray in contrast falls back and just renders your scene on your CPU if it’s too big. Apart from that iray offer really neat motion blur.

Q: What about Materials? A: You build them using C4D’s material editor just as you would with any standard C4D-material.

For some GPU rendered eye candy click here…