5min - iray rendering - MR Sun and MR Sky
3 days ago, Autodesk throught a Subscription pack introduce the famous iray from mental Images. Lots of people were waiting for it for a while.
Some, like me, even tried to unlock the baby though manipulation of the 3DSMax 2011 contents folder and text editing. Without great success…
Anyway, now it is useless, iray is there.
Mental Images® and Autodesk® talk about iray® in this words:
“Creating realistic images has never been easier with 3ds Max®, using the newly integrated iray® rendering technology from mental images. Another major milestone in the Rendering Revolution, iray enables artists to set up their scene, press “render,” and get predictable, photo-real results without worrying about rendering settings just like a “point-and-shoot” camera. Artists can focus on their creative vision as they intuitively use real world materials, lighting, and settings to more accurately portray the physical world; iray® progressively refines the image until the desired level of detail is achieved. iray® works with standard multi-core CPUs. However, NVIDIA CUDA®-enabled GPU hardware will significantly accelerate the rendering process.
And the help in these one:
“Mental Images iray renderer creates physically accurate renderings by tracing light paths. It requires little setup compared to the mental ray renderer.
The principal approach of the iray renderer is time-based: You can specify the length of time to render, the number of passes to compute, or you can simply launch the rendering for an indefinite amount of time, and stop it when you are satisfied with the appearance of the result.”
“Early passes of the iray renderer appear more grainy than the results from other renderers. The graininess becomes less apparent, the more passes you render. The iray® renderer is especially good at rendering reflections, including glossy reflections.”
“If you have a graphics card with a Graphics Processing Unit (GPU), this will improve the performance of the iray renderer. However, the result is not the same as hardware viewport shading: The computation carried out by the iray renderer is physically correct, and the result of a hardware-assisted iray rendering is the same as the result when you render using software only.
A rule of thumb for GPU usage is that one gigabyte (GB) of memory can store 5 to 10 million triangles (5–10M) of geometry. If textures (usually shared among face triangles) can also fit into GPU memory, that improves rendering performance as well.”
“The performance of a ray-tracing renderer such as the iray renderer is relatively independent of how complex the scene geometry is. The complexity of light paths is more important: A candle in a labyrinth, or light rays diverging from a narrow window, will take longer to yield a good-quality rendering than light shining through a broad skylight or picture windows. As with other renderers, performance is also proportional to the resolution of the rendered image. The complexity of materials in the scene also affects performance: The more textures, blending, and noise a material has, the longer it takes to calculate the results.”
So from far iray® is a light path rendering engine. Barely the same as unbiased engine like Fry, Maxwell, Thea, Indigo or Octane.
Let’s have a try with iray and see what it does.
- 5 min - iray® rendering – interior scene with sun and sky
We can see there a pretty decent rendering for a interior scene with a complex geometry in Glass shader, the light is a SUN attached to a daylight system. 8AM o’clock.
The scene is pretty bright from scratch without any tweaks. A good point. When I say any tweaks, it seems iray® doesn’t give the opportunity to make a lot of changes. As they said in the presentation. That’s TRUE 
Another things interesting, the shaders you use for iray® are the same you use for Mental Ray®. makes the stuff easy when it’s time to switch from a light path solution to a more convienient and manageable Ray Trace engine like Mental Ray® and vice versa.
But those shaders are not physically compliant truly speaking. That is something which irritates me a bit. Except some which are labelled phisic, like Glass.
Now the shadows produced by the render are nice and soft. A bit to much maybe.
The glass parts are well rendered and are pretty plausible, realistic. Maybe the tinted glass are not that much vivid and reflective. the reflectiveness is set at 10, beyond this value, shader was to dark. Diffraction is normal.
For a 5 min rendering, which combines 2 Xeons 5482 + the GPU of the Quadro 4600, we obtain a render pretty noisy, which is the trademark of an unbiased Technic.
Let’s compare now the same scene rendered with Fry 1.5 and Maxwell 2.1 in 5 min render each.
5min - FryRender® rendering - Fry sun and Sky
The FryRender® one is less noisy, almost ok for production. The physical sky is obviously slightly different. The colored glass shaders are more vivid and cast TRUE caustic on the floor and such. But the ambiant light inside the room is dimmer than the iray one. It is part of the settings I applied to the scene. (Not really took time to setup the scene, whatever, not a big deal for this purpose)
Now a Maxwell rendering:
5min - Maxwell® rendering - Daylight system
The Maxwell® render is really similar to the FryRender® one. Not a big surprise. Even in the caustic, the pattern are ridiculously the same.
The level of noise is quite a bit higher from the FryRender® one. Not much, but still…
Some close-up:
iray test close-up
CONCLUSION:
Pro: Interoperability of the shader system and simplicity of used (for some people)
Cons: Slow. iray® remain at the first glance, SLOW. It is using the CPU’s and the CUDA®. It more noisy than Fry or Mxl which are rendering only with the CPU support.
the simplicity of the settings makes it ALSO a cons.
I will push my overview and testing of iray, bigger scene, longer time, blablabla….
, everybody knows that. So XSI rolled back to Autodesk Softimage but more and more started to loose its visibility on his father website www.autodesk.com. At a point where even at SIGGRAPH, Softimage was not marketed.