Way too low iterations and grainy images

aliefkan

Hello I am new to this program and trying to learn but no matter what I do I always have grainy results also low iterations like between 400-1000 range. I have amd gpu and cpu I use my cpu while rendering with iray can it be the problem? 

thanks for the help.

Leana

Rendering with the CPU in Iray is much longer than with a Nvidia GPU.
You'll probably simply need to let the render run longer.

Richard Haseltine

It also depends on the scene, and particularly the lighting. If you have an enclosed scene then you almost certainly want lights of some kind in the scene, the default HDRI won't easily bounce in. If there are a lot of nooks and crannies, or if the light source is in one place and large areas are in sahdow, then you are waiting for light to bounce into those areas often enough for them to settle on a final value (the graininess is down to some spots being bright because they've received a light bounce, or several and others being dark because thery haven't). One way to even-out the lighting is to use a promitive plane (or more than one), apply the Emissive shader preset (Shaders>Iray), and then lower the Cutout Opacity to a really small, but non-zero, value; you will then need to adjust Tone mapping (or edit the final render) to get the exposure you want.

SpottedKitty

How long is it taking to reach that 400-1000 iterations?

Keep in mind that Iray uses three "stop conditions" — the number of iterations, default 5000; render time, default 2 hours (measured in seconds); and convergence %, default 95%. That last one is closest to a measure of "render quality", although it isn't really. Whichever stop condition is reached first will stop the render, unless you stop it manually.

Note those default values; if you want to change the defaults to let your render "cook" a bit longer, go to the Render Settings pane, Progressive Rendering sub-tab. (For the time setting, 7200 seconds is two hours.)

Also note that "low iterations" doesn't really mean a lot; I've done renders that looked good at less than 400 iterations, and others that were still grainy at over two hours. It all depends on exactly what's in the scene, how it's lit, and what the materials are like. And to be honest, "looking good" is the unspoken and most important fourth of the three stop conditions.