Iray why so grainy

onefromb5b4

Could anyone help me out here. Everytime I do an Iray render it comes out very grainy. see attached link. I use the default settings in iray but turn ON the NOISE FILTER.

http://onefromb5.deviantart.com/art/Satin-Dewss-2017-01-30-660645687

Tobor

The scene appears to be lit entirely (or nearly entirely) with indirect light. This requires a lot more iterations to converge a final picture, and your render settings are probably reaching one or more of the prescribed limits. 

These topics have been heavily discussed in the forum. Do a search to find dozens (if not hundreds) of threads that explain what's going on, and how to fix it.

 

Mark C Holloway

That happened to me too. I just reset my Daz to its defaults and that fixed it. Not sure but that might work for you

marius_if

Blurbs deleted.

Sorry for the inconvenience.

fastbike1

@marius_if 

Most of those settings don't make sense. "Quality to few thousands" would result in incredible render times if the other render limits don't kick in. Smaller ISO and shorter exposure time are going the wrong way.

Light bounces greater than 10 or so don't make a noticeable difference to the render. The default setting of -1 allows for infinite bounce.

The simple answer is just more light. More light allows fewer iterations to meet convergence. Tone mapping can be used to make the scene darker or brighter but is not a substitute for more light.

Tobor

I agree that some of these settings aren't going to have a benefit. Environment resolution doesn't do anything for the convergence of the scene, only the detail of the highlights and shadows. The '512' value is the resolution of the polar value; the azimuth is 1024. You can maybe go a step higher (1024/2048) but it really only makes sense when the HDRi is imparting a high range for strong shadows. As any light this HDRi may be producing is indirect into the scene, it seems rather pointless.

These kinds of scenes with predominately indirect lighting are helped by using the architectural sampler, but then rendering times balloon. I think it's better to try to solve the problem in other ways before trying that route..

I'd add one or two broad lights aimed into the scene to provide a direct light source. You can then adjust the ratios of these lights with the indirect ambient light that's otherwise reaching the interior. Aim for a balance between the two to suit the nature of the scene you're trying to depict.