Weird splotches in an interior scene

So I’m working on a bathroom scene and when I render, really weird splotches appear on the objects and specially on the walls. I am using filmic and lighting the scene with a sun at 1200. This image was render at 500 samples and denoising set with a strength of .5 and a radius of 8.
I don’t know what is causing it, so any help will be apreciated.

Probably denoising by the looks of it. How noisy is your render without it? If it’s off are there still splotches?

500 seems low when basing all lighting on bounced lighting. I’m betting if you turn denoiser off, it will look absolutely horrible. Caustics will also cause horrible noise. Increasing samples will lower the overall contrast in the noise, which makes the denoiser perform better. Earlier without denoise (and tons of lights in interior scenes without daylight) I could do overnight renders of 20000 samples - that’s with the “optimizations” below.

Turning off caustics will naturally lead to energy loss but a lot cleaner render, so I render everything without caustics. To compensate for loss, I use a node setup going something like “if seen by diffuse, reflect as diffuse”. So a mirror surface or glossy component of a surface will not reflect light in a direction based on light direction, but as if it was completely diffuse. Yeah, it will not look “right”, but energy loss is prevented and in many cases only you will know so who cares :slight_smile:

I pretty much never use environment lighting (in what we do, we actively try to prevent light pollution from outside). But in the event of getting noisy, I sometimes have success with turning off Multiple Importance for non significant/non dominant materials. In your case (at least for that specific view), I would leave it on for the wall, floor, and possibly ceiling - off for anything else. I don’t have a clue what MIS actually does, and it may only be my imagination. :slight_smile: