Light dots on my planes - where do they come from?

[Jardar]

Hi, guys!

I'm redoing this scene in Sketchup just for getting used to Indigo. The problem is mostly with the grey wall. At first, it looks 100% grey, but after rendering for some 5 minutes I start to get light brown dots all over the wall (and on the chairs too). What do they stem from? Is it reflections from something?

Some info on the materials if they help:
The wall and ceiling - 95% diffuse/phong blend with the same albedo. Diffuse has a slight bump (0,3 mm), phong has smoothness 50, IOR 1.33

The floor and the plywood wall - phong, smoothness 912, IOR 1.196

The door and frames - phong, smoothness 300, IOR 1.33

The chairs - phong, this material (http://www.indigorenderer.com/materials/materials/246)

The rest of the walls are Exit Portals.

[dcm]

use pathtracing not MLT

[Headroom]

Those are reflections or "color bleeding".

Let it cook for for an hour (or a few hours) and the "spotty" appearance should disappear.

[Jardar]

With path tracing (the first attempt was with MLT):



It looked good till about 30 minutes in, then fireflies started appearing. Is this the same as color bleeding?

[StompinTom]

With Pathtracing, it starts to sample caustic effects and reflections, but it sucks at it, so you end up with little specks that take ages to resolve, if they ever do. I'd suggest BiDir + MLT and let it cook. The brown splotches are probably caustic reflections from the floor or walls.

[Jardar]

Bidirectional Path Tracing seems to do the trick! 51 minutes, 340 spp.

[dcm]

if you want to get rid of fireflies, use higher Supersampling value (im uising 4 every time)