Yafray: GI problem

Hello, following this (click) tutorial on lightning with Yafray, i am trying to set up the lightning for my scene here. The problem is, I get a lot of these weird clouds or sthing all over the render. I’ve tried rendering with different settings under photon panel in yafray but it still looks like this. Can somebody tell me how to get a nice clean result like the one in tut? (mean ‘the final result’ of cornell box)

here’s the render:

oh and why some things (like chairs) doesnt cast shadows? :confused: could use some help here as well

Have you looked on Yafray wiki? there is a nice tutorial which explains these flecks and how to eliminate them.

yes, that tutorial will help. In this thread there are also some examples you can learn from: