Hi Han5,
Interesting that you should post this, yesterday I have been further tweaking the caustics settings, to hopefully improve things even more.
Having a quick look at your model, the top part is blue because it is the sky, your yellow wall is only 100cm high.
Will try some further tests this evening!
db4tech
Edit:
Could the colour of the blocks on the right be being ignored because it has the "g sweethome3d_window_pane" name set, so it is made invisible when rendered?
