I don't see any noise. If you do, and are not happy, then make yourself your own scene :)
I note the smiley so I know you don't mean that in a nasty way -
I don't know nearly enough about Corona right now to even pass judgement on anyone's scene
I am at the empty room with a tea pot and sun system in it sort of stage right now. :)
I thought your demo scene was excellent and I have enjoyed looking at the settings - the materials and playing with the renderer
It has helped me get a good understanding of the renderer in a very short space of time.
I can see the effect the portal has on the image and I now understand its about the way the direct light penetrates the scene.
I have learned from this and I can now make my own scene to start using as my own test bed.
I hope I can post that scene up when finished for other people to test with.
Lets see where I get to.
Thanks again for your help -
Yep, i indeed meant it as a joke. You have +1 point for not being oversensitive like some of other users on this forum :)
My point was that if you were to make your own scene, you would likely run into other scenarios, where you would see something you would consider an artifact.
People coming from renderers with interpolated GI, such as Mental Ray, will not often be used to so accurate light simulation, and consider some of the occurrences artifacts, while they are just regular effects of physically plausible lighting, which their previous too biased renderer was not able to deliver.
You will rarely run into splotches or smudges with Corona. Even if you start to see some in corners, it's likely a scenario with some Cad model where walls aren't really air-tight, so some light leaks through the narrow gap.
Portal does not change looks of image in any way. It's purely performance tool. Basically a marker for renderer to point it where it should sample with more rays.