VCM vs Refraction

[lacilaci]

Keymaster already mentioned that without using merge function it is a bi-dir tracing.

So, should I avoid using (in architecture openings) single sided one face glass object with 2sided glass material? Or will VCM handle this correctly?

[lacilaci]

Well I tried simple scene without any, heavy thick glass caustic causing stuff. If I understand this right, this is not the kind of scene in which using VCM pays off, but wanted to try it just out of curiosity...

1: default VCM settings
2: default VCM without Merge function
3: large 24 pixel, initial radius default
4: large 24 pixel, initial radius without using MIS

The scene has in openings single sided object using 2sided material for glass.

[Ondra]

1 face with twosided mtl will always be more efficient, but last time I tried it, there was a bug when using it with bidir... I would just recommend using path tracing for this scene. bidir/VCM will never be faster in such type of scene, path tracing is the optimal algorithm here.

[lacilaci]

Yes I get it, it is definitely more efficient in the scene as it is now and this was me just wanting to see the difference myself, and asking that if in any case I needed to switch to VCM or BiDir if I should replace window glass models for those methods when I need to use them (lets say evening or night shots with artificial lights I want to see creating caustics in complex environment etc..). So I get it that 1face-twosided glass panes are okay for any case...

Why I'm asking this in the first place is if I fill an interior with loads of furniture and have it prepared even for a evening or night shots to see how interior lighting works (lets say some stylish ceiling lamp partially enclosed with 1-2 layers of objects with transparent material.. this is what I'm trying now) pathtracing seems to be not an option...

[lacilaci]

Another question..

in the screenshot I attached I have a lamp that has light bulb (material emission) and it's shaded by 2 layers of glass lampshades. My memory consumtion goes up every iteration(tracing particles) and I'm pretty much out of memory and paging(6GB) by 3rd iteration. I tried to leave it running and surprisingly it reached 19th iteration but then rendering process freezes and I have to kill the process(max).

Is VCM expected to be memory intensive in certain situations or is this a bug?

(I'm currently cleaning the scene to leave only things that are needed to reproduce the effect so if it's possibly a bug I'll send it to you..)
EDIT: It's actually happening with any lightsource (material emission, corona lights and environment) but using environment is increasing memory consumption by much less than lights... and its happening even with PPM and in VCM without merge funcion on so I don't know if I have screwed something there or if it is normal and I haven't noticed that till now or a bug in current release(using legacy18.12.2012).

[Ondra]

yes, it is memory-intensive. It could be remedied at cost of some performance though.

[lacilaci]

wow... I've uploaded simplified version anyways (just press render)...

Just to make sure it's not me screwing some stuff again causing this behavior.

It's a bit weird that 6GB ram gets lost in first 4-5 passes in a scene where is only a light and empty room :D.