I was trying to render 2 white cups (other colors ended up ok) in a studio environment with light cache but I couldn’t make them stand out from the background and floor (I tried lowering the environment light too), it all looked so white. I changed the secondary GI to QM and it did a wonderful job. I want to know how it would be possible to get the same kind of render with light cache? It seemed impossible to me
Here are my 2 pics, one with QM and one with LC and I’m also posting the visoption files.
thanks, I would appreciate if anyone could tell me as to why I can’t get a similar result.
Well, first off LC is much brighter than QMC because of 2 reasons… 1) more bounces are calculated as opposed to just 3 which is the default for qmc. 2) LC doesn’t separate bounces, so it calculates the first bounce as well. The fix for this is to, when using LC, decrease the secondary bounce multiplier (to about .8 will do). That will make those shadow details not as flat.
The second thing is that the default sample size is too big (IMHO) for a good LC solution. A smaller sample size will lead to better details. The default is .02 and I bring that down to .01 or even .005
In general QMC is a far more accurate calculation the IM or LC. That only means that its a little easier to get good results from it, but this goes along with longer render times. The right tweeks of LC or IM will yield results that are comparable to QMC, but not nearly as time intensive.
“Do not apply perfectly white or very close to white materials to a majority of the objects in the scene, as this will cause excessive render times. This is because the amount of reflected light in the scene will decrease very gradually and the light cache will have to trace longer paths. Also avoid materials that have one of their RGB components set to maximum (255) or above.”
I tried changing the color from a 255 255 255 white to something very similar and it yielded much better results too.
Yea, spot3d is a great site…if it weren’t for that I’d would be in the dark about allot of V-Ray..
Anyway, that image should really not be taking any more then 1-2 min at max. There aren’t very complex interactions going on, so you don’t need settings that are overkill. I’ve attached two images and the visopts that go with each. The first was done with my standard defaults that I use. That image came out @ 11-12 sec. The second one was done with what I would consider good quality for this type of scene. Again, only about 53 sec. This was also done with a 4 year old, non multitreaded, cheap laptop…so its not like I’ve done these on a screamer either. Enjoy
EDIT: Those cups are available in the V-Ray for Rhino Training Scenes.
It may be a version issue because I do have an internal build…but I haven’t run into those issues before…weird.
As far as the shadows its best to decrease the sample size for Light Cache (thats one of the common elements from the two images that I posted before). The default is .02, which is too big. Either .01 or .005 is better and should get rid of that.
