i don’t do interior often, and when I do it seems I stumble through the process. For some reason my interior are way to dark, and unless I turn of the glass in my windows, I can’t get enough light into the scene. Why would my glass be blocking most of my sun?
Glorybound,
First and foremost make sure you have AFFECT SHADOWS ON, in your glass material settings. This will allow shadows through the windows. Ive seen alot of people place Vray lights at the windows (just inside the window pane) set to invisible. One last thing Id suggest is to use an exponential color mapping to take away in overbright areas..
Just my 2 cents.
Arkitec
I read just the opposite, but regardless, it doesn’t make a difference for me. I think I am getting something decent by playing with settings.
Are you using skylight portals?
maybe because when the light pass thru the glass to get realistic results you do need caustics, for normal arquitectural visualization you could turn the glass OFF for GI.
the glass in the most common if you threat it as reflective/Reflaction surfaces would be enought.
Turn off “cast shadow” in object properties, that should do the trick.
Are you using Linear Workflow ? It help getting more light indoors.
Also i like to use a VrayAmbientLight placed over the whole scene, it helps giving a diffuse lighting. Then i use VrayLights as planes to simulate light coming from the windows.
Pretty decent results with this technique and it’s easy to setup.
presuming with your glass everything is ok and you get light through your windows, but your scene is still to dark.
This is a common problem. The easiest way to solve this, as suggested allready is to use some sort of exponential or similar color mapping.
I would suggest to use “Reinhard tone mapping” as it´s the most intuitive to use.
Basically all this linear workflow nonsense started because
the renderings were “to dark”, so people brightend them by adjusting global gamma settings. Physical cameras are to dark or to overbright
depending on their exposure because thats how real cameras work. Now we can do better in 3D because we are not bound to those realworld
behaviours.
So just use a physical Sun/Sky (Or an overbright Direct and Environment as I prefer it). Use either a standard camera or a physical camera
where every cam exposure features are turned of (exposure, vignettting, white ballance). If you hit render now you will usually get an overbright render.
Switch your color mapping to “Reinhard”. Now you can expose your scene just like you want it. Turn down the Multiplier to make it darker and decrease
The burn value to reduce the overall contrast. So for example with a very low burn value but a high multiplier you can get even large rooms
with just a tiny window completely bright without the windows burning out. You don´t need any tricks like Skylight Portals, Ambient Lights or increased GI
Multipliers. It´s basically the same what modern HDR Photography does only that we can do it in one render.
Reducing contrast to get a scene bright also result in less saturation, but you can adjust this with the “Saturation” parameter (Vray Indirect Lighting rollout/Post processing)
Another thing I notice is that a lot of the actual designs you end up doing have quite small windows and use a lot of medium or dark woods which are going to suck light out. Your renderings look correct for the type of colours in there, you’re never going to get the big open airy look of Peter Guthrie’s stuff With smaller, low ceilinged cabin / lodge type stuff!
I like to use the Vray Override Mtl in this case with a light grey or white material in the GI slot.
Or, more extreme, a Vray Material Wrapper Mtl with increased Receive GI value.
For interior scenes I always switch off the GI for my glass (vray properties); I’m not sure why glass needs to participate in the GI solution.
Dont render any glass with your internals. do it as a seperate pass.
here comes a noobish question. how exactly do you mean that? turn the windows off in the first shot and then do a second one just with the glass? so where will then the reflections come from? I’m in maya but I think it should be the same as in max. so cubic can you give me some step by step hints to do that, please?
thanks in advance
Select the glass objects (which have shadow casting turned off), apply a fully reflective material, select inverse, then set alpha to -1. render
hmmm.. the inverse and the alpha settings just become available when i have an image plugged in any shading slot, which I don’t need for glass. so where can I set that values else?
Do you use Multisubobject Materials by chance? If I recall, Glass materials that were nested within MultiSub materials didn’t react with the GI properly (This may have been fixed - I don’t know). As suggested above, Detaching my Glass ID’s seemed to make a difference.
-Pixel
I’m not sure what Cubiclegangster means by “inverse”, but what I think he means is
create a fully reflective material (white 255 in the reflection slot)
then in the VRayProperties for the object (select object, right-click in viewport, “V-Ray Properties”) then set the “Alpha Contribution” to -1.0. Is that right Gangster? I’m curious what you mean too.
hey colin,
that sounds better to me =) I’ll give it a try.. thanks for the hint!
Sacha,
Yeah no worries, I’m curious too, because I’ve always rendered it in render because you can’t get reflections on matte objects so I’ve never tried with a separate pass. I hope Cubicle shares his secrets 
Whoops… didnt mean to overcomplicate it. i meant ctrl + I - select inverse of the objects. you dont want them to render, you only want the glass object to render.
So yeah:
you select the glass object
apply a fully reflective material
select every other object in the scene
change vray properties to alpha -1 and check on matte object (forgot to mention that)