Lighting an Interior with no windows

[david murphy]

Hey,

-What is the best way to light an interior scene were there are no windows, Is there a way I can use the GI to Light the Interior scene.

-In Artlantis render you can click on the ceiling and tell it not to cast shadows, this allows the sunlight to pass through your ceiling and light up your interior, Yeah cheating I know but it works, can you do this in Vray.


All help appreciated...............

zzzSPUDzzz ???

[dalomar_cg]

Re: Lighting an Interior with no windows

-What is the best way to light an interior scene were there are no windows, Is there a way I can use the GI to Light the Interior scene.

I'd say put some lights in, but thats just me What you add depends on what you're looking for. Try to match the lighting scheme that you're trying to recreate.

-In Artlantis render you can click on the ceiling and tell it not to cast shadows, this allows the sunlight to pass through your ceiling and light up your interior, Yeah cheating I know but it works, can you do this in Vray.

mmmm...you could do that, but my question is why would you want to? If I have an interior scene that isn't open to the outside, using exterior lighting would lead to a pretty unrealistic result. I'd suggest going through the steps of adding light within your interior environment and seeing how that works before resulting to tricks that will decrease the realism of your scene.

[david murphy]

Re: Lighting an Interior with no windows

Hey Dalomar,

Yeah I suppose lights would be a good start , I'm trying to light a very large interior and I am trying to use the GI with a HDRI map to give me an overall lighting solution without having to add loads of lights, not trying to cheat my way around adding lights but I can never seem to get the interior ambient lighting right, trust me I have tried but this just seems to be my Achilles heal.

What would be the best way to approach illuminating my interior, without tricks of course ;D

zzzSPUDzzz

[dalomar_cg]

Re: Lighting an Interior with no windows

One of the keys to interiors it to try and set things up in a manner that allows for the maximum amount of light to "reverberate" through the space with the minimum amount of actual lighting. IOW, you want to make the light that you do have really work for you. However, this is all without sacrificing realism. So here are a few tricks that I use...

1. Color Mapping set to an Exponential mode. The reason for this is simple...exponential modes will prevent your image from being "burned" by adjusting the color response as those values approach white. In a more practical sense, this means that if I have a light pretty close to a wall, then I can increase the intensity more before it looks really burned, thus allowing more light to propagate through the scene. There are 3 differnent Exponential modes in V-Ray; Exponential, Intensity Exponential, and HSV Exponential...My favorite is HSV Exponential as this seams to preserve colors better.

2. Manage Decay. If you're using point or spot lights, then you can choose between Linear decay (not recommended), Inverse Decay, and Inverse Square Decay. Inverse Square is the physically correct method, but Inverse will preserve more of that intensity as you get farther away from the light. And this can bypass the need for more lights. Unfortunately, with rec lights this isn't an option...its either all or nothing.

3. Light Cache for Secondaries. Most people don't know this, but Light Cache calculates all bounces all the time, regardless of how its being used. Thats why when most advanced users have LC for secondaries they will decrease the multiplier to counteract this. Well, we can also use this to our advantage. Most of the illumination that you'll be getting in interiors will be due to secondary bounces, so having the "extra headroom" that comes along with Light Cache can be helpful. In most situations I use IR/LC and have my secondary multiplier set to .8. If I find that I need a little bit more light, than I may bring that multiplier back up to .9 or 1. The only thing that you'll have to watch with this is color bleeding, but you can always precalculate your LC or IR maps with different materials to get around this.

Those are 3 basic steps that I take when it comes to interiors. Try and mess around with those as best you can. Also, having a number of lights goes along with interiors, so its kind of a necessary evil....one last pointer; if you're using IR and have Rec Lights, try enabling Store With Irradiance Map as that tends to help speed things up.

[david murphy]

Re: Lighting an Interior with no windows

Thanks Damien I will give that a shot........

What values would you recommend for Shutter Speed, F-number & ISO and if I need to brighten my scene which is the one best to use, I know they will change depending on my scene but a good starting point would help.....


zzzSPUDzzz

[dalomar_cg]

Re: Lighting an Interior with no windows

I can't tell you which ones to use bc that will depend on what level of illumination you have in your scene...the only thing I can tell you is which way to adjust values based on brightness or darkness.

Fstop - lower values will make your scene brighter - higher values darker
Shutter Speed - lower values will make your scene brighter - higher values darker
ISO - lower values will make your scene darker - higher values brighter