[interior lighting] Sun & Sky vs area lights in windows?

[Rich O]

Just wondering which way people prefer? I'm attempting to use the Vray Sun & Sky system in Maya and am having real difficulty getting the interior nice and light vs having highlights blow out horribly.

I've actually ditched the Sun & Sky and used an HDRI with a similar sun position, and used Reinhard colour mapping with the 'burn value' set to about 0.2

 

(note that I am set up for linear workflow and am using a Vray physical camera)

Edited September 24, 2012 by Richard7666

[Chris MacDonald]

Go and take a photo with any camera and correctly expose the interior, during a sunny day; The outside will be completely blown out. It is what happens in real life.

 

I like the "burnt out" exteriors when used with a subtle bloom/glare effect. Alternatively if you really must avoid this, try increasing the light multipliers inside - not photoreal, but achieves the desired effect.

 

[edit] Check this: http://www.mrmaterials.com/jeffs-blog/68-realistic-results-with-the-mr-photographic-exposure-control.html

 

It's Mental Ray, but the concept is still exactly the same in any render engine that simulates realistic lighting.

Edited September 24, 2012 by Macker

[Umesh Raut]

That is a great source, Chris, thank you very much.

[salvador]

Go and take a photo with any camera and correctly expose the interior, during a sunny day; The outside will be completely blown out. It is what happens in real life.

 

I like the "burnt out" exteriors when used with a subtle bloom/glare effect. Alternatively if you really must avoid this, try increasing the light multipliers inside - not photoreal, but achieves the desired effect.

 

[edit] Check this: http://www.mrmaterials.com/jeffs-blog/68-realistic-results-with-the-mr-photographic-exposure-control.html

 

It's Mental Ray, but the concept is still exactly the same in any render engine that simulates realistic lighting.

 

Very helpful Chris. Even if it's for MR (which I don't use) I'm thinking I can create an mr daylight system and let it do the math via presets for a correct exposure and then apply the correspondent values to my VRay system / camera. (Turning off mr of course). This way I can skip a lot of the hassle of starting from scratch with light / exposure tweaking.

 

Thanks.

[Chris MacDonald]

I think the best way anybody can get to grips with it is try it in real life, with a real camera; almost all cameras (even cheap point & shoot ones) have some form of exposure control and an SLR will give you exactly the same controls as your render engine and it's instantaneous - no render times!

 

Set it up inside and make sure there is a window in your shot, then play around to see how the ISO, shutter speed and f number all affect the image brightness. Try the same from outside too, during the day and during the night - you'd be surprised just how little you can see into a building on a bright sunny day, the glass becomes almost mirror-like.

[Rich O]

Thanks Chris, that was good advice!

What I'm trying to do is attain an 'eye realistic' image like this one. My situation is I have a patio area I'd like to see from out of a window, similar to how the awning out the leftmost window in this render isn't over-exposed, yet is still part of the render.

Edited March 28, 2013 by Richard7666

[Chris MacDonald]

Yeah the problem you'll always have is that render engines are set up to mimick cameras, not the human eye - and the way they handle dynamic range is wildly different.

 

I suppose if it were me, I'd either increase the interior lighting or alternatively render out two seperate passes; one with the interior exposed correctly, and one with the exterior exposed correctly - then take them into photoshop and correct it through there. Be sure to render out an object ID pass for the glass, or alpha channel just to aid with selection in photoshop.

 

The second method would also be how I'd attempt it if I were photographing the space, also. One exposure for the interior and one for the exterior.

 

Have a look at this; http://www.peterguthrie.net/blog/2009/04/architectural-photography/

Edited September 26, 2012 by Macker
typo

[pixelperfectg]

Save yourself some time by:

 

1. Render the properly exposed interior to 32-bit floating point format (like .tif, .hdr, .exr).

2. Render some b/w masks for the windows or use render elements and object ID's, etc.

3. In Photoshop: Adjust the exposure on the windows (using the masks) to make the outside visible.

 

Same method applies to animations, just use something like AE, Composite, Combustion, etc.

[Chris MacDonald]

Excellent tip ^

 

Also, as you're using VRay... If you make sure you're using the Vray frame buffer instead of the max one, you can alter the exposure in there (as it's floating point) and simply save out both exposures as whatever file format you want. This or Jeffs method will save you having to re-render the image for a seperate exposure.

[Rich O]

Cheers guys, I'll test that out tomorrow. Opted to use objectID render elements.