Augmented Reality: Looking through the window / Exposure Control

[nisus]

Hi All,

 

We all know the problem caused by exposure control when we want to light an interior: interior is good, but exterior is blown out OR exterior is good but interior is dark. Not so much in between imho... Also, software vendors tend to make this distinction very hard, with the 'exterior daylight' checkbox (on/off, no tweening...).

Well, I know this IS reality (at least for a camera, not for the human eye), but since CG is augmented reality, I figured there should be a way to similute the visual reality of or eye (which still is so much better than any camera)

 

I wonder how to make a material that 'filters' the light, much like some kind of polarized glass. Anyone got a clue how to make it?

Preferably standard materials or MR-mat.

 

rgds,

 

nisus

[Brian Cassil]

Hi Evert,

 

For me it's quite simple, I don't use photometric lights. The reason I don't is for the very reason you state. I want to be in control of what I get in the rendered image. I don't want a program telling me how something "should" look. I find I can get this much more easily by using standard light multipliers. I got really tired of fighting what the programs were trying to do automatically.

 

I don't use MR, although I've considered trying to learn it (can it possibly be more complex than FR?) FR has a somthing in the advanced refraction called absorption. It pretty much does what you are asking for, but I have no idea if that exists or is reffered to the same in MR.

[nisus]

Hi Brian,

 

Well, I like the assemblies that lighting firms make, so I'm searching a way to implement them easily. For now, I have one working setup for exterior and one working for interior + an additional half-working one when the image is both interior and exterior. (The latter is what we have to do most of the times... pain in the ass!)

 

Anyone who uses these assemblies can share any tips about lighting setup?

 

nisus

[ShaunDon]

I take it then that exposing for the interior lights and then manually cranking down the sunlight to bring it within a visual range doesn't work? I've never tried to do something like this myself -- perhaps it would look strange if the intensity of the sun were reduced.

 

Shaun

[Ismael]

Here, a good article on this issue.

 

http://www.cs.utah.edu/~reinhard/cdrom/tonemap.pdf

 

Ismael

 

PS. A good visual of some T-map methods at:

 

http://netra.felk.cvut.cz/~cadikm/tmo/

[psv1]

the main issue in such kind of situations is the way in wich mr handles the

 

visibility trough the glaas or whatsoever medium separating interior/ exterior..one solution should be a photon shader attached and caustics on...waay to long to render

 

a transparency shadow shader atached to shadow slot seem to work fine(i`ve noted o reduction in burned areas ) seen from interior troug ext.

in max +mr one thing to avoid is exposure control , mr does not use it fully..and is something wich will literally kill your specular highligts..

a better way to do that is to save yours render output in EXR format via an output shader if have one... ahd adjust it in post

that`s till max 8 came out

 

or use gamma corection for an adequate tone mapping .....

mr gives the option to have separate intensities for direct and indirect light,,,that should help too. cause the intensities needed for under exposed areas will be smaller.

 

Sorin Vladimir

[vertexART]

Just while I was thinking about starting something called I see this thread ...

 

From my experience, I find the best way is not to use exposure in MR, and deal with interior/exterior separately. On my ongoing Mirada house, I have rendered the interior with alpha channel, then rerendered the exterior only with adjusted light setup. It works really well and it's pretty fast.

One of the reason for this was a photon mapping issue which scattered too many photons around just because my exterior layout was huge. When I removed the exterior I got much better lit interior. Another reason is that exterior is made by different person, but that's irrelevant.

 

As for the glass, I find MR's lume glass very realistic and easy to setup. I think it's the environment that will raise or kill the glass effect in 99% cases.

 

I hope this topic stays updated and hopefully stretched to MR mats, lights, setups, etc so we can all learn from each other.

Cheers

[auvn]

This topic is really great. More and more building use glass, so to show both interior and exterior will be really common. Most of the exterior renderings with glass buildings are too much reflection are almost with sky, very few of them has show interior.

 

it would be great if someone can contribute some images to illustrate.

 

AUVN

 

p/s:I would attach some images but it is to difficult to attach images.

[nisus]

Strange, I use exposure control a lot in MR... prob is... different settings for interior, exterior and day, night...

If someone could only find ONE setting for all... ;-^p

 

nisus

[Advisor]

I don't know how relevant is this, but one of the images I received in Vismasters had this approach an interior room with exterior both had the right exposure. Although it's obvious the exterior is a bitmap. It didn't look very realistic Imho but very effective the one who did it took an artistic licence and it worked.

Applying this on full cg needs a bit of compositing (like Mr. Ivanovic did and explained in his Post)

It really took the industry a long way to get a realistic lighting model. I don't think we can ask for more at this time. but a customizable lighting model would be very nice.

As for Glass. I have no expeiance in MR but isn't using a MR lume a bit of an overkill?

that said. I used glass with an enviroment map as a test before.

this is my result:

 

In order to avoid burning the env. I simply increased its output to 2.0 or so.