Correcting Overexposed Windows

[ivanjay]

Good morning,

 

I render interior scenes, many of which have windows to the outside world. I know my exposure is "correct" as the interior looks good and the windows are blown out, as they really would be.

 

However, is there a way to correct this for the sake of a good looking image?

 

Currently, I take the image in photoshop and paste into the shape of the window a sky background. The result is a bit faux looking though....

 

My other thought is to render two passes, overlay them in photoshop, and apply a mask. But, that seems time consuming to render twice...

[Dave Buckley]

first reduce the burn setting in the exposure to 0.01-0.02

 

then select the sky portal (assuming you are using them?)

open the modify panel to access the portals parameters

expand the 'advanced parameters' rollout

click the colour swatch next to transparency

set the value to 0.1

 

this should do the trick

 

the colour swatch next to the transparency represents a value, where white is opaque and black is transparent. however i always find that pure black gives funny results and 0.1 works perfectly fine

 

let me know how you get on

[braddewald]

It would help if you uploaded an image, so we know exactly what to help you with.

[Dave Buckley]

based on his other posts i reckon my response should be fine (he mentions mental ray in another post) and what he describes is a common result on interiors as the result is 'physically/photographically correct)

 

however to replace the sky you also wouldn't need to render two passes, just save as tga or tif and use paste into in photoshop using the alpha channel as a selection

[DavidR]

I would add that using linear workflow will help in those situations, because your light will penetrate further into the scene so you can lower the camera's exposure, which will make the windows blow out less.

[Dave Buckley]

I would add that using linear workflow will help in those situations, because your light will penetrate further into the scene so you can lower the camera's exposure, which will make the windows blow out less.

 

i kind of disagree with this, again forgive me if i'm wrong but a linear workflow just engages the fact that things ae consistent between the entire workflow

 

i.e. an image when taken with a camera has a gamma of 2.2 burnt into it so therefore when using an image in max we need to tell max that the incoming image has a gamma of 2.2 so that what we see is what we get

 

the above is a very very generic explanation, i just doubt that lwf has anything to do with over exposed windows

[ivanjay]

Thanks for the comments guys.

 

Sorry I forgot to attach the image, I meant to do that. Attached is my last rendering with these settings changed. My scene is a bit overexposed, I need to turn it up a notch but the windows are still blown out.

 

The settings are also attached and you can see in the window the sky portal settings as well.

 

I have never worked with alpha channels in photoshop. Can you walk me through how I would go about pasting the sky environment map back into the windows in PS? I manually do it now which is a pain in the !@#

 

I am also now getting this weird purple on my rendering. Any idea where that is coming from?

[BBB3]

I don't use MRay, so not sure about this, but the way I do it in Vray is to render a 32bit image and compress the dynamic range in post using tonemapping.

[ivanjay]

I don't use MRay, so not sure about this, but the way I do it in Vray is to render a 32bit image and compress the dynamic range in post using tonemapping.

 

Can you give me a little more information on how you do that?

[aaronrumple]

Can you give me a little more information on how you do that?

 

Export to *.exr and use Picturenaut....