interior scene - how do you show skies outside?

[scostumatu]

Hi

 

I was just after some workflows that some of you do out there in terms of showing skies in interior scenes through windows.

 

Im currently doing a project where there is an abundance of windows and im currently using the vray sun/sky workflow. Problem is, the skies are all white and I want to show some colour (either slightly cloudy or overcast).

 

Ive tried to use skydomes in the past but i had trouble with colour casting even though I disabled cast/receive shadows. There seemed to be a yellow cast in my scene and i kinda gave up due to time constraints.

 

Theres always the option to do it in post but with so many windows, im worried it might look too artificial.

 

Would love to know your methods or workaround in this situation.

 

Cheers guys

[Bruce Hart]

Hi John - just check your Vray Camera settings. The default camera is set to use a light blue "daylight" filter, which means it will subtract some of that blue colour away from the image - leaving you with a yellow tint (Also make sure vignetting is off). You could try making the filter neutral to avoid any colour casting, and add desired colour correction in post.

 

What you could also try is separating the displayed image in the skydome from what appears in the background. Set the dome light to be invisible, and then add an image to the background environment slot (press 8). This could be the same HDRI with an altered intensity or even a different sky image all together. If you used a photograph this way you may need to uncheck the "affect background" setting in the Vray colour mapping area.

 

Some people just use a self illuminated plane backdrop outside the windows with a sky mapped on, or they add the sky later in photoshop. The post option requires that your window glass material affects alpha. The advantage of this method is that you can place your sky in the scene exactly at the intensity you want. The disadvantage is that the image won't be appearing in reflections in the scene (however it may not matter), and is generally applicable to still images for obvious reasons.

 

HTH

[RyderSK]

No matter what solution you take on, showing happy blue sky or any sort of sky in correctly exposed interior will look artificial, it should be white, because the EV difference is huge unless your interior space has full glass walls so the illumination is more even.

 

I will list few solutions starting with the LEAST artificial to the most fake.

 

1:Tonemapping your image to show great dynamic range in terms of EVs displayed. You can do this through linear output adjusted by curves in post (you will need unclampled image and correct LWF setup) or inside renderer through exponential (or near exponential reinhard) color mapping.

 

Bear in mind, depending on how large the EV difference is, you might need quite extreme highlight crushing to point that whole image looks rather dull (washed out midtones, very unnatractive).

 

Fakes:

 

Bear in mind any of the following fakes you will make, it will scream "unnatural" to laics, and "CGI" to us.

 

Differently exposed environment--) two domelights, bacground overwrite,etc..

 

Planes---) this is actually really stupid solutions, because any geometry outside of your scene affects sampling in worst possible way, but it looks like "cool" tricks to some people. This is year 1992 solution, same as mapping hemisphere as actual geometry, don't do it.

 

Pasting in sky in photoshop without taking any care about tone-mapping inside of spaces. It just looks "pasted". The environment (city, forrests,etc..) should be visible, but sky almost never.

 

Last, it's about photography approach, not CGI technical tricks. Vray sun/sky isn't to blame, it does what is right.

 

 

Maybe if you excuse me ( maybe I could use some raw photography of interior, but I don't have one on hand and I am not photographer.. ) I can illustrate with test render from one more recent project.

 

There is no post-production on it only one curve that does quick and dirty tonemapping. The first one is close to linear with slight shoulder only in highlights, and the second has very aggressive shoulder and toe alike. But it shows the Sky. There is no masking or anything advanced, just dirty 5 minute job to illustrate how tonemapping is powerful. Our renders are like super-raw in top cameras and that gives super flexibility.

 

Almost linear:

 

 

Over-crushed:

 

 

 

Of course, even fakes are valid in our work, but I am of opinion they should be used much more carefully than are most of the times. If we ever want to avoid the dreaded CGI look, even small things help.

 

So sometimes best solution is to combine all tricks together: Plan out lighting (flesh, soft boxes,reflective planes,etc..) tonemap carefully, mask out areas, swap or adjust backgrounds slightly, implement glows, dodge/burn, etc..

Edited October 31, 2013 by RyderSK

[scostumatu]

Thanks guys for your replies.... Juraj, awesome advice thanks so much... although i dont know as much about tonemapping as i should... im getting there. Do you know anywhere in particular where i could learn that?

 

So with your images attached (which are beautiful by teh way), did you have a HDRI in the environment? did you use the 2 dome set up? What set up was that?

I find when i use anything other than the vray sun/sky, the render times usually increase by over 60%.

 

I sometimes find myself using the vray sun/sky combo, but i link the vray sky to the sun and disable the sun so that I dont have the sun beaming into the room.

 

its one thing ive been struggling with, interior lighting. I cant seem to get it right. I mean it looks good and i eventually get there, but its a bit of a grind.

 

 

No matter what solution you take on, showing happy blue sky or any sort of sky in correctly exposed interior will look artificial, it should be white, because the EV difference is huge unless your interior space has full glass walls so the illumination is more even.

 

I will list few solutions starting with the LEAST artificial to the most fake.

 

1:Tonemapping your image to show great dynamic range in terms of EVs displayed. You can do this through linear output adjusted by curves in post (you will need unclampled image and correct LWF setup) or inside renderer through exponential (or near exponential reinhard) color mapping.

 

Bear in mind, depending on how large the EV difference is, you might need quite extreme highlight crushing to point that whole image looks rather dull (washed out midtones, very unnatractive).

 

Fakes:

 

Bear in mind any of the following fakes you will make, it will scream "unnatural" to laics, and "CGI" to us.

 

Differently exposed environment--) two domelights, bacground overwrite,etc..

 

Planes---) this is actually really stupid solutions, because any geometry outside of your scene affects sampling in worst possible way, but it looks like "cool" tricks to some people. This is year 1992 solution, same as mapping hemisphere as actual geometry, don't do it.

 

Pasting in sky in photoshop without taking any care about tone-mapping inside of spaces. It just looks "pasted". The environment (city, forrests,etc..) should be visible, but sky almost never.

 

Last, it's about photography approach, not CGI technical tricks. Vray sun/sky isn't to blame, it does what is right.

 

 

Maybe if you excuse me ( maybe I could use some raw photography of interior, but I don't have one on hand and I am not photographer.. ) I can illustrate with test render from one more recent project.

 

There is no post-production on it only one curve that does quick and dirty tonemapping. The first one is close to linear with slight shoulder only in highlights, and the second has very aggressive shoulder and toe alike. But it shows the Sky. There is no masking or anything advanced, just dirty 5 minute job to illustrate how tonemapping is powerful. Our renders are like super-raw in top cameras and that gives super flexibility.

 

Almost linear:

 

 

Over-crushed:

 

 

 

Of course, even fakes are valid in our work, but I am of opinion they should be used much more carefully than are most of the times. If we ever want to avoid the dreaded CGI look, even small things help.

 

So sometimes best solution is to combine all tricks together: Plan out lighting (flesh, soft boxes,reflective planes,etc..) tonemap carefully, mask out areas, swap or adjust backgrounds slightly, implement glows, dodge/burn, etc..

[RyderSK]

It's only single HDRi in environment :- ). But I used Corona renderer, not Vray. If did this in Vray, it would use single DomeLight.

 

Yes, you are correct about increased render times, IBL with GI will never be so fast as optimised model light such as Sun+Sky. 60perc. increase is actually rather conservative :- ) it can be even double, tripple...depending on other eventualities.

 

When you mention the linking, I can show you my favourite way of using Sun+Sky for interiors that is in general good starting point. I use definitely MUCH weaker sun (to simulate some cloudyness) 0.05-0.1 in intensity, blurriness (2-4 in size) and maybe even desaturate the Sky in material editor (to simulate overcast sky).

 

You can achieve pretty much ANY light with Sun/Sky, the reason for HDRi is reflections/background, not different light quality as many people think. Light is just Light.