Problem with maintaining white walls in interiors

[DanieloDanielo123]

Hi,

I have a problem with maintaining white walls in interiors. On the wall I applied " interior diffuse white " , I set the settings on " interior " , for interior lighting I use " Area light " but I still get all the colors except white. I will be grateful for any advice
In the attachments I send renders and the scene.

Daniel

[DMerz III]

In photorealism, the walls would not be true white. I believe the "interior white wall" material by default has a value of around 84% (if I recall correctly), which is technically the maximum value light could reflect based on true physics. (Disclaimer; I am not a scientist or even great at math.)

You could technically cheat this and increase the value of the diffuse color, but you still won't get pure white, which is not what you'd want anyway, unless you're going for a  visually flat render?

Could you offer up an example image of what you're going for, so we can help troubleshoot what levers to pull?

[DanieloDanielo123]

Hi,

In attachments I'm sending pfotos with the expected effect 

Daniel

[DriesV]

These images will have undergone significant color corrections after rendering.
It looks to me like the highlights (bright areas in the image) have been desaturated.

Dries

[DriesV]

So the solution here lies in post-processing, more than in rendering.

Attached is a quick example.
Left: rendering straight out of KeyShot. Right: the same rendering after post-processing.

Dries

[DanieloDanielo123]

I do not know if I understood correctly, getting a white wall effect is not possible in Keyshot ?

[DriesV]

The thing is that lighting in KeyShot is physically correct. So when light hits a colored floor and then bounces onto a white wall, that wall will have some color bleeding from the floor. This is how light behaves in reality. White is never 100% white.
While the reference images you posted look nice, I wouldn't call them realistic. In reality those walls would never look that white.

You can avoid color bleeding in KeyShot by disabling Global Illumination. This, however, will cause indirectly lit areas to be dark. So you will need to put a number of Area Lights inside your interior to make sure the scene is evenly lit. Without Global Illumination the white walls will not be colored.

Dries

[mattjgerard]

Another 3D guru once told me that no asset created directly out of a 3d rendering program is 100% finished. I would argue that nearly every 3D image you see is post processed in some way or another. Even real time 3D in games and VR go through real time post processing before they are displayed. Trying to get the perfect final image out of any render engine is difficult, nigh-impossible and really isn't a workflow that is embraced by many.

SO, post processing in the image editor of your choice isn't a negative slight on your render work in keyshot, its an extension of the toolbox to make the image look the way you want.

Lots of times with rendering, photography, shooting motion pictures, the images are intentionally shot lit and exposed a certain way to allow more freedom in post to form the image color and dynamic range into the look the directors want. If you saw the washed out colorless desaturated images that are actually being recorded by most professional high end digital cinema cameras these days for the most popular films, you'd wonder what was wrong with the gear. But they do that to allow the look to be manipulated in post to the max efficiency and benefit of the film.

Which is why I'm interested greatly in the 32bit PSD format. Mean to start playing with that more, I'll be there will be much more latitude with color and contrast manipulation in post.

Dries has some great advice when it comes to post work, he helped me greatly with this thing called tone-mapping when I couldn't get the look that I wanted with some LED"s behind cloudy plastics. The final image that he showed me was exactly what I wanted, but I had to set  up the render in a certain way to get that look in photoshop and the final image was perfect, while the render direct out of KS looked pretty horrible.

[DriesV]

Btw, we are looking at adding comprehensive real-time color adjustments and tone mapping to KeyShot 8.
This should allow to eliminate a few post-processing steps that now require a multitude of tools and plugins.

For people interested in high quality compositing, with a lot of granular control, I can recommend looking into Fusion by Blackmagic Design.
https://www.blackmagicdesign.com/products/fusion/
It is a highly capable node-based compositing tool (like Nuke). A big plus is that the base version is free.

Dries

[DanieloDanielo123]

Hi,
Thank you very much for your advice I just started to set the scene according to your suggestions, it is a big improvement  
When I get the rendering effect, I will put it in the post.
I know there are no white walls in the realism but sometimes I need to get an approximate white effect.
Thanks again for the help.

Daniel

[fario]

thank you!

Very interesting topic!

Antoine