cutoff parameter

[Karonte]

hi All,
i found this problem. I use LWF and often when i use dark color, with fresnel reflection, in the editor and in the render, i see the problem in image cutoffA001. My gradient reflection ( driven by fresnel parameter)seems to be "cutted".
If i pull down CUTOFF value to 0,001 instead of 0,01 ( default) things are ok ( also in render).
So, my question is: is better to use cutoff always set to 0,001? this slow down rendering times?



Regards.

[NicoC]

Hello,

I've noticed the same problem. I've set Cut Off to 0.005 instead, and it seems ok, while keeping render time reasonable.

[Karonte]

thanks for sharing your experience.
Do you put 0,005 always in every material ( to stay safe) or only in the darkest one? ( or the one you think have proplems...)

[NicoC]

Hello,

To be honest, it's something I've just discovered, thanks to a friend (Martin not to name him ). Not sure it's a good idea to put 0.005 at a "default" value for everything though, we'd need more information from other users and/or Chaos Group guys about that ...
On a side note, I'd like to know if such a problem can "only" occur with materials with Glossiness < 1.0 ... really, it's something still a bit unclear for me for the moment.

[Karonte]

I discovered this thing... 1 year ago. I have to make huge black glossy tile wall. i cannot find any solution....but Nikki Candelero tell me to try this cut off parameter.
It's strange because without LWF methods all works well.
wait for Vlado....

[pixela]

How does cutoff parameter help with the huge black glossy wall?

[Karonte]

@pixela : it works if you use LWF first of all ( as you can see in my images).
Second, if you put the parameter down, like 0,005 or less, you can see all the small fresnel reflection in the material. If you let the parameter as default, reflections seem to be...cutted. When i will go to the office try to post some rendering crops of my old work.

PS: i use this post to say that your works are Amazing!! one of the great artist that i follow.

[instinct]

The cutoff helps to reduce rendertimes (less rays to be casted obviously). The default has been selected to be usually not noticable while still helping
rendertimes. Depending on the scene and the amount of reflection the default value may be cutting too much.

Regards,
Thorsten

[pixela]

@pixela : it works if you use LWF first of all ( as you can see in my images).
Second, if you put the parameter down, like 0,005 or less, you can see all the small fresnel reflection in the material. If you let the parameter as default, reflections seem to be...cutted. When i will go to the office try to post some rendering crops of my old work.

PS: i use this post to say that your works are Amazing!! one of the great artist that i follow.

The cutoff helps to reduce rendertimes (less rays to be casted obviously). The default has been selected to be usually not noticable while still helping
rendertimes. Depending on the scene and the amount of reflection the default value may be cutting too much.

Regards,
Thorsten

Thank you both for explaining me
It really looks strange with the default parameter. I never had this problem.
Actually never touched this parameter at all.
When I want to see more fresnel, I usually play with the fresnel curve.
Karonte: Thanks for the kind words about my works. I am happy that you like.

Cheers!

[PIXELBOX_SRO]

Hi Pixela
i mostly set this straight to 0.
everytime i use falloff or fresnel....its no too drastic on the render times
Best

[vlado]

We might have to adjust the default value for this; it was set long before the LWF stuff caught on.

Best regards,
Vlado

[Karonte]

Good work Vlado! Thanks

[pixela]

Hi Pixela
i mostly set this straight to 0.
everytime i use falloff or fresnel....its no too drastic on the render times
Best

I see.
I will try this.

And thanks Vlado