Problem -- default cutoff value [Reflections] in Vray material using Falloff

[3DMK]

Hi all,

There seems to be a problem with the default cutoff value [Reflections] in Vray material using a Falloff map.
The default value of 0.01 seems to be way too high and produces no reflections or a sever cutoff/edge when using a Falloff map.[SEE images below]
Have had this problem a few times now & can consistently reproduce the same issue.

Is there some way to change this default value in Vray material??? So that I don't have change all mats manually or with scripts.
Thanks

[bob-cat]

Never had this problem before, using a falloff mat.
Could it be something else, or is this value "unit related" and your max units are out.
Upload the file and I'll see if it happens this end?

[3DMK]

Never had this problem before, using a falloff mat.
Could it be something else, or is this value "unit related" and your max units are out.
Upload the file and I'll see if it happens this end?

All my work is Architectural work so it's all to scale. I do use meters mostly for [world units]

[I'll upload the scene later today when I get time ...THANKS]


Here how I can reproduce it every time--

Try setting your falloff map to [Fresnel] & to the following colours 0 [black] & about 22 [grey]

Look straight at the object

...Happens to me every time

Could it be IOR stuffing up the Falloff map???

Cheers

[bob-cat]

Ok, done some quick tests and can't reproduce the problem.
The reflection values are so low that I can't even get a reflection on the surface! - which is what appears in your first image.
So if your material colour is black and its not getting any illumunination is will render black.

[3DMK]

Ok, done some quick tests and can't reproduce the problem.
The reflection values are so low that I can't even get a reflection on the surface! - which is what appears in your first image.
So if your material colour is black and its not getting any illumunination is will render black.

Here is the scene.....http://www.3dmk.com.au/3dmk-vray/Ref...ff%20SCENE.zip

I forgot to tell you to make sure you look at the Vray RAW-Reflection layer as it is easier to see the reflection cutoff.

I did also notice just then that the cutoff gets worse as the IOR gets lower

Thanks for your help

Cheers

[bob-cat]

Spent the last hour trying heaps of things, new scenes, different units, reset renderer, new camera's, using a mix map,..... etc. etc. etc.

The only way I can get it to render correctly is to change the view axis in the falloff map to use the local Z.?

[vlado]

This might happen if the material reflects something is way too bright; the default values work fine in many cases though.

Best regards,
Vlado

[3DMK]

This might happen if the material reflects something is way too bright; the default values work fine in many cases though.

Best regards,
Vlado

Thanks Vlado

This appears NOT to be the case this time as when I turn off the Falloff map & just use the same reflection value the cutoff of 0.01 works fine.
It must have something to do with the falloff map as it only happens when I use this map type.
It appears that when Vray looks at the falloff map & the straight-on value is 0 [black] it figures that this is below the Cutoff value & doesn't render any reflections there. As the falloff angle increases, the Reflection value is above the cutoff & it renders reflections fine.
I will do a test also using the inbuilt fresnel falloff in Vray Material & see if it's any different to the Max one.

Thanks
Jamie

[jstrob]

WOW thank you for this post! I had exactly the same problem with a fresnel reflection with a low value for the IOR (les than 1.3 or more than 0.85). I'm trying to make a car shader with a blend materail and I got those cutoff all over spending hours trying to nail it. Thanks to you, I just discover the cutoff value!!!

[Sushidelic]

Hi,

if you just want to disable all vraymtl cutoffs anywhere in your scene, you can use

(getclassinstances vraymtl).option_cutoff = 0

or change the value to whatever you want.

Best regards,
Michael