fresnel bug??

V-Ray V-Ray for 3ds Max Issues
1

don’t know about you guys, but i am having this problem with lwf.
i am using vray 1.47.03
this is the setting.
just pitch black material
reflection : grey, value 50
click on the fresnel
this is what i get.

then with the same setting, i change the material reflection to
grey, value 30
and this is what i get
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so. i know it’s a small problem, probably, someone would say,
dont use lwf then, or don’t use reflection under the value of 50…
:slight_smile:

but then also this is not visible when you are not using wide angle camera, since my client is a wide angle camera freak, so i am getting this effect on my floor. very sharp line between the reflective and not reflective area..

any advise my good fellas??
thanks

2

Can you show an image with that floor with the sharp line.
Thanks.

Best regards,
nikki Candelero

3

Hello dominique,

Decrease the cut-off threshold for the vraymtl and it will be fine.

Best regards,
Vlado

4

sorry vlado..
the idea of having fresnel is to have reflection ---->to non reflection..
if i lower the cutoff treshold, it looks like it loses it’s fresnel.
hmm… any other solutions?
thanks

niki, this is the image

you will see a curve sharp line below..
thanks

5

Can you also show a render with vlado’s suggestion - to see the difference ; as that is how it should be set.

Best regards,
nikki Candelero

6

this one is with vlado’s suggestion.

the question is, can i don’t have that reflection at the bottom…
but a gradient from reflection--to non reflection

thanks

7

looks fine to me…the windows are fading out towards the bottom. The amount (or falloff) of the fresnel is depending on the reflektive IOR (wich by default is locked to the refractive IOR), so to tune the look you’d have to untick the L button and adjust the IOR, no ?

Thorsten

8

if i lower down the fresnel, the cut-line is happening again…

9

Try using a Blend material, which has for 1st mat - the one with reflections, and a second with pitch dark diffuse and no reflections at all.
Then use a Falloff map for the masking between them. Should do what you need, with no tweaking on the IORs.

Best regards,
nikki Candelero

10

:smile: thanks niki
that’ll do!!

11

but will increase rendertimes alot i think. :?

12

if the 2nd mat has no reflections, that wouldn’t be much of a pain.

Best regards,
nikki Candelero

13

couldnt you just use a falloff map in the reflection slot ?

14

same thing..
will also occur

15

Yes, that’s another option, which might also do it.
Actually that is even simplier. Thanks.

Best regards,
nikki Candelero

16

the same thing will happen.

17

I think you should try and go Vlado’s way (duh, that was a smart bet…): lower the cutoff, which will insure even the fainter reflections will be picked up, and then readjust the material ior.
If you use a falloff map, make sure you are adjusting the proper ior depending on the “override ior” checkbox state, and try and play with the output curve so to have a finer controll of the falloff.

In any case, if the problem indeed sits with the cutoff, the same material with a different falloff type (towards/away, for example) should exhibit the same issue at the reflection fringe.

Lele

18

you may also try fall off map, I find that gives you much more control over the falloff curve.

19

thats correct…i am always using fall off map, but if you use fresnel option in the falloff map you should be careful about mode specific parameters, there is a tick -override material IOR- i think it needs to be ticked and you specify the fresnel IOR there, if unticked you would be applying fresnel twice i suppose…anyway using fall off map with fresnel option can sometimes cause splotches

20

if you use a falloff map in reflection slot, then uncheck fresnel option in vray mat…
and then do your magic from falloff map only.