Fresnel Reflections, what's going on here?

Thu Apr 16, 2015 1:16 am

Working with the newest version, with the fresnel issue fixed, is this working as expected? I did some tests below. These are using a black glossy material with various reflection settings. the index is set at 1.55 on all of these.

Shouldn't the middle two version's fresnel reflections be much more pronounced (i can't even tell if these have any fresnel reflections going on) and look closer to the version I did with the falloff node? Is something still broken or do I just have a misunderstanding over how to set the ettings?

Thu Apr 16, 2015 1:55 am

What are you doing? What is the IOR, what is the specular reflection value?

Thu Apr 16, 2015 2:14 am

sorry, I used the wrong terminology in my image, i updated it.

basically it's the same black glossy material in each image, just with varying specular values, noted above each sphere. It's just a black material is index of 1.55 and varying spec values. The left sphere is placed in a white environment for lighting/reflections. The other three use the same envrionment HDR for lighting/reflections

I know you mentioned that fresnel reflections were fixed but things still seemed too reflective so that's what I was testing in this scene. Are these results behaving as expected? it just seems like the reflections are extremely pronounced on the middle two compared to what I expected to see. I expected to see something closer to the last sphere using the falloff node.

Thu Apr 16, 2015 2:19 am

itsallgoode9 wrote:sorry, I used the wrong terminology in my image, i updated it.

basically it's the same black glossy material in each image, just with varying specular values, noted above each sphere. It's just a black material is index of 1.55 and varying spec values. The left sphere is placed in a white environment for lighting/reflections. The other three use the same envrionment HDR for lighting/reflections

I know you mentioned that fresnel reflections were fixed but things still seemed too reflective so that's what I was testing in this scene. Are these results behaving as expected? it just seems like the reflections are extremely pronounced on the middle two compared to what I expected to see. I expected to see something closer to the last sphere using the falloff node.

What's the IOR? That's critical here.

Thu Apr 16, 2015 2:31 am

I said that in both posts buddy

it's 1.55

also, i'm working in the latest maya plugin using 2.22 engine.

Thu Apr 16, 2015 2:44 am

itsallgoode9 wrote:I said that in both posts buddy it's 1.55

Sorry, obviously I can't read...

also, i'm working in the latest maya plugin using 2.22 engine.

For me it looks as if the index is set to 1, i.e. it's fully reflective. Does it make a difference if you reduce the IOR? If not, the IOR that is passed to Octane is 1 instead of the value you said.

Thu Apr 16, 2015 2:47 am

Tougher to judge with a b+w image, but here's a quick color test comparison in V-Ray.

: V-Ray - Diffuse: 0, Specular: 1, IOR: 1.55

: Octane - Diffuse: 0, Specular: 1, IOR: 1.55

So, everything seems normal here to me.

Thu Apr 16, 2015 2:48 am

This is what I get in 2.22.2 with a black glossy sphere with an index of 1.55:

That's what you got in 2.21.1:

EDIT: Fixed the HDRI gamma and also uploaded a render from version 2.21.1.

Thu Apr 16, 2015 2:56 am

abstrax wrote:This is what I get in 2.22 with a black glossy sphere with an index of 1.55:

It definitely changes when I change the IOR value, so I can tell it's not defaulting to 1. I just seems like the differences between normal and grazing are very low or something? Looking at the first sphere i posted, with no HDR environment, shouldn't the normal angle look much darker than that?

could I borrow your HDR and i'll render so I can compare to yours? i dunno, maybe it is just my hdr image making it look like it's not working or something. is your specular set to 1 in your render?

Thu Apr 16, 2015 3:01 am

itsallgoode9 wrote:
abstrax wrote:This is what I get in 2.22 with a black glossy sphere with an index of 1.55:
It definitely changes when I change the IOR value, so I can tell it's not defaulting to 1. I just seems like the differences between normal and grazing are very low or something? Looking at the first sphere i posted, with no HDR environment, shouldn't the normal angle look much darker than that?

could I borrow your HDR and i'll render so I can compare to yours? i dunno, maybe it is just my hdr image making it look like it's not working or something.

It's "Ridgecrest Road" from http://www.hdrlabs.com/sibl/archive.html

Here's the project:

fresnel2.orbx: (6.69 MiB) Downloaded 202 times