[Witt3D]

It´s there a way to configure a material with real fresnel reflections?

I say the opposite as appears on the maxwell material. When you increase the ND you have stronger reflections butall over the surface.

There lots of materials, like plastic, wood, cars, ceramic, that have only strong reflections on 90º of the surface.

Thanks

[Mihai]

This is normal since increasing ND will eventually remove the fresnel effect - the surface will be equally reflective no matter the viewing angle. With a normal plastic material with 2 bsdfs and ND around 3 for the shiny layer you get a fresnel effect, it will be very shiny at the edges but not so much at 0 angle. You can also lower a lot the refl0° color to avoid reflections seen from the front.

[Witt3D]

Thanks Mihai, but it´s a bit contradictory, no?

If i decrease ND and lower a lot the refl0º color i will have lower reflection. Then how can i get very strong reflection on edges?

I will prove your piece of advice, but i guess i will get reflection on the edges more than on the front but not very strong effect.

I´m talking of almost a mirror efect like this example.

two photos of a normal wood door, one in front and the other one in a very strong angle:






Thanks.

[Thomas An.]

It´s there a way to configure a material with real fresnel reflections?

You do have real reflections with Maxwell (if you do not touch the ref-90 HS(V) value. Leave the (V) at maximum, since many materials are very reflective at grazing angles).

Use realistic ND values (up to 2.5 or so for dielectrics) and for metals you can consult this thread

[hyltom]

Why not use a custom .r2 file? Check the material pack that NL has given at the end of the year. Most of the material are using some .r2 file to enhance the reflection at grazing angles.

And i'm not agree with what Thomas said earlier. I really don't think Maxwell have some real reflection. And i remember one thread where is has been shown that maxwell's reflection are not correct at grazing angle.

One of the most popular material from the mxm website

In this sample, it feel like the wood is not part of the scene. Look at the stick, it 's like if there was no relation between it and the wood.

Here what you can get by using .r2

Here i get a much better feeling (may be over pronounced but it's was to show you the difference). Now the wood material look like it is part of the scene and see the reflection of the stick on the wood.

Comparison

[hyltom]

This is an heavy GIF file, so wait few minutes that all the frame are loaded.

[Witt3D]

Hi hyltom,

this effects is what i´m trying to achieve.

Which of all .r2 files produces this effects at grazing angles as shown on your wood material?

Thanks

[hyltom]

The .r2 file should look like 50-0, 60-0, 80-0, 88-0...the first number is the starting point (angle) of the reflection.

In the exemple of the African Mohogany, i have added another BSDF layer.

[Fernando Tella]

I don't think it's so hard to get fresnel effect. Nd of water-glass does it pretty nice.
1.3-1.5 makes it quite noticeable.

[hyltom]

Fernando, can you show me how to do then? Because putting ND to 1.3, 1.5 doesn't change anything in the case of the material i toke as example.

[Fernando Tella]

Probably using r2 files gives better results, but you can obtain fresnel using just Nd; this is from a scene a use to test materials for archviz in sunlight:





This is the mxm:

http://www.ftella.com/links/madera_fresnel.mxm

Don't have much more time to write about it, I hope it explains itself.

[hyltom]

The effect is here but not very strong compare with the reference photo from Witt3D. Adding a layer using r2 file to handle the reflection at grazing angle is the best solution i have found.

Here are my tests using a copy of your scene Fernando.

Test 1 using the African Mohogany material from the library. The reflection at grazing angle is very poor.


Test 2 using the African Mohogany material with another layer to enhance the grazing reflection. The reflection at close angle doesn't change.


Test 3, same then test 2 but here i have removed all reflection at close angle.


Test 4 using the African Mohogany material from the library. But i set ND at 1.3, reflectance 0 at 0,0,0 and reflectance 90 at 255,255,255 and weight at 100. So at grazing angle the reflection is stronger but it's also true at close angle even if my setting show that i don't want any reflection at reflectance 0.

[Witt3D]

Thanks hyltom and Fernando for all those tests, and Thomas for your master piece class. (link)

I don´t know really about all these materials "African Mohogany", and r2 files (80-0.r2). I only have the default materials with the install of maxwellrender.

Where can i get them?

So, if i have understand in a proper way, r2 files only tell at which angle starts reflections?? (so for the default 76-0, i will have only reflection starting on a 76 degrees angle?

Thanks, for your time and explanations.

[Tea_Bag]

Great Test Guys!

Witt3D - You can get all kinds of materials here:

http://mxmgallery.maxwellrender.com/

And if you need to know abit more bout r2 files Mike Verta explains all here:

http://www.maxwellrender.com/forum/view ... highlight=

[Thomas An.]

Not convinced by these tests. In the reference photo the door was completely glazed (no roughness at all) the lighting was different and there were a number of objects being reflected while the camera was in a shaded area (hallway ?). The tests in this thread do not reconstruct these conditions.

Doing "eyeballing" tests like this (of what we think, might, should, ought, to be happening) is not conclusive; especially when dealing with subtleties of fresnel strength.

However, if you guys want to do a Cornel box in controlled lighting and a photo of a grazing angle in it reflecting on some pattern, then we can compare it with Maxwell and see what goes on.