Material/Rendering - Physically Correct Fuzz?

Ace-Angel

Hey to all,

I was wondering if anyone might have an idea on what is the best way to create a Peach-Fuzz like effect on a model, that in theory, would be 'correct'?

From what I gathered, many people just throw in a simple Fresnel/Rim in the Ambient and call it a day, but that sounds like the dirtiest solution to a very subtle effect I'm trying to recreate.

Anyone have any ideas or hints as to where to start? Google-Fu is coming up empty on my searches outside of expired topics or links.

Cheers!

maze

you could use a shader with high difuse roughnes as well as reflection roughness (very very low gloss) then use a incidense (fresnel) to drive reflection color from an inner orangy/reddish fading to a whitish on the edges as I quickly seen on some refs in google images...

thats the basic, besides using maybe a very low freq fractal to break reflections and give some volume. From there if you are going for something more specific a ref would help.

Lighting plays a Huge role as well... but I bet you know that

Ace-Angel

Cheers Maze,

I'm a little confuzzled as to the Inner Orange/Red to White part, do you mean the effect should 'wash out' the diffuse colors at grazing angles (fresnel) or do you mean something else?

Cheers!

illo

all I got.

http://developer.download.nvidia.com/shaderlibrary/webpages/shader_library.html#EdgeFuzz

maze

Hello Ace,

Well I used this reference when I wrote my post above:
http://2.bp.blogspot.com/-yyywUujOFY8/TxY597gxqtI/AAAAAAAAAP0/NNzf1u1Pwe8/s1600/fruits_peaches-5531.jpg

so I thought that to help the "whitish" effect on the edges, which again you can derive from fresnel (incidense) values. I would use a suble reflection color (besides the color map itself, meaning difuse map) and have a reddish/yellowish in the middle of the peach and fading to white in the edges, so basically a "mix 2 colors" node with the weight map being the fresnel/incidense angle.

I wont use any reflection map other than the shader values, as imo there is no need as there is no nuances in reflection scale in that type of object. try something like 0.5 difuse roughness, 0.9 ..reflection roughness and then in reflection itself I like balancing between fresnel values and reflection scale (reflection value) so if I raise my fresnel I would lower my reflection so that it does not wash my albedo map (difuse) for this type of asset. try something like 0.2 reflection and 0.26 fresnel... (although I am using arnold, so this might vary in regards to your engine)

important thing to note is that the object is pretty rough in diffuse as well as reflection rough. And also because you want to break the lighting to catch some highlights, I would try and use a subtle overall bump with a low freq fractal black/white (just very soft black & white values) to break the shape a little bit and get better lighting response...
that besides your higher freq detail on the bump/normal...

I do apologize if I sound a bit confusing, hope I am explaining right!

Ace-Angel

Cheers illo,

That's one of things I'm basing my search on, but am still unable to understand how correct nvidia's implementation of the fuzz is, since they're outright getting rid of the underlying diffuse with replacing it with a color.

Also, for some reason, I am unable to load it properly, in any application to actually test it (I only looked at the code, and it's look pretty cheap).

Cheers!

EDIT:
Hey Maze,

Don't worry, I understood perfectly in your second post what you mean. That does seem like the best solution for what I'm looking for currently.

Cheers!

maze

sounds good, glad it helped !