Feather shading and the Hair Direction on Poly modifier

[cem]

Perhaps the best way of modeling a feather would be to model it properly with actual strands. However, if you are going to have tens of thousands of them on a character, it might be a good idea to use a transparent texture on a flat plane to represent each feather instead of modeling them all with great detail. As Anish showed us in the forum, we can use this technique to cover a character with feathers using the new improved HairTo Instances modifier.

What I want to show you here is another new tool, which is very handy for feather shading, among other things. I'm talking about the new Hair Direction on Poly modifier. This modifier changes surface normals based on the chosen UVW channel, so that you can use hair materials on regular polygonal objects and get expected results. As a result the polygonal surface looks like it is made up of parallel hair strands. Turns out this is perfect for shading feathers!

Here is an example. I exaggerated the speculars a little bit so that you can clearly see the difference. These two materials are using the same parameters and the light is coming from the same direction. As you can see, one of them looks like a plane with a texture on it, while the other one properly captures anisotropic speculars on feathers.

feather.jpg (72.76 KiB) Viewed 28014 times

This is the actual object without any texture:

plane.jpg (27.81 KiB) Viewed 30299 times

The difference is much more apparent in the following video. This video shows the change in shading with changing light direction. The light is simply rotating around the feather.

feather.flv

(1.3 MiB) Downloaded 24252 times

[Infinite]

Nice one Cem, this looks ace. Anishmations was doing something with feathers on a previous thread some where? Would be great to see the 2 techniques combined!

[anishmations]

Thats wonderful Cem. Great to see you are extending the feather creation part further!! I don think any hair plugin would do this or beat this ever now!!
Let me see if I can make something out of this now ..
Thanks again!

[anishmations]

Dear Cem,
Can u please post a screen shot of the simlpe hair material used for this feather ? I tried it, but am not quite getting it
Thanks!

[cem]

Here is the modifier stack I used:

modlist.gif (2.09 KiB) Viewed 30284 times

All modifiers except for "Hair Direction on Poly" and "Unwrap UVW" are just for modeling the plane, to give it the shape shown in my first post.

Hair Direction on Poly is using UVW channel 2 (channel 1 is reserved for the feather texture) and it sets hair directions based on the V direction of that UVW channel. Here are all the settings:

hdironpoly.gif (1.41 KiB) Viewed 30284 times

The trick here is in setting the V direction of UVW Channel 2 correctly. I used the Unwrap UVW modifier for this task. All it is doing is to align the V direction with the direction of the feather barb (branches).

uvwunwrap.gif (117.88 KiB) Viewed 30284 times

Another trick here is that the feather plane is made up of 3 separate parts, the rachis (the spine column of the feather) is a separate element. The only reason why I did this is to make sure that the V direction on the barb surface would not be smoothed out with the V direction on the rachis. This is not so crucial though. Also you might want to assign a separate material for the rachis, which I didn't do.

After you do all this, you can assign a hair material and use it just like the standard material of 3ds Max.

[pluMmet]

Really fantastic

[anishmations]

Brilliant! thaanks!

[pitiwazou]

Very good !!

[Alexander_Tomchuk]

That's awesome, I would love to see the whole bird with this, should be nice