Anisotropic Material in UE4.25

The new anisotropic BRDF (beta) is available to use and it is an input in the Base Material node. With the tooltip saying the following:
“Controls how anisotropic the Material roughness is. Anisotropy of 0 is isotropic. Anisotropy of 1/-1 is Maximally anisotropic along the tangent/bi-tangent respectively.”

What would be the best way to use this new input? Like would Metal be 1, What would be -1? What about if I want to simulate radial anisotropy or a brushed feeling, would input a grayscale map with the anisotropy lines and how will this look like or the values on the map? What would be 0 or as it has been debated wood can have some anisotropy what can this value be?

I am looking forward to using this value but I am a bit confused about the way that I should be using or working with these new parameters. I would appreciate a lot that any can clear my confusion.


I haven’t tried this out yet but metalness shouldn’t have an impact other than the higher reflectance, as usual. The -1/1 should determine which direction the anisotropic reflection is distorted, horizontally or vertically. If it’s like the other shading models, 0 would be no effect. The Tangent input should give you the radial input provided you give it the correct texture, but I’m not sure if it takes a grayscale texture with a gradient or an actual RG normal texture. Hopefully I can check it out later tonight

Thanks a lot for your reply. I look forward to the results that you post tonight.


I tried to play with new Anisotropic material but I don’t understand how it works and there is to info in web how to use it and sure no official info because 4.25 is not published yet, just beta. Did you find any working way how to implement new anisotropic material? I tried to put black/white mask in anistropy slot and +1 or -1 with mask on reflection, no luck yet… :frowning:

I am as well waiting for more information on how to use this correctly or how is it supposed to work in Unreal.

What I found is that the anisotropy node just takes -1 to 1 to set strength, and you then use a flow map in the tangent node to control anisotropy direction.
Tool tip say the difference between -1 and 1 is tangent or bi-tangent. I have no idea what would be physically correct.

Hello. I also tried the new anisotropic material from Unreal Engine 4.25.
However I don’t know if this is a good way, but it looks good!!

very Nice!
can I ask, how did you create the anistropic texture map?


even more interesting. how to you activate the anisotropy slot? if you create a new material, the slot is not active. How to make it active?

what good is anistropy in ue4 if you dont have a directional angle map!:wink:

to enable:
use the Project Settings to set Use Anisotropic BRDF to true…elimprovements

i currently have this setup. you can either have your aniso maps or a single color for simple linear directions

btw. idk if world aligned normal is the correct node. perhaps world aligned texture is sufficient here

to understand flowmaps, go here FLOW MAPS - Understanding Maps without Code - YouTube

thanks for sharing…

yeh saw that video after seeing trying to generate my own angle and tangent maps…got something very rudimentary/dirty but quick [and seemed to work] by turning of a normal maps Blue Channel…not a proper flow map per se but opposing colours seem to give it a very clear directional nature…

yes. you can get a feel for flow maps when using this flow map painter. when making vertical strokes, only the red channel is painted, for horizontal, only the green channel is utilized. blue can be ditched. although it does somthing to the orientation at least in unreal. but i cannot grasp what it is doing.

Thanks will check it ou!

It seems:

Anisotropy - 0/1 for blending into and out from the anisotropy shader
Tangent - XY is remapped from 0/1 to -1/1, and specifies the direction of the anisotropy. I assume RG is masked from all other inputs.

From there, normal maps can alter the angle of the effect (better to think of it as actually deforming the mesh into a new angle) while roughness controls the size. For some reason, I can’t achieve the stretched “brush metal” look with the specular highlights, it’s only stretching the images.

Also getting mixed results. Hope Epic will release documentation on how to set it up properly soon.

Anisotropic in CGi is a combination o 2 parameters. Have a look at any other software like Maya of 3DSMax and you can understand a bit more about it. In case of UE there is some documentation in the official Youtube channel but I think it is not so exhaustive

I’m well aware of how anisotropy works, still getting inconsistent results in UE4. What documentation on Youtube are you referring to exactly?

I’ve also been getting some strange results (video below), and a general sense of suspicion related to the implementation. It would appear through roughness 0-.998 the specular from the direct light won’t react predictably. It’s possible this is a ‘feature’, but I don’t recall epics documentation mentioning this. It would appear at a glance the the ambient reflections react more correctly through the 0-.998 range.

When >.998 the specular from directional light begins to appear more classically anisotropic (it’s above this point the tangent appears to work correctly, etc). But perhaps I’m misunderstanding. Any insight would be helpful! Thank you…

I appreciate everyone’s reply, it has helped me clear a lot of doubts I had about how this feature is working. Hopefully, Epic provides more insight and documentation related to this.