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I'm confused about when to use Specularity map (like the one made in CrazyBump) vs Fresnel node. Both are recommended to make materials look more realistic, I use them to combine Diffuse node with Glossy one (white colour), but everytime I'm using Specularity map, material looks too glossy and bright, while Fresnel gives more realistic look. What's the actual difference between that two?

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In an ideal situation you would use both actually. The Fresnel node will simulate the real physical property of many surfaces that causes more light reflection grazing angles. Think looking through a glass pane perpendicularly (transparent, see through) or sideways (you will see more reflection).

The specular map will deal with differences of reflectivity along the surface of the material due to uneven or varying surface properties (more polished areas versus more rough surfaces)

To achieve to most realistic results your could mix both with a Color Mix node and tweat blending values to the desired result

Edit: Here are two examples, either add the texture to the roughness input of a glossy shader

enter image description here

Or add the image texture to the mix value of a shader mix node.

enter image description here

Or both, and if desired you can additionally use it for bump mapping if necessary

enter image description here

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  • $\begingroup$ Thanks for the answer! How do I go about using them both? I've tried some node setups, but the glossiness doesn't seem right, can you provide an example? $\endgroup$ – Alexander Pukhalski Mar 9 '16 at 13:12
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    $\begingroup$ Updated original answer with details $\endgroup$ – Duarte Farrajota Ramos Mar 9 '16 at 17:16
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Actually we cant compare the 2 of them.

Fresnel node is used to make more reflection at high angles,and specular maps are used to define where those reflections should be no matter what the angle is.

Fresnel is mostly used in dilectric materials like PVC plastic along with specular map in some cases.

The right way to make a material is to use both of them if needed.

Example:

Making Scratched PVC plastic:

I have a specular map and i want to use it,easy !

Just add the fresnel to the specular map.

Adding

And this will give us:

Plastic

Note: If the specularity is very high when using specular map,just darken it using the rgb curve or other color node.

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  • $\begingroup$ Wrong, you shouldn't add it to fresnel. You may rather express IOR from specular map and plug in(e.g. multiply the specular map by 2 and add 1 to it). $\endgroup$ – Adrians Netlis Mar 8 '16 at 19:38

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