The PBR Specular Material

The PBR Specular material is diﬀerent from the PBR Metalness material. There are three main properties to use in the PBR Specular material: Diﬀuse (similar to Base Color), Specular (controls the value of the specular reﬂectivity as well as its color), and Glossiness (controls how tight or broad the specular reﬂections appear in the material). You may think of the Glossiness property as being the inverse of Roughness in the PBR Metalness material as the texture maps are the inverse of each other.

In Specular there is no Metalness property. This means that in order to achieve a metal looking material the Diﬀuse Color will be set to a dark color (usually black), and the Specular color will be used to determine the tint of the specular reﬂections of the metal. The Glossiness value will most likely be high in order to create a highly reﬂective metal. It can also be lowered to achieve a more tarnished or dusty metal.

Diﬀuse - Similar to the Base Color of the object. It is the main color that will appear on the object. The diﬀuse color can be modiﬁed in two ways.

• Color - This is a color picker and if no texture is applied will be the color of the object.

• Texture - A texture map can be uploaded and displayed on the object for the Diﬀuse. The Color is multiplied over the texture. This means that the texture can be tinted a diﬀerent color if

the Color value is not a grey scale value. The texture can also contain transparency through the use of a .png ﬁle. Make sure to enable Opacity if a texture with transparency is used. This will ensure that the map with transparency displays correctly.

In this image the Diﬀuse Color has been changed to red.

Checkered texture with no Diﬀuse Color.

The PBR Specular Material

Diﬀuse Color Red and Diﬀuse texture set to a checkered pattern. You can see that the white areas of the texture have been tinted by the color swatch.

Specular - Controls the amount of reﬂection on an object.

• Color - Specular reﬂections can be tinted through the color picker. The Color property will also multiply over the texture placed into the specular texture property.

• Texture - A texture map can be uploaded to apply color to the specular of an object. Lighter color textures will make the object more reﬂective. Darker colors will make the object less reﬂective: Black is non-reﬂective and white is fully reﬂective.

Here we can see the specular reﬂections change from highly reﬂective to non-reﬂective as we change the Specular Color from white (value of 1) to black (value of 0). Please note that the shape of the specular reﬂections do not change. They remain sharp because that is controlled by the glossiness value which remains at 1 throughout this set of images.

The PBR Specular Material

When using a texture in the Specular texture slot we can see the same result. The white parts of the texture are rendered with a high specular reﬂectivity and the black parts of the texture are rendered non-reﬂective.

Specular values can also take color information. When the color swatch is used it will tint the texture. The white sections of the texture are now tinted red and the black parts of the texture remain non-reﬂective.

The PBR Specular Material

Similarly, the texture itself can contain color information for the Specular. Here we can see that the colored texture is tinting the specular reﬂectivity of the material across the object.

Glossiness - Modiﬁes how the object reﬂects light. If the value is high then the reﬂection is sharpened across the object and the object will appear glossy or smooth in nature. If the value is low then object will appear more rough and the refection will be blurred.

• Texture - This is a grey scale map where black equals a low glossiness value (object will appear rough) and white has a high glossiness value (the object will appear smooth with sharp reﬂections). The Texture can also be a combined specular_glossiness_map, a single texture that contains information for both Glossiness and Specular in one texture instead of two, where Glossiness information is in the alpha channel and the Specular color information in the RBG channels.

• Strength - This is a multiplier of the texture. The value of the Strength should be set to 1 if a texture is applied. If the value is set to less than 1 then the textures values are reduced and the object will appear progressively rougher as the strength approaches 0.

The PBR Specular Material

Because Glossiness is a grey scale value the color information in textures has no eﬀect. Only the brightness values (dark to light or black to white) of the texture will control the glossiness of the material. Here we can see that the white sections of the texture are rendered with a tight specular reﬂectivity and the dark sections of the texture are rendered with a broad or rough reﬂectivity.

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