SUBSTANCE DESIGNER PBR UTILITY NODES FOR UNREAL 4
These PBR utility nodes were designed to work with UE4's PBR range. Three of them use physically-based data for dielectric, metallic, and specular presets. Another validates whether your dielectric/metallic albedo values are within/outside UE4's PBR range, while the final PBR utility node can adjust out-of-range base colors.

UNREAL 4 Neutral Lighting Environment

The neutral lighting environment below uses all dynamic effects, like LPVs, DFAO, SSR, SSAO, RTDF, volumetric lighting, Convolution Bloom, bokeh lens flares, utilization of real-world data, etc., for quick material/asset testing without the need to bake lighting. The scene includes varying, physically-approximated TODs, tools, and PBR materials for visual reference. 

UNREAL 4 Cubemap Orientation GUIDE

​Cubemap panels need to be arranged in a specific manner for correct orientation within UE4. The chart below represents these panels ordered from left-to-right, as you go down the list. 
AXIS
ROTATION
+X
90° CCW
-X
90° CW
+Y
180°
-Y
No Rotation
+Z
No Rotation
-Z
No Rotation

​GENERAL TEXTURING GUIDE

Albedo maps should only store base color information (Most base colors exist in the midtone range.), not shading and lighting data. This means AO and cavity, for example, should not be baked into them, nor should highlights be painted in. 

UE4 works in linear space, so it’s important that textures are interpreted in the correct color space. Below is a guide for varying texture types and which color spaces they should be read as by UE4.
MAP TYPE
NUMBER OF CHANNELS
COLOR SPACE
Albedo
3 | RGB
sRGB
Normal
3 | RGB
Linear RGB
AO, Cavity, Height, Metallic, Opacity, Roughness, and Transmissive
1 | Grayscale
Linear RGB
Proper edge padding can minimize color bleeding artifacts from mip mapping. The list below shows varying texture resolutions with corresponding edge padding values for UV shell spacing and textural downsizing processes. 
TEXTURE RESOLUTION
EDGE PADDING VALUE
256 x 256
2px
512 x 512
4px
1,024 x 1,024
8px
2,048 x 2,048
16px
4,096 x 4,096
≥ 16px

UNREAL 4 PBR Guide

Both UE4's environment and color picker live in linear color space (In effect, the color swatches below were created with their linear RGB-equivalent values.), so the values found below are listed first in linear RGB. Additionally, some of the values were designed to work best within UE4 and may not be suited for other applications.​

Albedo grayscale range

MATERIAL TYPE
DESCRIPTION
COLOR SWATCH
HEXADECIMAL VALUES
RGB CHANNEL VALUES
NORMALIZED VALUES
Charcoal 
Dielectric albedo values control reflected color. Charcoal is the darkest, dielectric albedo value that should be used. Insulators do not typically have colored specular reflectivity, but light source color can influence reflected color values.
Linear RGB = 050505
​​sRGB = ​​2b2b2b
Linear RGB = ​5
​​sRGB = ​43
Linear RGB = ​​​0.02
​​sRGB = ​0.169
Fresh Snow 
Dielectric albedo values control reflected color. Fresh snow is the brightest, dielectric albedo value that should be used. Insulators do not typically have colored specular reflectivity, but light source color can influence reflected color values.
Linear RGB = cfcfcf
​​sRGB = ​​e9e9e9
Linear RGB = ​207
​​sRGB = ​233
Linear RGB = 0.81
​​​sRGB = 
​0.91
Metallic
​Metallic albedo values control reflectance properties that can contain color. Conductive albedo values fall within this row’s range. 
-◼
Linear RGB = b3b3b3 - ffffff
​sRGB = dadada - ffffff
Linear RGB = 179 - 255
​​sRGB = 218 - 255
Linear RGB = 0.7 - 1
​sRGB = 0.85 - 1

Metallic Grayscale Range

MATERIAL TYPE
DESCRIPTION
COLOR SWATCH
HEXADECIMAL VALUES
RGB CHANNEL VALUES
NORMALIZED VALUES
Dielectric
Reflectivity is interpreted by the metallic map. Most non-metals should have a value of 0 or no metallic map. Metallic properties should represent the top layer of a material, like painted metal, which should not be defined as metallic.
Linear RGB = 000000
​sRGB = 000000
Linear RGB = 0
​sRGB = 0
Linear RGB = 0
​​sRGB = 0
​Metallic
Reflectivity is interpreted by the metallic map, and most metals have a value of 1. Gradient transitions between insulators and conductors are acceptable. Exceptions, like metalloids, may use values that are neither 0 or 1.
Linear RGB = ffffff
​​sRGB = ffffff
Linear RGB = 255
​​sRGB = 255
Linear RGB = 1
​​sRGB = 1
The images below display ​increasing dielectric-to-conductor metallic properties.

Metallic

Roughness Grayscale Range

The roughness map controls size/spread, sharpness, and light direction for rough/smooth reflective surface properties. Real-world data is not used for its rendering, thus allowing for more artistic interpretation. The images below display increasing rough-to-smooth roughness properties for both dielectric and metallic materials.


Dielectric


​​Metallic

Specular GUIDE

MATERIAL TYPE
DESCRIPTION
COLOR SWATCH
HEXADECIMAL VALUES
RGB CHANNEL VALUES
NORMALIZED VALUES
Ice
UE4’s specularity does not correlate to real-world data. The default value is 0.5 and should be left alone; semiconductors/gemstones can have higher values. All materials have specularity so never set it to 0. You can input cavity maps but they should be multiplied by the default 0.5 value . Metals are not affected since their albedo maps control specularity.
Linear RGB = 393939
​​sRGB = 828282​
Linear RGB = 57
​​sRGB = ​130
Linear RGB = 0.224​
​​sRGB = ​0.507
Water
UE4’s specularity does not correlate to real-world data. The default value is 0.5 and should be left alone; semiconductors/gemstones can have higher values. All materials have specularity so never set it to 0. You can input cavity maps but they should be multiplied by the default 0.5 value. Metals are not affected since their albedo maps control specularity.
Linear RGB = 414141​
​​sRGB = ​898989
Linear RGB = 65
​​sRGB = ​137
Linear RGB = 0.255​
​​sRGB = ​0.537
Milk
UE4’s specularity does not correlate to real-world data. The default value is 0.5 and should be left alone; semiconductors/gemstones can have higher values. All materials have specularity so never set it to 0. You can input cavity maps but they should be multiplied by the default 0.5 value. Metals are not affected since their albedo maps control specularity.
Linear RGB = 464646​
​​sRGB = ​​8f8f8f
Linear RGB = 71
​​sRGB = ​143
Linear RGB = 0.277​
​​sRGB = ​0.558
Skin
UE4’s specularity does not correlate to real-world data. The default value is 0.5 and should be left alone; semiconductors/gemstones can have higher values. All materials have specularity so never set it to 0. You can input cavity maps but they should be multiplied by the default 0.5 value. Metals are not affected since their albedo maps control specularity.
Linear RGB = 595959​
​​sRGB = ​​9f9f9f
Linear RGB = 90
​​sRGB = ​159
Linear RGB = 0.35​
​​sRGB = ​0.621
Glass
UE4’s specularity does not correlate to real-world data. The default value is 0.5 and should be left alone; semiconductors/gemstones can have higher values. All materials have specularity so never set it to 0. You can input cavity maps but they should be multiplied by the default 0.5 value. Metals are not affected since their albedo maps control specularity.
Linear RGB = 7f7f7f​
​​sRGB = ​​bbbbbb
Linear RGB = 128
​​sRGB = ​187
Linear RGB = 0.5​
​​sRGB = ​0.73
Plastic
UE4’s specularity does not correlate to real-world data. The default value is 0.5 and should be left alone; semiconductors/gemstones can have higher values. All materials have specularity so never set it to 0. You can input cavity maps but they should be multiplied by the default 0.5 value. Metals are not affected since their albedo maps control specularity.
Linear RGB = 7f7f7f​
​​sRGB = ​​bbbbbb
Linear RGB = 128
​​sRGB = ​187
Linear RGB = 0.5​
​​sRGB = ​0.73
Quartz
UE4’s specularity does not correlate to real-world data. The default value is 0.5 and should be left alone; semiconductors/gemstones can have higher values. All materials have specularity so never set it to 0. You can input cavity maps but they should be multiplied by the default 0.5 value. Metals are not affected since their albedo maps control specularity.
Linear RGB = 919191​
​​sRGB = ​c6c6c6
Linear RGB = 146
​​sRGB = ​198
Linear RGB = 0.570​
​​sRGB = ​0.775
The images below display increasing specular properties.

Specular

 Index of Refraction gUIDE

MATERIAL TYPE
DESCRIPTION
INDEX OF REFRACTION VALUE
Air
​The Index of Refraction, or IOR, describes how much light bends through medium to another. IOR values are based off of real-world, optical measurements. 
Linear Grayscale = 1
Ice
​The Index of Refraction, or IOR, describes how much light bends through medium to another. IOR values are based off of real-world, optical measurements. 
Linear Grayscale = 1.31
Water
​The Index of Refraction, or IOR, describes how much light bends through medium to another. IOR values are based off of real-world, optical measurements. 
​​Linear Grayscale = 1.33
Glass
​The Index of Refraction, or IOR, describes how much light bends through medium to another. IOR values are based off of real-world, optical measurements. 
​​Linear Grayscale = 1.52
Diamond
​The Index of Refraction, or IOR, describes how much light bends through medium to another. IOR values are based off of real-world, optical measurements. 
Linear Grayscale = 2.42
The images below display increasing index of refraction properties.

Refractive

GRAY GUIDE

GRAY TYPE
DESCRIPTION
COLOR SWATCH
HEXADECIMAL VALUES
RGB CHANNEL VALUES
NORMALIZED VALUES
sRGB Neutral Gray
Neutral gray can be  used for texturing. 
Linear RGB = 808080
​sRGB = bbbbbb
Linear RGB = 128
​sRGB = 187
Linear RGB = 0.5
​sRGB = 0.73
Linear RGB Middle Gray 
18%-gray can be used for testing lighting.
Linear RGB = 2e2e2e
sRGB = 767676
Linear RGB = 46
​sRGB = 118
Linear RGB = 0.18 
sRGB = 0.461

Color Space Conversions

COLOR SPACE CONVERSION TYPE
FORMULA
Linear RGB-to-sRGB Conversion
​[normalized linear RGB value] ^ (1 / 2.2) = normalized sRGB value
normalized sRGB value * 256 = sRGB channel values 
sRGB-to-Linear RGB Conversion
​[normalized sRGB value] ^ 2.2 = normalized linear RGB value
normalized linear RGB value * 256 = linear RGB channel values

 Dielectric ALBEDO VALUES GUIDE

MATERIAL TYPE
COLOR SWATCH
HEXADECIMAL VALUES
RGB CHANNEL VALUES
Forged Iron
Linear RGB = ​0a0a0b
sRGB = ​3a383b
Linear RGB = ​(10, 9, 10)
sRGB = ​​​(58, 56, 59)
Dark Soil
Linear RGB = 170b07
sRGB = ​​553d31​
Linear RGB = ​(23, 11, 7)
sRGB = ​​​(85, 61, 49)
Worn Asphalt
Linear RGB = ​1a1a1a
sRGB = ​​5b5b5b​
Linear RGB = ​(26, 26, 26)
sRGB = ​​​(91, 91, 91)
Varnished Wood
Linear RGB = ​3e1b0b
sRGB = ​​875c3c​
Linear RGB = ​(63, 27, 11)
sRGB = ​​(135, 92, 60)
Tree Bark
Linear RGB = ​2b221a
sRGB = ​​72675b​
Linear RGB = ​(43, 35, 26)
sRGB = ​​(114, 103, 91)
Green Vegetation
Linear RGB = ​323913​
sRGB = ​​7b824e
Linear RGB = ​(51, 58, 19)
sRGB = ​​​(123, 130, 78)
Gray Plaster
Linear RGB = ​383838​
sRGB = ​​818181​
Linear RGB = ​(57, 57, 57)
sRGB = ​​​(129, 129, 129)
Brick
Linear RGB = ​4b342d
sRGB = ​​947d75​
Linear RGB = ​(77, 53, 46)
sRGB = (148, 125, 117)
Old Concrete
Linear RGB = ​3e3f3a
sRGB = ​​878883​
Linear RGB = ​(63, 64, 59)
sRGB = ​​(135, 136, 131)
Gray Paint
Linear RGB = ​5d5d5d
sRGB = ​​a3a3a3​
Linear RGB = ​(95, 95, 95)
sRGB = ​​(163, 163, 163)
Sand
Linear RGB = ​70623b
sRGB = ​​b1a784​
Linear RGB = ​(114, 100, 60)
sRGB = ​​​(177, 167, 132)
Clean Cement
Linear RGB = ​86857f
sRGB = ​​c0bfbb​
Linear RGB = ​(136, 134, 128)
sRGB = ​​(192, 191, 187)
Rough Wood
Linear RGB = ​be9264
sRGB = ​​e0c7a8​
Linear RGB = ​(191, 147, 101)
sRGB = ​​​(224, 199, 168)

Metallic Albedo Values GUIDE

MATERIAL TYPE
COLOR SWATCH
HEXADECIMAL VALUES
RGB CHANNEL VALUES
Gold
Linear RGB = ​​ffc456
sRGB = ​ffe39d
Linear RGB = ​​(254, 197, 87)
sRGB = ​​(255, 227, 157)
Iron
Linear RGB = ​8f9194
sRGB = ​c6c7c9
Linear RGB = ​​(145, 147, 150)
sRGB = ​​​​(198, 199, 201)
Copper
Linear RGB = ​f4a389
sRGB = ​fad1c2
Linear RGB = ​​(243, 164, 139)​
sRGB = ​​​​(250, 209, 194)
Silver
Linear RGB = ​f8f5ea
sRGB = ​fcfbf6
Linear RGB = ​​(247, 245, 235)
sRGB = ​​​​(252, 251, 246)
Cobalt
Linear RGB = ​a9a7a2
sRGB = ​d5d4d1
Linear RGB = ​​(171, 169, 164)​
sRGB = ​​​​(213, 212, 209)
Aluminum
Linear RGB = ​e9ebec
sRGB = ​f5f6f7
Linear RGB = ​​(232, 235, 237)​
sRGB = ​​​​(245, 246, 247)
Titanium
Linear RGB = ​8a7f72
sRGB = ​c3bbb3
Linear RGB = ​​(141, 128, 117)​
sRGB = ​​​​(195, 187, 179)
Chromium
Linear RGB = ​8c8e8d​
sRGB = ​c4c5c5
Linear RGB = ​​(142, 144, 144)
sRGB = ​​​​(196, 197, 197)
​Platinum
Linear RGB = ​aca395
sRGB = ​d6d1c9
Linear RGB = ​​(173, 164, 150)​
sRGB = ​​​​(214, 209, 201)
Nickel
Linear RGB = ​a89b86
sRGB = ​d5cdc0
Linear RGB = ​​(171, 157, 136)
sRGB = ​​​​(213, 205, 192)