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albedo real world values and roughness maps for UE4

Greetings, I had a quick question about albedo and roughness maps for UE4. Ive read all about the pbr workflow on the mormaset site and other useful tutorials, knowing that the albedo is basically a diffuse without the AO light information added, I cant wrap my head around using the real world color value chart provided on the mormaset site. Should you actually copy and paste the color value for say concrete from the color chart into your texture to make it match? Or does it just need to be similar? Also, I'm struggling with how to create a roughness map from the albedo. Is there any good starting point to go with for roughness map such as inverting or saturation to the albedo and go from there? Or should roughness map always start from scratch with black and white values? Any good tips or tutorials you guys have on this subject would be greatly appreciated, thanks!!

Replies

  • EarthQuake
    The material values in our PBR tutorials are examples of specific materials, there will be variation with all materials depending on a variety of conditions so no you don't have to use those values directly, those are there mostly as a point of reference so you can see the reflectance values in relation to other materials.

    Gloss or roughness maps literally define how rough or smooth the surface is. There generally is no quick hack to create these maps, you need to use logical values here that define the surface qualities. If you try to make a roughness map from a diffuse map you will probably get texture variation (eg random dark and bright spots) that has nothing to do with the surface roughness. Generally I would start with flat values for each material (if your texture has multiple material types) to get the right highlight shape, and then add logical texture variation on top of that base color. Examples of texture variation would be a noisy texture if your surface has a grainy finish, duller areas if you have a glossy paint material where the finish has been rubbed off, and glossier areas where a matte finish has been rubbed off of a polished metal.

    Once you determine which material you are representing and what that material's surface properties are, the process becomes rather simple.
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