Texture layering-Photoshop
polycounter lvl 10
Hello, I was reading this tutorial:
https://area.autodesk.com/tutorials/street_cop_workflow_by_mashru_mishu In the texturing part, the artist mentions adding an ao and green channel of the normal map to the flat diffuse color map to give it some shading and reference on which other textures would be built upon. I completely get the adding green channel part setting it to multiply or screen over ur flat diffuse.
I am wondering about AO, isn't that too much shading for ur diffuse, especially as pbr is used nowadays or offline renderers are way more realistic. Also how accurate is the AO as it can affect lighting if applied to the model in question.
I completely get this is an old tutorial. I am just wondering about how this can be implemented in todays cg. I am used to painting in 3d. Surprising how flexible painting in flat uvs in PS is.
https://area.autodesk.com/tutorials/street_cop_workflow_by_mashru_mishu In the texturing part, the artist mentions adding an ao and green channel of the normal map to the flat diffuse color map to give it some shading and reference on which other textures would be built upon. I completely get the adding green channel part setting it to multiply or screen over ur flat diffuse.
I am wondering about AO, isn't that too much shading for ur diffuse, especially as pbr is used nowadays or offline renderers are way more realistic. Also how accurate is the AO as it can affect lighting if applied to the model in question.
I completely get this is an old tutorial. I am just wondering about how this can be implemented in todays cg. I am used to painting in 3d. Surprising how flexible painting in flat uvs in PS is.
Replies
When using AO in a 3D PBR environment, it will block out lighting at the black part of the texture on the model.
Applying it onto diffuse map and other textures can work, but then it is not necessarily blocking out lighting. It only affects those texture, and become pure colour information.
Handpainted textures often multiple AO with the base color to create the actual shading.
So it is accurate as long as it is baked. And the quality of the accuracy depends on what you have used to bake it. (lowpoly model or the highpoly model)
There is one problem. Because AO map is an still image. So no matter how your character moves their body, the AO map will stay the same. Thus the shadowy effect on the model will stay the same while the character is animating. Which in real life, when a person move, the ambient occlusion effect on his body will always be changing.
Thanks for clarifying. Will probably not use AO then.
http://filmicgames.com/archives/547
Seems kinda of confusing. I am guessing this is by all means accurate to the real world. It's a bit baffling to notice rough non conductive materials having colored specular values. I thought this was reserved for metallic/conductor materials.
Question now is how do u know what color a specular value should be or has if u are using a Photo reference. What determines the specular color of an object when light hits it. Is it that light isn't completely white or it is tainted by some other light colors from reflected surfaces. The most surprising is the cardboard.What confirms my suspicion about light is how complete flat the diffuse textures are when the specular is removed.
But then what about the bump or displacement property of these materials don't the affect the specular/diffuse values in anyway? I do feel bump/displacement affects specular and gloss but not diffuse from this link. So maybe adding the green channel of your normal to your color map to get some shading is wrong if u are trying to achieve photorealism?
The exact specular colour of a material or substance has to be scientifically measured. There are charts of specular colours for many standard materials on the internet, and they are accurate if not exact. When light hits an object, base on its atoms, structure and bunch of other micro-reasons, parts of the light is reflected, and some are absorbed. And what is reflected become specular color and diffuse color. so Specular is actually the most intense part of the reflected lights. What a specular map does, is to let the render know what is the reflected light's color on specific parts of the object. And light isn't white. if you shine a pure green light on an apple, you won't see the red part too much because the green light doesn't have red in it, thus the apple's surface have nothing to reflect, and the greens are mostly absorbed.
Don't worry about these crap above, lighting is very complicated, and sometimes people try to cheat for realistic effect, like what the tutorial you've saw. And what every video game does.
So for the cardbox, bump and displacement map won't affect specular/diffuse value, but it affects the surface normal of the object. Thus the light will bounce off the surface of the carbox differently, both for diffuse and specular. If you take the normalmap's green channel and multiply it as a layer on top of the cardbox, you are only altering the base colour of the object.
And yes, it is probably wrong to take something from a normal map and use it on a diffuse map, unless you know what you are doing and what you want.
So what each texture does:
Diffuse map: Indirect light color(which is basically base color or albedo color). if using Metallic & Roughness workflow, it will also determines the specular color of the object.
Specular map: Reflected light color, the amount/intensity of light being reflected & sometimes indirect light color
Glossiness map: The softness of light reflected off the object, like how rough is the surface.
Bump/Displacement/Normal map: creates variations for surface facing angle, so the surface doesn't look too flat.
AO map: create a mask that reflected light won't go through.
And they don't necessarily do the same thing in different applications.
Specular is the light that is reflected from an object. Non conductive materials do not change the light hitting the object. This does not mean they don't reflect colours. If you're shining a red light on a conductive material you get a red specular value. If your object is outdoors and there's a blue sky you're going to get blue in the specular. So in this case the colours you're seeing are the environment around the object reflecting.