Can you simply and clearly explain what UV, normal maps, baking are?

Question

3D

In general, I model in blender, I came across such concepts as "UV, normal map, texture baking, etc." With UV-unwrapping it is even more or less clear, UV-unwrapping can be "decorated" and then superimposed on the model. I worked with this. But these concepts of "normal maps, some other maps, baking, etc." - they don't make sense to me. How many of these cards are there? In some sources, these card names are in English, in others in Russian, because of this, I got the impression that there are an uncountable number of these cards. And do these maps differ depending on the 3D package? Maybe 3D MAX has its own maps, but Blender has its own? But I need information about Blender.
Please be as detailed and clear as possible.

Answer 1

What game engine will you create content for? (Or not for the engine?)
(for games one thing is real-time rendering and there are some requirements, for other rendering systems there are other requirements)
You need to understand the basic concepts of a computer. charts. (model \ mesh, polygon, vertex, edge, topology, retopology, normals, RGBA, channels, masks, alpha, etc.)
But when you figure them out, you can look towards PBR (Physically-Based Rendering) (most likely content " under it" you will cut)
"UV-sweep can be "decorated" and then applied to the model."
It's not like that, you need to decorate not the UV-unwrapping, but prepare a set of texture maps to be applied to the model.
After all, no one needs a model with only one diffuse texture.
UV-map is a projection of all surfaces of a 3d model onto a plane (because the textures themselves are flat)
Remember paper models (for example, a cube)
This is the scan you need to build a paper cube

spoiler

And to get the UV-scan of the cube, you need not to assemble the cube, but to cut and unfold it.
Baking (you can bake a lot of maps - Normal Map, AO, etc.)
Normal Map Baking
Here you have a shoe model (there are a lot of polygons) and you need to transfer the detailing of the sole from this very shoe model to a simpler shoe model. (Who looks at the character's shoe soles? You don't need a lot of polygons there)
You bake a Normal Map and an image of the sole is created on it. (Information moved from high poly model to normal map) then you overlay it on a simple boot model and voila!
Pseudo relief appeared on an almost flat sole
Lighting in the engine reacts to this very Normal Map and creates the appearance of a relief for the observer. You look and it seems that the sole is rich in details!
And so they do with the whole model.
"And do these maps differ depending on the 3D package? Maybe 3D MAX has its own maps, but Blender has its own?" - no, there is no difference. All such large 3d packages are similar and not inferior to each other.
But you must understand that there are special software for working with textures. (MARI, Substance Painter, etc.)
(of course, you can do without them, but it will be equally difficult for a beginner with or without them)
"In some sources, these map names are in English, in others in Russian" (everything is much more more fun!)
Enter into the search engine "Texture map terminology confusion"
Look for articles in Russian where not translation is used, but the spelling of English words in Russian letters, or simply where the names of the cards are not translated.
In no case do not Russify your programs (this will only spoil everything)
Depending on the model, on the game engine or rendering system, you will need different "sets" of texture maps.
The engines have a material editor and he can hint what textures he "eats"

For example here

(exactly in this editor where it says Bump map they push Normal map)
Here are the maps for the "old method" (For PBR, some other maps and a "couple" of maps from here are used - for example Normal map)
Diffuse maps are just an object color texture (without glare and so on)
Normal map - already wrote about it (pseudo relief)
Specular map - affects the reflectivity of the material (specular map)
Glossiness\gloss map - this texture corresponds to how blurry the reflections will be
Ambient occlusion map\AO map - this texture creates soft shading model (the light source is not directed directly at it)

Emissive map\emission map\glow map

- determines where the "lights" are located on the model (actually, the mask itself is the Emissive map) - if you do not have lights on the model, then this map is not needed.
Displacement map - one of the numerous height maps (squeezes out the real relief on the model) - for example, wrinkles on the face can be "squeezed out"
There are a lot of texture maps and it makes no sense to write about the rest. (Especially about PBR)
"But I need information about Blender"
Thousands of videos in many languages ​​of the world, hundreds of pages of articles and books at your service!
(To watch the video and understand the logic of the program, you do not need to know English\Japanese\Hindi - for example, I watched the lessons in Italian! And sometimes I heard familiar words)
This applies not only to the blender.
ps
Remember the 80/20 rule (80% practice, 20% theory) if it’s the other way around, then everything will be bad. You will drown in theory (you do not know how to approach it correctly)
Our answers will not help you much.
Until you start, you will not plunge into work. You will not understand what cards you need, and what you are going to do.

Answer 2

Just_Graf I can't write for a long time. In short, you should look for answers from game writers / game devs / game dev
Here is my interpretation.
- UV coordinates are a projection of geometry (triangles) onto a flat sheet for convenient and ideally distortion-free texture/map mapping. The simplest example is a globe sweep in a projection with distortions at the poles and a "slice" projection https://ru.wikipedia.org/wiki/%D0%9F%D1%80%D0%BE%D...
- The normal map records (namely records/encodes, it is not necessary to try to visually understand it) information about the direction of the surface in each pixel. If you look perpendicular to a flat sheet, then at each point the normal is directed exactly at the observer, if there is some kind of relief, the normal deviates. Used to simulate relief surfaces - an advanced analog of a bump map / bump map
- Texture baking / texture baking - the process of rendering a model (often heavy and high-poly) with all the effects and complex textures superimposed in a million layers, exposed to lighting in one finish texture. This texture can be stretched over a simplified low-poly model. Baking is used in games and real-time game engines like Unreal Engine and Unity. Never used in my practice.

Answer 3

https://www.youtube.com/watch?time_continue=558&v=...