Do alpha&rgb mask/channel textures work in Unity?

In Blender, and I suppose other 3d software as well, you can have a main texture for a terrain that is just black and white and then you can assign black to be a....for example green grass texture and white can be desert or gravel texture. You then control (size, specularity, normal maps,etc.) the grass/gravel textures separately from the main black/white image and you can have very large terrains, but you don't need extremely large textures to prevent the terrain looking pixelated. If I am correct, essentially this is what you are doing in 99% cases in map editors in various games when you have a brush that paints a texture on the terrain.



So, how does Unity deal with this? I have a black/white image, a grass and a gravel texture, so 3 images in total and I just need to assign them to work somehow in Unity. Also, if this works, is there a way to add more textures? In Blender you can add 3 textures using a RGB channel, so instead of painting black and white, you paint red, green or blue, but I think that that is the maximum in using this in Blender.

 

Also looking for an answer to this. Trying to texture a map for my game but even in smaller chunks it is too big.

 

Apparently this is what we are searching for: https://docs.unity3d.com/Manual/StandardShaderMaterialParameterDetail.html

"Secondary Maps (or Detail maps) allow you to overlay a second set of textures on top of the main textures listed above. You can apply a second Albedo colour map, and a second Normal map. Typically, these would be mapped on a much smaller scale repeated many times across the object’s surface, compared with the main Albedo and Detail maps.

The reason for this is to allow the material to have sharp detail when viewed up close, while also having a normal level of detail when viewed from further away, without having to use a single extremely high texture map to achieve both goals."

However either I am too dumb to understand or it's simply not explained how to have 2 textures that are based on the main black/white one.

 

Man I have no idea...

 

Can I then turn meshes into terrains somehow, but while still keeping their regular textures? Regular as in just average, not masking textures or anything, just a average diffuse texture. If I need to paint the high res texture inside Unity on a terrain object, then maybe I can paint a low res version in Blender, save it as a regular low res texture and then bring it in Unity and repaint it with a higher resolution brush in Unity?

I know that I can bring a mesh into Unity and turn it into a terrain, there is a free script you can download to do that, but that just gives you a white terrain without anything and I need something to base where I paint high res textures on, because I want to paint over a satellite imagery terrain and I want a gravel texture where there's gravel in real world and so on. I can do that in Blender and already have, I just want to know how I can get that to work in Unity.