leather and skin in texturing

Your opinion may be different. But here's mine with some observations thrown in.

When searching for a texture set you may encounter something like this:

And often such works get incredibly popular. Because it's "realistic" (it is not) and because it shows how rough and tough the character is (it does not). Especially in games like Skyrim.

For some reason people think that prolonged exposure to dirt, cold and wind will turn your skin into a tanned leather that has undergone numerous treatments to make it rough, but elastic and solid; waterproof, so water slides off..

But this is (obviously) not how skin reacts to harsh conditions. Including the solutions that are used to tan hides.

Here's what I mean:

Top left: photo of an aged guy who obviously didn't care about his skin care.

Bottom right: tanned leather.

Bottom left: presumably a guy who doesn't care about his skin care.

Top right: tanned leather overlayed on a photo.

You may argue that if you look closely, the texture will be almost identical:

However, human skin is much softer. Because it doesn't suffer the same treatment tanned leather gets. When we're talking about skin, we usually mean something alive, while tanned leather.. well, you get it.

Tanned leather doesn't regenerate and it doesn't have any protective reactions going on (for example, calluses are made by your body to protect the skin so you won't rub your skin off down to the bone). It's just dead, dry, rough, animal leather. On the other hand, if your skin is very dry, exposed to cold or dehydrated, it looks like this:

You can tell that the skin on the pictures is in a pretty rough condition. Anything worse will result in cracked, bloody skin (like top right, but slightly more extreme and on a bigger scale. Note that the damaged places are the ones that creases most and are most exposed, on the knuckles.)

And as you can see, this still looks nothing like a tanned leather (bottom left). Tanned leather is dry, even in color and rough all around. Real skin is pink, different from area to area and bleeding.

Here's two photos of hands, young and old (both are man hands):

And it still looks nothing like tanned leather.

You can use tanned leather textures as an overlay, or use it smartly, but there are a few issues: scale and authenticity.

What I mean by authenticity is that skin is different on different parts of the same area. It's softer on the face than on hands and feet, top of the feet are softer than heels. Your skin constantly creases and wrinkles differently in different places and that affects how deep the creases are (while on tanned leather all creases and wrinkles are even).

And scale. Speaks for itself:

So in order for this to work you'll have to use a very big texturemap, on which you will layer your leather texture with pinpoint accuracy with an effort to replicate a realistic looking creases, at the same time changing the scale and transparency. All at the same time.

How it's usually done VS how it should be done (no overlay):

Really, just use photos or paint from scratch in software designed for it:

And just in case you were wondering..

Here's a tanner's hand:

These hands were in contacts with the same tanning agents that are used to tan leathers. As you can tell, it looks nothing like leather on your jacket.

Photo above: "The Worker's Hand" by George Rosen, M.D. in Ciba Symposia (July 1942):