Hello
Well i have a question about how i do a proper setup between each application.
If i make a box in 3ds max that is 100cm(1meter) .How big is the correct size in photoshop ? 1024x1024 px / 2048x2048px ? or is it 100x100cm even there. Then this will result in a huge texture 
Hi Thewiruz!
There really is no such thing as the ācorrect sizeā for textures. What you do is typically to establish some baseline value in terms of texture pixels per meter, and then stick to that as far as possible. This involves the UV space as well, so the final ideal size of any given texture boils down to how your objects are unwrapped, if the texture tiles or not, etcetera.
To further complicate the issue, not all texture types need the same resolution, and this again depends on the nature of the texture itself: does it have a lot of high-frequency information or not? Does it matter if itās a bit blurry or not? And so on.
In your example, letās say we decide to go with 512 pixels per meter. If all six faces on the box can use the texture space, you can get away with a 512 x 512 pixel texture. If you need four unique sides, you could go with a 1024 x 1024.
At any rate, itās generally better to make the textures too large rather than too small. You can always scale them down later (the other way aroundā¦ not so useful).
Thanks !!!