Understanding map resolutions?

[Playdo]

I'm sure this would have been discussed before, so point me to to it if so.

 

I'm fine with resolution in general but I need a better understanding on how map resolution works within Max.

 

I take it resolution has nothing to do with the actual scale of the object but of the resolution that it takes up in the render? ie. a 10x10cm object would render out at the same clarity as a 100x100cm if they had the same res. map and took up the same amount of the render frame.

 

If rendering a 1500x3000px jpeg and, say a mapped wall took up 1/3 of the render space. Would you aim to make that map 500x1000px?