you're talking about different things:
your talking about how maya "dices up" the rendered image so that it creates smaller and smaller tiles where there is information to be rendered. You don't need to worry about that.
You need something like this:http://www.highend3d.com/maya/downlo..._ray/3785.html
I haven't tried it but it seems to allow you to split up your image and render at higher resolutions. think about it this way: if you can only render at 2k then if you had four cameras placed so that trhe edges lined up perfectly then you could arrange them in a square to get an image that was 4k... that's what the script does I think. try searching google for maya tile render
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