I'm building a isometric, top-down sort of RPG in d3d IM using height map based data. In attempting to create a smooth scrolling world, minus large load intervals in the middle of play I've come across this problem:

How large can you're world values be? I'd rather avoid transforming my whole mesh to always be from <0,0,0> on every frame but then if I did not the z and x could become rather large as the player walked further from the initial world origin. Would this be problem? I understand that d3d will only render items that would appear in the viewing area and I also intend to only transform items that are in that area. By going this route, though, I could have z and x unit values in the several thousands if not more. As for my app itself, becuase this is a simple tile map based engine mem requirements to store large world segments are not very high, so that is not an issue for me. I wanted to make sure that there was not issue with d3d, particulary performance wise, in doing my engine in this manner. Does d3d consider world space to be always a tight area around the camera or are the limitations simply the application data?

Thanks ahead of time and hopefully this makes sense.