you can merge the scenes for the final render by opening the first scene normal and then go to file/merge to open the second scenefile into it. that way it renders as if it where just one scenefile. The advantage of having 2 or more scenefiles however is that you can move objects around faster if you only load one of those scenes. It's more of a workflow increasing technique then a technique to allow for bigger scenes, but when bryce thinks the scene is to big to handle you already thought it was too slow to work on much earlier.

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