Is there a method or S/W available to stitch together a DLP projector's output into a "moving picture" to SLA print in a larger area than its output?
Cool Idea.

I know using a projector sounds like solution; but, I in practice, think it is going to be difficult.  

My concern with trying to use a projector would be two-fold.


It would have to project on a large flat surface.  Since basic optics wants to focus on a sphere, when projecting on a flat surface you have to adjust for a focus distance that varies with angle and also deal with keysoning. I know this is a common problem fro projectors; but, there is no perfect solution so either.    The focus issue may be solvable with custom optics; but, that is not something that is easy to DIY.  The keystoning could be corrected for with optics and/or in software; but even then you are going to have inconsistent resolution.  Not only that; but, the problem gets worse the wider and closer you are, which is EXACLY what you want to do.  
I would be concerned that the frequency range that the SLA resin cures at will be outside the normal range of projector so you would require A LOT more power/time to get it to cure.


On the other hand, lasers light projectors are a well established technology.  They moved into the entertainment space quite a few years ago; so, I suspect you could get one that covers the space you are interested in for a reasonable price. 


Since laser beams are very narrow, focus should not be an issue.  Keysoning can be easily accounted for in the sweep algorithm.
You could choose the frequency of the laser to that it in the most efficient curing frequency for the resin you want to use.