We generate graphs for huge datasets. We are talking 4096 samples per second, and 10 minutes per graph. A simple calculation makes for 4096 * 60 * 10 = 2457600 samples per lineg
Not sure if this is helpful, but could you use time as a dimenion? i.e. one frame is one z? That might make things clearer, perhaps? Then perhaps you could effectively be applying deltas to build up (i.e on z axis) the image?