uStitchHub: Stitching Multi-touch Trajectories on Tiled Very Large Tabletops

It is common to tile normal sized units together to obtain very large tabletops or interactive digital walls. Usually cameras are adopted to capture the touch input on the surface, which demands for fusing several multi-touch input feeds into a single feed in real time. Common approaches of stitching camera frames into aggregate images do not scale to larger number of cameras. We present uStitch Hub to address these challenges, which is specifically applied in the tabletop domain. It is a fusion mediator which accept detected blobs from multiple cameras that do and don´t have overlapped field of view, remapping blobs to the dimension of the entire large tabletop, match blobs with real touches on the surface, and concatenate touch trajectories which are performed over two or more units. We conducted laboratory evaluation of uStitch Hub on its stitching success rate and as well as latency. The results prove that uStitch Hub processes fast and provides not only good stitch on touch trajectories but also low latency.