A touch-based user interface system comprising an arrangement for scanning a tactile sensor array to produce a corresponding array of measurement values that are presented to a processor for computation. The computation produces a plurality of running sums created from selected measurement values or functions of selected measurement values. A post-scan computation algorithm derives at least three independently-adjustable interactive control parameters responsive to at least displacements or angles the contact of a single area of threshold contact or threshold proximity. The system provides output control signals responsive to the independently-adjustable interactive control parameters. In one aspect of the invention, n algorithmic element for handling of regions of threshold contact or threshold proximity having non-convex shapes. In another aspect of the invention, an algorithmic element calculates the rate of change of one or more of the independently-adjustable interactive control parameters. Other aspects of the invention include shape and gesture recognition.