A Unified Model for User Identification on Multi-Touch Surfaces: A Survey and Meta-Analysis.

User identification on interactive surfaces is a desirable feature that is not inherently supported by existing technologies. We have conducted an extensive survey of existing identification techniques, which led us to formulate a unified model for user identification. We start by introducing this model that (1) classifies existing user identification approaches in five categories according to the identification technology, (2) identifies eight characteristic identification system parameters, and (3) proposes a way for visualizing the system's characteristics as points on a radar chart to allow for quick comparison and contrast between systems. This model is then used to present our survey of existing user identification approaches and visualize their characteristics, highlighting their strengths and limitations. The model also makes it possible to visually represent requirements of systems that require user identification, identify existing approaches that can meet an application's requirements, and help report on and evaluate new approaches to user identification systematically.