René Hempel, Patrick Westfeld (2009): Statistical Modeling of Interpersonal Distance with Range Imaging Data. In A. Esposito, A. Hussain, M. Marinaro and R. Martone (eds.), Multimodal Signals: Cognitive and Algorithmic Issues, Springer Berlin/Heidelberg, pp. 137-144.
Patrick Westfeld, René Hempel (2008): Range Image Sequence Analysis by 2.5-D Least Squares Tracking with Variance Component Estimation and Robust Variance Covariance Matrix Estiamtion. The International Archives oft he Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol. XXXVII. Part B5, pp. 933-938