Geert Willems Tinne Tuytelaars Luc J. Van Gool An Efficient Dense and Scale-Invariant Spatio-Temporal Interest Point Detector. 650-663 2008 ECCV (2) http://dx.doi.org/10.1007/978-3-540-88688-4_48 conf/eccv/2008-2 db/conf/eccv/eccv2008-2.html#WillemsTG08