\input zb-basic \input zb-ioport \iteman{io-port 05487868} \itemau{Liu, Xu; Doermann, David; Li, Huiping; Lee, K.C.; Ozdemir, Hasan; Liu, Lipin} \itemti{A novel 2D marker design and application for object tracking and event detection.} \itemso{Bebis, George (ed.) et al., Advances in visual computing. 4th international symposium, ISVC 2008, Las Vegas, NV, USA, December 1--3, 2008. Proceedings, Part I. Berlin: Springer (ISBN 978-3-540-89638-8/pbk). Lecture Notes in Computer Science 5358, 248-257 (2008).} \itemab Summary: In this paper we present a novel application which uses 2D barcode for object tracking and event detection. We analyze the relationship between the spatial efficiency of a marker and its robustness against defocusing. Based on our analysis we design a spatially efficient and robust 2D barcode, M-Code (Marker-Code) which can be attached to the surface of static or moving objects. Compared with traditional object detection and tracking methods, M-Code not only identifies and tracks an object but also reflects its position and the orientation of the surface where it is attached. We implemented an efficient algorithm that tracks multiple M-Codes in real time in the presence of rotation and perspective distortion. In experiments we compare the spatial efficiency of M-Code with existing 2D barcodes, and quantitatively measure its robustness, including its scaling capability and tolerance to perspective distortion. As an application we use the system to detect door movements and track multiple moving objects in real scenes. \itemrv{~} \itemcc{} \itemut{} \itemli{doi:10.1007/978-3-540-89639-5\_24} \end