A practical implementation of free viewpoint video system for soccer games

In this paper, we present a free viewpoint video generation system with billboard representation for soccer games. Free viewpoint video generation is a technology that enables users to watch 3-D objects from their desired viewpoints. Practical implementation of free viewpoint video for sports events is highly demanded. However, a commercially acceptable system has not yet been developed. The main obstacles are insufficient user-end quality of the synthesized images and highly complex procedures that sometimes require manual operations. In this work, we aim to develop a commercially acceptable free viewpoint video system with a billboard representation. A supposed scenario is that soccer games during the day can be broadcasted in 3-D, even in the evening of the same day. Our work is still ongoing. However, we have already developed several techniques to support our goal. First, we captured an actual soccer game at an official stadium where we used 20 full-HD professional cameras. Second, we have implemented several tools for free viewpoint video generation as follow. In order to facilitate free viewpoint video generation, all cameras should be calibrated. We calibrated all cameras using checker board images and feature points on the field (cross points of the soccer field lines). We extract each player region from captured images manually. The background region is estimated by observing chrominance changes of each pixel in temporal domain (automatically). Additionally, we have developed a user interface for visualizing free viewpoint video generation using a graphic library (OpenGL), which is suitable for not only commercialized TV sets but also devices such as smartphones. However, practical system has not yet been completed and our study is still ongoing.