We present a novel auto-calibration approach for multi-projector displays using a handheld camera. Most existing researches adopted active structured light pattern. These approaches require mounted camera or observation of entire projection area. An elaborate camera installation is needed due to these constraints. This paper introduce a new structured light pattern scheme based on M-arrays and geometric calibration method for multi-planar space. These techniques enable an auto-calibration of multi projection system using a handheld camera.