AirContour:Building Contour-based Model for In-Air Writing Gesture Recognition 44:11 .'imy 0202 m m m 02 (a)3D contour (b)2D contour by PCA (c)2D contour with re-(d)2D contour with ro- versal tation Fig.10.Contour of character "m"written with right hand;xaxis mean the projection of xhyh, zhaxis,respectively. (c 0 02 xm] xim) 8时 0 0202 (a)3D contour (b)2D contour by PCA (c)2D contour with re-(d)2D contour with ro versal tation Fig.11.Contour of character "e"written with right hand;xyaxis mean the projection of xh yh. Zh-axis,respectively. 0 0.2 x0(m) 0 m 飞m 02 xm) (a)3D contour (b)2D contour by PCA (c)2D contour with re- (d)2D contour with ro- versal tation Fig.12.Contour of character "g"written with right hand;xaxis mean the projection of xh.h Zh,-yh-axis,respectively. E 202 m m (a)3D contour (b)2D contour by PCA (c)2D contour with re-(d)2D contour with ro- versal tation Fig.13.Contour of character'd"written with right hand;axis mean the projection of Zh-axis,respectively. ACM Transactions on Sensor Networks,Vol.15,No.4.Article 44.Publication date:October 2019.AirContour: Building Contour-based Model for In-Air Writing Gesture Recognition 44:11 Fig. 10. Contour of character “m” written with right hand; x  h, y h, z h-axis mean the projection of xh, yh, zh-axis, respectively. Fig. 11. Contour of character “e” written with right hand; x  h, y h, z h-axis mean the projection of xh, yh, zh-axis, respectively. Fig. 12. Contour of character “g” written with right hand; x  h, y h, z h, −y h-axis mean the projection of xh, yh, zh, −yh-axis, respectively. Fig. 13. Contour of character “d” written with right hand; x  h, y h, z h-axis mean the projection of xh, yh, zh-axis, respectively. ACM Transactions on Sensor Networks, Vol. 15, No. 4, Article 44. Publication date: October 2019