When I rotated the object, I calculated the area of the contours. I do not know why there is so far differences between two areas although the shape was not changed so much.
1st image: area is about 11300 2nd image: area is about 120
The program is the same in this link, so simple: http://docs.opencv.org/2.4/doc/tutorials/imgproc/shapedescriptors/moments/moments.html
Please help me to solve this problems!