In this paper, we propose a 3D coordinate estimation for 3D space using a mono camera
in mobile devices. Generally, a marker is used for the detection of 3D movement in 2D
images. However, this marker-based system has obvious defects since markers always need to
be included in the image. To overcome this problem, we replaced the markers with a planar
face by estimating the face detection. The experimental result indicates the feasibility of the
proposed algorithm for face movement-based mobile user interfaces.