Systems, circuits, and devices for recognizing gestures are discussed. A mobile device includes a housing, an orientation sensor, a camera implemented on the housing, a memory for storing a lookup table comprising multiple gestures and corresponding commands, and a controller coupled to the orientation sensor, the camera, and the memory. The controller is configured to generate trace data corresponding to a gesture captured by the camera, wherein x, y, and z coordinates of the trace data are applied according to an orientation of the housing during the gesture. The controller is also configured to determine an orientation angle of the housing detected by the orientation sensor. The controller is further configured to recognize the gesture through accessing the lookup table based on the trace data and the orientation angle of the housing.