A method for displaying a mask area of an observation system including a camera part photographing an observation area, comprising the steps of
- photographing the observation area;
- inputting a user-set command for selecting a privacy zone within the observation area, the privacy zone requiring no observation;
- outputting a control signal setting the mask area for masking the privacy zone according to the user-set command;
- generating a plurality of vertexes forming the mask area according to the control signal;
- masking the privacy zone photographed by the camera part according to a mosaic scheme based on the mask area formed by the plurality of vertexes;
- and displaying the mask area wherein the step of generating the plurality of vertexes further comprises storing position data corresponding to the plurality of vertexes, the position data including a rotating angle of the camera part in a horizontal direction, a rotating angle of the camera part in a vertical direction, and a zoom value of the camera part, each corresponding to the plurality of vertexes,
- wherein the step of generating the plurality of vertexes further comprises calculating the mask area corresponding to a position and a size of the privacy zone when the privacy zone is photographed by the camera part,
- wherein the step of calculating the mask area models the rotating angle of the camera part in the horizontal direction, the rotating angle of the camera part in the vertical direction and the zoom value of the camera part into the position data corresponding to the plurality of vertexes on a hemispheric three-dimensional coordinate system, and
- wherein the step of calculating the mask area converts the rotating angle of the camera part in the horizontal direction, the rotating angle of the camera part in the vertical direction and the zoom value corresponding to the plurality of vertexes modeled on the hemispheric three-dimensional coordinate system into the position data with x and y coordinates on a two-dimensional coordinate system by using the following equations:
- x coordinate of each vertex=R*Z*cos(T)*sin(P−Pc), and
- y coordinate of each vertex=R*Z*cos(Tc)−R*Z*cos(T)*cos(P−Pc),
- in which R is a radius of circle modeled on the two-dimensional coordinate system when the hemispheric three-dimensional coordinate system is projected to the two-dimensional coordinate system, Pc is the rotating angle of the camera part in the horizontal direction corresponding to a center of a camera screen photographed by the camera part, Tc is the rotating angle of the camera part in the vertical direction corresponding to the center of the camera screen photographed from the camera part, P is the rotating angle in the horizontal direction corresponding to the position having the x and y coordinates with respect to the Pc, T is the rotating angle in the vertical direction corresponding to the position having the x and y coordinates with respect to the Tc, and Z is the zoom value used in obtaining each vertex.