Abstract: Techniques pertaining to methods and devices for calibrating camera parameters are disclosed. According to one aspect of the present invention, objects on an image are detected and features on the objects, such as the top of a person, are identified. Perspective parallel lines based on the object features are constructed and vanishing points from the converged perspective parallel lines are determined. A vanishing line is defined according to the vanishing points. The intrinsic parameters, such as focal length, and the extrinsic parameters, such as tilting and pan angles, of a camera are calibrated according to the vanishing points, the vanishing line and a reference object with known dimensions, or known camera angles, The calibrated camera parameters are used for accurate photogrammetric measurements and computer vision applications.

Abstract: Techniques for detecting stationary targets in videos or frame images are described. According to one aspect of the present invention, a sequence of frame images is being received from a video system. Each of the frame images into a plurality of image blocks, and dividing a background image is divided into a plurality of corresponding background image blocks. Characteristic values of the image blocks in each of the frame images are calculated. A plurality of characteristic value sequences is then formed, each of the characteristic value sequences comprises a predefined number of characteristic values for each of the image blocks in the frame images. A histogram of each of the characteristic value sequences is computed to determine whether one of the image blocks in one of the frame images contains a stationary target.

Abstract: Techniques pertaining to methods and devices for calibrating camera parameters are disclosed. According to one aspect of the present invention, objects on an image are detected and features on the objects, such as the top of a person, are identified. Perspective parallel lines based on the object features are constructed and vanishing points from the converged perspective parallel lines are determined. A vanishing line is defined according to the vanishing points. The intrinsic parameters, such as focal length, and the extrinsic parameters, such as tilting and pan angles, of a camera are calibrated according to the vanishing points, the vanishing line and a reference object with known dimensions, or known camera angles, The calibrated camera parameters are used for accurate photogrammetric measurements and computer vision applications.

Abstract: Techniques for updating background in a video surveillance system are disclosed. According to one aspect of the present invention, a background frame is obtained before detecting motion. An absolute value of a difference between a pixel of the current frame image and a corresponding pixel of the current background frame is calculated; a probability density of the one pixel of the current frame image is calculated to update the corresponding pixel of the current background frame according to the one pixel of the current frame image, unless the absolute value is larger than a difference threshold and the probability density is less than a probability density threshold.