Abstract: The invention relates to a method for detecting an object (1) in relation to a surface (2). A synthetic image (3c, 4c) is produced from at least two distinct viewpoints (3, 4), for each of said viewpoints, by means of a geometrical transformation comprising at least one perspective projection (3a, 4a) of the object on the surface (2), each synthetic image being associated with the viewpoint concerned. By discriminating between the synthetic images, it is possible to detect the presence of and determine the position of the object (1) in relation to the surface (2), by searching for contrast inversions. The invention can be used for surveying a swimming pool.

Abstract: A system for monitoring a swimming pool to prevent drowning accidents includes sensing devices (D1, D2, D3) for providing electrical signals forming images of bodies immersed in the pool water. Appropriate hardware (10) digitizes the resulting images, and the digital image data is compressed and stored at a series of times. Digitized images of a single body are compared at a series of times. The nature of a body, the path of the body and changes in the position of the body are estimated on the basis of the series of images; and an alarm is activated should the path or movement of the body being observed give cause for concern.