Method and system for determining a region of water clearance of a water surface

A method for determining a region of water clearance of a water surface, the method comprising:

• receiving image data (ID) of an image captured by a camera;
• determining water surface pixels of the image from the image data (ID), wherein the water surface pixels show an imaged water surface within the image;
• determining image coordinates of at least a first group (GP1) of the determined water surface pixels in an image coordinate system, wherein the first group (GP1) is representative for the imaged water surface;
• determining solid object pixels of the image which show an imaged solid object touching the imaged water surface;
• determining image coordinates of at least a second group (GP2) of the determined solid object pixels in the image coordinate system, wherein the second group (GP2) is representative for the imaged solid object;
• determining whether the solid object, which is represented by the imaged solid object in the image, physically touches the water surface in real world;
• determining a position and an orientation of the camera at a time the image has been captured;
• determining real-world coordinates (RWC) of the corresponding water surface in the real world by transferring at least the image coordinates of the first group (GPI) to a real-world coordinate system under consideration of the determined position and orientation of the camera;
• determining real-world coordinates (RWC) of the corresponding solid object in the real world by transferring at least the image coordinates of the second group (GP2) to the real-world coordinate system under consideration of the determined position and orientation of the camera, when the solid object physically touches the water surface in the real world;
• determining a region of the water surface, which is defined by the determined real-world coordinates of the first group (GPI), as the region of water clearance;
• and
• determining a region, which is defined by the determined real-world coordinates (RWC) of the second group (GP2), as not being part of the region of water clearance.