A method for the determination of a fill level of a cylindrical oil tank with a shell wall and a floating roof, comprising the steps: - Transmission from an oblique viewpoint of microwaves, from a satellite that is orbiting or stationary in an earth orbit, in the direction of the cylindrical oil tank located on the earth's surface, - Reception of microwaves reflected from the cylindrical oil tank, and generation of a radar image using a synthetic aperture method, characterised by the steps: - Determination of a multiplicity of point scatterers from the radar image by means of image processing and/or signal processing, such that the radar image then has only binary information, wherein the point scatterers are produced by reflections of microwaves striking the cylindrical oil tank, and appearing on the radar image as points that stand out in colour, - Generation and adjustment of at least two semicircles using a method of non-linear optimisation, or a Hough transformation, such that the point scatterers lie on, or as close as possible to, the semicircles, wherein the semicircles have at least the following: a first semicircle assigned to a line of contact between an outer face of the shell wall and the ground, and a second semicircle assigned to a line of contact between an inner face of the shell wall and an upper end face of the floating roof, - Determination of a diameter of the oil tank, and a height of the floating roof relative to the ground, from the respectively adjusted first semicircle and second semicircle, and - Determination of the fill level of the oil tank from the diameter of the oil tank and the height of the floating roof determined. - Transmission from an oblique viewpoint of microwaves, from a satellite that is orbiting or stationary in an earth orbit, in the direction of the cylindrical oil tank located on the earth's surface, - Reception of microwaves reflected from the cylindrical oil tank, and generation of a radar image using a synthetic aperture method, characterised by the steps: - Determination of a multiplicity of point scatterers from the radar image by means of image processing and/or signal processing, such that the radar image then has only binary information, wherein the point scatterers are produced by reflections of microwaves striking the cylindrical oil tank, and appearing on the radar image as points that stand out in colour, - Generation and adjustment of at least two semicircles using a method of non-linear optimisation, or a Hough transformation, such that the point scatterers lie on, or as close as possible to, the semicircles, wherein the semicircles have at least the following: a first semicircle assigned to a line of contact between an outer face of the shell wall and the ground, and a second semicircle assigned to a line of contact between an inner face of the shell wall and an upper end face of the floating roof, - Determination of a diameter of the oil tank, and a height of the floating roof relative to the ground, from the respectively adjusted first semicircle and second semicircle, and - Determination of the fill level of the oil tank from the diameter of the oil tank and the height of the floating roof determined.