A method for measuring an area of a target surface having the form of a parallelogram, the method comprising: generating and transmitting a plurality of measurement signals from a signal generating device to a plurality of points (1, 2) on the target surface and a plurality of points (3, 4, 5) outside the target surface, wherein the plurality of points on the target surface and the plurality of points outside the target surface together define a plane and comprise: a first point on a boundary of the target surface; a second point on a boundary of the target surface opposite to and aligned with the first point; third, fourth and fifth points (3, 4, 5) aligned linearly outside the target surface, the third point being arranged between the fourth and fifth points and aligned linearly with the first and second points (1, 2); the first and second points (1, 2) spanning one of a width and a height of the target surface; and, the third, fourth and fifth points (3, 4, 5) spanning the other of the width and the height of the target surface; receiving respective measurement signals reflected from each of the plurality of points on the target surface and the plurality of points outside the target surface, wherein the signal generating device is arranged substantially orthogonally to the plane from the third point; determining a respective distance (402, 404, 406, 408, 410) between the signal generating device and each of the plurality of points (1, 2) on the target surface and the plurality of points (3, 4, 5) outside the target surface; deriving, automatically, a plurality of parameters associated with a geometry of the area of the target surface based on the determined distances (402, 404, 406, 408, 410); and calculating, automatically, the area of the target surface using the plurality of parameters derived. generating and transmitting a plurality of measurement signals from a signal generating device to a plurality of points (1, 2) on the target surface and a plurality of points (3, 4, 5) outside the target surface, wherein the plurality of points on the target surface and the plurality of points outside the target surface together define a plane and comprise: a first point on a boundary of the target surface; a second point on a boundary of the target surface opposite to and aligned with the first point; third, fourth and fifth points (3, 4, 5) aligned linearly outside the target surface, the third point being arranged between the fourth and fifth points and aligned linearly with the first and second points (1, 2); the first and second points (1, 2) spanning one of a width and a height of the target surface; and, the third, fourth and fifth points (3, 4, 5) spanning the other of the width and the height of the target surface; a first point on a boundary of the target surface; a second point on a boundary of the target surface opposite to and aligned with the first point; third, fourth and fifth points (3, 4, 5) aligned linearly outside the target surface, the third point being arranged between the fourth and fifth points and aligned linearly with the first and second points (1, 2); the first and second points (1, 2) spanning one of a width and a height of the target surface; and, the third, fourth and fifth points (3, 4, 5) spanning the other of the width and the height of the target surface; receiving respective measurement signals reflected from each of the plurality of points on the target surface and the plurality of points outside the target surface, wherein the signal generating device is arranged substantially orthogonally to the plane from the third point; determining a respective distance (402, 404, 406, 408, 410) between the signal generating device and each of the plurality of points (1, 2) on the target surface and the plurality of points (3, 4, 5) outside the target surface; deriving, automatically, a plurality of parameters associated with a geometry of the area of the target surface based on the determined distances (402, 404, 406, 408, 410); and calculating, automatically, the area of the target surface using the plurality of parameters derived.