To provide a method which realizes high measurement accuracy by using an optical measuring constitution having practical dimensions, and to provide the optical measuring constitution which executes the method.

A measuring method contains a step, at which light is radiated to the surface area of the surface of an object from one radiation direction at a first moment in time, and a step at which its radiation comprises different intensities in different points of its intensity profile and which is a part of the light radiation,, having a substantially constant intensity profile with reference to time. The surface area is imaged so as to generate image information by executing an imaging operation from an imaging direction deviating from the radiation direction by a known direction difference. The radiation and the imaging operation are executed at least at two other instances in time. The intensity value ratio is generated, on the basis of intensity values composed of the imaging information generated from the radiated surface area, and the ratio determines a point on the intensity profile. The height of the surface area is determined, in order to determine the shape of the surface of the object.