1. Method for determining the topography or optical properties of a moving subject, in which method at least two images (KX 1 , KX 2 , KX 3 ) are taken, on an image-formation area ( 10 ), of approximately the same subject (X), the topography or the optical properties of a surface of the subject (X) are determined on the basis of the images (KX 1 , KX 2 , KX 3 ), characterized in that at least two images (KX 1 , KX 2 , KX 3 ) are taken on the image-formation area ( 10 ) of the subject (X) at different moments in time (t 1 , t 2 , t 3 ), in such a way that, in each image (KX 1 , KX 2 , KX 3 ), illuminations of essentially different types relative to each other are aimed at the subject (X), in addition, images (KY 1 , KY 2 , KY 3 ) are taken, on the image-formation area ( 10 ), of a reference area (Y) near the subject (X) synchronously with the images of the subject (X), in such a way that, in each image (KY 1 , KY 2 , KY 3 ), illumination of mutually essentially the same type is aimed at the subject (Y), the images (KY 1 , KY 2 , KY 3 ) created of the reference area (Y) are used to position the image areas corresponding to the same area of the subject (X) of the images (KX 1 , KX 2 , KX 3 ) of the subject (X).