Method for determining the relative position of an object in space in six spatial degrees of freedom, comprising the following steps: applying a marking pattern with at least three markings on the object; providing an optical detection apparatus with a two-dimensional sensor surface; moving the object in the detection region of the optical detection apparatus in such a way that the marking pattern can be detected by the detection apparatus; projecting the markings onto assigned image locations on the two-dimensional sensor surface; establishing image coordinates of the image locations, associated with the markings, on the sensor surface; determining the relative position of the marking pattern by evaluating the image coordinates using an evaluation method which is performed in a computer unit (340, 400) assigned to the detection apparatus and characterized by the following steps: selecting a first image location (L i) and a second image location (R i), with the first image location being assigned to a first marking and the second image location being assigned to a second marking of the marking pattern; wherein a first vector between a projection center (P i) of the detection apparatus and the first image location (L i) and a second vector between the projection center and the second image location (R i) include a first angle (ε) and span a reference plane, and wherein a perpendicular projection of a third image location (M i), associated with a third marking, on the reference plane defines a foot (M i ') of the third marking; and establishing the location of a fixed point, with the location of the fixed point being constant, independent of the location of the projection center (P i) and the location of the foot (M i '), and a connecting straight line through the projection center (P i) and the foot always extending through the fixed point, wherein a reference circle is established, which extends through the first marking, the second marking and the projection center (P i) and has a center, and wherein the location of the fixed point on the reference circle is established. applying a marking pattern with at least three markings on the object; providing an optical detection apparatus with a two-dimensional sensor surface; moving the object in the detection region of the optical detection apparatus in such a way that the marking pattern can be detected by the detection apparatus; projecting the markings onto assigned image locations on the two-dimensional sensor surface; establishing image coordinates of the image locations, associated with the markings, on the sensor surface; determining the relative position of the marking pattern by evaluating the image coordinates using an evaluation method which is performed in a computer unit (340, 400) assigned to the detection apparatus and characterized by the following steps: selecting a first image location (L i) and a second image location (R i), with the first image location being assigned to a first marking and the second image location being assigned to a second marking of the marking pattern; wherein a first vector between a projection center (P i) of the detection apparatus and the first image location (L i) and a second vector between the projection center and the second image location (R i) include a first angle (ε) and span a reference plane, and wherein a perpendicular projection of a third image location (M i), associated with a third marking, on the reference plane defines a foot (M i ') of the third marking; and establishing the location of a fixed point, with the location of the fixed point being constant, independent of the location of the projection center (P i) and the location of the foot (M i '), and a connecting straight line through the projection center (P i) and the foot always extending through the fixed point, selecting a first image location (L i) and a second image location (R i), with the first image location being assigned to a first marking and the second image location being assigned to a second marking of the marking pattern; wherein a first vector between a projection center (P i) of the detection apparatus and the first image location (L i) and a second vector between the projection center and the second image location (R i) include a first angle (ε) and span a reference plane, and wherein a perpendicular projection of a third image location (M i), associated with a third marking, on the reference plane defines a foot (M i ') of the third marking; and establishing the location of a fixed point, with the location of the fixed point being constant, independent of the location of the projection center (P i) and the location of the foot (M i '), and a connecting straight line through the projection center (P i) and the foot always extending through the fixed point, wherein a reference circle is established, which extends through the first marking, the second marking and the projection center (P i) and has a center, and wherein the location of the fixed point on the reference circle is established.