Apparatus for determining rectifying homographies for a linear camera array to be arranged along a common base line and have optical axes (18 1, 18 2, 18 3) of three cameras (10a, 10b, 10c) of the linear camera array extending in parallel to each other, the apparatus being configured to provide feature point triplets in three images (32a, 32b, 32c) of a scene captured by the three cameras (10a, 10b, 10c) of the linear camera array; using positions ( u,v), ( u',v'), ( u",v") of the feature point triplets, form, per feature point triplet, a linear equation of type A x ⇀ = b ⇀, where x ⇀ is a vector the components x i of which comprise geometric parameters including pan, tilt and roll of non-reference cameras of the three cameras (10a, 10b, 10c) relative to a reference camera of the three cameras (10a, 10b, 10c), and A is a matrix and b ⇀ is a vector, both dependent on the positions ( u, v), ( u',v'), ( u",v") of the respective feature point triplet such that A x ⇀ = b ⇀ is rewriteable into u ′ v ′ 1 x u T 1 + v T 2 + T 3 u " v " 1 x = 0 3 × 3 where,, are correlation slices of a trifocal tensor linearized according to a Taylor expansion around a perfect state of the linear camera array being perfectly aligned which has all terms of second and higher order omitted, wherein the elements of the correlation slices of the trifocal tensor relate to projection matrices P, P ′ = a i j, P " = b i j describing the projections of a first, second and third of the three cameras (10a-10c), respectively, wherein P, P' and P" are of the form P = KR [1|- C], P ' = K ' R '[1|- C '] and P" = K " R "[1|- C "], where K, K ', K" are intrinsic matrices, R, R', R" are rotation matrices and C, C', C" are 3D vectors pointing to the camera centers (12a-12c) of the three cameras (10a-10c), and being equal to each other in two dimensions other than the common base line, and K = f 0 0 0 f 0 0 0 1 and R =1; and determine values for the components x i which solve A x ⇀ = b ⇀ for the feature point triplets; and derive homography matrices H ' and H" for the second and third cameras (10b, 10c) using the determined values for x i, wherein the apparatus is configured such that P ′ = α f ′ + 1 − α z ′ α y ′ − c x ′ α f ′ + 1 α z ′ α f ′ + 1 − α x ′ − c x ′ α z ′ − α y ′ α x ′ 1 c x ′ α y ′ with R ′ = 1 − α z ′ α y ′ α z ′ 1 − α x ′ − α y ′ α x ′ 1, C ′ = c x ′,0,0, and K ′ α f ′ = 1 + α f ′ 0 0 0 1 + α f ′ 0 0 0 1, and P " = α f " + α r " + 1 − α z " α y " + p x " − c x " α f " + α r " + 1 α z " α f " + 1 − α x " − c x " α z " − α y " α x " 1 c x " α y " with R " = 1 − α z " α y " α z " 1 − α x " − α y " α x " 1, C " = c x ",0,0, and K " α f ", α r ", p x " = 1 + α f " 1 + α r " 0 p x " 0 1 + α f " 0 0 0 1, so that T 1 = 1 + α f ′ + α f " + α r " Δ c x α z " Δ c x − α y " Δ c x α z ′ Δ c x 0 0 − α y ′ Δ c x 0 0 T 2 = − α z " c x ′ + α z ′ c x " 1 + α f ′ + α f " c x ′ α x " c x ′ − 1 + α f ′ + α f " + α r " c x " α z ′ c x ′ − α z " c x " α y " c x " − α x ′ c x " − α y ′ c x ′ 0 T 3 = α y " + p x " c x ′ − α y ′ c x " − α x " c x ′ 1 + α f ′ c x ′ α x ′ c x " 0 α z ′ c x ′ − 1 + α f " + α r " c x " − α z " c x " − α y ′ c x ′ + α y " c x " a base line parameter is defined dependent on c" x and c' x, the first camera is the reference camera and the second and third cameras are the two non-reference cameras, the components x i of x ⇀ are α b, α f ", α' f, α r ", α x ′, α x ", α y ′, α y ", α z ′, α z ", p x ", where α b is an additive correction for the baseline distance of the two non-reference cameras (10b,c), measured/normalized by the baseline distance between the reference camera 10a and the second camera, and α f ", α' f, α r ", α x ′, α x ", α y ′, α y ", α z ′, α z ", p x ", are the geometric parameters, namely - from left to right - an additive correction of the two additive corrections of the focal lengths the two non-reference cameras (10b,c), measured/normalized by the focal length of the reference camera, an additive isotropy deviation of the third camera, two tilt correction angles for the two non-reference cameras, two pan correction angles for the two non-reference cameras, two roll correction angles for the two non-reference cameras and a shift of the principal point along the common base line of the third camera, wherein the apparatus is configured to perform the derivation of the homography matrices H' and H" for the second and third cameras using the determined values for x i such that applying the homography matrices H' and H" to trigonometrical projection matrices P trig ′ = K ′ R trig ′ 1 | − C ′ and P trig " = K " R trig " 1 | − C " with R trig ′ = 1 + cos α y ′ + cos α z ′ − sin α z ′ sin α y ′ sin α z ′ 1 + cos α x ′ + cos α z ′ − sin α x ′ − sin α y ′ sin α x ′ 1 + cos α x ′ + cos α y ′, R trig " = 1 + cos α y " + cos α z " − sin α z " sin α y " sin α z " 1 + cos α x " + cos α z " − sin α x " − sin α y " sin α x " 1 + cos α x " + cos α y ", result in H ′ P trig ′ = 1 0 0 c x ′ 0 1 0 0 0 0 1 0, and H " P trig " = 1 0 0 c x " 0 1 0 0 0 0 1 0, respectively.