Camera system having at least two first cameras and two second cameras

[0001] This application is a continuation-in-part application of European patent application PCT/EP 01/07693, filed Jul. 5, 2001, and claiming priority from German patent application 100 34 601.4, filed Jul. 14, 2000.

[0002] The invention relates to a camera system for photogrammetrical applications as well as for applications in aerial reconnaissance.

[0003] Digital cameras are increasingly used in photogrammetry as well as in aerial reconnaissance. On the one hand, there is the desire for a high spatial resolution of the images to be recorded and, on the other hand, the desire for recording color information. Maximum spatial resolution is presently achievable with panchromatic cameras which only make possible the recordation of black/white information.

[0004] The space which is available for the entire camera system in aircraft is limited. For this reason, there is the desire to have a compact arrangement of several cameras.

[0005] It is the object of the invention to provide a camera system having at least two first cameras and two second cameras which is configured so as to provide an economic utilization of space.

[0006] The camera system of the invention includes at least two first cameras, which each have their own objective. The optical axes of the objectives are inclined to each other. The camera system furthermore includes at least two second cameras which are mounted displaced to these first cameras in the viewing direction of the first cameras.

[0007] The optical axes of the objectives of the first cameras are arranged inclined to each other and, as a consequence thereof, these axes intersect. For this reason, the smallest envelope, which surrounds the aperture cones of the first cameras, has a constriction. The second cameras are preferably mounted in the region of this constriction.

[0008] In a further advantageous embodiment, at least three first cameras are mounted symmetrically to an axis of symmetry and the second cameras are mounted displaced to the first cameras in the direction of this symmetry axis.

[0009] Especially advantageous are a total of four first cameras mounted symmetrically to a symmetry axis. With four cameras, a high image coverage is achieved, that is, a large simultaneously detected angular region.

[0010] The first cameras can be panchromatic digital cameras with which the recordation of the topography, which is to be measured, takes place with high lateral resolution but without color information. The second cameras are then designed as multichromatic digital cameras with which also the color information of the passed-over topography is recorded but with reduced lateral resolution.

[0011] Preferably, four second cameras are also provided which likewise are mounted symmetrically to the symmetry axis of the first cameras. The optical axes of the second cameras can then be aligned parallel to each other.

[0012] For the later photogrammetric evaluation of the image information recorded with the camera system, all aperture cones of the first and second cameras should have a common central overlapping region.

[0013] The invention will now be described with reference to the drawings wherein:

[0014] FIG. 1 is a side elevation view of the camera system according to the invention;

[0015] FIG. 2 is a perspective view of the camera system of FIG. 1; and,

[0016] FIG. 3 is a schematic representation of four second cameras viewed in plan of the camera system shown in FIGS. 1 and 2.

[0017] The camera system in FIGS. 1 to 3 includes four first cameras (1, 2, 12, 13) and four second cameras (10, 11, 14, 21). The second cameras (10, 11, 14, 21) are mounted displaced with respect to the first cameras (1, 2, 12, 13) in the viewing direction of the first cameras (1, 2, 12, 13). Each of these four first and second cameras includes a housing, an objective mounted in the housing corresponding thereto and a CCD-image sensor mounted behind the objective corresponding thereto. The image sensors (not shown) of the first cameras (1, 2, 12, 13) are panchromatic CCD-image sensors designed for the highest lateral resolution. The CCD-sensors of the second cameras (10, 11, 14, 21) are configured as high-resolution image camera chips.

[0018] The four first cameras (1, 2, 12, 13) are mounted symmetrically to a symmetry axis 9. The first cameras (1, 2, 12, 13) are mounted inclined to each other by the same angular amount and relative to the symmetry axis 9 so that the optical axes of the first cameras intersect in a common intersect point 5 which lies on the symmetry axis 9. In FIG. 1, only two of these optical axes (7, 8) are shown.

[0019] Because of the mutually inclined arrangement of the first cameras (1, 2), there arises a region (b) directly ahead of the objectives (3, 4) of the first cameras wherein the smallest envelope, which encloses the aperture cones of the first cameras, has a constriction in the lateral direction, that is, in a direction perpendicular to the symmetry axis 9. This constricted region is schematically represented by the vertical segments (24, 26) of the heavy solid lines (28, 30). In this region (b), the diameter of the envelope, which encloses the aperture cones of the first cameras (1, 2, 12, 13), is constant. The second cameras (10, 11, 14, 21) are mounted in such a manner that the aperture cones of the first cameras (1, 2, 12, 13) are not cropped by the housings of the second cameras (10, 11, 14, 21). The support structure 6 for the second cameras (10, 11, 14, 21) has, for this purpose, a correspondingly large opening for the clear passage of the aperture cones of the first cameras.

[0020] The envelope indicated by the solid heavy lines 28 and 30 defines the composite aperture cone of the first cameras (1, 2, 12, 13). This composite aperture cone has a constant diameter only in region (b) and the envelope therefore has a shape corresponding to an inverted funnel.

[0021] The optical axes of the second cameras are aligned parallel to the symmetry axis 9. In FIG. 1, only the optical axes (17, 18) of second cameras (10, 11), respectively, are shown.

[0022] In a central region 19, the aperture cones of all first cameras (1, 2, 12, 13) and second cameras (10, 11, 14, 21) overlap.

[0023] The objectives of the first cameras are so designed that each of the first cameras records an image angle of at least 20. In FIG. 1, the objectives (3, 4) of first cameras (1, 2) are shown. The relative inclination of the first cameras to each other is so selected that all first cameras together include an image angle of over 400 in two mutually perpendicular directions perpendicular to the symmetry axis 9.

[0024] The objectives of the second cameras (10, 11, 14, 21) are so designed that all second cameras, in common, include an image angle of over 50 in two mutually perpendicular directions perpendicular to the symmetry axis 9.

[0025] With the camera system of the invention, an optimal compact arrangement of the individual cameras is achieved. The unified viewing field of the first cameras as well as of the second cameras ensures a 100% ground coverage, that is, there is no non-included or non-detected angular region between the individual aperture cones.

[0026] Because of the compact configuration and the resulting minimal need for space, the arrangement of the cameras according to the invention ensures also a high stability with respect to vibrations and temperature behavior as a consequence of the short distances of the individual cameras with respect to each other.

[0027] In the embodiment described, the distances of the first cameras with respect to each other are greater than the distances of the second cameras with respect to each other.

[0028] It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.