Passive measurement of terrain parameters

摘要

The present invention relates to determination of a terrain parameter relative to a vehicle ( 100 ) by registering a first image from the vehicle ( 100 ) when it is located at a first point in space (O₁). The first image includes a primary representation of a first terrain point (P₁) and a primary representation of a second terrain point (P₂). Then, a second image is registered from the vehicle ( 100 ) when it is located at a second point in space (O₂). This second image includes secondary representations of the first and secondary terrain points (P₁) and (P₂) respectively. Moreover, vehicle movement data is received, which describes at least one of a translation ({overscore (R) between the first and second points in space (O₁; O₂), and a rotation ({overscore (A) between the first and second points in space (O₁; O₂). A first image velocity vector is determined, which describes a movement of the primary representation of the first terrain point (P₁) in the first image to the secondary representation thereof in the second image. Correspondingly, a second image velocity vector is determined, which describes a movement of the primary representation of the second terrain point (P₂) in the first image to the secondary representation thereof in the second image. A terrain vector ({overscore (Xi) is then resolved, based on the first and second images, a camera model describing a geometric relationship between a particular terrain point and its projected representation onto an image plane, and a respective relationship expressing each of the first and second image velocity vectors as a function of the translation ({overscore (R) and the rotation ({overscore (A). The terrain vector ({overscore (Xi) extends between one of the first and second points in space (O₁; O₂) and a particular terrain point (T) in proximity of the vehicle ( 100 ). Thus, based on the terrain vector ({overscore (Xi), for instance an altitude (Z_O1) of the vehicle ( 100 ) may be determined.