A geo-referencing of the terrestrial objects on the basis of coplanarity conditions

1Tkachenko, AI
1International Research and Training Center for Information Technologies and Systems of the National Academy of Sciences of Ukraine and Ministry of Education and Science of Ukraine, Kyiv, Ukraine
Space Sci. & Technol. 2018, 24 ;(6):24-29
Publication Language: Russian
The problem of the geo-referencing of unknown terrestrial objects as an important aspect of remote sensing of the Earth from the space is considered. Onboard optical-electronic system of the low-Earth spacecraft is used for resolving the above-mentioned problem. The geo-referencing includes the flight stage as the shooting of objects from the orbit and the ground stage as the processing of images transmitted to the ground altogether with the synchronously received indications of the star tracker and the equipment of GPS customer. Special computer algorithms should be elaborated for processing of the space snapshots and accompanying data.
                  The purpose of proposed work is to construct new original algorithm for geo-referencing. Such an algorithm should be investigated and compared with the formerly developed methods of analogous destination. Two types of measuring equations are exploited in the construction of the proposed geo-referencing algorithm. The first of these types is the traditional photogrammetric coplanarity condition. The second one is associated with coplanarity of the geo-referencing object’s line of sight, geocentric position vector of the above-mentioned object and geocentric position vector of the spacecraft. It is supposed that the preliminarily pointed location of the geo-referencing object is known with accuracy of the order of 1 ... 2 km or hundreds of meters. This allows us to direct the camera's optical axis to the vicinity of the geo-referencing object in such a way that to be ensured that this object is captured by the field of view of the camera and the geo-referencing has accuracy of the order of tens of meters. While presented algoritm is applied to the geo-referencing of an object lying upon the spacecraft’s flight trace, a geocentric position vector of such an object is weakly observable. Computer simulation had demonstrated satisfactory accuracy of proposed geo-referencing algorithms for positioning of objects which had lying further than 20…30 kilometers aside the spacecraft trace.
Keywords: camera, coplanarity condition, geo-referencing, object of geo-referencing, spacecraft, star tracker
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