An efficient wide area imaging scheme based on spiral scanning

There are three common scanning schemes for large area imaging for airborne cameramulti lens splicing, circumferential scanning or reciprocating scanning. However, the lens splicing form requires multiple lenses, and the system is cumbersome. The circumferential scanning imaging obtains a wide area image through azimuth continuous scanning and the field of view in the pitching direction of this imaging method is a fixed value. And the imaging efficiency of reciprocating scanning form is low due to the need for multiple mechanism turns. In this paper, a new spiral scanning scheme method over large area imaging is proposed, which carries the area array camera on the two-dimensional platform with external azimuth gimbal and internal pitch gimbal. Scanning in azimuth combined with pitch motion, the spiral scanning trail is composed for wide-area imaging, and this method requires only one area array camera and only one rotation in pitch direction in one imaging process, which has high imagery efficiency. At the same time, the spiral dynamic scanning algorithm which can isolate attitude disturbance and compensate flight movement to achieve the scanning imaging for large area of the specified area is deduced. Then the implementation form of the scanning method is also derived. Finally, we take some simulation to test the method. The results show that the spiral scanning algorithm can compensate the attitude disturbance and aircraft attitude disturbance, and can obtain the staring imaging of 254km(2) (mapping radius of 9km) in 3.8 seconds, when the field of view angle of area array camera is 7.5 degrees x11.25 degrees, the flight speed is 360km/h, the azimuth attitude disturbance is 15 degrees, the pitch attitude disturbance is 15 degrees, and the roll attitude disturbance is 8 degrees, at the flight altitude of 7500m. Therefore, the spiral scanning algorithm scheme is suitable for wide area imaging of moving carrier and has certain significance for the research of wide area scanning imaging system.