In the aerial photogrammetry, the position and attitude information of the aerial camera at the time of exposure can be obtained through the positioning and orientation system carried on board, which is introduced into the collinear equation to solve the geodetic coordinates of the target points, and the direct geographic positioning can be completed and positioning the lever arm of directional system will bring the output error, resulting in collinear equation of deviating from the collinear condition, thus affecting the precision of the target for the quantitative analysis of the lever arm effects on the accuracy of positioning and orientation system, this paper analyzes the inertial measurement unit under different installation method of the lever arm type, use the data analysis of two kinds of semi-physical simulation installation effect the precision of the system, in when the pendulum is swept at 60 degrees, the attitude error is about 0.01. According to the results, the error compensation model of the lever arm is established, which provides a theoretical basis for compensating the influence of the lever arm error.
KEYWORDS: Cameras, Modulation transfer functions, Optical engineering, Temperature metrology, Monochromatic aberrations, Picosecond phenomena, Thermal effects, Satellites, Signal to noise ratio
Thermal design is highly related to the performance of space cameras as temperature changes cause thermal displacements of the cameras’ optical and mechanical systems, consequently affecting imaging quality. However, most existing thermal design methods for space cameras focus on several thermal design parameters without a comprehensive and quantitative analysis. Therefore, we proposed an optimization thermal design method for space cameras based on thermo-optical analysis and the Taguchi method. We first established the thermal balance equations of space cameras, and by analyzing the thermal design parameters in the equations, we identified the key parameters that affect the temperature field, thermal displacements, and imaging quality of the camera. Furthermore, we evaluated the influence of each thermal design parameter on imaging quality based on the integrated thermo-optical analysis. Thereafter, we applied the Taguchi method to quantitatively calculate the effect of each thermal design parameter on imaging quality. Finally, we implemented an optimal thermal control scheme for space cameras based on the results of the Taguchi method. The experimental results demonstrated that the proposed method is reliable and efficient and would be beneficial to researchers working on the thermal design of optical instruments.
To a high resolution digital camera which works in visible light and is on the space-based platform flying in 500 km orbit, analyzed the principle of image acquisition, established the collinear equation and target location model from the system measured the pose of camera and single image without control points, and researched the method to calculate the geographic coordinate of target point. Analyzed the consisted factors of target location accuracy, and generated the formula for calculating target location accuracy based on the accuracy theory. For the cameras working in this mode, gave the elements of orientation and the parameters of camera, then obtained the target location accuracy is 16.1 meter through the simulation analysis to the model. The analysis to the target location accuracy provides a theoretical base for the practical use of the space camera. Analyzed the impact of the camera parameters and operation mode on the location accuracy, and put forward some measures to improve the target location accuracy.
In order to acquire the geographic location information of sea-surface, aiming at feature that sea-surface elevation is known. A self-location algorithm independent of ranging equipment was developed. The paper uses camera’s position and attitude information measured by position and orientation system which rigid connect with camera. Then the paper compensates the lever arm which comes from GPS Antenna phase center and camera center of photography. So that accuracy position was got. The collinearity equation is built by the camera’s position, attitude and the known sea-surface elevation which equals zero to calculate target geodetic coordinates. The error model is built basing on total differential method. At last the location error of different detection range and angles of strabismus is analysed.
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