In order to enhance the speed and accuracy of ellipse detection, an ellipse detection algorithm based on edge classification is proposed. Too many edge points are removed by making edge into point in serialized form and the distance constraint between the edge points. It achieves effective classification by the criteria of the angle between the edge points. And it makes the probability of randomly selecting the edge points falling on the same ellipse greatly increased. Ellipse fitting accuracy is significantly improved by the optimization of the RED algorithm. It uses Euclidean distance to measure the distance from the edge point to the elliptical boundary. Experimental results show that: it can detect ellipse well in case of edge with interference or edges blocking each other. It has higher detecting precision and less time consuming than the RED algorithm.
Camera calibration is the first step of computer vision and one of the most active research fields nowadays. In order to improve the measurement precision, the internal parameters of the camera should be accurately calibrated. So one high-accuracy camera calibration algorithm is proposed based on the images of planar targets or tridimensional targets. By using the algorithm, the internal parameters of the camera are calibrated based on the existing planar target at the vision-based navigation experiment. The experimental results show that the accuracy of the proposed algorithm is obviously improved compared with the conventional linear algorithm, Tsai general algorithm, and Zhang Zhengyou calibration algorithm. The algorithm proposed by the article can satisfy the need of computer vision and provide reference for precise measurement of the relative position and attitude.
It is an important measure to observe target by using laser sensor in the field of target detection. Exact and reliable dynamic laser scatter characteristics of observing target, can not only be used for the design and development of laser sensor as well as the research of algorithm for target capture, recognition and tracking, but also can offer reference bases for the test flow programming. A set of simulation, measurement system for the dynamic laser scatter characteristics of observing target is introduced in this paper. The simulation problem of dynamic laser scatter characteristics of observing target is solved, under the circumstance of laboratory with different azimuth angle and pitch angle of observation. The dynamic laser scatter characteristics of observing target can be obtained directly by such system, the test data can be used for the verification of the analyzing model for the laser scatter characteristics of observing target, and can also offer basis for the development of laser detecting sensor.
In order to achieve the rendezvous and capture of the space non-cooperative target, the relative position and pose measurement of non-cooperative target must be resolved. Since the marker is not installed into the non-cooperative target and there is no inter satellite link to transfer the information, so it is very difficult to measure the relative position and pose measurement of non-cooperative target. The solar array connecting frame of non-cooperative targets have their characters and are easy to capture, so the position and pose measurement of specific operation site of non-cooperative target based on stereo vision has been studied in this paper. The method composed of image acquiring, image filtering, edge detection, feature extraction and relative pose measurement. Finally, the relative position and attitude parameters of the solar wing connection were obtained and provided to the control system. The results of simulation and ground verification show that the algorithm is accurate and effective, and can satisfy the technical requirements of the on orbit operation. The measurement approach can be used for engineering implementation.
KEYWORDS: Target detection, Signal to noise ratio, Computer programming, Aerospace engineering, Surveillance systems, Image processing, Digital breast tomosynthesis, Computer simulations, Sensors, Detector development
With the development of Space Technology, the demand to Space Surveillance System is more urgent than before. The paper studies the dim and small target of long range. Firstly, it describes the research status of dim and small target abroad and the two detection principle of DBT and TBD. Secondly, it focuses on the higher-order correlation method, dynamic programming method and projection transformation method of TBD. Finally, it studies the image sequence simulation of different signal to noise ratio (SNR) with the real-time data from the aircraft in orbit. The image sequence is used to experimental verification. The test results show the dim and small target detection capability and applicable occasion of different methods. At the same time, it provides a new idea to the development of long-distance optical detector.
Exact and reliable dynamic visible scatter characteristics of space target, can not only be used for the design and development of visible sensor as well as the research of algorithm for target capture, recognition and tracking, but also can offer reference bases for the flow programming of space test. A set of simulation measurement system for the dynamic visible scatter characteristics of space target is introduced in this paper. The simulation problem of dynamic visible scatter characteristics of space target is solved, under the circumstance of laboratory with different azimuth angle and pitch angle of solar illumination as well as different azimuth angle and pitch angle of observation. The dynamic visible scatter characteristics of space target can be obtained directly by such system, and the test data can be used for the verification of the analyzing model for the visible scatter characteristics of space target.
In order to make the visible image of target indicating its active state as real as possible, a kind of method for space target imaging simulation based on target visible scatter characteristics is proposed in this paper. The online real-time imaging simulation with high fidelity is implemented, which provides a good foundation for the researches of space-based target detection, recognition and tracking techniques.
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