Infrared (IR) small target detection is widely used in both civilian and military security fields. However, IR small target detection in complex backgrounds faces many challenges. For example, small targets often occupy only a few pixels in IR images, lacking texture and contour features. IR images are seriously disturbed by clutter and noise, which results in the target being easily submerged. Therefore, it is difficult to achieve a low false alarm rate and a high detection rate at the same time. In this paper, a small target detection method based on local image alignment is proposed. First, the thermal IR imaging system is combined with the range-gated technology. The range-gated technology can be used to shield the background of the non-gated area. Second, the continuous frames in the sequence are accumulated to suppress noise. The movement of the target will form a trailing line in the accumulated image, and the trailing line contains the motion information of the target. Third, the trailing line is detected and extracted. Each trailing line corresponds to a suspected target area, including the real target and edges in the background, and the motion information of the suspected target can be calculated from the length and direction of the trailing line. Then, according to the motion information, the local images of the suspected target in a certain number of consecutive frames are aligned and accumulated. In the accumulated image, the real small target will shrink to a bright spot, and the signal-to-noise ratio will be significantly improved, while the background edge still appears as a line. Finally, the target is extracted from the accumulated image.
In the pulse laser ranging system based on time-of-flight measurement, since different targets have different reflection characteristics, the echo light intensity will affect the leading edge moment received by the range finder, which results in the deviation of the ranging result. In order to address this problem, this paper proposes a leading edge time correction model based on pulse width. The pulse width of the echo is positively correlated with the light intensity, so the pulse intensity can be used to characterize the light intensity and correct the leading edge time. According to Marius law, the leading edge moment acquisition experiments are carried out under different echo intensities produced by polarization state generator (PSG). It has been demonstrated that the presented model is consistent with experimental data. From the analysis and discussion, it is shown that the correction model can effectively correct the error caused by the echo light intensity of the pulsed laser ranging system, thus improving the accuracy of ranging.
Camera’s internal parameter calibration is an important problem in computer vision. The moment, a precise targets like checkboard is required when camera calibration is performed. But this method is not suitable for a telephoto lens. In order to overcome this problem, a new camera calibration model is constructed by installing the debugged telephoto camera on an accurate two-dimensional rotating platform. Let the camera move around the rotating axis of the rotating platform. The camera takes pictures of distant objects directly. Then, the next picture is get by rotating the two-dimensional platform. The image coordinates , of the same point in space, in different images are obtained by image matching. The motion matrix of the camera is calculated from the readings of the two-dimensional rotating platform. Last, the optimization equation can be enumerated to solve the internal parameters. The experimental results show that the internal parameters obtained by the algorithm can satisfy the calculation accuracy.
Nowadays, with the boosting incomes and rapid development of science, car has become one of the most important transport vehicle. Driving environment and safety has attracted much attention in the automotive design field. Therefore, it is extremely urgent to develop the intelligent and reliable safety technologies such as vehicle active collision warning system. There are lots of studies focused on the critical research of machine vision ranging technology, however, the installation error of binocular ranging may result in inaccurate measurement accuracy. In this study, we use an improved monocular ranging to measure distance. The traditional monocular ranging models based on the principle of pinhole imaging, static image ranging model and etc. Most of the models require specific prior information of the vehicle, the applicable conditions of the model may be too idealistic and not applicable to general situations. In order to solve the contradiction, our research proposes a creative monocular ranging model to measure the distance between two vehicles. The model is based on the camera space projection relationship taking the factors of the camera's pitch angle into account. Our model has universal application significance using the simple implementation method with residual method. Based on the model, we amended the camera's pitch angle after the experiments. Meanwhile, the accuracy of the model is guaranteed by analyzing the factors affecting the accuracy of the range. The experimental results show that the error is controlled within 10%, which can meet the accuracy requirements of the system.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.