With the continuous development and application of multispectral technology, multispectral cameras play an increasingly important role in the field of camouflage target reconnaissance. By simultaneously obtaining image data from different bands, they provide richer spectral information for target recognition. In the imaging requirements of high-speed dynamic scenes, fast and accurate registration of multispectral images has become a key technical issue, directly affecting the imaging quality and practicality of the system. In response to this situation, this article proposes an improved ORB image registration algorithm. Firstly, a scale pyramid is constructed and the ORB algorithm is used to extract feature points. The BEBLID descriptor is used to describe the feature points, and the nearest neighbor ratio (NNDR) algorithm is used for coarse matching; Then, based on feature point voting, an optimized geometric constraint is constructed to further optimize the feature points. The Random Sampling Consistency (RANSAC) algorithm is used to calculate the transformation matrix and obtain a high-precision transformation matrix; Finally, affine transformation is used to achieve image registration. The experimental results show that the algorithm has high registration accuracy and low registration time. Compared with traditional algorithms, the proposed algorithm has higher registration efficiency and can complete high-precision image registration while reducing image registration time.
When the airborne infrared imaging system searches and strikes ground targets, it is mainly used to extract target information from complex background interference images on the ground and transmit it to the driving or automatic guidance system, forming the position and motion information of the missile relative to the target, in order to better track the target and output information to control the missile's flight. The airborne infrared imaging system detects, recognizes, and the tracking performance is closely related to the infrared radiation characteristics of the background. This article focuses on the research of multiband characteristics of military application targets and backgrounds. On the basis of unified standards, a database management system is established to meet the management and query functions of measured infrared characteristics data of typical backgrounds such as deserts, grasslands, mountains, and forests in different seasons and at different times, as well as the development of an infrared imaging detection performance evaluation system, We studied the detection and recognition probabilities of infrared imaging systems for targets at different distances in different background environments, and provided theoretical calculation results for the detection range of a certain type of installed airborne infrared imaging detection system for 2m * 2m sized targets in the 3.7μm-4.8μm band at 9:00, 16:00, and 21:00 in a summer grassland background in a certain area. This provides support for the design and development of infrared imaging weapons and equipment.
This paper has carried out experiments on the influence of spectral resolution and channel number on the camouflage target recognition of imaging spectrometer. Based on the measured data, the camouflage helmet is selected as the spectral curve of camouflage target for resampling, and the spectral curve obtained under different spectral resolution and channel number conditions is simulated. Qualitative analysis is carried out by graphic method, interpolation operation is carried out on the resampling spectral data, and quantitative analysis is carried out by using SAM (Sepctral Angle Mapper) method. The resampling target characteristic spectral curve is compared with the original spectral curve in different ranges. The experimental conclusion is obtained by analyzing the spectral characteristics of the camouflage target under different spectral resolution and different channel number conditions, it can provide theoretical basis and technical support for the determination and optimization of spectral resolution and channel number of imaging spectrometer used for camouflage target recognition.
KEYWORDS: Optical fibers, Data transmission, Data communications, Time division multiplexing, Optical communications, Optical networks, Field programmable gate arrays, Passive optical networks, Fiber optic communications, Control systems
Passive Optical Network (PON), which possess the advantages of high efficiency, high speed and high bandwidth utilization, is a type of fiber channel technology that acquires the most concern. As a type of key technology in military weapon electronic system, the target of fiber channel data bus is to offer actual-time, high-speed and reliable communication link between instruments. In this article, a type of fiber channel data bus, which is based on PON topology, is raised and elaborated. The elaboration is concentrated on the designation of the topology and protocol used in the fiber channel data bus. On this basis, the research emphasis is the upstream Media Access Control (MAC) layer in the Network Terminal (NT) of the fiber channel data bus which is designed. Firstly, the upstream synchronization method and frame structure in GPON standards are analysed. Then, the upstream MAC layer control is actualized through Xilinx FPGA devices.
KEYWORDS: Data communications, Telecommunications, Fiber optics, Data transmission, Interfaces, Optical communications, Systems modeling, Optical fibers, System integration, Network architectures
A new kind of fiber optic data bus (fiber tree bus, FTB) is presented, mainly aiming at some defects of available standard bus, which is lack of real-time performance, has no information interactive transmission index, and uncontrollable transmission delay when it is applied in high bandwidth, distributed real-time information transmission and interactive conditions. The internal working mode, tree topology and Transfer protocol of FTB are designed. The main technical characteristics and real-time transmission performance of FTB are introduced in details. A photoelectric information transmission system has been established based on FTB, to meet the application requirements of the military vehicle-borne photoelectric system. It can access and transmit a variety of communication data at the same time, such as Gigabit Network, CAN, RS232, RS485, RS422, SDI, etc. The compared results of analysis and test show that the new bus system is capable of transferring a various types of real-time information. The characteristics and advantages of FTB application are summarized finally.
An infrared imaging spectrometer based on a variable gap interferometer is introduced, which is working in 7.7μm~14μm, and often used in spectral measurement, camouflage target detection and gas component identification. In this paper, the wedge prism shapes processed by grinding and diamond knife turning is compared, which affects the phase distribution near zero phase of the interferogram, and results in the difference of spectrum in the result. Finally, the turning process with less damage to the sharp edges was selected. An adjusting device and monitoring software are designed to ensure the symmetry of the wedge angle of the interference cavity with variable gap, so that two sides of the interferogram are sampled at equal intervals. The working mode is designed as the interferometer’s linear translation scan inside the imaging spectrometer. This working mode can reduce the volume of the system, and decrease the noise caused by the nonuniformity of the FPA response, improving signal-to-noise ratio. Stepper motor, rail and slide block are used to realize uniform reciprocating scanning. Finally, some measurement results using this infrared imaging spectrometer are presented.
With applications ranging from the desktop to remote sensing, the long wave infrared (LWIR) interferometric spectral imaging system is always with huge volume and large weight. In order to miniaturize and light the instrument, a new method of LWIR spectral imaging system based on a variable gap Fabry-Perot (FP) interferometer is researched. With the system working principle analyzed, theoretically, it is researched that how to make certain the primary parameter, such as, wedge angle of interferometric cavity, f-number of the imaging lens and the relationship between the wedge angle and the modulation of the interferogram. A prototype is developed and a good experimental result of a uniform radiation source, a monochromatic source, is obtained. The research shows that besides high throughput and high spectral resolution, the advantage of miniaturization is also simultaneously achieved in this method.
Interference imaging spectroscopy is the advanced subject among the infrared remote sensing, and it has become an important technique to detect spatial information and spectral information of targets. It has the advantages of high flux, high spectral resolution and high spatial resolution that can be used for detecting more details of the spectral and spatial information. Based on a Michelson interferometer with its mirrors replaced by corner-cubes, principles of a hand-held, static, long-wave infrared Fourier Transform(FT) imaging spectrometer using an uncooled microbolometer array are introduced. Because in such FT-based spectral imager, the interferogram is acquired over the whole field of the camera while the scene of interest scans the path difference range, vignetting should be strongly limited while keep the size of the interferometer as small as possible. Interferometer size is given and interferential light path is verified through TracePro software. First results of field and laboratory measurements using the spectral imager are presented. Remotely obtained spectrums collected with this instrument and with those of high precise Michelson spectrometer are compared, and the measured values turned out to be closely corresponded. The results, in turn, verified the feasibility of the systematic working mode. The resulting system tested here provides datacubes of up to 640×480 pixels over the 7.7~13μm spectral range, this wavelength range reveals important information about scenes such as gas or landmine detection, and the instrument has a spectral resolution of about 8cm-1 that fulfils the requirement for most targeted applications. Examples of sky and buildings detection are shown.
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