Infrared Image Non-uniformity Correction Based on Joint Surface of Radiation and Environment Temperature

在传统红外图像非均匀性校正方法中,探测器均处在常温环境下,当探测器的环温在一个较宽的范围内变化时,这些方法的校正效果便会恶化、不适应。针对此问题,本文在原常温多点标定法的基础上提出了一种基于曲面拟合的校正方法,把原先标定曲线加上探测器环温维度扩展成标定曲面。随后的纵向对比实验和横向对比实验表明该方法能够显著降低非均匀性,并能适应环温变化的情况

Calculating model for equivalent thermal defocus amount in infrared imaging system

The main effect of temperature change on infrared imaging system is the focus shift of infrared lenses. This paper analyzes the equivalent influence on imaging between the temperature change and the defocus at room temperature. In order to quantify the equivalence, we define an equivalent thermal defocus amount (ETDA). The ETDA describes the distance of the photosensitive surface shifting at room temperature, which has the same effect on imaging as the temperature changes. To model the ETDA, the expression of the focal shift as a function of temperature is obtained by solving partial differential equations for the thermal effect on light path firstly with some approximations. Then point spread functions of the thermal effect and defocus at room temperature are modeled based on wave aberration. The calculating model of ETDA is finally established by making their PSFs equal under the condition that the cutoff frequency of infrared imaging systems is much smaller than that of infrared lens. The experimental results indicate that defocus of ETDA at room temperature has the same influence on imaging as the thermal effect. Prospectively, experiments at high/low temperature can be replaced by experiments at room temperature with ETDA

A line mapping based automatic registration algorithm of infrared and visible images

There exist complex gray mapping relationships among infrared and visible images because of the different imaging mechanisms. The difficulty of infrared and visible image registration is to find a reasonable similarity definition. In this paper, we develop a novel image similarity called implicit linesegment similarity(ILS) and a registration algorithm of infrared and visible images based on ILS. Essentially, the algorithm achieves image registration by aligning the corresponding line segment features in two images. First, we extract line segment features and record their coordinate positions in one of the images, and map these line segments into the second image based on the geometric transformation model. Then we iteratively maximize the degree of similarity between the line segment features and correspondence regions in the second image to obtain the model parameters. The advantage of doing this is no need directly measuring the gray similarity between the two images. We adopt a multi-resolution analysis method to calculate the model parameters from coarse to fine on Gaussian scale space. The geometric transformation parameters are finally obtained by the improved Powell algorithm. Comparative experiments demonstrate that the proposed algorithm can effectively achieve the automatic registration for infrared and visible images, and under considerable accuracy it makes a more significant improvement on computational efficiency and anti-noise ability than previously proposed algorithms

ZnSe-material phase mask applied to athermalization of infrared imaging systems

This paper reports a ZnSe-material phase mask that is applied to athermalization of a conventional infrared imaging system. Its principle, design, manufacture, measurement, and performance validation are successively discussed. This paper concludes that a ZnSe-material phase mask has a permissible manufacturing error 2.14 times as large as a Ge-material phase mask. By constructing and solving an optimization problem, the ZnSe-material phase mask is optimally designed. The optimal phase mask is manufactured and measured with a form manufacturing error of 1.370 μm and a surface roughness value of 9.926 nm. Experiments prove that the wavefront coding athermalized longwave infrared (LWIR) imaging system works well over the temperature range from -40°C to +60°C

Rectilinear-motion space inversion-based detection approach for infrared dim air targets with variable velocities

Dim targets are extremely difficult to detect using methods based on single-frame detection. Radiation accumulation is one of the effective methods to improve signal-to-noise ratio (SNR). A detection approach based on radiation accumulation is proposed. First, a location space and a motion space are established. Radiation accumulation operation, controlled by vectors from the motion space, is applied to the original image space. Then, a new image space is acquired where some images have an improved SNR. Second, quasitargets in the new image space are obtained by constant false-alarm ratio judging, and location vectors and motion vectors of quasitargets are also acquired simultaneously. Third, the location vectors and motion vectors are mapped into the two spaces, respectively. Volume density function is defined in the motion space. Location extremum of the location space and volume density extremum of motion space will confirm the true target. Finally, actual location of the true target in the original image space is obtained by space inversion. The approach is also applicable to detect multiple dim targets. Experimental results show the effectiveness of the proposed approach and demonstrate the approach is superior to compared approaches on detection probability and false alarm probability. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

遥感技术在塔里木河流域自然资源调查中的应用

该项课题应用航空遥感为主，结合多种信息资料，首次对我国最长的内陆河——塔里木河两岸进行资源与环境的综合性调查，完成了地貌、水系、土地类型、土地资源、土地利用、沙漠化、植被、胡杨林、草地等９种专题系列图件，共编制１∶１０万标准图幅专题图３１４幅，并编写了说明书，量算了资源、环境类型面积；获取了一套较新和系统完整的资源、环境数据；探讨了遥感应用的新方法，为合理制订流域规划和开发利用塔里木河的水资源等提供了依据