地球临边场景红外遥感成像仿真方法

Infrared remote sensing imaging simulation method for earth’s limb scene

地球临边场景仿真是卫星红外探测领域的关键组成部分,是空中高速目标远距离探测场景模拟的重要基础。临边观测下的地球表面近似于球面,传统的基于海洋三维形态并计算表面辐射特性的海洋红外图像仿真方法不适用。云层的厚度和高度对红外辐射传输特性的计算有重要影响,视云层为粒子团的处理方法会大大降低仿真的计算速度。因此,研究了海洋和云的红外辐射模型、地球-空间坐标系与红外相机坐标系的转换关系和大气传输模型,提出地球临边场景红外遥感成像仿真方法。根据场景组分的差异,分别建立海洋分布模型、多层云分布模型,并根据海洋和云层的红外辐射与反射特性,构建地球临边场景红外辐射模型。通过地球-空间坐标系与相机坐标系的转换关系,利用大气传输理论和传感器效应仿真,计算各观测角度的地球临边场景卫星遥感红外仿真图像。实验结果表明:仿真得到的红外图像画质清晰,符合地球临边场景红外辐射特性,其平均拉普拉斯算子和可达0.15,平均灰度梯度可达0.70。

Simulation of earth’s limb scene plays a key role in satellite infrared detection field.It is an important basis for long-range detection of high-speed airborne targets.In limb detection,the traditional infrared ocean simulation method based on three-dimensional ocean appearance and the calculation of radiation characteristics is not applicable,because the earth surface approximates a sphere.Also,the thickness and height of clouds have important influence on the calculation of infrared radiative transmission characteristics,where the method of considering the cloud as particle cluster would greatly reduce the speed of simulation.Therefore,the infrared remote sensing imaging simulation method for earth’s limb scene was established by conducting the infrared radiation model of ocean and cloud,the transformation relationship between earth-space coordinate system and infrared camera coordinate system,and the atmospheric transmission model.According to the components of scene,the ocean distribution model and multi-layer clouds distribution model were established respectively,and the infrared radiation model of the earth’s limb scene was established according to the infrared radiation and reflection characteristics of ocean and clouds.The infrared remote sensing simulation images of the earth’s limb scene under various observation angles were calculated by the conversion relationship between earth-space coordinate system and camera coordinate system,the theory of atmospheric transmission and the sensor effect.The simulation results show that the infrared image accord with the infrared radiation characteristics of earth’s limb scene.The average Laplacian sum of simulation images is 0.15,and the grayscale gradient average value of the images is 0.70.