利用特征地物计算HJ-1卫星CCD波段间配准精度

自HJ-1双星成功发射后,两台设计原理完全相同的CCD相机分别搭载在HJ-1A、HJ-1B星上,其覆盖范围广、回访周期短,具有较高的空间分辨率和光谱分辨率。波段间的配准误差是评价影像质量的重要指标之一,也是传感器研发的一项重要参数。因此,对遥感多光谱影像进行波段间配准误差评价是十分必要的。本文以山东省东营市辛安水库库区为对象,提出了一种基于特征地物计算HJ-1卫星CCD波段间配准精度的算法。辛安水库形状独特,有多条条状水体和拦水坝且相互交叉排列。基于HJ-1卫星CCD相机4个波段的水库影像,分别提取出水库在沿轨和跨轨方向的像元响应与像元位置的关系,利用响应曲线中的峰、谷位置,计算出同名特征点在不同波段图像中的位置。根据位置的差异,计算出HJ-1卫星CCD相机波段间配准在沿轨方向和跨轨方向的实际偏移量。从而实现对影像波段间配准精度的评价。

Using Ground Features to Calculate Band to Band Registration Accuracy Based on CCD Data of HJ-1A/B

HJ-1A/B satellite, designed for observing the environment of water, atmosphere, and ecosystem, was launched successfully on September 6th, 2008 from Taiyuan Satellite Launching Centre. Its products have been widely used in many application areas, such as agriculture, forestry, land use, ecological environment and natural disasters, and greatly improved the ability of environment and disaster monitoring. There is a 4-band CCD cam-era boarded on both HJ-1A and HJ-1B platforms with the wavelength range from visible to near-infrared spec-trum. Different bands need to be combined together while retrieving the application products. The error of Band-to-Band Registration （BBR） is a significant parameter which can impact the image quality and product ac-curacy. Therefore, calculating the BBR of CCD is important for enhancement of its usage. In this paper, an ap-proach based on ground features is presented to compute BBR of HJ-1A/B CCD. In our approach, Xin’an reser-voir located in Dongying City, Shandong Province is selected as the target area, within which several water and dam strips are interlaced. In satellite images, the responses of water and dam have a strong contrast feature, which forming continuous peaks and troughs. There are three steps in our algorithm. Firstly, we used the reser-voir observation images in each band of CCD sensors to extract the pixel reflectance and pixel position to calcu-late the real position of the ground measurements. There are three procedures in second step, data preprocessing, radiometric calibration, and atmospheric correction. Finally, according to the deviations in the image of each band, the BBR was calculated in both along scan and along track directions. With several study cases, that the BBR of HJ-1A CCD1 in both along track and along scan directions is about 0.2 pixel for all bands except the band 2 whose along track BBR reaches 0.36 pixel and along scan BBR reaches 0.55 pixel;the BBR of HJ-1B for all bands is almost between 0.2 to 0.3 pixel.