天绘二号01组SAR图像质量评价

SAR image quality assessment of satellite TH-2-01

天绘二号01组卫星于2019年4月30日成功发射,包含高分辨率的合成孔径雷达以及高精度的星间相对状态测量设备等有效载荷,可以获取全天候、全天时的雷达干涉图像数据和辅助测量数据,用于科学试验研究、国土资源普查及测绘地理信息等领域。为了衡量该卫星的成像能力,本文利用基于点目标和基于面目标的多项SAR图像客观质量评价指标,对该星组两颗卫星的图像进行了客观、全面地评价分析。分析结果显示,天绘二号A星、B星的成像质量均可以达到卫星设计指标的要求,意味着天绘二号卫星图像在后续的目标区域选择与分析、图像目标识别、目标特征提取等应用中具有可靠的精度保证。两颗卫星的大部分客观指标基本相当,并且两颗卫星都满足距离向的空间分辨率优于方位向的空间分辨率,距离向的积分旁瓣比和峰值旁瓣比优于方位向。在距离向上,点目标的能量越集中,从雷达图像中检测出暗目标和弱目标的能力越强。通过试验分析,在距离向A星拥有更低的峰值旁瓣比,即在距离向成像质量上A星略优于B星。

The satellite TH-2-01 was successfully launched on April 30, 2019, equipped with the high-resolution synthetic aperture radar(SAR) and the high-precision inter-satellite relative state measurement equipment and other payloads, which was able to obtain all-day and all-weather InSAR image data and auxiliary measurement data for scientific experimental research, land and resources census, geographic information mapping and other fields. In order to measure the imaging capability of the satellite, we comprehensively evaluated and analyzed the satellite A and satellite B of TH-2-01 by employing objective quality evaluation indexes based on point target and area target. The analysis results prove that the imaging quality of both satellite A and satellite B are able to meet the requirements of the satellite design index, which means that the images of satellite TH-2-01 can meet high-accuracy in the application of target area selection and analysis, target identification, target feature extraction, etc. Most of the objective indexes of satellite A and satellite B are similar, and the spatial resolution in the range direction is better than that in the azimuth direction, and the values of the range direction integral side lobe ratio and the peak side lobe ratio are better than that in the azimuth direction, that is, the more concentrated the energy of the point targets is in the range direction, the better ability to detect the dark target and the weak target from the radar image. The experimental results show, the images of satellite A has lower peak side lobe ratio in the range direction, that is, satellite A is slightly better than satellite B in range direction imaging quality.