摘要
严格的几何精校正可以提高遥感影像的实用价值。对于CASI(compact airborne spectrographic imager)推扫式单线阵航空高光谱传感器而言,由于每次飞行装机都要重新安装GPS(global positioning system)接收机、差分定位与惯性测量单元(inertial measurement unit,IMU),因此GPS、IMU和传感器之间的几何方位标定并不严格,从而导致外方位元素精度受到影响,几何校正结果不理想。为提高几何校正精度,需要依据共线方程,结合地面控制点,计算相应的辅助校正参数。然而实验区属于高海拔无人区,难以实施地面控制点测量,且无其他高精度正射影像可参考。为此实验以机载LiDAR(light detection and ranging)数据为辅助,一方面基于LiDAR高程信息生成数字高程模型;另一方面,通过对LiDAR回波强度信息进行校正,提高基于回波强度的地物判读性,并以回波强度图为参考选取控制点。然后,结合控制点和数字高程模型,完成了CASI高光谱影像的几何精校正。通过对航带间同名地物点坐标对比,证明其精度得到了很大提高。结果表明,利用LiDAR回波强度信息可以解决控制点缺少的问题,显著提高遥感图像几何校正精度,未来也可在地物分类等方面发挥更大作用。
Geometric precision correction is very important for improving the quality of remote sensing images.CASI( compact airborne spectrographic imager) is an airborne 1-dimensional pushbroom sensor,and must be integrated with GPS( global positioning system) receiver and IMU( inertial measurement unit) before performing data acquisition. Each time CASI is installed on airplane with GPS and IMU,the geometric parameters among them must be got precisely. Usually obtained by manual measurement,which is not a very accurate way,values of these parameters are not precise,which means the precision of exterior orientation elements is influenced,and finally lead to errors of geometric correction results. According to the collinear equation,which is the basic principle of geometric correction,auxiliary correction parameters should be applied to exterior orientation elements,and these can be calculated by taking some ground control points as reference. For the study area is depopulated,it’s hard to survey ground control points in field,and also there is no other high spatial resolution orthoimage which can be used,so how to get control points is the key problem. Li DAR( light detection and ranging) data contain many kinds of information,such as 3-dimensional coordinates,echo intensity,echo number. Li DAR data synchronously acquired with CASI was used from two aspects. First,the DEM of study area was produced mainly based on 3-dimensional coordinates. Besides that,the intensity image was also generated based on the echo intensity after it was calibrated,of which the main purpose was to improve its interpretation of ground objects. Then some control points were chosen by taking the Li DAR intensity image as reference. Combined with DEM and these control points,geometric precision correction of CASI image was completed. Through comparison of the coordinates of corresponding image points in two adjacent strips before and after correction aided by control points,the results showed that the geometric precision had been improved obvious
作者
伊丕源
童鹏
赵英俊
李瀚波
吴文欢
YI Pi-yuan;TONG Peng;ZHAO Ying-jun;LI Han-bo;WU Wen-huan(National Key Lab. of Remote Sensing Information and Image Analysis Technique, Beijing Research Institute of Uranium Geology, Beijing 100029, China)
出处
《科学技术与工程》
北大核心
2019年第14期22-28,共7页
Science Technology and Engineering
基金
国防重点实验室发展基金(遥ZS1802)
国防预研基金(321030204)资助
关键词
激光雷达
回波强度
航空高光谱
单线阵
控制点
几何校正
Li DAR
echo intensity
airborne hyperspectral
1-dimensional pushbroom sensor
control point
geometric correction
