Lidar (light detection and ranging) remote sensing is a breakthrough of active remote sensing technology in recent years. It has shown enormous potential for forest parameters retrieval. Lidar remote sensing has the unique advantage of providing horizontal and vertical information at high accuracies. Especially it can be used to measure forest height directly with unprecedented accuracy. Large footprint lidar has demonstrated its great potential for accurate estimation of many forest parameters. The geoscience laser altimeter system (GLAS) instrument aboard the ice, cloud and land elevation satellite (ICEsat) has acquired a large amount of data including topography and vegetation height information. Although GLAS’ primary mission is the topographic mapping of the ice sheets of greenland and antarctica, it has potential use over land, especially for vegetation height extraction. These data provide an unprecedented vegetation height data set over large area. After a general discussion of GLAS waveform pre_processing, the waveform length extraction method has been developed. Then the waveform length from GLAS Laser 2a data in the northeast China was calculated. The waveform length map was analyzed together with land cover map from Landsat ETM+. The waveform length shows good accordant with land cover types from Landsat ETM+ data. As for forest area, the waveform length map contains much more information about forest height information, which can be used to inverse other forest parameters quantitatively together with other remote sensing data.
在研究现有距离-多普勒（RD）定位模型解法方法的基础上,发展了一种基于斜角坐标系变换的RD模型直接定位分析算法,并在定位过程中引进了数值解算方法,使该定位算法兼有了纯分析法和纯数值计算法的特点.利用一景ERS-2 SAR SLC数据比较评价了所发展算法与现有算法的定位效果,结果表明,该算法不仅定位精度较高,而且执行效率比纯粹的基于很多迭代过程的数值分析算法有了很大的提高.
