真正射纠正中地物遮挡区域自动检测与标识方法研究

本文基于真正射纠正的原理,探讨了图像遮挡区域处理的方法。针对真正射纠正中重叠区域和建筑物遮挡区域等影像的检测与标识问题,基于Z-Buffer算法和阈值选择法,通过将图像一分为四进行真正射纠正对Z-Buffer算法进行改进。试验表明,所提出的改进算法能够实现快速真正射纠正,具有良好的应用效果。     

城市大比例尺真正射影像阴影与遮挡问题的研究

为解决城市大比例尺正射影像生成的问题,从真正射影像的关键技术入手,着重研究其中的阴影与遮挡问题并提出相应解决方法。将这些方法应用在美国丹佛城区的真正射影像生成的项目中,取得了令人满意的效果。     

基于光谱和纹理特征的山区高分辨率遥感影像分类

本文在只做阴影补偿而不做地形校正的情况下,使用光谱和纹理特征相结合的方法进行山区高分辨率遥感影像分类。实验取得了78%的分类精度,表明该方法合理可行,具有一定的实用性。     

低低卫卫跟踪恢复地球重力场的误差分析

基于卫星轨道的动力学积分法,定量分析了SST-LL模式主要有效载荷测量误差对重力场恢复结果影响的特点及相互关系。结果表明,1μm/s的星间距离变化率误差与10-9m/s2的非保守力测量误差所引起的重力场误差基本相当,不同载荷的测量精度应相互匹配,单独提高某一载荷的精度对改善重力场并无多大意义。     

Change detection in urban areas by object-based analysis and on-the-fly comparison of multi-view ALS data

The use of helicopters as a sensor platform offers flexible fields of application due to adaptable flying speed at low flight levels. Modern helicopters are equipped with radar altimeters, inertial navigation systems (INS), forward-looking cameras and even laser scanners for automatic obstacle avoidance. If the 3D geometry of the terrain is already available, the analysis of airborne laser scanner (ALS) measurements may also be used for terrain-referenced navigation and change detection. In this paper, we present a framework for on-the-fly comparison of current ALS data to given reference data of an urban area. In contrast to classical difference methods, our approach extends the concept of occupancy grids known from robot mapping. However, it does not blur the measured information onto the grid cells. The proposed change detection method applies the Dempster–Shafer theory to identify conflicting evidence along the laser pulse propagation path. Additional attributes are considered to decide whether detected changes are of man-made origin or occurring due to seasonal effects. The concept of online change detection has been successfully validated in offline experiments with recorded ALS data streams. Results are shown for an urban test site at which multi-view ALS data were acquired at an interval of 1 year.