星载激光测高系统数据处理和误差分析

发布时间：2018-04-26 05:17

本文选题：激光遥感 + 激光测高系统　；参考：《武汉大学》2013年博士论文

【摘要】：星载激光测高系统是一种主动式测量系统,通过接收卫星平台激光器发出的激光脉冲经地表反射的微弱回波,并精确计算激光脉冲在卫星和地面之间的渡越时间,得到卫星和地表的距离；结合卫星精密轨道和姿态数据,生成激光脚点精确地理位置和高程结果。通过卫星连续运行,最终得到覆盖地球表面DEM模型。激光测高系统发射的激光脉冲能穿透植被获取三维地形,具有传统摄影测量方式无法取代的优点；其激光发散角在亚毫弧量级,水平定位精度和分辨率远远高于微波雷达方式；位于大气透过窗口的1064nm波长激光可以直接被冰盖和海洋表面反射,几乎没有穿透效应,高程精度可达15cm。这些优点使其广泛用于南北极冰盖变化监测、极区附近海冰变化监测、植被年际变化监测,少量用于海洋环境监测等领域；如果作为遥感影像的地面高程控制点,可以生成1：10000的大比例尺地形图。 ICESat卫星搭载的GLAS系统于2003年发射升空,在轨间断运行7年,是目前为止唯一一颗用于全球地表观测的星载激光测高系统。对地球观测的GLAS系统的观测成果不仅包含器件本身所带来的误差,也包含如光束穿越大气产生的散射和折射,由章动和岁差等产生的固体潮汐等环境误差,以及由地表斜率或粗糙度等引起的目标误差。因此,建立测高系统回波和误差模型,以及完整的数据处理方法对激光测高系统参数设计、误差评估和数据产品的有效性和准确性至关重要。论文针对具有全波形记录功能、对地球观测的星载激光测高系统进行完整的回波理论和误差分析研究,完成了由测高系统原始回波数据直至高程数据产品的完整数据处理流程,并编写了批量数据处理软件。在回波理论方面,完善了星载激光测高系统固体地表的回波理论模型,建立了海洋表面回波理论模型,并完善了固体地表和海洋表面参数的反演理论；在误差分析方面,完善了固体地表的激光测距误差模型,建立了海洋表面距离和回波脉宽误差模型,并建立了完整的星载激光测高系统脚点高程误差分析模型；在数据处理方面,以GLAS系统为例,使用底层原始回波数据与ICESat卫星辅助工程数据进行粗略距离、精确距离、粗略高程和精确高程解算,生成最终高程数据产品,将中间过程和最终结果与NASA处理结果一一作对比验证,并改进了若干数据处理方法；在数据应用方面,结合美国宇航局GLAS测高数据、美国国家环境预报中心NCEP气象数据和丹麦科技大学ALS机载激光雷达数据,利用海洋回波模型和GLAS实测数据反演了海洋表面风速、波高结果,利用ICESa卫星交叉和重复脚点对估计了2003-2009年3月格陵兰岛2000m以上地区冰盖高程变化,并改进了交叉点的计算方法,利用ALS激光雷达数据生成GLAS激光脚点DEM图用于评估GLAS高程测量精度。使用海洋回波模型模拟的海洋回波与GLAS真实海面回波有很好的相似性,参数误差小于6%；利用GLAS数据反演的海平面上方风速与NCEP气象数据风速有较好的一致性；GLAS与TOPEX雷达测高数据计算的平均海平面也显示出较好一致性。GLAS数据处理过程距离粗值偏差小于2.5cm,距离修正偏差小于3cm,固体潮汐修正小于3mm,由GLA01原始回波数据解算的最终高程结果与GLAS结果对比,在斜率和粗糙度较小冰盖表面偏差可以控制在10cm以内。利用脚点高程精度和空间分辨率更高的ALS机载激光雷达数据与GLAS高程数据对比,结果符合所建立的高程误差模型,并验证在较平坦的冰盖表面,GLAS系统高程精度可以达到设计值-10cm。利用GLAS交叉和重复脚点对格陵兰岛2000m以上地区冰盖监测结果表明,2003-2009年3月份其冰盖表面高程年均增长3.80cm,标准差为0.91cm,交叉点和重复点结果趋势一致,重复点数量多但分布不均匀,使用ICESat数据分析格陵兰地区冰盖时,较大区域适合使用交叉点方法,较小区域适合使用重复点方法。论文最后加入了GLAS标准数据存储格式、数据分类等级以及不同数据等级间的转换关系,对于理解论文中数据处理和应用有一定帮助；基于VS2008平台用于激光测高系统数据处理的整套软件也进行了简单展示,包括使用C++语言编写的功能算子部分和VB语言编写的窗体操作部分,软件集数据读取、数据处理、数据分析和结果评价功能于一体。论文中数据处理流程和关键技术在对地观测的激光测高系统中具有较强通用性,对我国未来发射对地观测星载激光测高系统的数据处理具有借鉴意义；回波理论和误差模型对于星载激光测高系统的系统参数的优化设计和测量误差的评判具有重要意义。
[Abstract]:The satellite borne laser altimetry system is an active measurement system. By receiving the weak echo of the laser pulse from the satellite platform laser, and calculating the distance between the satellite and the ground accurately, the distance between the satellite and the ground is calculated accurately. Accurate location and elevation results. Finally, the DEM model covering the earth's surface is finally obtained through continuous operation of satellites.
The laser pulse emitted by the laser altimetry system can penetrate the vegetation to obtain the three-dimensional terrain, which has the advantages of the traditional photogrammetry. The laser divergence angle is at the sub milli arc, and the horizontal positioning accuracy and resolution are far higher than the microwave radar mode; the 1064nm wavelength laser located in the atmosphere through the window can be directly covered with ice cover and sea. Ocean surface reflection, almost no penetration effect, high range precision can reach 15cm., which make it widely used for monitoring change of Arctic ice cover, monitoring of sea ice change near polar region, monitoring of interannual variation of vegetation, small amount of application in marine environment monitoring and so on. If as ground elevation control point of remote sensing image, it can generate a big ratio of 1:10000. A topographic map of a ruler.
The GLAS system carried by the ICESat satellite is launched in 2003 and is running intermittently for 7 years. It is the only star borne laser altimetry system for global surface observation so far. The observation results of the earth observation GLAS system include not only the error caused by the device itself, but also the scattering and refraction of the beam through the atmosphere. The environmental errors such as nutation and precession, such as solid tides, as well as the target error caused by the slope or roughness of the surface. Therefore, the establishment of the echo and error model of the altimetry system and the complete data processing method are very important to the design of the parameters of the laser altimetry system, the error evaluation and the validity and accuracy of the data products.
In view of the full waveform recording function, the complete echo theory and error analysis of the earth observation satellite borne laser altimetry system are studied. The complete data processing flow from the original echo data of the altimetry system to the high range data product is completed, and the batch data processing software is written. In the echo theory, the satellite load is perfected. The theoretical model of the echo of the solid surface of the laser altimetry system is established, and the theoretical model of the sea surface echo is established, and the inversion theory of the surface and ocean surface parameters is perfected. In the error analysis, the laser range error model of the solid surface is perfected, the distance of the ocean surface and the error model of the echo pulse width are established, and the integrity of the model is established. In the aspect of data processing, using the GLAS system as an example, using the underlying original echo data and the ICESat satellite aided engineering data for rough distance, accurate distance, rough elevation and accurate elevation, the final elevation data products are generated, and the intermediate process and final result and NASA are used in data processing. The results are compared and verified, and a number of data processing methods are improved. In the field of data application, the sea surface wind speed is retrieved from the ocean echo model and the measured data from the ALS airborne laser radar data of the Technical University of Denmark, the American National Environment Forecast Center NCEP meteorological data and the Technical University of Denmark ALS airborne laser radar data. The results of wave height are estimated by using ICESa satellite crossover and repetition foot point to estimate the change of ice cover elevation in the area above 2000m of Greenland in March, and improve the calculation method of intersection point. Using ALS laser radar data to generate GLAS laser foot point DEM map to evaluate the accuracy of GLAS elevation measurement.
The sea echo simulated by the sea echo model has good similarity with the real sea surface echo of GLAS, and the parameter error is less than 6%. The wind speed above the sea level retrieved from the GLAS data is in good agreement with the wind speed of the NCEP meteorological data; the flat average sea level of the GLAS and the TOPEX radar altimetry data also shows a good consistency.GLAS number. According to the processing process, the distance deviation is less than 2.5cm, the distance correction deviation is less than 3cm, the solid tide correction is less than 3mm, the final elevation result calculated by the original GLA01 echo data is compared with the GLAS result, and the surface deviation of the slope and the roughness of the smaller ice cover can be controlled within 10cm. The higher accuracy of the foot point and the higher spatial resolution of ALS can be obtained. The airborne lidar data are compared with the GLAS elevation data. The results conform to the established elevation error model and verify that the GLAS system elevation accuracy can reach the designed value -10cm. on the flat surface of the ice cover. The results of the ice cover monitoring over the 2000m area above Greenland, using the GLAS cross and repeated feet, show that the ice cover table in March was 2003-2009. The average elevation is up to 3.80cm, the standard deviation is 0.91cm, the intersection point and the repeat point are the same, the number of repeat points is much more, but the distribution is uneven. When using ICESat data to analyze the ice cover in Greenland area, the larger area is suitable for using the intersection point method, and the smaller area is suitable for using the repeat point method.
At the end of the paper, the GLAS standard data storage format, the data classification level and the conversion relationship between different data levels have been helped to understand the data processing and application in the paper, and the software for the data processing of the laser altimetry system based on the VS2008 platform is also simply displayed, including the work written in the C++ language. Energy operator part and form operation part written in VB language, software set data reading, data processing, data analysis and result evaluation function in one.
The data processing flow and key technology in this paper have strong generality in the ground observation laser altimetry system, and have reference significance to the data processing of the satellite borne laser altimetry system in our country in the future, and the optimization design and measurement error of the echo theory and error model for the system parameters of the spaceborne laser altimetry system The judgment is of great significance.

【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：P225.2;P236

【参考文献】