THE APPLICATION OF MINIATURE UNMANNED AERIAL VEHICLE IN 25 NOVEMBER 2016 ARKETAO MW6.6 EARTHQUAKE

In order to complete the field investigation to the 25 November 2016 Arketao M_W6.6 earthquake, ultra-low altitude remote-sensing data were obtained from miniature unmanned aerial vehicle. The surface rupture surveying has important significance for earthquake research. This paper selects the macro-epicenter of Arketao as the study area. The pictures were obtained with DJI Phantom 3 professional input into the software, the Digital Elevation Model (DEM), Digital Orthophoto Map (DOM) were acquired based on photogrammetry method using the overlapped optical remote-sensing images of UAV. Using these data, we can identify surface ruptures that have vertical dislocation. We selected six feature points and drew the elevation profile. In the elevation profile map, we chose smooth part of the surface rupture sides and obtained the trend line. A stable point in the surface rupture was selected and the abscissa of the point was taken into the equation of two straight lines. Then subtracting the results of the two equations, we can get the vertical dislocation of the surface rupture. On this basis, we chose six feature points and determined their vertical dislocation, which are between 4.4cm and 10.4cm. What's more, taking Bulungkou Xiang in Xinjiang Uygur Autonomous Region for example, we speculated some surface ruptures that have vertical dislocation. It can provide a new method for identifying surface rupture in the field. In addition, we get DEM data of the Bulunkou area where ambient conditions are very poor, by using miniature unmanned aerial vehicle and taking 255 photos. Putting those photos into the EasyUAV software, we got the area digital elevation of 2cm resolution. Comparing these data with RTK data, we summarized some practical problems and solutions in the practical operation and evaluated the accuracy of miniature unmanned aerial vehicle data. The Pearson Correlation Coefficient is 0.996 6. In terms of absolute elevation, the average result of UAV and RTK differs by 156.96m. In terms of relative elevation, the average result of UAV and RTK differs by 9.74m. Compared with the previous test of Pishan County, there is a notable divergence in the results. It shows that the data accuracy will be affected to some extent in the cold weather in high elevations. The specific impact needs further exploration.     

A classification method of building structures based on multi-feature fusion of UAV remote sensing images

In order to improve the accuracy of building structure identification using remote sensing images, a building structure classification method based on multi-feature fusion of UAV remote sensing image is proposed in this paper. Three identification approaches of remote sensing images are integrated in this method: object-oriented, texture feature, and digital elevation based on DSM and DEM. So RGB threshold classification method is used to classify the identification results. The accuracy of building structure classification based on each feature and the multi-feature fusion are compared and analyzed. The results show that the building structure classification method is feasible and can accurately identify the structures in large-area remote sensing images.     

Precision estimation and geomorphological analysis based on the DEM generated by InSAR: Taking Damxung-Yangbajain area as an example

Digital elevation model (DEM) can be generated by interferometric synthetic aperture radar (InSAR). In this paper, the interferometric processing and analyses are carried out for Damxung-Yangbajain area in Tibet, using a pair of Europe remote-sensing satellite (ERS)-1/2 tandem SAR images acquired on 6 and 7 April 1996. A portion of the In- SAR-derived DEM is selected and compared with the 1:50 000 DEM to determine the precision of the InSAR-derived DEM. The comparison indicates that the root mean squared er...     

APPLICATION OF DEM GENERATION TECHNOLOGY FROM HIGH RESOLUTION SATELLITE IMAGE IN QUANTITATIVE ACTIVE TECTONICS STUDY: A CASE STUDY OF FAULT SCARPS IN THE SOUTHERN MARGIN OF KUMISHI BASIN

Traditional method to generate Digital Elevation Model (DEM)through topographic map and topographic measurement has weak points such as low efficiency, long operating time and small range. The emergence of DEM-generation technology from high resolution satellite image provides a new method for rapid acquisition of large terrain and geomorphic data, which greatly improves the efficiency of data acquisition. This method costs lower compared with LiDAR (Light Detection and Ranging), has large coverage compared with SfM (Structure from Motion). However, there is still lack of report on whether the accuracy of DEM generated from stereo-imagery satisfies the quantitative research of active tectonics. This research is based on LPS (Leica Photogrammetry Suit)software platform, using Worldview-2 panchromatic stereo-imagery as data source, selecting Kumishi Basin in eastern Tianshan Mountains with little vegetation as study area. We generated 0.5m resolution DEM of 5-km swath along the newly discovered rupture zone at the south of Kumishi Basin, measured the height of fault scarps on different levels of alluvial fans based on the DEM, then compared with the scarp height measured by differential GPS survey in the field to analyze the accuracy of the extracted DEM. The results show that the elevation difference between the topographic profiles derived from the extracted DEM and surveyed by differential GPS ranges from -2.82 to 4.87m. The shape of the fault scarp can be finely depicted and the deviation is 0.30m after elevation correction. The accuracy of measuring the height of fault scarps can reach 0.22m, which meets the need of high-precision quantitative research of active tectonics. It provides great convenience for rapidly obtaining fine geometry, profiles morphology, vertical dislocations of fault and important reference for sites selection for trench excavation, slip rate, and samples. This method has broad prospects in the study of active tectonics.     

高起伏区无人机摄影测量精度评估?以西秦岭光盖山-迭山断裂为例

经过近10年的迅速发展,无人机摄影测量已成为活动构造研究的常用方法之一。但对于无人机摄影测量的精度评估,尤其是高起伏地区的精度评估存在不足。为此,选择白龙江北岸光盖山-迭山断裂沿线的黑峪寺、化马村,开展无人机摄影测量,并构建正射影像（DOM）和数字地表模型（DSM）,配合差分GPS测绘进行校正和精度验证。通过对比实测控制点和图像提取点分析点精度,通过对比实测剖面与提取剖面分析剖面精度。研究结果表明,未经控制点校正的图像提取点与实测点存在较大误差,水平误差为5～8 m,垂直误差为几十米至上百米,但通过少数控制点校正后,点精度可达20 cm以内;6条实测剖面与提取剖面（提取自控制点校正后的图像）平均垂直精度总体为分米级,即0.16～0.65 m,标准差为0.13～0.69 m,略低于低起伏区的精度,对于测量条件恶劣的高起伏区,该精度是可接受的;异常高的垂直误差常出现在地形突变、低矮植被密集、行走困难等测量条件不理想位置。图像控制点中心点的准确识别、提取剖面线的修正准确性等因素也会影响精度评估的可靠性。     

RESTORATION OF THE ORIGINAL TOPOGRAPHY OF THE XIAONANHAI LANDSLIDE IN CHONGQING AND CALCULATION OF ITS VOLUME

As documented in history, an M6¼ earthquake occurred between Qianjiang, Chongqing and Xianfeng, Hubei(also named the Daluba event)in 1856. This earthquake caused serious geological hazards, including a lot of landslides at Xiaonanhai, Wangdahai, Zhangshangjie and other places. Among them, the Xiaonanhai landslide is a gigantic one, which buried a village and blocked the river, creating a quake lake that has been preserved to this day. As the Xiaonanhai landslide is a historical earthquake-induced landslide, it is impossible to obtain the remote sensing image and DEM data before the earthquake, which brings certain difficulties to the estimation of landslide volume and the establishment of numerical simulation model. In this paper, the original topography before the earthquake is inferred by the methods of geomorphic analogy in adjacent areas and numerical simulation, and the volume of the Xiaonanhai landslide body is calculated. Firstly, the principle and application of UAV aerial photography are introduced. We employed an unmanned airplane to take pictures of the Xiaonanhai landslide and adjacent areas, yielding high-precision DOM images(digital orthophoto graph)and DEM data which permit generating terrain contours with a 25m interval. We also used the method of intensive manual depth measurement in waters to obtain the DEM data of bottom topography of Xiaonanhai quake lake. Based on field investigations, and combining terrain contours and DOM images, we described the sizes and forms of each slump mass in detail. Secondly, considering that the internal and external dynamic geological processes of shaping landforms in the same place are basically the same, the landforms such as ridges and valleys are also basically similar. Therefore, combining with the surrounding topography and landform of the Xiaonanhai area, we used MATLAB software to reconstruct two possible original landform models before the landslide. The original topography presented by model A is a relatively gentle slope, with a slope of 40°~50°, and the original topography presented by model B is a very high and steep slope, with a slope of 70°~80°. Thirdly, Geostudio software is used to conduct numerical simulation analysis on the slope stability. The safety factor of slope stability and the scale of landslide are analyzed under the conditions of static stability, seismic dynamic response and seismic dynamic response considering topographic amplification effect. The results show that large landslide is more likely to occur in model B, which is more consistent with the reality. In order to verify the credibility of recovered DEM data of valley bottom topography, we visited the government of Qianjiang District, collected the drilling data of 11 boreholes in two survey lines of Xiaonanhai weir dam. It is verified that the recovered valley bottom elevation is basically consistent with that revealed by the borehole data. Finally, according to the two kinds of topographic data before and after the landslide, the volume of the landslide is calculated by using the filling and excavation analysis function of ArcGIS software. There is a gap between the calculation results of filling and excavation, the filling data is 3×10⁶m³ larger than the excavation data. The reasons are mainly as follows: 1)Due to the disorderly accumulation of collapse blocks, the porosity of the accumulation body became larger, causing the volume of the fill to expand; 2)It has been more than 150a since the Xiaonanhai earthquake, and the landslide accumulation has been seriously reconstructed, therefore, there are some errors in the filling data; 3)The accumulation body in Xiaonanhai quake lake might be subject to erosion and siltation, this may affect the accuracy of the filling data. In conclusion, it is considered that the calculated results of the excavation are relatively reliable, with a volume of 4.3×10⁷m³.     

基于DEM的低阶地提取新方法

以相对易于提取的低阶地为研究对象, 提出了一种基于DEM的简便实用的低阶地提取方法。 以构建泰森多边形的方法生成拔河高度数据, 同时结合低阶地发育特征及低阶地分布区拔河高度频度统计, 提出低阶地拔河高度统计图中低阶地识别的客观标志, 从而形成了一套较为系统、 科学的基于DEM的低阶地提取分级方法, 为阶地的定量研究开拓了新思路。 在桑干河王家湾宽谷段进行实验, 结果表明低阶地提取结果与实际吻合较好, 该方法可以应用于阶地野外实测前的室内解译, 使野外调查工作更具有针对性。     

基于P5像对与GeoEye-1影像的近地表地层产状的提取

通过对P5立体像对、GeoEye-1影像的处理与分析,分别进行了数字高程模型的提取和地层的划分,用检查点法和目视检查法对提取的数字高程模型的误差评估结果显示,误差在5m以内,满足产状提取的要求.根据地层划分结果,在不同时代的地层边界处和同时代地层内部选择岩层三角面发育较好、产状相对稳定的区域,选取用于地层产状提取的点,...     

高分遥感影像震害提取的变化检测算法改进

本文针对遥感多时相变化检测应用于地震灾害信息提取中存在的问题, 提出一种改进算法, 通过搜索震后影像上建筑物在震前影像上对应区域周边一定范围内的影像相关性最大值(区域寻优)来代替传统上严格对应像元的相关系数值, 以减少因配准精度、 摄影方位、 地表高程、 建筑物高度等造成的同名地物变形对变化检测结果的影响, 提高基于相关系数变化检测的精度。 以都江堰市城区在2008年汶川地震震前的QuickBird影像和震后的航空遥感影像为实验对象, 采用本文方法进行了震害变化检测实验, 并与传统方法进行了比较, 表明改进的算法能够提高震害信息提取的精度且具有一定的稳定性。     

Evaluation of DEM generation based on Interferometric SAR using TanDEM-X data in Tokyo

This study is focused on the evaluation of a Digital Elevation Model (DEM) for Tokyo, Japan from data collected by the recently launched TerraSAR add-on for Digital Elevation Measurements (TanDEM-X), satellite of the German Aerospace Center (DLR). The aim of the TanDEM-X mission is to use Interferometric SAR techniques to generate a consistent high resolution global DEM dataset. In order to generate an accurate global DEM using TanDEM-X data, it is important to evaluate the accuracy at different sites around the world. Here, we report our efforts to generate a high-resolution DEM of the Tokyo metropolitan region using TanDEM-X data. We also compare the TanDEM-X DEM with other existing DEMs for the Tokyo region. Statistical techniques were used to calculate the elevation differences between the TanDEM-X DEM and the reference data. Two high-resolution LiDAR DEMs are used as independent reference data. The vertical accuracy of the TanDEM-X DEM evaluated using the Root Mean Square Error (RMSE) is considerably higher than the existing global digital elevation models. However, the local area DEM generated by Geospatial Information Authority of Japan (GSI DEM) showed the highest accuracy among all non-LiDAR DEM’s. The vertical accuracy in terms of RMSE estimated using the 2 m LiDAR as reference is 3.20 m for TanDEM-X, 2.44 m for the GSI, 7.00 m for SRTM DEM and 10.24 m for ASTER-GDEM. We also compared the accuracy of TanDEM-X with the other DEMs for different types of land cover classes. The results show that the absolute elevation error of TanDEM-X is higher for urban and vegetated areas, likewise to those observed for other global DEM’s. This is probably because the radar signals used by TanDEM-X tend to measure the first reflective surface that is encountered, which is often the top of the buildings or canopy. Hence, the TanDEM-X based DEM is more akin to a Digital Surface Model (DSM).     

地震灾后区域无人机GPS遥感定位技术研究

传统基于云计算的地理位置定位方法进行目标定位时需要分析大量的地理数据信息,造成目标定位过程复杂且容易出现定位差错。提出新的地震灾后区域无人机GPS遥感定位方法,其功能包括遥感传感子系统、遥感空中控制子系统、无人机平台、无人机地面控制子系统、三维模型影像重建以及目标定位分析。重建地震灾区的三维影像模型时,先提取地震灾区的DEM数据,将无人机GPS遥感测量得到的影像纹理映射到DEM上,构建地震灾区的三维地物模型;目标定位分析采用测距目标定位法,利用无人机在不同位置对目标进行定位分析,实现对地震灾后区域的定位分析,得到目标的坐标结果。实验结果说明,所提方法能提高目标定位的精度,缩短目标定位用时。     

Effect of uncertainty in Digital Surface Models on the extent of inundated areas

The impact of uncertainty in ground elevation on the extent of areas that are inundated due to flooding is investigated. Land surface is represented through a Digital Surface Model (DSM). The effect of uncertainty in DSM is compared to that of the uncertainty due to rainfall. The Monte Carlo method is used to quantify the uncertainty. A typical photogrammetric procedure and conventional maps are used to obtain a reference DSM, later altered to provide DSMs of lower accuracy. Also, data from the Shuttle Radar Topography Mission are used. Floods are simulated in two stages. In the first stage, flood hydrographs for typical return periods are synthesized using generated storm hyetographs, the Soil Conservation Service–Curve Number method for effective rainfall, and the Soil Conservation Service synthetic unit hydrograph. In the second stage, hydrographs are routed via a one‐dimensional hydraulic model. Uncertainty in DSM is considered only in the second stage. Data from two real‐world basins in Greece are used. To characterize the inundated area, we employ the 90% quantile of the inundation extent and inundation topwidth for peak water level at specific river cross‐sections. For topwidths, apart from point estimates, also interval estimates are acquired using the bootstrap method. The effect of DSM uncertainty is compared to that for rainfall. Low uncertainty in DSM is found to widen the inundated area; whereas, the opposite occurred with high uncertainty. SRTM data proved unsuitable for our test basins and modelling context.     

Micro Landform Extraction Based on UAV Photography Technology?Taking Kunzhong Fault (Balong Wenquan Section) as An Example

无人机测量具有高清晰度、大比例尺、小面积、高现势性的优点,为地貌参数获取提供更准确可靠的活动构造定量参数,克服传统测量方法工作量大、效率低、受自然条件限制等缺点,可提供厘米级定位数据,从而显著提升图像元数据的绝对精度。利用大疆精灵4 RTK小型多旋翼高精度航测无人机,获取昆中断裂（巴隆-温泉段）在龙通村北的高精度DEM地貌数据,通过对微地貌的提取,初步确定断裂在该处的水平位错量为2.1～15.4 m。分析获取的8条陡坎剖面,认为其中5条陡坎形成后受到水流侵蚀作用较小,陡坎高度基本相似,断裂实际垂直位错量为0.6～0.9 m。研究结果表明,无人机航测技术是识别复杂地貌构造信息并提取相关活动构造参数的有效手段,可为断裂的定量研究提供可靠的数据基础。     

利用遥感图像数据基于模板匹配的震毁灾损研究

有效评估震灾损失可及时、可靠地了解地震灾区实时情况,提高破坏性地震下人们的反应能力,满足应急指挥需求。为提高震灾损失评估精度,对所获取遥感图像进行滤波及局部灰度调整处理,提出基于遥感图像模板匹配的震毁灾损研究。首先获取震区的遥感影像,考虑所获取图像与模板图像的偏移状况对图像进行模板匹配,提取与模板匹配后特征区域的特征值,获取空间网格点上的成像值,依据成像点自动评估震灾损失,其中能量最大的点即为震害受损最严重的位置,对图像所有内廓像素点结果进行遍历,确定提取地震灾区整体的受损特征结果。仿真实验发现,所提方法可提取出震灾损失状况,初步为地震灾害损失评估提供参考借鉴,但仍需要进一步研究,以提高方法的普遍适用性。     

DATA COMPARATIVE ANALYSIS BETWEEN SFM DATA AND DGPS DATA: A CASE STUDY FROM FAULT SCARP IN THE EAST BANK OF HONGSHUIBA RIVER,NORTHERN MARGIN OF THE QILIAN SHAN

With the development of the techniques acquiring high-resolution digital terrain data,the digital terrain data acquisition technology has been widespread applied to the geoscience research.A revolutionary,low-cost and simply operative SfM (Structure from Motion) technology will make obtain high-resolution DEM data more convenient for researches on active tectonics.This paper summarizes the basic principles and workflows of SfM technology and processes and selects the Hongshuiba River area along the northern margin of the Qilian Shan to conduct data collection.We use a series of digital pictures to produce a texture with geographic information,in which data resolution is 6.73cm/pix and average density of point cloud is 220.667 point/m².The coverage area is 0.286km².Further,in order to compare the accuracy between SfM data and differential GPS (DGPS) data in details,SfM data are vertically shifted and tilt-corrected.After optimizing corrections of SfM data,the absolute value of elevation difference between two data substantially concentrates around 20cm,roughly equivalent to 2-folds of data error only after the elevation error correction.Elevation difference between two data is 10~15cm in 90% confidence interval.The maximum error is about 30cm,but accounts for less than 10%.Along the direction of fault trace,the height of fault scarp extracted from SfM data shows that vertical displacement of the latest tectonic activity in the east bank of Hongshuiba River is about 1m,and some minimum scarps height may be 0.3m.The results show SfM technology with high vertical accuracy can be able to replace differential GPS in high-precision topographic survey.After correcting of SfM data,elevation difference still exists,which may be associated with methods of generating DEM and SfM data accuracy,which in turn is controlled by the number and distribution of Ground Control Points (GCPs),photos density and camera shooting height,but also related to surface features,Fodongmiao-Hongyazi Fault     

遥感影像的分类评价及可视化分析——以平顶山市平煤矿区附近区域为例

选取平顶山平煤矿区附近区域作为研究区,使用无人机进行拍摄,以获悉矿区周边地物种类,补充辅助决策中的居民地、道路等信息,重点研究遥感影像的分析处理.为实现遥感影像分类并增强可视化效果,以无人机影像为源图像,分别采用无人机正射影像的主流处理软件Photoscan和Pix4d,完成图像的预处理及拼接,发现利用Pix4d软件进...     

基于迭代融合的InSAR技术获取数字高程模型研究

数字高程模型是重要的地理空间数据,可以提供丰富的地形信息.为了获得时效性好、分辨率高的数字高程模型,本文以南京市为实验区域,利用德国宇航局TerraSAR-X卫星同一轨道上的两幅StripMap模式SAR影像对,主从影像时间间隔只有66天,空间分辨率为3 m.采用InSAR技术,通过迭代的方法来提高获取DEM的分辨率,并结合JAXA/EORC提供的AW3D30数字表面模型与迭代后的DEM进行融合来解决阴影等问题,最终获取了南京地区的高精度数字高程模型.将实验结果分别与90 m分辨率的SRTM、30 m分辨率的ASTER GDEM、30 m分辨率的AW3D30进行相互对比分析.结果表明,相比三种常用的DEM而言,本文获取的DEM能够更精确的获取地面的细节信息,特别是对于分布稀疏的大型单体建筑物,能够很好的恢复其三维信息,但是对于建筑物分布较为密集的区域,由于传感器视线受阻,不能观测建筑物的全貌,阴影分布较多,导致此类区域的DEM结果不理想,还需进一步深入研究,提高精度及可靠性.     

基于深度学习网络的地震地质灾害识别研究

遥感影像识别方法是破坏性地震震后地质灾害快速、准确获取的重要方法之一,传统的遥感影像识别方法主要以人工目视识别方法和半自动识别方法为主,需投入大量的人力和时间。针对破坏性地震震后地质灾害解译时间长、投入人力多等问题,以2017年8月8日四川九寨沟7.0级地震震后高分辨率无人机遥感影像为研究样本,提出基于深度学习网络的地震地质灾害识别方法。首先结合震后遥感影像解译资料和现场调查资料,提取九寨沟地震地质灾害无人机遥感影像特征,并构建研究区地震地质灾害解译指标和分类数据集;然后采用DeepLabv3+网络结构及softmax损失函数,建立基于深度学习网络的地震地质灾害遥感影像图像语义分割模型方法;最后采用半监督学习方法进行结果验证。研究结果表明,基于深度学习网络的地震地质灾害识别方法可有效识别九寨沟地震地质灾害分布信息,整体分类识别准确率为94.22%,F₁分数值为0.77,结果具有较好的一致性和准确性,可提升地震现场灾情获取和重点地震隐患识别等工作效率及服务能力。     

基于梯度变换的浅水湖泊围网区遥感提取算法

获取并掌握浅水湖泊围网养殖区域的时空分布信息对合理规划围网养殖进而提升湖泊水质具有重要意义.本文以长江下游典型的围网养殖浅水湖泊——阳澄湖作为研究区,利用资源三号(ZY-3)高分遥感影像,针对围网区与非围网区的光谱空间变化特征,采用梯度变换方法,尝试提出一种浅水湖泊围网区的遥感提取算法;并以人工解译结果作为参考,对提取结果进行验证.研究结果发现该算法对浅水湖泊围网养殖区的提取精度为90.66%,可进一步用于开展长时序的浅水湖泊围网区动态变化研究,进而为湖泊环境的政府部门制定湖泊水质提升和围网区合理规划政策提供决策依据.     

基于CryoSat-2测高数据的全南极冰盖DEM的建立与精度评估

数字高程模型(DEM)是南极冰盖变化研究的基础,由于现场实测数据的稀缺,卫星测高数据是南极地区构建DEM的'主要数据来源.CryoSat-2是新一代用于极地冰盖、海冰监测的测高卫星,本文利用2012-12-2015-01两个完整周期的CryoSat-2测高数据建立一个新的南极冰盖DEM.坡度是影响卫星测高精度的重要因素之一,利用改进的重定位方法对CryoSat-2数据进行坡度改正.插值方法是影响DEM精度的重要因素,通过对几种常用插值方法的比较,最后选用克里金插值方法对测高数据进行插值,建立了1km分辨率的南极DEM.在88°S以南的CryoSat-2数据空白区,利用南极数字数据库(ADD)的等高线数据对DEM进行填补,建立了全南极冰盖DEM.利用ICESat卫星测高数据、IceBridge航空测高数据以及GPS地面实测数据对新建立的CryoSat-2 DEM进行精度验证,并与Bamber 1 km DEM、ICESat DEM、RAMPv2 DEM以及JLB97 DEM等四种国际上常用的南极DEM进行比较.结果表明:新建立的CryoSat-2 DEM的整体精度约为0.730±8.398 m;在冰弯顶部区域,DEM精度优于1 m;在冰架上,DEM精度约为4 m;在内陆冰盖大部分地区,DEM精度优于10 m;在地形复杂的山区和沿海边缘地区,DEM误差超过150 m.