Disparity-Based Generation of Line-of-Sight DSM for Image-Elevation Co-Registration to Support Building Detection in Off-Nadir VHR Satellite Images

The integration of optical images and elevation data is of great importance for 3D-assisted mapping applications. Very high resolution (VHR) satellite images provide ideal geo-data for mapping building information. Since buildings are inherently elevated objects, these images need to be co-registered with their elevation data for reliable building detection results. However, accurate co-registration is extremely difficult for off-nadir VHR images acquired over dense urban areas. Therefore, this research proposes a Disparity-Based Elevation Co-Registration (DECR) method for generating a Line-of-Sight Digital Surface Model (LoS-DSM) to efficiently achieve image-elevation data co-registration with pixel-level accuracy. Relative to the traditional photogrammetric approach, the RMSE value of the derived elevations is found to be less than 2 pixels. The applicability of the DECR method is demonstrated through elevation-based building detection (EBD) in a challenging dense urban area. The quality of the detection result is found to be more than 90%. Additionally, the detected objects were geo-referenced successfully to their correct ground locations to allow direct integration with other maps. In comparison to the original LoS-DSM development algorithm, the DECR algorithm is more efficient by reducing the calculation steps, preserving the co-registration accuracy, and minimizing the need for elevation normalization in dense urban areas.

Imaging simulation and analysis of attitude jitter effect on topographic mapping for lunar orbiter stereo optical cameras

The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo mapping camera equipped on lunar orbiter before launching.In this work,an imaging simulation method consid-ering the attitude jitter is presented.The impact analysis of different attitude jitter on terrain undulation is conduct-ed by simulating jitter at three attitude angles,respectively.The proposed simulation method is based on the rigor-ous sensor model,using the lunar digital elevation model(DEM)and orthoimage as reference data.The orbit and attitude of the lunar stereo mapping camera are simulated while considering the attitude jitter.Two-dimensional simulated stereo images are generated according to the position and attitude of the orbiter in a given orbit.Experi-mental analyses were conducted by the DEM with the simulated stereo image.The simulation imaging results demonstrate that the proposed method can ensure imaging efficiency without losing the accuracy of topographic mapping.The effect of attitude jitter on the stereo mapping accuracy of the simulated images was analyzed through a DEM comparison.

Estimation and mapping of water erosion and soil loss:Application of Gavrilovic erosion potential model(EPM)using GIS and remote sensing in the Assif el mal Watershed,Western high Atlas

Water erosion is a serious problem that leads to soil degradation,loss,and the destruction of structures.Assessing the risk of erosion and determining the affected areas has become crucial in order to understand the main factors influencing its evolution and to minimize its impacts.This study focuses on evaluating the risk of erosion in the Assif el mal watershed,which is located in the High Atlas Mountains.The Erosion Potential Model(EPM)is used to estimate soil losses depending on various parameters such as lithology,hydrology,topography,and morphometry.Geographic information systems and remote sensing techniques are employed to map areas with high erosive potential and their relationship with the distribution of factors involved.Different digital elevation models are also used in this study to highlight the impact of data quality on the accuracy of the results.The findings reveal that approximately 59%of the total area in the Assif el mal basin has low to very low potential for soil losses,while 22%is moderately affected and 19.9%is at high to very high risk.It is therefore crucial to implement soil conservation measures to mitigate and prevent erosion risks.

基于MAPGIS的DEM制作技术研究

结合具体的项目工程,主要以MAPGIS软件对DEM制作的过程和遇到的技术问题进行了探讨研究,比较分析了不同数据转换方式的差异,有效地实现了从DGN格式数据到最终DEM的生成,并在制作过程中优化了数据流程.

基于VRMap平台上的电子沙盘研制

通过与国内外数字沙盘制作方式及功能的比较,详细介绍了数字沙盘研究方面的一些方法,并以中原油田数字沙盘的研制为例,选择北京灵图公司的VRMap2 3软件作为平台制作中原油田数字沙盘,为油田开发提供基本资料。

基于MAPGIS平台下三维效果地质图的生成

阐述了基于MAPGIS平台,完成地形图从二维到三维效果图的转换,在此基础上叠加套合二维地质图,从而生成一幅三维效果地质图。设置不同的飞行参数可以进行不同方位的观察。

基于MapBasic下MapInfo地形分析功能的扩展

MapBasic语言是地理信息系统 (GIS)软件MapInfo提供给用户进行二次开发的一个系统工具 ,能够用来扩展MapInfo的功能。本文给出了在MapBasic开发环境中如何实现由二维矢量地图生成数字高程模型(DEM)和由数字高程模型 (DEM)生成坡度图和坡向图 ,并给出了具体算法和实现过程。

An Object-based Approach for Two-level Gully Feature Mapping Using High-resolution DEM and Imagery： A Case Study on Hilly Loess Plateau Region, China

Gully feature mapping is an indispensable prerequisite for the motioning and control of gully erosion which is a widespread natural hazard. The increasing availability of high-resolution Digital Elevation Model(DEM) and remote sensing imagery, combined with developed object-based methods enables automatic gully feature mapping. But still few studies have specifically focused on gully feature mapping on different scales. In this study, an object-based approach to two-level gully feature mapping, including gully-affected areas and bank gullies, was developed and tested on 1-m DEM and Worldview-3 imagery of a catchment in the Chinese Loess Plateau. The methodology includes a sequence of data preparation, image segmentation, metric calculation, and random forest based classification. The results of the two-level mapping were based on a random forest model after investigating the effects of feature selection and class-imbalance problem. Results show that the segmentation strategy adopted in this paper which considers the topographic information and optimal parameter combination can improve the segmentation results. The distribution of the gully-affected area is closely related to topographic information, however, the spectral features are more dominant for bank gully mapping. The highest overall accuracy of the gully-affected area mapping was 93.06% with four topographic features. The highest overall accuracy of bank gully mapping is 78.5% when all features are adopted. The proposed approach is a creditable option for hierarchical mapping of gully feature information, which is suitable for the application in hily Loess Plateau region.

MAPGIS软件在绘制激电测深断面图方面的应用

本文主要介绍了SURFER图件到M APG IS图件的转换,使用M APG IS软件中的图象转换、控制点文件及图件“误差校正”等功能绘制激电测深断面图的详细方法和步骤,解决了剖面地形起伏不平和AB/2供电极距不等间距情况下计算机制作激电测深断面图方面的难题。

Global Mapper软件在复杂地表条件下的应用

复杂地表条件给施工前的踏勘、施工设计、试验点选择、表层点位布设带来很大的难度,以往只依赖于纸质地形图的施工方法难以满足复杂的施工要求。复杂地表条件下合理的表层点位布设一直是困扰技术人员的难题,特别是二维施工,测网稀、施工范围广、穿过障碍物多,逐条测线踏勘浪费大量的人力物力,提高踏勘效率及提供合理的测线调整方案是地震采集人员急需解决的问题。Global Mapper软件结合数据库及其强大的功能,在复杂地表的施工中,能很好地解决以上技术难题,大大提高了施工效率。

Floodplain Mapping of Nashwaak River,Canada:An Assessment Based on High-Resolution Hydraulic Simulation

Recent advances in hydraulic modeling create improved methodology to accurately predict the extent of floodplain map in order to assist policy makers to develop flood hazard mitigation measures and timely inform the local communities with the flood risk alerts.However,accurate prediction of the inundation map also depends on the spatial resolution of the topographic data.In this study,we developed a novel high-resolution modeling framework for Nashwaak River watershed,New Brunswick,Canada to capture significant flooding along the banks of the river for the two historic flood events and accurately map the floodplains for both the gauged and ungauged areas of the watershed.The model is based on HEC-RAS(US Army Corps of Engineers Hydrologic Engineering Center River Analysis System)hydraulic model and the topographic data were generated from high-resolution LiDAR data of~0.5 m.The model runs were driven by observed flow conditions applied at the boundary and the framework is based on different spatial resolution to determine the effect of spatial resolution on the predicted inundation.We validated the model simulated water surface elevation with the observed data and the model reproduces reasonably good skill score.Results from the numerical simulation suggest that apart from the strength of the stream velocity,design of the modeling framework plays an important role in determining the inundation depth as well as the maximum flooding extent.

MAPGIS软件在矿区重金属元素环境累积效应研究的应用

矿产资源开发引起的重金属污染是人们对资源利用过程中主要环境问题之一。如今,重金属污染的问题已经十分严重,时刻威胁着我们的生活质量。如何通过模拟分析等手段,借助“3S”技术,达到对矿区重金属元素环境累积效应危害的研究分析是当前重要的课题。针对MAPGIS6.7制图工作的一点经验做以总结,旨在使矿区环境污染研究者了解MAPGIS软件在研究重金属环境累积效应中的一点应用。

Facility Mapping of University of Lagos

This paper shows a detailed methodology for creating 2D and 3D visual facility map of the campus. The purpose of this study work is to develop an interactive interface containing the 2 and 3-Dimensional features of all the facilities within the University of Lagos. The spatial attributes of the facilities were collected with the aid of total stations. The most recent Google earth software was used as source of data to produce 2-dimensional facilities of the study area through digitization process. SRTM Digital elevation model image was downloaded from United State Geological Survey website to give the elevation data required for the 3-dimensional representation. All these data were processed with ArcGIS 10.2.1.

Digitally Mapping the Hydro-Topographical Context for Community Planning: A Case Study for the Upper Choapa River Watershed in Chile

Urban and non-urban settlements in many regions are usually located on the lands bordering shores, rivers, canals or streams. However, housing complexes, landfills, and areas for agriculture and mining are often assigned to locations without sufficiently detailed hydrographic information about subsequent potential if not actual flow and flooding impacts. Yet, for sustainable community planning with emphasis on harmonizing social, economic, environmental and institutional aspects, such information is essential. This article demonstrates how this need can in part be accommodated by way of digital elevation and wet-area modelling and mapping using the upper component of the Choapa watershed in Chile as a case study. The terrain of this area has sharply incised valleys, with communities, fields and roads strung narrowly along the Choapa River and its tributaries. Above these locations along the Estero de Los Pelambres near the Chile-Argentina border are major mining and mineral refining activities. This article provides modelling and mapping details about the wet-to-moist area zonation along the upper Choapa River valleys, and addresses some of the mining-induced changes from 2000 to 2010.

Environment map building and localization for robot navigation based on image sequences

SLAM is one of the most important components in robot navigation. A SLAM algorithm based on image sequences captured by a single digital camera is proposed in this paper. By this algorithm, SIFT feature points are selected and matched between image pairs sequentially. After three images have been captured, the environment’s 3D map and the camera’s positions are initialized based on matched feature points and intrinsic parameters of the camera. A robust method is applied to estimate the position and orientation of the camera in the forthcoming images. Finally, a robust adaptive bundle adjustment algorithm is adopted to optimize the environment’s 3D map and the camera’s positions simultaneously. Results of quantitative and qualitative experiments show that our algorithm can reconstruct the environment and localize the camera accurately and efficiently.

Quantitative Estimation of Altimetric Variations Using Residual DEM from Topographical Maps between Two Epochs 1893 and 1985: Case Study: The Endorheic Basin of Enfidha-Tunisia

This article endeavours to analyse the recent deformation in the Enfidha region. This analysis has been carried out using the Residual Digital Elevation Model (DEM). It is the altimetric difference between two DEM generated from the contour lines of two topographical maps over a period of 100 years. This deformation has been studied by some authors who report the presence of recent ground movements by comparing contour lines with a downward trend in elevation from 1893 to 1985. In 2006, this study area was marked by the presence of two earthquakes that occurred in several coastal cities located in the northeastern part of Tunisia. Our study involves a quantitative estimation of altimetric variations under a Geographic Information System (GIS) environment. Our proposed methodology aims at the mapping of residual (DEM) and the extraction of parameters that have a morphological and morphostructural signature. The extraction of quantitative morphostructural parameters requires the integration of multi-source and multi-scale data. This can only be done if the problem of heterogeneity at the level of scale and coordinate system is solved through the use of GIS tools and the obtainment of the vectorial shapefile format. Then, in order to compare the DEM generation errors with reference to recent and old data, they must be projected in the same projection system and on the same scale. The available data are two topographic maps of Enfidha which represent two different epochs. The first one is an old topographic map of 1893 (type 1922) at a scale of 1:50,000 and the second one is a recent topographic map of 1985 at a scale of 1:25,000. These topographical maps have the Lambert (IGN) projection system. This methodological approach, based on residual (DEM), allows to highlight an estimated subsidence of 3 m/100years located in the Enfidha plain and extends to the south coast of Cap Bon area in Tunisia. The variation of the contour lines shape between the old and the recent map can be studied in correlation with a relay structure fault observed and recognized by some analysts in this area. These relay accidents remain active according to the results obtained by the residual (DEM) and validated by the field observations of two sites that we have carried out in the Enfidha endorheic basin.

Global Mapper软件在新建铁路预可研阶段选线中的应用

新建铁路项目前期投入较少的人力、物力,缩短项目周期是设计单位所需解决的问题,因此选线过程中快速生成多方案的地形DEM数据模型尤为重要。Global Mapper软件作为一款小型地理信息软件,应用软件专题地图制作功能,可绘制项目地理位置示意图、线路平纵断面缩图,易于操作,出图效率高。该软件支持栅格、矢量、高程数据等多种显示和处理,应用全球免费的STER数据,可以高效生产研究区域内的DEM高程模型,能够达到铁路项目预可研以及部分项目可研阶段的精度要求,具有实用参考价值。

Terrain-Aided Navigation Considering Map Error

Terrain referenced navigation estimates an aircraft navigation status by utilizing a radar altimeter measuring a distance between the aircraft and terrain elevation. Accurate digital elevation map is essential to estimate the aircraft states correctly. However, the elevation map cannot represent the real terrain perfectly and there exists map error between the estimated and the true maps. In this paper, an influence of the map error on measurement equation is analyzed and a technique to incorporate the error in the filter is proposed. The map error is divided into two sources, accuracy error and resolution error. The effectiveness of the suggested technique is verified by simulation results. The method modifies a sensor noise covariance only so there is no additional computational burden from the conventional filter.

基于RTAB-Map视觉里程计的地形环境高程建图研究

在基于视觉的即时定位与建图(Simultaneous Localization and Mapping,SLAM)中,RTAB-Map是一个比较经典的解决方案,它包含有鲁棒的视觉里程计,同时也提供稠密点云地图、2D占据栅格地图和Octomap(3D占据栅格地图)三种地图构建形式。但稠密点云地图数据量大,无法适用于机器人导航;2D占据栅格地图虽数据量小,但无法反映复杂地形特征,一般只用于室内扫地机器人导航;Octomap能较好地反映三维空间内障碍物的信息,多用于无人机的导航,但对于地面移动机器人来说存在信息冗余。为RTAB-Map扩展了2.5D高程栅格地图构建模块,这种地图可以很好地反映地形环境特征,且地图所占用存储空间更小,更能充分利用移动机器人有限的存储和计算资源。

陆地生态系统碳监测卫星自主任务规划研究

低轨遥感卫星往往以全球或全国范围内的特定地物为探测目标。为提高卫星在轨运行的自主性,文章提出了一种面向地物目标属性的遥感卫星自主任务规划方法。首先外推出预报点90 min后的星下点经纬度,并根据星载地图和太阳高度角,得到预报点的阳照/阴影、陆地/海洋、境内/境外属性。对地物目标属性信息进行平滑处理后,根据各载荷的地物目标属性,识别出各载荷的工作任务时间段,可实时实现提前约1个轨道圈的载荷自主任务规划。