Extracting building stock information from optical satellite imagery for mapping earthquake exposure and its vulnerability

The paper focuses on automatic extraction of building stock information for quantifying physical exposure and its vulnerability from High and Very High Resolution (VHR) optical satellite imagery. We use two case studies. In Sana’a (Yemen), we use automatic techniques to extract the building stock as well as building height that is used to characterize its vulnerability. In Port-au-Prince (Haiti)—the area affected by the 2010 earthquake—we map the building stock based on a pre-disaster imagery, and we show the added value of area-based information when added to point-based damage assessment from visual change interpretation of post-disaster aerial images. This paper shows that VHR imagery can be used to locate and quantify the building stock and its height. This paper also shows that damages measured from changes detected from pre- and post-disaster imagery can in principle map and provide vulnerability information related to the structural fragility of the building stock.     

基于地学信息图谱的龙口市土地利用动态变化研究

阐述了地学信息图谱的内涵及其概念模式,以山东省龙口市为例,在RS和GIS技术支持下,利用1989年和2003年数字遥感图像、土地利用图及自然、社会经济统计数据,建立了龙口市土地利用动态变化信息图谱。根据信息图谱从空间和时间两方面分析了龙口市土地利用动态变化过程,推测出其土地利用变化的主要驱动力。     

Remote sensing of soil moisture: implications for groundwater recharge

Remote sensing provides information on the land surface. Therefore, linkages must be established if these data are to be used in groundwater and recharge analyses. Keys to this process are the use of remote sensing techniques that provide information on soil moisture and water-balance models that tie these observations to the recharge. Microwave remote sensing techniques are used to map the spatial domain of surface soil moisture and to monitor its temporal dynamics, information that cannot be measured using other techniques. The physical basis of this approach is presented with examples of how microwave remote sensing is utilized in groundwater recharge and related studies. Electronic Publication     

城市泥石流风险评价探讨

探讨了城市泥石流风险评价的系统方法,该方法包括泥石流扇形地危险区划、城市易损性分析和城市泥石流风险评价三个主要内容。泥石流堆积扇危险区划是基于数值模拟计算出的泥深和流速分布图进行叠合完成的。以美国高分辨率的“快鸟”卫星影像为数据源,完成了研究区的城市土地覆盖类型遥感解译,在此基础上完成了城市泥石流易损性分析,应用地理信息系统提供的统计和分析工具,完成了研究区泥石流风险评价。该风险区划图可用于指导对泥石流易泛区的不同风险地带的土地利用进行规划和决策,从而达到规避和减轻灾害的目的,也为生活在泥石流危险区的城市居民提供有关灾害风险信息,以作避难和灾害防治的依据。     

Evaluation of the seismic risk of the unreinforced masonry building stock in Antioquia,Colombia

This work focuses on the exploitation of very high-resolution (VHR) satellite imagery coupled with multi-criteria analysis (MCA) to produce flood hazard maps. The methodology was tested over a portion of the Yialias river watershed basin (Nicosia, Cyprus). The MCA methodology was performed selecting five flood-conditioning factors: slope, distance to channels, drainage texture, geology and land cover. Among MCA methods, the analytic hierarchy process technique was chosen to derive the weight of each criterion in the computation of the flood hazard index (FHI). The required information layers were obtained by processing a VHR GeoEye-1 image and a digital elevation model. The satellite image was classified using an object-based technique to extract land use/cover data, while GIS geoprocessing of the DEM provided slope, stream network and drainage texture data. Using the FHI, the study area was finally classified into seven hazard categories ranging from very low to very high in order to generate an easily readable map. The hazard seems to be severe, in particular, in some urban areas, where extensive anthropogenic interventions can be observed. This work confirms the benefits of using remote sensing data coupled with MCA approach to provide fast and cost-effective information concerning the hazard assessment, especially when reliable data are not available.     

Application Research of Remote Sensing Technology in Regional Hydrogeological Survey

Regional hydrogeological survey is groundwork for regional water resource development and utilization. In order to promote working efficiency and work cycle of traditional general survey, remote sensing technology is used to obtain the information of the region surveyed, such as landscape, quaternary geology, geological disasters, geologic structure, hydrographic features, etc, thus building diagrams, such as regional remote sensing interpretation geomorphologic map, quaternary geological map, hydrogeologic map, tectonic map, etc. This paper takes application of remote sensing in hydrogeological general survey (revision) of 1:200 000 mountain region in Hebei Province as an example, to systematically introduce technical route and technical method of remote sensing applied in regional hydrogeological survey as well as main content of interpretation. The paper also combines the latest remote sensing technological development to look far ahead into application of remote sensing in regional hydrogeological survey and introduces a new direction     

A GIS and remote sensing based evaluation of groundwater potential zones in a hard rock terrain of Vaigai sub-basin, India

In this paper, remote sensing, geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Vaigai basin, Tamilnadu. Several digital image processing techniques, including standard color composites, intensity–hue–saturation transformation and decorrelation stretch were applied to map rock types. Remote sensing data were interpreted to produce lithological and lineament maps such as geology, geomorphology, soil hydrological group, land use/land cover and drainage map were prepared and analyzed using GIS Arc Map GIS Raster Calculator module as geomorphology?×?12?+?drainage?×?9?+?lineament?×?5?+?geology?×?8?+?land use?×?2?+?relief?×?4. The final cumulative map generated by applying the above equation had weight values ranging from 0.315 to 4.515. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan, the thematic maps for the study area.     

一种新的遥感蚀变信息编图方法

利用遥感蚀变信息进行成矿预测已经得到普遍应用, 但是并没有系统的编图方法, 提出遥感蚀变信息等密度制图法以进行改进.它借鉴了地球化学场的编图思路, 通过统计单位面积内各蚀变信息所占的面积百分比, 进而生成面密度等值线图.利用该方法并结合线、环构造信息在内蒙古东乌旗地区圈定了8个成矿远景区.这种新的编图方法, 既能有效增强多种蚀变同时出现时小面积蚀变信息, 又能更直观的表达蚀变信息的总体空间分布特征和浓集中心, 对圈定成矿远景区和优选野外验证点十分有利.      

Mapping of seawater inundation along Nagapattinam based on field observations

Nagapattinam, in the east coast of India, was severely affected during the deadliest Indian Ocean tsunami of December 26, 2004. The tsunami caused heavy damage to life and property, and the death toll was about 3,378 in Nagapattinam taluk. Certain villages along the coast witnessed large inundation while adjacent villages were protected from the fury of the tsunami waves. This study was carried out to examine the underlying causes for the vulnerability along Nagapattinam coast with the help of field observations, remote sensing, and geographical information system as tools. Coastal areas with high sand dunes have been protected from tsunami, and areas adjacent to backwaters were inundated. Realtime Kinematic Global Positioning System and high-resolution satellite data were used to map the topographic information and maximum extent of inundation. Thematic maps on land use, land cover, and coastal geomorphology were generated using remote sensing and field data. Using field data as the primary source of information, tsunami hazard maps have been generated for Nagapattinam.     

Landslide investigations in Russia and the former USSR

The impact of natural hazards on mankind has increased dramatically over the past decades. Global urbanization processes and increasing spatial concentrations of exposed elements induce natural hazard risk at a uniquely high level. To mitigate affiliated perils requires detailed knowledge about elements at risk. Considering a high spatiotemporal variability of elements at risk, detailed information is costly in terms of both time and economic resources and therefore often incomplete, aggregated, or outdated. To alleviate these restrictions, the availability of very-high-resolution satellite images promotes accurate and detailed analysis of exposure over various spatial scales with large-area coverage. In the past, valuable approaches were proposed; however, the design of information extraction procedures with a high level of automatization remains challenging. In this paper, we uniquely combine remote sensing data and volunteered geographic information from the OpenStreetMap project (OSM) (i.e., freely accessible geospatial information compiled by volunteers) for a highly automated estimation of crucial exposure components (i.e., number of buildings and population) with a high level of spatial detail. To this purpose, we first obtain labeled training segments from the OSM data in conjunction with the satellite imagery. This allows for learning a supervised algorithmic model (i.e., rotation forest) in order to extract relevant thematic classes of land use/land cover (LULC) from the satellite imagery. Extracted information is jointly deployed with information from the OSM data to estimate the number of buildings with regression techniques (i.e., a multi-linear model from ordinary least-square optimization and a nonlinear support vector regression model are considered). Analogously, urban LULC information is used in conjunction with OSM data to spatially disaggregate population information. Experimental results were obtained for the city of Valparaíso in Chile. Thereby, we demonstrate the relevance of the approaches by estimating number of affected buildings and population referring to a historical tsunami event.

     

震害遥感快速提取研究——以2003年2月24日巴楚—伽师6.8级地震为例

论述了遥感影像提取震害的研究进展 ,提出了基于GIS和数字图像处理技术的震害遥感快速提取与损失评估的技术途径。在此基础上 ,介绍了巴楚—伽师地震的航空与卫星遥感资料的获取、图像数字处理与震害提取过程 ;描述了地震造成的建筑物震害与地质灾害的遥感图像特征 ;根据以往震害遥感影像统计经验与本次地震震害遥感特征 ,提出了遥感震害分级分类标准和地震烈度划分标准 ,进而得到基于震害遥感影像的伽师地震等震线图。文中对所得到的地震烈度与地面实际调查结果进行了比较。通过遥感信息源空间分辨率要求与信息获取与处理的时效性分析 ,认为我国利用航空遥感与卫星遥感资料获取地震灾情信息已进入实用阶段     

A GIS and Remote Sensing-based Analysis of Land Use Change Using the Asymmetric Relation Analysis Method: A Case Study from the City of Hangzhou,China

Urbanization has been an important component of land use and land cover change. Quantifying land use patterns and their changes is essential for monitoring and assessing the impact of urbanization. Data on existing and changing land use provide crucial clues for future development. Combining the application of remote sensing with geographic information systems (GIS) data, this study accomplishes (i) the creation of time-series land use maps in the core urban area of the city of Hangzhou, China; (ii) the examination of the land use cross-tabulation matrix to assess the transitions between land use types; and (iii) the introduction of a new asymmetric relation analysis method to explore the dependency relationship of different times in land use. The investigation was based on a 12-year time series dataset (1990–2002), compiled from fine-resolution satellite imagery and GIS-based maps. The results of the study showed that, first, there are strong associations between different stages (1990, 1996, and 2002) in land use development, and, secondly, the dependency between land use states was asymmetric in both stages of development. In addition, urbanization in Hangzhou has resulted in notable increases in the surface area of urban land and sharp decreases in the surface area of cropland.     

遥感技术在城市规划中的应用：以广州市城市规划应用实践为例

遥感影像具有丰富的地表信息,作为空间调查手段和信息源可以满足日益增长的城市建设及其规划的需求,结合传统规划线划图,能为城市规划发挥日益重大的作用。本文结合广州市城市规划中所涉及的总体规划、分区规划、违章建筑调查、环境规划等若干实际应用方面的工作及成果,对遥感技术在城市规划中的具体应用进行了介绍。     

全球变化与地表参数的定量遥感

从全球变化研究对遥感获取地表时空多变要素信息的需求 ,论述定量遥感中对地表多尺度空间信息作地学描述的新思路和新方法。在分析了变差图描述方法的特点及其不足的基础上 ,提出了直方变差图的概念 ,通过定义驻点和边界点 ,尝试采用直方变差图分解的方法分析地物空间分布规律 ,并通过一个实验对此方法进行了说明。进而基于对地表空间分布信息的提取 ,将可见光、近红外波段遥感信息用于热红外遥感的地温反演 ,利用地表空间结构和大气温度空间分布模式的差异 ,将热红外遥感图像分为地表贡献和大气贡献两部分 ,通过空间相关性分析 ,寻求从热红外遥感图像中直接分离出大气的空间分布模式的方法 ,以解决地温反演中面临的困难。已有的研究结果说明了在全球变化和定量遥感研究中 ,对地表多尺度空间变化信息作简洁的地学描述的必要性及其重要的应用意义。     

城市居住单元环境质量的高分辨率遥感评价方法研究

高分辨率遥感影像由于其较高的空间分辨率使得在居住单元的尺度上进行城市环境质量的遥感评价成为可能。所研究的评价方法在选取传统的环境评价指标如绿地景观结构参数、建筑容积率参数基础上,提出了平均可视面积、影像地物交替复杂度以及山体、水体、绿地、道路等外界地物影响力等指标,进一步研究了相关指标的分析方法。最后采用模糊评判的方法得到各参数指标的评判矩阵,进一步获得各居住单元综合指标评价的最终结果。使用厦门市QuickBird遥感影像进行了相关评价方法的实验,对8个典型居住单元的环境评价实验研究表明,利用高分辨率影像进行城市人居环境质量评价是一种成本较低、简便可行的方法。     

A critical look at representations of urban areas in global maps

According to the UN, the number of urban dwellers is expected to increase from roughly 3.2 billion today to more than 4.9 billion by 2030. An accurate and regularly updated estimate of the extent and spatial distribution of urban land is an important first step in our search for realistic responses to the ecological and social consequences of what promises to be the most rapid urbanization in world history. By employing circa-2000 satellite remote sensing imagery, geographic information systems, and census data, six groups from government and academia in both the EU and the US have created global maps that can be used to describe urban land. We compare these maps from global to sub-national scales, for the first time applying Discrete Global Grids to the problem of global-scale map comparison. Although most of these maps share common data inputs, they differ by as much as an order of magnitude in their estimates of the total areal extent of the Earth’s urban land (from 0.27 to 3.52 million km²). A sub-national analysis of the spatial distribution of urban land reveals that inter-map correlations are highest in North America ( $ \ifmmode\expandafter\bar\else\expandafter\=\fi{r} $  = 0.90), intermediate in Europe, South and Central America, and Sub-Saharan Africa ( $ \ifmmode\expandafter\bar\else\expandafter\=\fi{r} $  = 0.78), and lowest in Asia ( $ \ifmmode\expandafter\bar\else\expandafter\=\fi{r} $  = 0.63). Across most regions, our analysis uncovers a degree of variance that is high enough to call into question the consistency of each group’s approach to urban land, pointing to the need for both a common urban taxonomy and a global urban assessment effort.     

An object-based image analysis for building seismic vulnerability assessment using high-resolution remote sensing imagery

Building seismic vulnerability assessment plays an important role in formulating pre-disaster mitigation strategies for developing countries. The occurrence of high-resolution satellite sensors has greatly motivated it by providing a promising approach to obtain building information. However, this also brings a big challenge to the accurate building extraction and its coherent integration with the assessment model. The main objective of this paper is to investigate how to extract building attributes from high-resolution remote sensing imagery using the object-based image analysis (OBIA) method, so as to accurately and conveniently assess building seismic vulnerability by the combination of in situ field data. A general framework for the assessment of building seismic vulnerability is presented, including (1) the extraction of building information using OBIA, (2) building height estimation, and (3) the support vector machine (SVM)-based building seismic vulnerability assessment. Particularly, an integrated solution is proposed that merges the strengths of multiple spatial contextual relationships and some typical image object measures, under the unified framework to improve building information extraction at different scale levels as well as for different interest objects. With the aid of 35 building samples from two powerful earthquakes in China, the cloud-free WorldView-2 images and some building structure parameters from field survey were used to quantity the grades of building seismic vulnerability in Wuhan Optics Valley, China. The results show that all 48 buildings among the study area have been well detected with an overall accuracy of 80.67 % and the mean error of heights estimated from building shadow is less than 2 m. This indicates that the integrated analysis strategy based on OBIA is suitable for extracting the building information from high-resolution remote sensing imagery. Additionally, the assessment results using SVM show that the building seismic vulnerability is statistically significantly related to structure types and building heights. Both the proposed OBIA method and its integration strategy with SVM are easily implemented and provide readily interpretable assessment results for building seismic vulnerability. This reveals that the proposed method has a great potential to assist urban planners for making local disaster mitigation planning through the prioritization of intervention measures, such as the reinforcement of walls and the dismantlement of endangered houses.     

Engineering geological data in support of municipal land use planning—a case study in Analandia, southeast Brazil

This paper presents a method for transforming the information of an engineering geological map into useful information for non-specialists involved in land-use planning. The method consists of classifying the engineering geological units in terms of land use capability and identifying the legal and the geologic restrictions that apply in the study area. Both informations are then superimposed over the land use and a conflict areas map is created. The analysis of these data leads to the identification of existing and forthcoming land use conflicts and enables the proposal of planning measures on a regional and local scale. The map for the regional planning was compiled at a 1:50,000 scale and encompasses the whole municipal land area where uses are mainly rural. The map for the local planning was compiled at a 1:10,000 scale and encompasses the urban area. Most of the classification and operations on maps used spatial analyst tools available in the Geographical Information System. The regional studies showed that the greater part of Analandia’s territory presents appropriate land uses. The local-scale studies indicate that the majority of the densely occupied urban areas are in suitable land. Although the situation is in general positive, municipal policies should address the identified and expected land use conflicts, so that it can be further improved.     

Land use/cover change and driving force analyses in parts of northern Iran using RS and GIS techniques

To accomplish integrated watershed management and land use planning, it is necessary to study the dynamic spatial pattern of land use and cover change related to socioeconomical and physical parameters. In this study, land use and cover change detection was applied to the Lajimrood Drainage Basin in northern parts of Iran, an area characterized by rich and diversified agricultural and forest mosaic. The main of changes in the study area were forest–arable land transformation, which was only considered in this study. In order to detect these changes, at first, based on 1:25,000 digital topographic maps dated 1967 and 1994 and ETM⁺ satellite image dated 2002, land use map in these three dates were prepared. The results showed that the area with forest land use decreased about 3.2% in transition 1967–2002. Also, arable land increased about 36.9%. We suggested a method to analyze the driving forces and the spatial distribution of land use change. The maps of elevation, slope, and aspect were derived and classified by using digital elevation model (DEM). Also, the maps of distance from road, drainage network, and building area were selected as socioeconomical factors. These maps were overlaid and crossed with land use change map and land use change area ratio was computed. The results showed that the elevation, slope, and aspect were physical effective factors in land use changing. Also, by increasing the distance from building area and roads, deforestation rate was reduced.     

Mapping acidic mine waste with seasonal airborne hyperspectral imagery at varying spatial scales

Airborne imaging spectrometer (also known as hyperspectral) remote sensing has been widely used to characterize mineralogy on mine waste surfaces, which is useful for predicting potential sources of acidity and metal leaching. The most successful applications employ fine spatial resolution—20-m pixels or smaller. Future satellite imaging spectrometer sensors are proposed to provide coarser spatial resolution—30- to 60-m pixels. This study examined the ability to map minerals related to acid mine drainage with visible to shortwave infrared hyperspectral imagery at varying spatial scales (2-, 15-, 30-, 60-m pixels) at the Leviathan mine Superfund site, located in the Eastern Sierra Nevada. Mineral maps were produced using spectral angle mapper and matched filtering algorithms. The 15-m images provided comparable maps to the 2-m images. The 30- and 60-m images lost the ability to identify smaller features; however, they were still able to identify high- and low-priority remediation zones at least 75 m in width. Based on our results, we believe 30-m spatial resolution on a satellite hyperspectral sensor will be sufficient for identifying hazardous surfaces at larger mine waste sites and provide important reconnaissance information that can help prioritize detailed ground-based studies.