基于空间插值彩色扫描地形图等高线的自动矢量化

本文主要描述了一种基于彩色扫描地形图等高线的自动提取以及自动矢量化的方法,提出了通过空间插值解决等高线不连通问题的新方法。首先利用图像分割方法分色提取出栅格等高线,自动矢量化等高线(CLs1),然后对这些不连续的等高线赋值,结合其他地形要素(高程点、山脊线、山谷线等)创建DEM,从DEM中提取等高线(CLs2),最后利用提取出的等高线(CLs2)修正从地形图中自动矢量化得到的等高线(CLs1),得到连通的矢量化等高线。通过实验证明此方法是有效的,提高了等高线自动化程度。     

基于GIS的地质图矢量化技术研究

将传统纸质媒介保存的地质图利用扫描仪转换为栅格图像,只能满足数字化存储的基本要求。要满足在信息化条件下进行地质图建库更新、共享利用与公开发布的要求,必须对地质图进行矢量化。应用现代GIS技术,使用通用的GIS软件平台,通过子图块拼接、几何校正、跟踪矢量化、地理底图标准化、矢量图编辑等过程实现地质图矢量化,对开展各类地勘活动、地学研究具有重要意义。本文结合浙江省地质图矢量化的实践,对利用GIS技术进行地质图矢量化的技术方法进行了阐述。     

Building footprint database improvement for 3D reconstruction: A split and merge approach and its evaluation

We present a general framework to improve a vectorial building footprint database consisting of a set of 2D polygons. The aim of this improvement is to make the database more proper to subsequent 3D building reconstruction at a large scale. Each polygon is split into several simple polygons guided by a digital elevation model (DEM). We say that this segmentation is vectorial as we produce segmentations that intrinsically have simple polygonal shapes, instead of doing a raster segmentation of the DEM within the polygon then trying to simplify it in a vectorization step. The method is based on a Mumford and Shah like energy functional characterizing the quality of the segmentation. We simplify the problem by imposing that the segmentation edges have directions present in the input polygon over which the DEM is defined. We evaluate the validity of the proposed method on a very large dataset and discuss its pros and cons based on this evaluation.     

Corel PowerTRACE X5栅格图矢量化在地图集编制中的应用

地图集编制中,主要数据均要求为矢量格式,栅格图矢量化是数据处理的一项重要工作,针对一般方法在彩色栅格图矢量化方面的不足,以Corel PowerTRACE X5为例对几类栅格图进行试验和应用,并对结果作分析,在交互控制自动矢量化过程中,当设置100%的精度时,彩色图矢量化精度达98%以上,黑白线画图接近零误差,矢量化取得了满意的结果。     

基于航片颜色分割的土地利用更新调查技术

本文对基于航片的土地利用更新调查作业流程进行了分析,对其中的地物提取、地图纠正技术进行了探讨,提出了基于神经元网络和启发式学习规则的彩色地图分层的方法,用以提取彩色地形图中的特征地物以及进行颜色分割。还构造了地图自动纠正算法,它自动准确地提取图内的格网,以进行纠正。这些算法提高了土地利用更新作业效率。     

基于混合智能的地图自动审核技术框架

地图审核是国家测绘地理信息行政主管部门的主要职责。当前我国的地图审核依赖人工目视判别,成本高、效率低。如何从高度依赖专家经验的人工检测走向混合智能的自动判断,是我国地图审核工作面临的技术难点和痛点问题。提出以知识为引导、算法为基础的地图自动审核的混合智能方法,设计了基于混合智能的地图自动审核技术框架,并指出需要重点突破的3项关键技术;并结合典型的“问题地图”智能化审核案例,给出了地图智能化审核的技术实现途径。     

Mining Trajectory Data and Geotagged Data in Social Media for Road Map Inference

As mapping is costly and labor‐intensive work, government mapping agencies are less and less willing to absorb these costs. In order to reduce the updating cycle and cost, researchers have started to use user generated content (UGC) for updating road maps; however, the existing methods either rely heavily on manual labor or cannot extract enough information for road maps. In view of the above problems, this article proposes a UGC‐based automatic road map inference method. In this method, data mining techniques and natural language processing tools are applied to trajectory data and geotagged data in social media to extract not only spatial information – the location of the road network – but also attribute information – road class and road name – in an effort to create a complete road map. A case study using floating car data, collected by the National Commercial Vehicle Monitoring Platform of China, and geotagged text data from Flickr and Google Maps/Earth, validates the effectiveness of this method in inferring road maps.     

GROUND CONTROL DETERMINATION FOR REGISTRATION OF SATELLITE IMAGERY USING DIGITAL MAP DATA

Work is reported on the production of terrain elevation data from SPOT imagery. An important step in this process is determination of exterior orientation parameters for the images. Although an initial estimate is available in the SPOT header, refinements are required based on plan and height data. These are generally derived from photogrammetric measurements (or sources such as global positioning satellite systems), but accurate manual determination is time consuming. This paper reports an alternative approach by investigating the use of existing map data (located on the earth's surface and in a known projection) to find corresponding “ground control points” in both map and image. Available maps may be in digital or paper form depending on the state of development of mapping in the part of the world being studied. The last revision date and the cartographic generalisation employed will also effect the fidelity of the final result. Practical semi-automatic techniques for determining the height of ground control points from existing map data are described, including multiple profiles through digitised contour data, a commercial terrain modelling package based on Delaunay triangulation and the use of triangulation points on prominent features. Comparisons between the methods are made and results obtained are compared with Institut Géographique National datasets and photogrammetric measurements. Methods for fully automating not only the height determination but also the location of ground control features within a map database are discussed. Map and image registration is described and illustrated using Laser-Scan's Rover software. Interactive and automated methods of registration are discussed.     

基于AutoCAD和RTK的地形图数学精度检测

当对一个较大测区用全站仪或摄影测量方法测绘某种比例尺地形图时,可获得数量较多的地形图。对获取的数字地形图进行精度评定,是质量检查中的一个重要环节,而且工作量较大。AutoCAD为平台开发的测图软件在测绘行业十分流行,测绘行业生产的数字地图一般都能转化为DWG格式。对于DWG格式的地形图,在AutoCAD打开的图上拾取若干地物点,并把这些点的坐标自动形成一个坐标文件,与外业测量仪器RTK采集相应点形成的坐标文件,通过精度评定程序进行同名点号的坐标值对比,获得数字地形图数学精度,大大提高了数字地图精度检测工作的效率。     

Investigating Issues in Map Accuracy When Using an Object-Based Approach to Map Benthic Habitats

In a recent study, benthic habitat maps were created of the Texas Gulf Coast from digital aerial imagery. The images were classified using an object-based image analysis (OBIA) approach and a classification and regression tree (CART) technique. The map was manually edited, changing 26% of the polygons' labels. Accuracy assessments of the unedited map and the edited map revealed the two were not significantly different. The research in this paper evaluates why these maps may have similar accuracies. Our analyses indicate that the small segmentation scale parameter used over-segmented the imagery, reducing the effectiveness of the CART technique and editing.     

Mapping diversified peri-urban agriculture – potential of object-based versus per-field land cover/land use classification

High spatial resolution satellite data contribute to improving land cover/land use (LCLU) classification in agriculture. A classification procedure based on Quickbird satellite image data was developed to map LCLU of diversified agriculture at sub-communal and communal level (7 km²). Segmentation performance of the panchromatic band in combination with high pass filters (HPF) was tested first. Accuracy of field boundary delineation was evaluated by an object-based segmentation, a per-field and a manual classification, along with a quantitative accuracy assessment. Sub-communal classification revealed an overall accuracy of 84% with a κ coefficient of 0.77 for the per-field vector segmentation compared to an overall accuracy of 56–60% and a κ coefficient of 0.37–0.42 for object-based approaches. Per-field vector segmentation was thus superior and used for LCLU classification at communal level. Overall accuracy scored 83% and the κ coefficient 0.7. In diversified agriculture, per-field vector segmentation and classification achieved higher classification results.     

Improving Representation of Land‐use Maps Derived from Object‐oriented Image Classification

Object‐oriented (OO) image analysis provides an efficient way to generate vector‐format land‐cover and land‐use maps from remotely sensed images. Such image‐derived vector maps, however, are generally presented with congested and twisted polygons with step‐like boundaries. They include unclassified polygons and polygons with geometric conflicts such as unreadable small areas and narrow corridors. The complex and poorly readable representations usually make such maps not comply well with the Gestalt principle of cartography. This article describes a framework designed to improve the representation by resolving these problematic polygons. It presents a polygon similarity model integrating semantic, geometric and spectral characteristics of the image‐derived polygons to eliminate small and unclassified polygons. In addition, an outward‐inward‐buffering approach is presented to resolve the narrow‐corridor conflicts of a polygon and improve its overall appearance. A case study demonstrates that the implementation of the framework reduces the number of the polygons by 32% and the length of the polygon boundaries by 20%. At the same time, it does not cause distinct changes the distribution of land‐use types (less than 0.05%) and the overall accuracy (decreased only 0.02%) as compared with the original image‐derived land‐use maps. We conclude that the presented framework and models effectively improve the overall representation of image‐derived maps without distinct changes in their semantic characteristics and accuracy.     

Landsat 8多光谱数据辅助下的高分影像多尺度分割

为解决高分影像分割的边缘锯齿性明显等问题,本文以黑龙江省伊春市桦皮羌子林场为研究区开展了有无多光谱数据辅助的高分影像分割对比试验。首先,本文设计了多尺度分割算法的相同尺度参数下分割试验,确定了该算法分割GF-2影像时应采用的最佳同质性准则组合参数;然后,基于影像分割对象同质性局部方差变化率反映最优分割尺度的思想,利用ESP2工具找出固定尺度范围内的最优分割尺度范围;最后执行最佳同质性准则组合参数配合下的最优分割尺度范围内各个尺度下的多尺度分割,并采用矢量距离指数、紧密度指数、形状指数对2种分割试验结果进行了评价。结果表明,与GF-2影像独立分割相比,Landsat 8多光谱数据辅助下的GF-2影像分割在矢量距离指数、紧密度指数、形状指数的质量上均有提升,平均提升率分别为8.05%、28.40%、11.76%。     

Georelief Transfiguration in Areas Affected by Open‐cast Mining

Open‐cast mining activity causes the largest georelief transfigurations all over the world. Large localities in north‐west Bohemia (the Czech Republic) are affected. In this area, we focus on a very significant case: the royal town Most, which has been turned into a lake. The main aim of this article is the reconstruction of the original georelief in different time periods together with analysis showing the process of landscape devastation. The workflow and analysis is based on precise elevation data obtained from aerial photographs and old maps. The georelief development is reconstructed using the digitized contour lines contained in Derived state‐map 1:5,000 (SMO5) from the years 1953, 1972, and 1980; maps of the 3^rd Military Survey (year 1936); and digital surface models (DSM) extracted, using the pixel correlation method, from aerial images (year 1953 and 2008). The most important results of the analysis are digital terrain models showing the evolution of the landscape which may be used for many purposes in landscape development analysis, historical applications, visualization or landscape reclamation.     

喜马拉雅山地区冰湖信息的遥感自动化提取

在“全域—局部”分步迭代水体信息提取方法的基础上, 通过对水体信息提取指标——水体指数的物理特性的分析实现了算法中全域阈值的自动选择与局部阈值的自适应调整, 并结合DEM 生成的山体坡度和阴影信息,减少局部迭代过程中对其他地表特征与水体信息的误判。在此基础上, 建立一种适合于高山地区冰川湖泊的自动化提取方案。试验采用Landsat 数据对喜马拉雅山地区的冰川湖泊进行信息提取, 结果表明该方法能够快速准确地完 成大区域范围内的冰川湖泊制图, 并能最大程度地消除高山地区湖泊水体识别中冰川和山体阴影的影响。     

An intelligent geospatial processing unit for image classification based on geographic vector agents (GVAs)

Spatial modeling methods usually use pixels and image objects as fundamental processing units to address real‐world objects, geo‐objects, in image space. To do this, both pixel‐based and object‐based approaches typically employ a linear two‐staged workflow of segmentation and classification. Pixel‐based methods segment a classified image to address geo‐objects in image space. In contrast, object‐based approaches classify a segmented image to identify geo‐objects from raster datasets. These methods lack the ability to simultaneously integrate the geometry and theme of geo‐objects in image space. This article explores Geographical Vector Agents (GVAs) as an automated and intelligent processing unit to directly address real‐world objects in the process of remote sensing image classification. The GVA is a distinct type of geographic automata characterized by elastic geometry, dynamic internal structure, neighborhoods and their respective rules. We test this concept by modeling a set of objects on a subset IKONOS image and LiDAR DSM datasets without the setting parameters (e.g. scale, shape information), usually applied in conventional Geographic Object‐Based Image Analysis (GEOBIA) approaches. The results show that the GVA approach achieves more than 3.5% improvement for correctness, 2% improvement for quality, although no significant improvement for completeness to GEOBIA, thus demonstrating the competitive performance of GVAs classification.     

Classification from Landsat TM of Indurated Volcanic Materials (tepetates) of the Mexican Neo‐volcanique Belt

Abstract

Tepetates, altered indurated and sterile volcanic tuffs, are located among the neo‐volcanic belt in central Mexico. They are divided into three classes according to the erosion level: outcrop tepetates, discontinuous tepetates (in process of erosion), and underlying tepetates (related to fragile areas with high erosion risk). For local communities and peasants, the existence of tepetates is a heavy constraint, with the impossibility to cultivate the land as it is. In order to know the localization and extension of tepetates, we experimented with various classification techniques of a Landsat Thematic Mapper satellite image. Masking techniques were used, assisted both by a DEM and photo interpretation, in addition to radiometric segmentation to obtain a map of tepetates in a study area. The resulting map showed the location of outcrop tepetates well, in agreement with existing soil maps, but underestimated underlying tepetates and high‐risk erosion localities, due mainly to the heterogeneity of the classes at the scale used (30 m pixel).     

改进的启发式分割算法在GNSS坐标时间序列阶跃探测中的应用

在启发式分割算法的基础上,引入z检验和标准正态均一性检验（standard normal homogeneity test,SNHT）,提出了一种新的阶跃探测法,并将其应用于20个陆态网（Crustal Movement Observation Network ofChina,CMONOC）和10个国际全球卫星导航系统服务（International Global Navigation Satellite System Ser-vice,IGS）参考站近5 a的坐标时间序列。结果显示,对于IGS站东（east,E）、北（north,N）、垂直（up,U）3个方向分量已知阶跃的平均准确探测率分别为68.5%、71.3%、64.8%,且利用阶跃点前后25 d初始拟合残差的平均值之差得到修复后的坐标时间序列保持了良好的连续性。基于剔除粗差后的坐标时间序列,利用坐标时间序列分析软件（coordinate time series analysis software,CATS）估计出的速度显示:对于由已知阶跃与改进算法探测出的阶跃历元的组合方式,所有测站E、N、U方向的估计速度与CMONOC官网发布的速度的平均偏差分别为2.86 mm/a、1.14 mm/a、2.31 mm/a,明显小于由已知阶跃和肉眼判断明显阶跃历元的组合方式获得的平均速度偏差。上述结果表明,改进的启发式分割算法可应用于坐标时间序列的阶跃探测。     

土地利用现状图的矢量化方法研究

土地利用现状图的数字化是建立土地利用数据库的主要技术手段之一,图斑作为土地利用现状图的主要要素,其矢量化方法的优化与否不仅关系着整个数据采集的进程,而且还将影响到土地信息系统的稳定与否。文章针对传统的图斑矢量化引起的面域交叉、对象撕裂等问题研究提出了基于弧段的图斑矢量化方法,并通过线状地物与图斑的叠合分析,建立线状地物...