基于JPEG2000无损压缩的DEM网络渐进传输方法

针对网络GIS海量DEM数据与有限带宽之间的矛盾,根据DEM数据特点和网络多分辨率渐进的应用需求,提出了一种在DEM各级分辨率具有良好精度性能、基于改进的JPEG2000高效无损压缩的DEM网络渐进传输方法.选用2/6整数小波分解DEM数据,利用辖区渐进压缩方法、压缩码流的索引文件检索码流实现了DEM的渐进传输.实验证明,2/6小波比标准中的5/3小波能够更好地在每级分辨率保持原始地形精度,相比传统方法,网络渐进传输时每级分辨率传榆的数据量平均减少了90.29%.     

机助旅游地图制图的一些结构特点——以青岛市交通游览图机助制图为例

本文认为在采用机助制图技术进行制图时,设计的系统结构特点要体现专题内容、数据结构和软件设计的统一,青岛—崂山旅游图的机助制图工作,主要目标有: 1.能够组织起不同专题内容多边形的数据; 2.街道在接点处相接准确; 3.各种实体的属性易于被区分,便于进行各种有关的操作。对于专题内容进行了分类分级,以达到制图综合和彩色绘图的目的,青岛市的街道被分成4级。从交点配准和提高速度方面考虑,把制图区域分成了13个子区。采用层次模型和多边形邻接表结构,该结构的管理与制图目标密切相关。     

电磁监测试验卫星(张衡一号)数据处理方法和流程

电磁监测试验卫星(张衡一号)共搭载3类8种科学载荷,第1类是用于电离层电磁场探测的载荷,包括高精度磁强计、感应式磁力仪和电场探测仪;第2类是用于原位等离子体参数探测的载荷,包括朗缪尔探针、等离子体分析仪和高能粒子探测器;第3类是用于电离层结构探测的载荷,包括GNSS掩星接收机和三频信标发射机。电磁卫星载荷探测方式均不同于以往的成像遥感卫星载荷,其数据处理方法和流程也有本质差异。本文首先介绍了中国电磁监测试验卫星产出的科学数据种类、数据分级和各级数据的定义,根据电磁监测试验卫星的特点,科学数据分为0—4级。随后描述了1—4级数据的总体处理流程,最后详细描述了8种载荷1—2级数据处理的方法、流程以及关键的数据处理算法。该数据处理方法和流程将应用于电磁监测试验卫星应用系统,作为数据处理分系统设计和研发的依据。     

时空大数据分类体系研究

“统一行使全民所有自然资源资产所有者职责,统一行使所有国土空间用途管制和生态保护修复职责”是自然资源部组建后对时空大数据组织分类提出的新需求。本文在梳理总结国内大数据分类体系的演化特点和解析中国现行时空大数据分类体系存在的问题的基础上,结合自然资源部对大数据分类的需求,通过历史继承、合并和添加,提出了一套既能服务于自然资源部“两统一”职责,又能服务于全社会的时空大数据分类体系。研究建立的时空大数据分类体系为3级分类,共6种类型,分为17个一级类型,68个二级类型,24个三级类型,该分类较之前最明显的变化是将自然资源数据单独分为一大类,该分类对于大数据的组织管理具有重要意义。     

测量网图的综合评价

<正> 以В.И.列宁的名字命名的Волжская水电站在其建设及其水平位移测定过程中作为测量保证的高精度三角网,曾按四种方案进行过平差(参看图)。边1—2为基线,图Ⅰ和Ⅱ、图Ⅲ和Ⅳ中的待定点数n,相应为7和6。图Ⅰ和Ⅲ不同于图Ⅱ和Ⅳ,前者增加了观测方向1—6、1—5、2—4、3—6、3—7、4—7、6—8、6—9和7—9,其中最短边和最长边分别为5—9和3—7(表1)。网的平差使用了EC—1035计算机和全苏工测生产联合会编制的“边角网中观测数据的自动采集、存储和处理系统”程序。     

面向数字孪生川藏铁路的实体要素分类与编码研究

川藏铁路广域范围内实体要素粒度差异大、语义繁杂,多学科多专业空间信息数据多源异构,时空基准与数据格式不统一,难以高效集成管理与融合分析。为构建川藏铁路时空信息统一表达的认知共享概念体系,提出地理、地质、设施、气象、生态、灾害、人员7大实体要素类型,并对其几何、尺度、拓扑、属性、行为特征及相互作用关系等进行刻画,将要素类型进行实体化分类,制定了川藏铁路实体要素的统一编码规则以及扩充方法,对高位分类(门类、亚门类、大类和中类)以及低位分类(一、二、三级小类)进行扩充与删减,形成共包含2个门类、6个亚门类、27个大类和87个中类的高维分类体系。在此基础上,建立川藏铁路实体要素分类体系,并对每一个实体要素进行编码,赋予其唯一的、无歧义的身份标识,实现川藏铁路多维动态时空信息与实体要素之间的精准映射,为数字孪生川藏铁路建设奠定坚实基础。     

最新国外测绘文献题录

PE&RS ,2 0 0 3,6 9(12 )0 4 0 4 0 1　用于水生数据开发的数字高程模型的比较=ComparisonofDigitalEle vationModelsforAquaticDataDevelop ment[英]/ClarkeS ,BurnettK .—136 7～13760 4 0 4 0 2　融合多源粗分辨率遥感数据进行城市区域制图=MappingUrbanAreasbyFusingMultipleSourcesofCoarseRes olutionRemotelySensedData [英]/SchneiderA ,FriedlMA ,McIverDM .—1377～11380 4 0 4 0 3　基于州级的GAP和NLCD土地覆盖数据比较分析=AState levelComparativeAnalysisoftheGAPandNL CDLand coverDataSets[英]/Wa…     

基于波段选择的MODIS全国土地覆盖分类

以MODIS多光谱和多时相数据为输入参数进行了全国土地覆盖分类研究。从试验区2007年MODIS 8 d数据的合成影像(MOD 09)中提取EVI、NDWI和NDSI 3个指数,并将其作为特征波段与原有的7波段(B1～B7)形成10波段影像。以统计分类J-M距离平均值和SVM分类总精度为标准评价不同波段对土地覆盖分类的贡献。在全国范围内,选择贡献最大的EVI、B7和B4这3个波段的月合成值,并分别对其作PCA变换,选取各PCA变换后的前3个波段进行分类运算。研究结果表明,在没有其他辅助信息的境况下,基于MODIS贡献最大的前3个波段结合多时相信息能够在中分辨率区域土地覆盖分类中取得较好的分类结果,其精度为78.04%。     

最新国外测绘文献题录

GPSSolutions,2 0 0 3,7(3)0 4 0 5 0 1　GPS广播与精密星历 :历史观=Broadcastvs.PreciseGPSEphemerides:aHistoricalPerspective[英 ]/WarrenDL ,RaquetJF .— 1 5 1～1 5 60 4 0 5 0 2　用于交通移动信息系统的一种通用地图匹配算法 =AGeneralMapMatchingAlgorithmforTransportTelem aticsApplications [英 ]/QuddusMA ,OchiengWY ,ZhaoLin ,NolandRB .—1 5 7～ 1 6 70 4 0 5 0 3　GPSP码快速直接获取 =FastDirectGPSP CodeAcquisition [英 \〗/PangJing ,GraasFV ,StarzykJ ,ZhuZhen .— 1 6 8～ 1 750 4 0 5…     

基于NPP-VIIRS灯光数据对收缩背景下县级城镇规模分布特征及演变分析——以黑龙江省为例

城镇体系是人口、经济、资源等集聚的空间载体,在城镇收缩背景下,对区域规模分布特征及演变趋势进行探讨是促进区域协调发展的前提.本文以黑龙江省为例,基于2012—2019年校正后NPP-VIIRS夜间灯光数据,利用首位度指数、Zipf位序-规模法则等方法探究收缩背景下县级城镇规模分布特征及其演变趋势.结果表明:1)省内县级城镇规模分布处于相对集中、稳定的状态.从演变趋势上看,城镇体系朝着合理缓慢转变.2)哈尔滨市自身规模的上涨以及省内第二大城市大庆的明显收缩,导致省内首位度指数占比已远超于理想状态,进入剥夺周边城镇资源、自身无序扩张的恶性循环.3)哈尔滨市外的高位序城市,与中、低位序城镇间规模差距正在减小,但大、中、小城镇规模差距依旧明显,短期内无法缩小,省内同时还存在中等规模过度城镇数量断层现象.     

Landuse classification for a part of kamiichi area,Japan, using visible,IR and thermal IR data

Bendix 11 channel aerial MSS data have been used to generate landuse thematic classification using Image‐100 interactive image processing system for a part of Kamiichi area, Japan. Two different classification schemes were attempted, once with Visible and IR data using supervised classification technique and then with Thermal IR data using density slicing technique. Comparison of both the results shows that main features of interest are uniquely classified in both the cases. In addition, higher order classification could also be achieved using Visible, IR and Thermal IR data for each class of interest.     

Area-based and location-based validation of classified image objects

Geographic object-based image analysis (GEOBIA) produces results that have both thematic and geometric properties. Classified objects not only belong to particular classes but also have spatial properties such as location and shape. Therefore, any accuracy assessment where quantification of area is required must (but often does not) take into account both thematic and geometric properties of the classified objects. By using location-based and area-based measures to compare classified objects to corresponding reference objects, accuracy information for both thematic and geometric assessment is available. Our methods provide location-based and area-based measures with application to both a single-class feature detection and a multi-class object-based land cover analysis. In each case the classification was compared to a GIS layer of associated reference data using randomly selected sample areas. Error is able to be pin-pointed spatially on per-object, per class and per-sample area bases although there is no indication whether the errors exist in the classification product or the reference data. This work showcases the utility of the methods for assessing the accuracy of GEOBIA derived classifications provided the reference data is accurate and of comparable scale.     

引导型专题数据分级处理研究

通过对已有的数据分级模型及分级模式进行分析,提出引导型专题数据分级处理流程。首先运用分级数确定模型给出分级数,再利用"秩和比法+熵值法"对系统中各个分级模型的分级结果进行评价,最后以向用户推荐分级数和分级模型的形式辅助用户选择合适的分级处理模型。结合实例,对引导型专题数据分级处理过程及关键步骤进行详细说明,并通过原型系统显示实例结果。结果表明,此数据分级处理模式能让普通用户快速准确地进行数据处理。     

迁移学习支持下的遥感影像对象级分类样本自动选择方法

面向遥感大范围应用的目标,自动化程度仍是遥感影像分类面临的重要问题,样本的人工选择难以适应当前土地覆盖信息自动化提取的实际应用需求。为了构建一套基于先验知识的遥感影像全自动分类流程,本文将空间信息挖掘技术引入到遥感信息提取过程中,提出了一种面向遥感影像对象级分类的样本自动选择方法。该方法通过变化检测将不变地物标示在新的目标影像上,并将过去解译的地物类别知识迁移至新的影像上,建立新的特征与地物关系,从而完成历史专题数据辅助下目标影像的自动化的对象级分类。实验结果表明,在已有历史专题层的图斑知识指导下,该方法能有效地自动选择适用于新影像分类的可靠样本,获得较好的信息提取效果,提高了对象级分类的效率。     

专题制图中多因素数据的Fuxxy-Grey局势决策综合分类

专题制图中，所收集到的数据经常是单因素的，而在专题地图上却往往需要把多个单因素专题数据进行综合分类来表示。本文中，采用Fuzzy-Grey局势决策（下简称F-G决策）来研究多因素专题数据的综合分类问题，把“数据的模糊性”引入到灰色局势决策之中，根据不同情况，讨论各局势上效果测度中模糊隶属度确定的建模方法，在合适的隶属函数的基础上，在计算机上对实例分类进行程序运行，获得满意的结果。研究表明应用该方法在专题制图中对多因素数据进行综合分类是一种有效的手段。     

顾及空间自相关的统计数据分级质量评价

详细分析了统计地图数据分级质量的评价指标，研究了数据分级中应当考虑的数据空间分布规律，并用实例证明了分级数与空间自相关系数之间的变化规律。     

Spectral Filtering and Classification of Terrestrial Laser Scanner Point Clouds

A method is presented for filtering and classification of terrestrial laser scanner point clouds. The algorithm exploits the four-channel (blue, green, red and near infrared) multispectral imaging capability of some terrestrial scanners using supervised, parametric classification to assign thematic class labels to all scan cloud points. Its principal advantage is that it is a completely data-driven algorithm and is independent of spatial sampling resolution since the processing is performed in four-dimensional spectral feature space. Its application to two data-sets of different spatial extent and spatial and spectral complexity is reported, for which respective overall classification accuracies of 87·0% and 82·0% were achieved. Analysis of the input data with emphasis on the characteristics pertinent to the anticipated outcomes precedes detailed analysis of the classification results and error sources and their causes. Erroneously classified points are attributed to radiometric errors stemming from both detector hardware and physical effects.     

Radar speckle reduction and derived texture measures for land cover/use classification: a case study

This study examined the appropriateness of radar speckle reduction for deriving texture measures for land cover/use classifications. Radarsat-2 C-band quad-polarised data were obtained for Washington, DC, USA. Polarisation signatures were extracted for multiple image components, classified with a maximum-likelihood decision rule and thematic accuracies determined. Initial classifications using original and despeckled scenes showed despeckled radar to have better overall thematic accuracies. However, when variance texture measures were extracted for several window sizes from the original and despeckled imagery and classified, the accuracy for the radar data was decreased when despeckled prior to texture extraction. The highest classification accuracy obtained for the extracted variance texture measure from the original radar was 72%, which was reduced to 69% when this measure was extracted from a 5 × 5 despeckled image. These results suggest that it may be better to use despeckled radar as original data and extract texture measures from the original imagery.     

Distribution of Errors in a Classified Map of Satellite Data

Abstract

The output from any spatial data processing method may contain some uncertainty. With the increasing use of satellite data products as a source of data for Geographical Information Systems (GIS), there have been some major concerns about the accuracy of the satellite‐based information. Due to the nature of spatial data and remotely sensed data acquisition technology, and conventional classification, any single classified image can contain a number of mis‐classified pixels. Conventional accuracy evaluation procedures can report only the number of pixels that are mis‐classified based on some sampling observation. This study investigates the spatial distribution and the amount of these pixels associated with each cover type in a product of satellite data. The study uses Thematic Mapper (TM) and SPOT multispectral data sets obtained for a study area selected in North East New South Wales, Australia. The Fuzzy c‐Means algorithm is used to identify the classified pixels that contained some uncertainty. The approach is based on evaluating the strength of class membership of pixels. This study is important as it can give an indication of the amount of error resulting from the mis‐classification of pixels of specific cover types as well as the spatial distribution of such pixels. The results show that the spatial distribution of erroneously classified pixels are not random and varies depending on the nature of cover types. The proportions of such pixels are higher in spectrally less clearly defined cover types such as grasslands.     

A rule-based system for forest land use planning

This paper reports the results of an exercise on the development and application of a rule-based software program,Combine for integration of thematic information in simplest possible way. The program was used for forest land use planning in a shifting cultivation area in north-east India. The program can integrate 28 thematic information layers with upto 256 classes in each layer using 8-bit data. Additionally the software can be used for many per pixel image processing operations like merging of digitally and visually classified images, merging of a large number of thematic classes into a few wanted ones, density slicing, image thresholding etc. conveniently.