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1.
Positional Accuracy of TIGER 2000 and 2009 Road Networks 总被引：1，自引：0，他引：1
The Topologically Integrated Geographic Encoding and Referencing (TIGER) data are an essential part of the US Census and represent a critical element in the nation's spatial data infrastructure. TIGER data for the year 2000, however, are of limited positional accuracy and were deemed of insufficient quality to support the 2010 Census. In response the US Census Bureau embarked on the MAF/TIGER Accuracy Improvement Project (MTAIP) in an effort to improve the positional accuracy of the database, modernize the data processing environment and improve cooperation with partner agencies. Improved TIGER data were released for the entire US just before the 2010 Census. The current study characterizes the positional accuracy of the TIGER 2009 data compared with the TIGER 2000 data based on selected road intersections. Three US counties were identified as study areas and in each county 100 urban and 100 rural sample locations were selected. Features in the TIGER 2000 and 2009 data were compared with reference locations derived from high resolution natural color orthoimagery. Results indicate that TIGER 2009 data are much improved in terms of positional accuracy compared with the TIGER 2000 data, by at least one order of magnitude across urban and rural areas in all three counties for most accuracy metrics. TIGER 2009 is consistently more accurate in urban areas compared with rural areas, by a factor of at least two for most accuracy metrics. Despite the substantial improvement in positional accuracy, large positional errors of greater than 10 m are relatively common in the TIGER 2009 data, in most cases representing remnant segments of minor roads from older versions of the TIGER data. As a result, based on the US Census Bureau's suggested accuracy metric, the TIGER 2009 data meet the accuracy expectation of 7.6 m for two of the three urban areas but for none of the three rural areas. The suggested metric is based on the National Standard for Spatial Data Accuracy (NSSDA) protocol and was found to be very sensitive to the presence of a small number of very large errors. This presents challenges during attempts to characterize the accuracy of TIGER data or other spatial data using this protocol. 相似文献
2.
A Snake-based Approach for TIGER Road Data Conflation 总被引：1，自引：0，他引：1
《制图学和地理信息科学》2013,40(4):287-298
The TIGER (Topologically Integrated Geographic Encoding and Referencing) system has served the U.S. Census Bureau and other agencies' geographic needs successfully for two decades. Poor positional accuracy has however made it extremely difficult to integrate TIGER with advanced technologies and data sources such as GPS, high resolution imagery, and state/local GIS data. In this paper, a potential solution for conflation of TIGER road centerline data with other geospatial data is presented. The first two steps of the approach (feature matching and map alignment) remain the same as in traditional conflation. Following these steps, a third is added in which active contour models (snakes) are used to automatically move the vertices of TIGER roads to high-accuracy roads, rather than transferring attributes between the two datasets. This approach has benefits over traditional conflation methodology. It overcomes the problem of splitting vector road line segments, and it can be extended for vector imagery conflation as well. Thus, a variety of data sources (GIS, GPS, and Remote Sensing) could be used to improve TIGER data. Preliminary test results indicate that the three-step approach proposed in this paper performs very well. The positional accuracy of TIGER road centerline can be improved from an original 100 plus meters' RMS error to only 3 meters. Such an improvement can make TIGER data more useful for much broader application. 相似文献
3.
Exposure to traffic‐related pollutants is associated with both morbidity and mortality. Because vehicle‐exhaust are highly localized, within a few hundred meters of heavily traveled roadways, highly accurate spatial data are critical in studies concerned with exposure to vehicle emissions. We compared the positional accuracy of a widely used U.S. Geological Survey (USGS) roadway network containing traffic activity data versus a global positioning system (GPS)‐validated road network without traffic information; developed a geographical information system (GIS)‐based methodology for producing improved roadway data associated with traffic activities; evaluated errors from geocoding processes; and used the CALINE4 dispersion model to demonstrate potential exposure misclassifications due to inaccurate roadway data or incorrectly geocoded addresses. The GIS‐based algorithm we developed was effective in transferring vehicle activity information from the less accurate USGS roadway network to a GPS‐accurate road network, with a match rate exceeding 95%. Large discrepancies, up to hundreds of meters, were found between the two roadway networks, with the GPS‐validated network having higher spatial accuracy. In addition, identifying and correcting errors associated with geocoding resulted in improved address matching. We demonstrated that discrepancies in roadway geometry and geocoding errors, can lead to serious exposure misclassifications, up to an order of magnitude in assigned pollutant concentrations. 相似文献
4.
The positional error in spatial data is defined as a vector by comparing the coordinates between the true position and the measured position. The standard tests to assess the positional accuracy use only the magnitude of the vector and omit the azimuth. This article suggests that the use of both values allows a much more complete analysis of the positional error. A set of tests is proposed that are relevant for this purpose and demonstrate that some important features are not identified by the common procedures. The test samples come from two datasets. The first is obtained from the comparison of 100 homologous points in two conventional maps, and the second one comes from the geometric calibration of a photogrammetric scanner. The results are analyzed and discussed, showing that important issues such as error anisotropy are detected only by means of the circular statistics tests and density maps of distribution. Therefore, tests that assess the goodness of fit for uniform distribution in azimuths, such as Rayleigh and Rao tests, give low probabilities (P = 0 and P > 0.01). Moreover, density maps working with both magnitude and angle can locate the outlier candidate and offer more information about the spatial distribution of error. 相似文献
5.
6.
Impacts of Positional Error on Spatial Regression Analysis: A Case Study of Address Locations in Syracuse, New York 总被引：1，自引：0，他引：1
Daniel A Griffith Marco Millones Matthew Vincent David L Johnson Andrew Hunt 《Transactions in GIS》2007,11(5):655-679
Positional error is the error produced by the discrepancy between reference and recorded locations. In urban landscapes, locations typically are obtained from global positioning systems or geocoding software. Although these technologies have improved the locational accuracy of georeferenced data, they are not error free. This error affects results of any spatial statistical analysis performed with a georeferenced dataset. In this paper we discuss the properties of positional error in an address matching exercise and the allocation of point locations to census geography units. We focus on the error's spatial structure, and more particularly on impacts of error propagation in spatial regression analysis. For this purpose we use two geocoding sources, we briefly describe the magnitude and the nature of their discrepancies, and we evaluate the consequences that this type of locational error has on a spatial regression analysis of pediatric blood lead data for Syracuse, NY. Our findings include: (1) the confirmation of the recurrence of spatial clustering in positional error at various geographic resolutions; and, (2) the identification of a noticeable but not shockingly large impact from positional error propagation in spatial auto‐binomial regression analysis results for the dataset analyzed. 相似文献
7.
Yukio Sadahiro 《Transactions in GIS》2005,9(3):323-344
The quality of spatial data is limited by the accuracy of their sources such as paper maps and satellite images. It is also reduced by errors in map digitization and photo interpretation. Spatial operations performed on spatial data such as map overlay, buffer operations and spatial smoothing, do not always work correctly because their accuracy depends on the quality of spatial data. The present paper evaluates the accuracy of the buffer operation on a point and a line segment in relation to the positional accuracy of spatial data. Two quantitative measures are introduced to assess the accuracy of the buffer operation. Their explicit forms are derived for a point, and a condition is presented where the measures can be evaluated efficiently by numerical calculation. Applications provide empirical findings that deepen our understanding of the relationship between the accuracy of spatial data and that of the buffer operation. 相似文献
8.
《制图学和地理信息科学》2013,40(2):217-223
The TIGER system was developed by the Geography Division of the U.S. Census Bureau to support agency censuses and surveys. The system has been crucial to meeting the demands placed on the U.S. Census Bureau. It has been widely used by the public for a large and diverse number of uses. As public uses evolved, demands evolved. In parallel, technology and spatial data collection evolved. TIGER should now support a larger purpose. This article discusses some developments of the TIGER system and presents some of the key components of TIGER modernization: improvement of positional accuracy, connection to the National Spatial Data Infrastructure (NSDI), and improved geographic analysis. 相似文献
9.
Geocoding urban addresses usually requires the use of an underlying address database. Under the influence of the format defined for TIGER files decades ago, most address databases and street geocoding algorithms are organized around street centerlines, associating numbering ranges to thoroughfare segments between two street crossings. While this method has been successfully employed in the USA for a long time, its transposition to other countries may lead to increased errors. This article presents an evaluation of the centerline‐geocoding resources provided by Google Maps, as compared to the point‐geocoding method used in the city of Belo Horizonte, Brazil, which we took as a baseline. We generated a textual address for each point object found in the city's point‐based address database, and submitted it to the Google Maps geocoding API. We then compared the resulting coordinates with the ones recorded in Belo Horizonte's GIS. We demonstrate that the centerline segment interpolation method, employed by the online resources following the American practice, has problems that can considerably influence the quality of the geocoding outcome. Completeness and accuracy have been found to be irregular, especially within lower income areas. Such errors in online services can have a significant impact on geocoding efforts related to social applications, such as public health and education, since the online service can be faulty and error‐prone in the most socially demanding areas of the city. In the conclusion, we point out that a volunteered geographic information (VGI) approach can help with the enrichment and enhancement of current geocoding resources, and can possibly lead to their transformation into more reliable point‐based geocoding services. 相似文献
10.
Using geographic information systems to link administrative databases with demographic, social, and environmental data allows researchers to use spatial approaches to explore relationships between exposures and health. Traditionally, spatial analysis in public health has focused on the county, ZIP code, or tract level because of limitations to geocoding at highly resolved scales. Using 2005 birth and death data from North Carolina, we examine our ability to geocode population‐level datasets at three spatial resolutions – zip code, street, and parcel. We achieve high geocoding rates at all three resolutions, with statewide street geocoding rates of 88.0% for births and 93.2% for deaths. We observe differences in geocoding rates across demographics and health outcomes, with lower geocoding rates in disadvantaged populations and the most dramatic differences occurring across the urban‐rural spectrum. Our results suggest that highly resolved spatial data architectures for population‐level datasets are viable through geocoding individual street addresses. We recommend routinely geocoding administrative datasets to the highest spatial resolution feasible, allowing public health researchers to choose the spatial resolution used in analysis based on an understanding of the spatial dimensions of the health outcomes and exposures being investigated. Such research, however, must acknowledge how disparate geocoding success across subpopulations may affect findings. 相似文献
11.
《制图学和地理信息科学》2013,40(4):301-318
The widespread use of Internet-based mapping and geospatial analysis has caused an increase in the demand for online geocoding services. Although such services provide convenience, low (or free) cost and immediate solutions, their characteristics, sometimes, overshadow the expectation of producing quality of geocoded results. In recent years, several geocoding techniques have emerged, including rooftop geocoding, but they have yet to receive much attention in the literature. This paper examines and compares the quality of online rooftop and street geocoding services based on match rates and positional accuracy. Six geocoding services by five providers (i.e., Microsoft Virtual Earth, Google, Geocoder.us, MapQuest, and Yahoo!) were evaluated using addresses in Allegheny County, Pennsylvania. Results of the comparison indicate that rooftop geocoding produces slightly lower match rates but significantly higher positional accuracy than street geocoding. The hybrid service, which combines the two techniques, produces match rates as high as other street geocoding services but improves in positional accuracy close to the level of rooftop geocoding. Geocoding services employing reference databases with similar quality trend to produce compatible match rates and positional accuracy. This paper examines the sensitivity of different address types on geocoding quality. The results reveal that both rooftop and street geocoding produce high match rates and high accuracy for residential addresses. However, positional accuracies of agricultural and industrial address types are not very reliable due to the small sample sizes. With these, it is recommended to use online rooftop geocoding services if high positional accuracy is the priority, use street geocoding if high match rate is the priority, and use the hybrid approach if both high match rates and high positional accuracy are required. 相似文献
12.
Existing research on DEM vertical accuracy assessment uses mainly statistical methods, in particular variance and RMSE which are both based on the error propagation theory in statistics. This article demonstrates that error propagation theory is not applicable because the critical assumption behind it cannot be satisfied. In fact, the non‐random, non‐normal, and non‐stationary nature of DEM error makes it very challenging to apply statistical methods. This article presents approximation theory as a new methodology and illustrates its application to DEMs created by linear interpolation using contour lines as the source data. Applying approximation theory, a DEM's accuracy is determined by the largest error of any point (not samples) in the entire study area. The error at a point is bounded by max(|δnode|+M2h2/8) where |δnode| is the error in the source data used to interpolate the point, M2 is the maximum norm of the second‐order derivative which can be interpreted as curvature, and h is the length of the line on which linear interpolation is conducted. The article explains how to compute each term and illustrates how this new methodology based on approximation theory effectively facilitates DEM accuracy assessment and quality control. 相似文献
13.
以TIGER这种既成事实的空间数据格式为例,详细介绍了TIGER的数据模型及文件组织形式,对TI-GER/Line如何描述空间对象信息进行分析,把这种格式作为空间对象拓扑模型实际实施的一种范例作以详细介绍,以起到抛砖引玉的作用,使读者能够更深入地了解空间对象表示的基本要求,对未来空间数据标准化起到一定的参考作用。 相似文献
14.
《制图学和地理信息科学》2013,40(2):117-127
A collection of permits granted for alterations to coastal wetlands in North Carolina from 1984 through 1992 was examined to determine the spatial accuracy of the data. Each permit site for which a precise location existed in its associated permit file was surveyed using a Global Positioning System, and the error was identified between the location described in the permit file and the true location. The error was analyzed with respect to direction of error, accompanying map type, and time. Results suggest that the spatial error found in the Permit Record for coastal North Carolina was too large to perform spatial analysis. Only 50 percent of the permit sites were found within 250 meters of their true location, and the rest were in error by as much as 45 kilometers. Errors were uniformly distributed in direction and not biased in any direction. The inclusion of maps with greater detail did not significantly reduce error in locating the permit site. There was a slight decrease in error over time, but the fit was not sufficiently strong to indicate an improvement in accuracy over time. The results suggest a need for better standards for gathering future data and call for more stringent spatial data quality controls on environmental permit data of this kind. 相似文献
15.
The assessment of OpenStreetMap (OSM) data quality has become an interdisciplinary research area over the recent years. The question of whether the OSM road network should be updated through periodic data imports from public domain data, or whether the currency of OSM data should rather rely on more traditional data collection efforts by active contributors, has led to perpetual debates within the OSM community. A US Census TIGER/Line 2005 import into OSM was accomplished in early 2008, which generated a road network foundation for the active community members in the US. In this study we perform a longitudinal analysis of road data for the US by comparing the development of OSM and TIGER/Line data since the initial TIGER/Line import. The analysis is performed for the 50 US states and the District of Columbia, and 70 Urbanized Areas. In almost all tested states and Urbanized Areas, OSM misses roads for motorized traffic when compared with TIGER/Line street data, while significant contributions could be observed in pedestrian related network data in OSM compared with corresponding TIGER/Line data. We conclude that the quality of OSM road data could be improved through new OSM editor tools allowing contributors to trace current TIGER/Line data. 相似文献
16.
An Adaptive Method of High Accuracy Surface Modeling and Its Application to Simulating Elevation Surfaces 总被引：3，自引：0，他引：3
An adaptive method is employed to speed up computation of high accuracy surface modeling (HASM), for which an error indicator and an error estimator are developed. Root mean‐square error (RMSE) is used as the error estimator that is formulated as a function of gully density and grid cell size. The error indicator is developed on the basis of error surfaces for different spatial resolutions, which are interpolated in terms of the absolute errors calculated at sampled points while paying attention to the landform characteristics. The error surfaces indicate the magnitude and distribution of errors in each step of adaptive refinement and make spatial changes to the errors in the simulation process visualized. The adaptive method of high accuracy surface modeling (HASM‐AM) is applied to simulating elevation surface of the Dong‐Zhi tableland with 27.24 million pixels at a spatial resolution of 10 m × 10 m. Test results show that HASM‐AM has greatly speeded up computation by avoiding unnecessary calculations and saving memory. In addition, HASM‐AM improves simulation accuracy. 相似文献
17.
对流层延迟是影响高精度定位与导航的主要误差之一,也是全球导航卫星系统（global navigation satellite system,GNSS）水汽探测的关键参数。美国航空航天局发布了最新一代的大气再分析资料（MERRA-2资料）,其可用于计算高时空分辨率的对流层延迟产品,但是目前尚无文献对利用MERRA-2资料计算天顶对流层延迟（zenith tropospheric delay,ZTD）和天顶湿延迟（zenith wet delay,ZWD）的精度进行分析。因此,联合2015年中国陆态网214个GNSS站ZTD产品和分布于中国区域的87个探空站资料,对利用MERRA-2资料在中国区域计算ZTD/ZWD的精度进行评估。结果表明：（1）以陆态网ZTD为参考值,利用MERRA-2资料积分计算ZTD的年均偏差和均方根误差（root mean square error,RMSE）分别为0.32 cm和1.21 cm,且偏差和RMSE均表现出一定的季节变化,总体上呈现为夏季精度低、冬季精度高;在空间分布上,偏差随纬度和高程的变化趋势并不明显,但RMSE随纬度和高程的增加总体上呈现递减的趋... 相似文献
18.
城市空间数据基础设施尺度和精度研究 总被引：1，自引：1，他引：0
对城市空间数据基础设施数据的尺度和精度进行了研究,分析了衡量城市空间数据尺度的4个指标:比例尺、范围、详尽程度和分辨率,总结了现有测量规范对主要城市空间基础数据的精度要求,论述了不同尺度和精度条件下城市空间基础数据的协调,提出了数字城市空间基础数据的平面精度分级体系,建立了此分级体系与传统测量精度指标及比例尺的对应关系。 相似文献
19.
矢量空间数据的可用性取决于其空间位置不确定性,直接受控于点元位置误差的二维空间概率分布模式。应用GPS RTK技术,对选定测量点的空间位置进行重复观测,累积观测20 d,采用一维、二维正态分布检验与数学模型拟合3种分析方法,研究了GPS RTK测点误差空间概率分布模式。结果表明,GPS RTK测点误差空间分布呈现为具有一定方向的二维正态分布形式,并且这种分布形式的显著性随着点元位置观测时间的缩短而不断提升。所得到的GPS RTK测点误差空间概率分布模式可为其测点误差空间分布影响因素分析与数学预测模型构建奠定基础,并有助于推动矢量空间数据位置不确定性的理论研究。 相似文献
20.
提出了一种用于空间数据整合的建筑物面实体对齐方法,可用来改善空间数据的位置精度。首先,采用基于最小外接矩形（minimum bounding rectangle,MBR）组合优化算法的匹配方法识别整合数据之间的同名实体;然后,提出基于几何相似性的成对约束谱匹配算法检测1:1、1:N和M:N同名实体之间的共轭点对;针对1:N和M:N匹配中不可避免存在弱对应点对和错误对应点对的问题,提出基于IGG1权重的最小二乘法来有效对齐同名实体。将所提出的方法应用于对齐较高位置精度的基础测绘地图数据和较低位置精度的谷歌地图数据中,结果表明,该方法不仅可检测存在复杂轮廓对应的1:N和M:N同名实体的共轭点对,而且可实现它们之间的有效对齐,使同名实体的位置信息差异最小化。 相似文献