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1.
Adopting a principle of “check-accept for the first rank, inspection for the second rank”, this paper briefly discusses the rationale of the sampling inspection and the sampling inspection schemes to digital products in GIS. The OC curve is drawn to explain the deficiency of the percent sampling inspection. Meanwhile, the method of One Time Limiting Quality of count selection is presented as the inspection scheme for production departments while the method of One Time After-inspection Mean Percent Defective Upper Limit of count selection is for acceptance departments. 相似文献
2.
抽样检验是测绘成果质量检验的基本方法,抽样方案与被检成果质量水平的匹配程度直接决定抽样检验的效果。针对抽样方案的适用性和有效性评价问题,提出了计数型抽样方案的质量不确定性区间（quality uncertainty interval,QUI）的概念,并以给定概率水平条件下的QUI的长度评价抽样方案的适用性和有效性,以比较客观地反映抽样方案的两类风险程度。对4个典型测绘成果质量检验的抽样方案和6个仿真抽样方案进行数值计算和分析,验证了该方法的正确性和合理性。结果显示,该方法不仅适用于测绘地理数据的统计分析和成果质量检验,还可用于各种计数型抽样方案设计和两类风险控制。 相似文献
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道路选取是根据比例尺的要求，在道路网中保留相对重要道路、舍弃相对次要道路的地图综合操作。从概念层和操作层对两种不同的道路选取策略进行了比较。一种是删除后更新策略，即删除一条道路后更新其他道路的重要度；另一种是删除后不更新策略，即删除一条道路后不更新其他道路的重要度。以常用的stroke重要度排序法为道路选取方法，运用长度、连通度、接近度和中介度的加权来描述道路的重要度，采用相似性、误删率、漏删率等定量指标以及定性的目视判别评价选取结果。以深圳市1:1万道路网和1:5万道路网作为研究数据进行了实验。理论上删除后更新策略优于删除后不更新策略，然而实证表明删除后不更新策略在常用定量评价指标上优于删除后更新策略，在定性评价方面则各有优劣。 相似文献
5.
With the development of Volunteered Geographical Information (VGI) data, the OpenStreetMap has high research value in terms of project activity, social influence, urban development, application scope, and historical richness and the number of buildings or roads is increasing every day. However, how to evaluate the quality of a large amount OpenStreetMaps efficiently and accurately is still not fully understood. This article presents the development of an approach regarding multilevel stratified spatial sampling based on slope knowledge and official 1:1000 thematic maps as the reference dataset for OpenStreetMap data quality inspection of Hong Kong. This multilevel stratified spatial sampling plan is as follows: (1) The terrain characteristics of Hong Kong are fully considered by dividing grids into quality estimate strata based on the slope information; (2) Spatial sampling for the selection of grids or objects is used; (3) A more reliable sampling subset is made, regarding the representation of the entire OpenStreetMap dataset of Hong Kong. This sampling plan displays a 10% higher sampling accuracy, but without increasing the sample size, particularly as regards building completeness inspection compared with simple random sampling and systematic random sampling. This research promotes further applications of the Open-Street-Map dataset, thus enabling us to have a better understanding of the OpenStreetMap data quality in urban areas. 相似文献
6.
Visual method for spectral band selection 总被引：1，自引：0，他引：1
We present a new method for performing band selection experiments with spectral data. This method allows for the visual inspection and assessment of the experiment results, and includes a statistical significance test. The method follows a standard feature selection approach in which a multivariate distance measure is used as a figure of merit in a search-optimization procedure. For this letter, we have chosen the Jeffries-Matusita distance between each sample and its immediate background. The band selection methodology uses either an exhaustive search over all possible combinations of 1-4 bands or sequential forward selection. To analyze the band selection results, we count the number of times that each band is selected as a member of the best set by the protocol, and we plot the results as a band frequency histogram. This allows us to visually discern spectral patterns that are not evident otherwise, and thus better assess the utility of each spectral band. We can compute band frequency histograms over individual classes of samples or over groups of classes. In addition, we can compute a significance statistic that gives us the probability that a given histogram is not the result of random band selection outcomes. 相似文献
7.
地形图数字化测绘成果质量检查与评定的实施 总被引：3，自引：0，他引：3
本文主要介绍了测绘生产单位对地形图数字化测绘成果最终质量检查与评定的实现方法。笔者通过生产检查实践,对地形图数字化测绘成果样本检查与内业数据检查的实施、检查项的选取、检查方法的选择和图幅扣分值调整系数的确定进行了探讨,供生产部门实施最终检查时参考。 相似文献
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就基础地理信息数据的空间位置精度进行了实地检测分析,同时对二个作业单位生产的同一区域的基础地理信息数据的质量及位置精度进行了检查分析。指出了生产和检查中应注意的影响数据精度的误差因素,提出了减小数据误差、提高基础地理信息数据的位置精度的方法。 相似文献
10.
As technology matures, Real Time Kinematic (RTK) global positioning system (GPS) receivers are providing increased performance
in accuracy, on-the-fly (OTF) initialization times, measurement speed, and latency. Leica's Dozer 2000 machine guidance system
combines an MC1000 GPS sensor, graphic intensive guidance software, a digital terrain model, and a digital site plan. Figure
1 shows the operator's view of the system. The end results is a highly accurate, extremely responsive local navigation system.
Engineers can easily upload design information onto a touch-screen machine guidance personal computer (PC) and greatly reduce
earthmoving costs while simultaneously recording “as-built” inspection data.
The Leica MC1000 machine control sensor is a true 10-Hz, centimeter-level-accuracy, open-architecture GPS sensor specifically
designed for machine guidance and control. At the heart of the MC1000's performance are a very stable oven-controlled oscillator
(3 × 10−11/s short-term stability), a low-power Intel 486-DX4-80 processor, and four user-configurable input/output (I7O) ports. Special
algorithms mitigate the effects of multipath and Selective Availability (SA) while providing centimeter accuracy up to 10
times per second with only 30 milliseconds' latency. The high update rate and low latency are essential for machine guidance
and control.
The MC1000 GPS reference station is capable of outputting RTK and Differential GPS (DGPS) data simultaneously, providing and
entire site with GPS information for machine guidance and control, tracking and dispatching of vehicles, and support of survey
crews.
This article describes how recent advances in technology have combined to produce the Leica Dozer 2000 – a machine guidance
system that is ideal for a wide range of earthmoving and inspection applications. ? 2000 John Wiley & Sons, Inc. 相似文献
11.
Shashikant A. Sharma Sushma Panigrahy Jai Singh Parihar 《Journal of the Indian Society of Remote Sensing》2011,39(3):407-413
Gathering timely information of the global agriculture production of major and commercially important crops has become essential
with globalization of the agriculture commodities. Remote sensing based crop production forecasting and monitoring is emerging
as one of the most viable solutions for such large area monitoring task. A suitable sampling strategy is the basic requirement
towards this. In the present study, different sampling sizes using agricultural area as the sampling frame has been used to
analyse the optimum sampling size for continent level assessment. Land use/cover map of the world using 300 m resolution MERIS
data was used to generate the agriculture area mask. Grid size of (i) 5° × 5° (ii) 1° × 1° (iii) 30′ × 30′ (iv) 15′ × 15′
(v) 7.5′ × 7.5′ and (vi) 5′ × 5′ were used. Percent crop area was estimated for the grids of all sizes. The grid size of 15′ × 15′
was found to be optimum for global monitoring, as not much change Ws observed in the distribution of the grids after reducing
the sample size. Stratification was done using simple random and stratified random sampling method. Stratification using the
‘cumulative square-root of frequency method that resulted in five strata performed best in terms of the variance of the population. 相似文献
12.
One of the most basic and important tools in optimal spectral gravity field modelling is the method of Wiener filtering.
Originally developed for applications in analogue signal analysis and communication engineering, Wiener filtering has become
a standard linear estimation technique of modern operational geodesy, either as an independent practical tool for data de-noising
in the frequency domain or as an integral component of a more general signal estimation methodology (input–output systems
theory). Its theoretical framework is based on the Wiener–Kolmogorov linear prediction theory for stationary random fields
in the presence of additive external noise, and thus it is closely related to the (more familiar to geodesists) method of
least-squares collocation with random observation errors. The main drawback of Wiener filtering that makes its use in many
geodetic applications problematic stems from the stationarity assumption for both the signal and the noise involved in the
approximation problem. A modified Wiener-type linear estimation filter is introduced that can be used with noisy data obtained
from an arbitrary deterministic field under the masking of non-stationary random observation errors. In addition, the sampling
resolution of the input data is explicitly taken into account within the estimation algorithm, resulting in a resolution-dependent
optimal noise filter. This provides a more insightful approach to spectral filtering techniques for noise reduction, since
the data resolution parameter has not been directly incorporated in previous formulations of frequency-domain estimation problems
for gravity field signals with discrete noisy data.
Received: 1 November 2000 / Accepted: 19 June 2001 相似文献
13.
“二级检查一级验收”作为测绘单位质量控制的基本制度,在成果质量保障中发挥着重要作用,但是部分单位因整改质量不高,造成在最终检查环节上执行不顺畅。通过质检实践,总结了常规最终检查模式下整改中存在的问题,针对基础测绘项目中整改效果不明显的实际情况,在常规检查模式的基础上提出了基于检查信息分层的粗反馈最终检查模式,并通过应用实例验证了该模式在提升整改质量中的有效性和实用性。 相似文献
14.
简述了地理国情监测成果质量检验与评定方法,明确了地理国情监测成果抽样过程、质量元素、质量子元素、检查项,给出了地表覆盖类、地理国情类地理国情监测成果样本质量评定指标和批质量判定方法。 相似文献
15.
Paulo Raposo 《制图学和地理信息科学》2013,40(5):427-443
A new method of cartographic line simplification is presented. Regular hexagonal tessellations are used to sample lines for simplification, where hexagon width, reflecting sampling fidelity, is varied in proportion to target scale and drawing resolution. Tesserae constitute loci at which new sets of vertices are defined by vertex clustering quantization, and these vertices are used to compose simplified lines retaining only visually resolvable detail at target scale. Hexagon scaling is informed by the Nyquist–Shannon sampling theorem. The hexagonal quantization algorithm is also compared to an implementation of the Li–Openshaw raster-vector algorithm, which undertakes a similar process using square raster cells. Lines produced by either algorithm using like tessera widths are compared for fidelity to the original line in two ways: Hausdorff distances to the original lines are statistically analyzed, and simplified lines are presented against input lines for visual inspection. Results show that hexagonal quantization offers advantages over square tessellations for vertex clustering line simplification in that simplified lines are significantly less displaced from input lines. Visual inspection suggests lines produced by hexagonal quantization retain informative geographical shapes for greater differences in scale than do those produced by quantization in square cells. This study yields a scale-specific cartographic line simplification algorithm, following Li and Openshaw's natural principle, which is readily applicable to cartographic linework. Open-source Java code implementing the hexagonal quantization algorithm is available online. 相似文献
16.
结合国家1∶50 000数字正射影像及地形要素综合判调更新成果外业检查验收工作,主要阐述了1∶50000数字正射影像及地形要素更新综合判调更新成果的外业核查验收方法,总结了外业核查验收的经验和技巧。对于生产单位的外业工作及质检部门的检查验收能起到积极的作用。 相似文献
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针对测绘地理信息产品抽样检验的要求，给出了两类错误概率的计算方法，并通过各种不同抽样方案的两类错误概率值，分析了现行的国标GB/T24356-2009抽样检验的特点。同时针对大批量整体抽样检验和分批抽样检验，通过实例计算，说明了大批量整体检验与分批检验对整体通过概率的等价性以及分批检验的不合理性。基于"纳伪"概率值分析，提出了低合格率总体条件下，抽样检验自身的高"纳伪"概率将导致抽样检验的失效性，并通过实际算例计算了导致检验结论失真的质量边界，对测绘地理信息产品的质量风险控制具有重要意义。 相似文献
18.
地理国情普查是新时期测绘与地理信息部门服务经济社会科学发展新的实践和重大任务,控制好地理国情普查成果质量至关重要。笔者依据相关国家标准、行业标准和国情普查相关技术规程,在充分考虑第一次全国地理国情普查成果生产、质量控制、成果特征的基础之上,结合自身多年的质量检查经验,对第一次全国地理国情普查成果的质量控制及检查方法进行探讨。 相似文献
19.
An acquisition method is proposed which saves processing time and rapidly finds the Global Positioning System (GPS) satellite
with high receiving power. The idea is to combine two or more Coarse/Acquisition (C/A) codes to process acquisition, thus
called “multi-C/A code acquisition method.” The proposed method will change the procedure of conventional Fast Fourier Transform
acquisition slightly, and it has the capabilities to combine with other acquisition methods to perform signal acquisition
simultaneously. In order to show how this multi-C/A code acquisition method may improve the Time To First Fix at the cold
start, the real raw Intermediate Frequency data from a GPS software receiver are used to validate this multi-C/A code acquisition
method. The results show that this method can save at least 23% processing time and it is able to detect the satellite more
rapidly. 相似文献