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1.
Smart card-automated fare collection systems now routinely record large volumes of data comprising the origins and destinations of travelers. Processing and analyzing these data open new opportunities in urban modeling and travel behavior research. This study seeks to develop an accurate framework for the study of urban mobility from smart card data by developing a heuristic primary location model to identify the home and work locations. The model uses journey counts as an indicator of usage regularity, visit-frequency to identify activity locations for regular commuters, and stay-time for the classification of work and home locations and activities. London is taken as a case study, and the model results were validated against survey data from the London Travel Demand Survey and volunteer survey. Results demonstrate that the proposed model is able to detect meaningful home and work places with high precision. This study offers a new and cost-effective approach to travel behavior and demand research.  相似文献   

2.
ABSTRACT

Quantitative attribution at the individual pixel level of the relative contributions of climate variability and human activities to vegetation productivity dynamics across Africa is generally lacking. This is because of the difficulty in establishing a baseline or potential vegetation against which the relative impacts of these factors can be assessed. This study addresses these gaps. First, annual potential net primary productivity (NPPP) for 2000–2014 was estimated for Africa using a model constructed from samples of NPP and environmental covariates from protected areas. Second, trends in NPPP, actual NPP (NPPA), and human-appropriated NPP (NPPH?=?NPPP ? NPPA) were estimated and used in quantifying the relative contributions of climate and human activities to NPP dynamics. Over 2000–2014, NPP improvement was largely concentrated in equatorial and northern Africa, while subequatorial Africa exhibited the most NPP decline. Parts of Mali, Burkina Faso, and the central Africa region are associated with the greatest influence of climate-driven NPP improvement. Areas where humans dominated NPP decline include parts of Ethiopia and South Africa. Climate had a stronger role in driving NPP decline in subequatorial Africa. Nonetheless, further work is required to validate the results of this study with high-resolution imagery and field information.  相似文献   

3.
《测量评论》2013,45(8):86-89
Abstract

THE article on Road-Surveying in the East by Mr. J. N. List in the Empire Survey Review, No.6, 263–74, is well worthy of perusal. From the beginning, with his apt quotation from Kipling, to the end where he compares the text-book ideal of road location with the indifferent compromise amidst difficulties that the British engineer in the East is lucky to be able to achieve, I felt in accord with his observations. Having spent four years on a similar kind of work, I consider that this article well deserves the appreciation of its author's profession.  相似文献   

4.
唐炉亮  阚子涵  段倩  李清泉 《测绘学报》2017,46(12):2024-2031
交通运输中能耗与污染物排放给人类环境带来了严峻挑战。本文提出了一种时空路径支持下的油耗、排放估计新方法。该方法首先在时空集成的三维坐标系下建立个体车辆的时空路径并从中识别移动/停留行为,然后根据时空路径段与提取的运动参数利用COPERT模型估计车辆的油耗和排放,最后提出一种时空路径的N维表达模型,将车辆的运动特征与时空路径段的油耗与排放统一进行可视化。试验中利用武汉市GPS轨迹大数据估计并分析了单辆车与路网片区的油耗与排放,结果显示本文提出的时空路径支持下的车辆油耗与排放估计方法在估计精度与可视化方面优于传统的基于平均速度估计方法,能够更加准确地估计和表达车辆油耗与排放。  相似文献   

5.
Abstract

This work presents a mapping and tracking system based on images to enable a small Unmanned Aerial Vehicle (UAV) to accurately navigate in indoor and GPS-denied outdoor environments. A method is proposed to estimate the UAV’s pose (i.e., the 3D position and orientation of the camera sensor) in real-time using only the on-board RGB camera as the UAV travels through a known 3D environment (i.e., a 3D CAD model). Linear features are extracted and automatically matched between images collected by the UAV’s onboard RGB camera and the 3D object model. The matched lines from the 3D model serve as ground control to estimate the camera pose in real-time via line-based space resection. The results demonstrate that the proposed model-based pose estimation algorithm provides sub-meter positioning accuracies in both indoor and outdoor environments. It is also that shown the proposed method can provide sparse updates to correct the drift from complementary simultaneous localization and mapping (SLAM)-derived pose estimates.  相似文献   

6.
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7.
ABSTRACT

There is an increasing availability of geospatial data describing patterns of human settlement and population such as various global remote-sensing based built-up land layers, fine-grained census-based population estimates, and publicly available cadastral and building footprint data. This development constitutes new integrative modeling opportunities to characterize the continuum of urban, peri-urban, and rural settlements and populations. However, little research has been done regarding the agreement between such data products in measuring human presence which is measured by different proxy variables (i.e. presence of built-up structures derived from different remote sensors, census-derived population counts, or cadastral land parcels). In this work, we quantitatively evaluate and cross-compare the ability of such data to model the urban continuum, using a unique, integrated validation database of cadastral and building footprint data, U.S. census data, and three different versions of the Global Human Settlement Layer (GHSL) derived from remotely sensed data. We identify advantages and shortcomings of these data types across different geographic settings in the U.S., which will inform future data users on implications of data accuracy and suitability for a given application, even in data-poor regions of the world.  相似文献   

8.
ABSTRACT

A method based on workflow technology and Open Geospatial Consortium (OGC) specification is proposed to establish a universal workflow conceptual model in the network environment. In this paper, the soil fertility evaluation conceptual model was developed as an evaluation method of soil fertility by analyzing the GIS-based fertility evaluation method and extracting the dynamic variable to verify the feasibility model. This validation process involves determining the instantiation of the conceptual model. The proposed conceptual model achieved the following goals. All data acquisition and processing functions were packaged into an OGC-compliant service model; these service models were organized into a processing chain in a certain order on the workflow platform by Petri-Net; the fertility evaluation was realized on the workflow platform by calling the processing chain. Results showed that processing functions and data can be shared in the network environment, and the network workflow model can be realized by the workflow technology. The successful implementation of fertility evaluation proved the feasibility of the network-based universal workflow conceptual model. In addition, the flexibility of our modeling method is demonstrated by reconstructing the workflow model.  相似文献   

9.
《测量评论》2013,45(21):407-413
Abstract

So much has been written in the Empire Survey Review and other publications on the somewhat controversial subject of “Luminous or Opaque Signals in Geodetic and Primary Triangulation” that it may be of interest to give an outline of the types of signals used on such work in Southern Rhodesia, with particular reference to the completion of the Eastern Geodetic Circuit in 1935 and the type of signal that it has been decided to adopt for future work.  相似文献   

10.
Abstract

A significant Geographic Information Science (GIS) issue is closely related to spatial autocorrelation, a burning question in the phase of information extraction from the statistical analysis of georeferenced data. At present, spatial autocorrelation presents two types of measures: continuous and discrete. Is it possible to use Moran's I and the Moran scatterplot with continuous data? Is it possible to use the same methodology with discrete data? A particular and cumbersome problem is the choice of the spatial-neighborhood matrix (W) for points data. This paper addresses these issues by introducing the concept of covariogram contiguity, where each weight is based on the variogram model for that particular dataset: (1) the variogram, whose range equals the distance with the highest Moran I value, defines the weights for points separated by less than the estimated range and (2) weights equal zero for points widely separated from the variogram range considered. After the W matrix is computed, the Moran location scatterplot is created in an iterative process. In accordance with various lag distances, Moran's I is presented as a good search factor for the optimal neighborhood area. Uncertainty/transition regions are also emphasized. At the same time, a new Exploratory Spatial Data Analysis (ESDA) tool is developed, the Moran variance scatterplot, since the conventional Moran scatterplot is not sensitive to neighbor variance. This computer-mapping framework allows the study of spatial patterns, outliers, changeover areas, and trends in an ESDA process. All these tools were implemented in a free web e-Learning program for quantitative geographers called SAKWeb© (or, in the near future, myGeooffice.org).  相似文献   

11.
《The Cartographic journal》2013,50(4):324-331
Abstract

Considerable attention has been paid in the literature to the changing style of Ordnance Survey mapping in the twentieth century. However, little has been written about the origins of the characteristic appearance of the first multi-colour editions, other that the Ordnance Survey used a military edition that was already in production. The distinctive style grew out of the work of a committee established in 1892 by the War Office to consider future army requirements for a map of the UK. This paper explores the work of the committee and its long-term implications for the look of mapping in the twentieth century.  相似文献   

12.
Abstract

This paper offers a review of the activities of Stirling Surveys, a small cartographic publishing company based in Stirling, Scotland. Established in 1987, the company produces maps for a range of clients in addition to publishing their own maps under the Footprint imprint. Meeting the needs of different maps users in an effective way is central to the design and production of these maps. The demands on a small publisher operating in a niche market are also considered.  相似文献   

13.
Space-based navigation and radar systems operating at single frequencies of <10 GHz require ionospheric corrections of the signal delay or range error. Because this ionospheric propagation error is proportional to the total electron content of the ionosphere along the ray path, a user friendly TEC model covering global scale and all levels of solar activity should be helpful in various applications. Since such a model is not available yet, we present an empirical model approach that allows determining global TEC very easily. Although the number of model coefficients and parameters is rather small, the model describes main ionospheric features with good quality. Presented is the empirical approach describing dependencies on local time, geographic/geomagnetic location and solar irradiance and activity. The non-linear approach needs only 12 coefficients and a few empirically fixed parameters for describing the broad spectrum of TEC variation at all levels of solar activity. The model approach is applied on high-quality global TEC data derived by the Center for Orbit Determination in Europe (CODE) at the University of Berne over more than half a solar cycle (1998–2007). The model fits to these input data with a negative bias of 0.3 TECU and a RMS deviation of 7.5 TECU. As other empirical models too, the proposed Global Neustrelitz TEC Model NTCM-GLis climatological, i.e. the model describes the average behaviour under quiet geomagnetic conditions. During severe space weather events the actual TEC data may deviate from the model values considerably by more than 100%. A preliminary comparison with independent data sets as TOPEX/Poseidon altimeter data reveals similar results for NeQuick and NTCM-GL with RMS deviations in the order of 5 and 11 TECU (1 TECU = 1016 electrons/m2) for low and high-solar activity conditions, respectively. The more extended data base of ionosphere information that accumulates in the coming years will help in further improving the set of coefficients of the model.  相似文献   

14.
Abstract

Most European countries have a national topographic map series at 1:100 000 scale, but currently Great Britain does not. The history of mapping at or around 1:100 000 in Britain is described briefly and consideration given as to why such a scale would be appropriate for a national series of mapping aimed at tourist and leisure users. The main focus of the article is to review a series of 1:100 000 scale maps of two sample areas of Great Britain, produced in the style of various western European medium scale topographic maps. Two further design examples are produced combining desirable characteristics of the maps examined. The results show both that many of the designs translate well to 1:100 000 scale maps of the British landscape and that there is considerable potential for a topographic base at this scale providing a basis for a national series aimed at tourist and leisure users.  相似文献   

15.
Abstract

First, an overview of the main terms used in the paper is presented, such as feature catalogue, object, feature, and so on. Then INSPIRE (INfrastructure for SPatial InfoRmation in Europe) Directive, STOKIS (Slu?beni topografski i kartografski informacijski sustav RH), ATKIS (Amtliches topographisch-kartographisches Informationssystem) and FACC (Feature and Attribute Coding Catalogue) are explained. The main section of the paper refers to the problem of defining features in feature catalogues. Adequate solutions to this problem are offered on the basis of conducted research. An overall acceptable model for feature definition is offered. The importance of the proposed model for defining features is explained on the feature ‘avenue of trees’. The research results are applicable in countries attempting to create their first feature catalogues with the aim of developing a topographic information system, or in those wanting to produce a new edition of their existing feature catalogue. Since the suggested model is included, it can be used for the future development of the INSPIRE feature.  相似文献   

16.
ABSTRACT

Mangroves are critical in the ecological, economic and social development of coastal rural and urban communities. However, they are under threat by climate change and anthropogenic activities. The Sunda Banda Seascape (SBS), Indonesia, is among the world’s richest regions of mangrove biomass and biodiversity. To inform current and future management strategies, it is critical to provide estimates of how mangroves will respond to climate change in this region. Therefore, this paper utilized spatial analysis with model-based climatic indicators (temperature and precipitation) and mangrove distribution maps to estimate a benchmark for the mangrove biomass of the SBS in six scenarios, namely the Last Inter-glacial Period, the current scenario (1950–2000) and all four projected Representative Concentration Pathways in 2070 due to climate change. Despite mangroves gaining more biomass with climate change (the increase in CO2 concentration), this paper highlighted the great proportion of below-ground biomass in mangrove forests. It also showed that the changes in spatial distribution of mangrove biomass became more variable in the context of climate change. As mangroves have been proposed as an essential component of climate change strategies, this study can serve as a baseline for future studies and resource management strategies.  相似文献   

17.
none 《测量评论》2013,45(54):331-332
Abstract

Although the title of this paper may appear to some to refer to a rather humdrum subject which hardly deserves much serious thought or consideration, it is the writer's experience that the vital necessity for keeping clear records of survey work in a permanent form in which they can easily be referred to at any future time is not always sufficiently appreciated by those whose duties do not involve constant or frequent reference to the records of old work. Accordingly, the following notes and suggestions, which are based on practical experience, may be of service in drawing attention to a matter which is really of great practical importance.  相似文献   

18.
《The Cartographic journal》2013,50(2):100-110
Abstract

Despite the recent publication of several dictionaries of surveyors and cartographers, little is known of the professional and personal background of the majority of such practitioners. This lack of detailed biographical analysis is particularly applicable to the surveyor in the seventeenth century. This paper examines the activities of one of the most prolific west Midlands' estate surveyors in that century, William Fowler. Present knowledge of surveying practice in that period is reviewed and Fowler's work is compared to this pattern. An appendix details Fowler's extant maps and surveys.  相似文献   

19.
ABSTRACT

The foundation of modern Digital Earth frameworks is the Discrete Global Grid System (DGGS). To standardize the DGGS model, the Open Geospatial Consortium (OGC) recently created the DGGS Abstract Specification, which also aims to increase usability and interoperability between DGGSs. To support these demands and aid future research, open implementations are necessary. However, several OGC conformant DGGSs are not available for researchers to use. This has motivated us to develop an open-source web service that allows users to create quadrilateral grids based on the rHEALPix DGGS. In this paper, we describe the implementation of the web service, including issues and limitations, and demonstrate how discrete global grids and regional grids can be created. Lastly, we present examples that show how vector data sets can be modeled and integrated at different levels of resolution – a key benefit of the DGGS model.  相似文献   

20.
《The Cartographic journal》2013,50(3):278-283
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