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1.
A short review is given of the involvement of the Institut Géographique National (IGN) in the European Space Agency Spacelab Metric Camera (MC) experiment. IGN has participated in this project from the early stages of its preparation in 1974. The assessment of MC data has been carried out for both metric and thematic purposes. Using a Matra Traster analytical plotter, a contoured map of Carpentras. included in the European standard test site of Marseille, has been prepared at a scale of 1:100 000 with 100 m and 50 m contour intervals. Preliminary comparison of this map with the topographic data base shows a height accuracy of about 30 m. Orthophotographs have been produced of the same area, at 1:100000 scale and at 1:250000 scale. showing good agreement with the basic line map. An infrared colour pseudo-orthophotograph has been produced for Khartoum (assuming that the ground was flat) and a space map of a desert area of Algeria has been printed at 1:200000 scale, allowing a good comparison with the drainage shown on the existing line map. Interpretation of the MC photography has also been assessed and compared with conventional IGN aerial photography taken over the European standard test site. Due to the low sun elevation and the apparent image motion which affected the MC photography, the result is not as good as was expected. Some linear features of 6m width are visible (for example, roads and hedges) but for positive identification a width of 18m is necessary. It is difficult to determine the extent of cities and land parcels less than 40 × 40m are not visible. However, the MC data can be used for checking and revising some features of small scale maps (smaller than 1:100000). Two experiments have been performed in thematic interpretation, one concerned with land use and the other with forest mapping. Some improvements of the MC are suggested in order to satisfy the major requirements of users while the possibilities of topographic mapping from these data are summarised.  相似文献   

2.
《The Cartographic journal》2013,50(3):221-233
Abstract

Cartographic generalization aims at simplifying the representation of data to suit the scale and purpose of the map. This paper deals with a method that implements the whole graphic generalization process (roughly defined as the operators simplification, smoothing, exaggeration and displacement) called simultaneous graphic generalization. This method is based on constraints, i.e. requirements that should be fulfilled in the generalization process. The constraints strive to make the map readable while preserving the characteristics of the data, which implies that all constraints cannot be completely satisfied. This study was concentrated on finding the optimal compromise between the constraints in simultaneous graphic generalization by setting weights for the constraints. Four strategies for determining the weights are described and their advantages and disadvantages are discussed. The discussion is based on the following assumptions: the constraints are independent, and the weights are only dependent on constraint type and object type. A comparison of the strategies reveals that the strategy constraint violation is the most promising. One advantage with this strategy is that it is related to the quality requirements of the map, and another advantage is that it provides a numerical measure for quality assessment. The paper concludes with a case study of the constraint violation strategy, in which visualization of the numerical quality measure is used. The case study shows that the constraint violation strategy gives a sound compromise between the constraints.  相似文献   

3.
AutoCAD环境下数字栅格图到数字线划图的简易转换   总被引：1，自引：0，他引：1  
数字栅格图和数字线划图是可以低成本获取的两种数字地图,而DLG是目前最普遍的矢量数据格式,是GIS的主要数据来源。在缺乏专业矢量化软件的条件下,利用AutoCAD环境对DRG图像经纠正、缩放、加载坐标系统等过程后进行矢量化,是获取DLG数据的简单有效方法。  相似文献   

4.
Editorial     
This article presents research that implements a fully automated workflow to generalize a 1:50k map from 1:10k data. This is the first time that a complete topographic map has been generalized without any human interaction. More noteworthy is that the resulting map is good enough to replace the existing map. Specifications for the automated process were established as part of this research.

Replication of the existing map was not the aim, because feasibility of automated generalization is better when compliance with traditional generalizations rules is loosened and alternate approaches are acceptable. Indeed, users valued the currency and relevancy of geographical information more than complying with all existing cartographic guidelines. The development of the workflow thus started with the creation of a test map with automated generalization operations. The reason for the test map was to show what is technologically possible and to refine the results based on iterative users’ evaluation. The generalization operations (200 in total) containing the relevant algorithms and parameter values were developed and implemented in one model. Particular effort was made to enrich the source data in order to improve the results. The model is context aware which means it is able to apply different algorithms or adjust parameter values in accordance with a specific area. The result of the research is a fully automated generalization workflow that produces a countrywide map at scale 1:50k from 1:10k data in 50 hours.

A fully automated workflow may be the only way to produce flexible and on-demand products; consequently, the results were implemented as a new production line in 2013. Issues for further research have been identified.  相似文献   

5.
Abstract

The Lack hitherto of studies of cycle-touring mapping in Britain is noted, and some basic attributes of cycle touring, including speed, daily distance, gradients and wind, are described. Essential and desirable qualities for a cycle-touring map are enumerated, including the need to depict all rural routes available to cyclists; it is concluded that the optimum scale is in the range 1:100 000–1:126 720, and that relief should by contours at an interval not greater than 30 metres. National mapping in the optimum scale range which were published after 1945 are then reviewed, and reasons suggested as to why none has been kept in print. The mapping available for cycle touring in Britain in 2001 is Ordnance Survey (OS) 1:50 000 Landranger series contains all the necessary information, it is too bulky to be suitable; and that most of the other maps published in the optimum scale range have inadequate relief information and all offer very limited geographical cover. The potential competition for the OS 1:50 000 from a national map series in the optimum scale range is acknowledged, and an outline specification for a 1:125 000 series is described, which seeks to minimize that competiton whilst providing all the necessary information for cycle touring.  相似文献   

6.
The angular effects of emissivity are ignored in current land surface temperature (LST) products. As a result, the directionality of these LST products limits their further application in many fields. Accurate correction of the angular problem of LST products requires explicit understanding of the angular effects of emissivity at the pixel scale. Currently, nearly ten years of global emissivity products of MODIS are available. However, the pixel-scale directionality of emissivity has never been analyzed. By performing a statistical analysis of 5-year MODIS emissivity products over most of East Asia, we generated the empirical relationships between the directional emissivity, land cover, and seasonal variations. Two look-up tables (LUTs) of directional emissivity were created for typical land cover types and applied to the generalized split-window algorithm to modify the MODIS LST. The results showed that the angular effect of emissivity could introduce a significant bias of −1-3 K to the 1 km resolution LST. Finally, the spatial scale effects of emissivity were analyzed, and it was found that the temperature differences caused by scale effects fell within +/−0.5 K for most pixels if 5 km emissivity was used in 1 km LST retrieval. Therefore, wide use of the LUTs can be expected.  相似文献   

7.
Edinburgh Castle is an ancient monument situated on a basalt crag which has steep cliffs falling away on three of its sides. Periodically, remedial measures have to be carried out on these cliffs by engineering geologists in order to stabilise loosened parts of the surface and thus prevent rock falls occurring. The rock structure on the sheer north-facing cliff is currently being studied to determine the extent of work required to ensure its stability. Before such a study could proceed satisfactorily it was necessary to obtain a large scale, contoured survey of the face and this has been achieved by terrestrial photogrammetric methods. Stereoscopic photography was taken with a Wild RC5A wide angle camera pointing horizontally, being specially mounted on its side in the elevated bucket of a Simon hydraulic platform, positioned 17 metres above ground level at a distance of 100 metres from the rock face and at eight successive locations in West Princes Street Gardens. The elevation was plotted with a Zeiss Stereoplanigraph C8 at a scale of 1 : 50 with contours (with respect to a vertical datum) at horizontal intervals of 250 mm.  相似文献   

8.
Efforts to monitor and map the changing water level and shoreline of a large mountain lake in Central Asia with aerial photographs are described. The essence of the work involved the mapping of the shoreline and position of river deltas from air photos from various years during the period 1949-1980, at uniform scale and at a level of accuracy permitting the quantitative (cartometric) as well as qualitative assessment of change. The sequence of work in compilation of map-diagrams for different parts of the shoreline involved the preliminary referencing of photos to a map, photo interpretation and compilation of large-scale “graphic diagrams,” preparation of a cartographic base, reduction and placement of diagrams on the base, and transformation of the image as a whole. Results of analysis of these map-diagrams are summarized. Translated from: Vestnik Leningradskogo Universiteta, ser. 7: geologiya, geografiya, 1986, No. 2, pp. 44-48.  相似文献   

9.
Cawthorn Camps is a Roman site of probable late 1st and early 2nd century date comprising two forts, one with a later annexe, and a camp. The site survives as earthworks and, within the main defences, there are many slight embanked structures. The current multidisciplinary programme of research has included geophysical prospection, excavation, ground and aerial survey; it is a joint initiative by the North York Moors National Park Authority and English Heritage. The project aims to increase academic understanding, improve information available to the public and assist the production of a revised management plan for this nationally important site.
Large-scale air photographs and digital photogrammetry have been used to produce a plan, at scale 1:500, of the earthworks to a precision of ±10 cm. This plan has been used as a base map with which to rectify other key photographs and plans allowing further detailed interpretation and mapping to be undertaken. The air photographic work has also investigated some of the products available through digital photogrammetric technology, such as digital elevation models (DEMs), orthophotographs and perspective views.  相似文献   

10.
详细介绍了MODIS气溶胶C005产品算法的改进情况。选择北京、榆林为试验区, 利用AERONET地基观测的气溶胶光学厚度数据, 对比分析了上午星TERRA、下午星AQUA的MODIS气溶胶C004、C005新旧产品的精度, 评价了它们在中国北方地区的适用性。采用波长插值、时空匹配将地基数据和MODIS 气溶胶产品匹配在一起, 然后采用线性拟合的方法进行对比分析。文中就MODIS气溶胶产品和地基数据的时空匹配, 摒弃了NASA关于MODIS气溶胶产品在全球所采用的方法, 引入当地月平均风速, 提出了中国北方地区时空匹配尺度。对比分析以及评价结果表明: (1) C005产品算法的改进并没有提高北京站点气溶胶光学厚度的精度, 在AOT<0.8时反而是下降的; C004、C005产品在北京站点不具有显著适用性, 但C004比C005产品效果好。(2) 榆林站点, TERRA-MODIS C004产品能够达到需求标准, 而AQUA-MODIS C004精度有所下降; 两星的C005产品精度较C004有很大程度的改善, 470、550、660nm 3个波段的气溶胶光学厚度与AERONET地基观测数据的相关系数均高于0.9, 具有显著适用性。这说明了新算法所采用的确定地表反射率的方法在植被覆盖好的地区是可行的, 在高反射地区效果不好。  相似文献   

11.
The author outlines a method for quantitative analysis of the completeness of information presented on maps of varying scale, i.e., for determining, upon reductions in scale of an original map A, what magnitudes of loss in graphic detail will result in derivative maps B, C, D that are of equal relative completeness to the original. Empirical formulae are derived which describe intensities of selection typical of maps devoted to particular topics (stream networks, urban socioeconomic indices, etc.) and graphic methods are described which can be used to determine scale denominators at which specific reductions in the number of features can occur without losses in “completeness” or, conversely, the number of particular kinds of features that can be eliminated on maps (or portions of maps) upon reductions in scale without losses in completeness. Translated from: Vestnik Moskovskogo Universiteta, geografiya, 1985, No. 5, pp. 17–23.  相似文献   

12.
张法 《四川测绘》2006,29(1):21-24
本文介绍了测度地图信息量的原理及方法,提出一种测度地图信息量的改进方法—特征信息量法,并在1:1万、1:5万、1:25万、1:100万地形图上分别选出图上100 cm2、实地域相重的三种地区,即居民地稀疏区(高山)、居民地中密区(丘陵)、居民地稠密区(平原)进行试验,最后对地图信息量进行评价并提出改进意见。  相似文献   

13.
Although increased woody plant abundance has been reported in tropical savannas worldwide, techniques for detecting the direction and magnitude of change are mostly based on visual interpretation of historical aerial photography or textural analysis of multi-temporal satellite images. These techniques are prone to human error and do not permit integration of remotely sensed data from diverse sources. Here, we integrate aerial photographs with high spatial resolution satellite imagery and use a discrete wavelet transform to objectively detect the dynamics in bush encroachment at two protected Zimbabwean savanna sites. Based on the recently introduced intensity-dominant scale approach, we test the hypotheses that: (1) the encroachment of woody patches into the surrounding grassland matrix causes a shift in the dominant scale. This shift in the dominant scale can be detected using a discrete wavelet transform regardless of whether aerial photography and satellite data are used; and (2) as the woody patch size stabilises, woody cover tends to increase thereby triggering changes in intensity. The results show that at the first site where tree patches were already established (Lake Chivero Game Reserve), between 1972 and 1984 the dominant scale of woody patches initially increased from 8 m before stabilising at 16 m and 32 m between 1984 and 2012 while the intensity fluctuated during the same period. In contrast, at the second site, which was formely grass-dominated site (Kyle Game Reserve), we observed an unclear dominant scale (1972) which later becomes distinct in 1985, 1996 and 2012. Over the same period, the intensity increased. Our results imply that using our approach we can detect and quantify woody/bush patch dynamics in savanna landscapes.  相似文献   

14.
Low and moderate spatial resolution satellite sensors (such as TOMS, AVHRR, SeaWiFS) have already shown their capability in tracking aerosols at a global scale. Sensors with moderate to high spatial resolution (such as MODIS and MERIS) seem also to be appropriate for aerosol retrieval at a regional scale. We investigated in this study the potential of MERIS-ENVISAT data to resolve the horizontal spatial distribution of aerosols over urban areas, such as the Athens metropolitan area, by using the differential textural analysis (DTA) code. The code was applied to a set of geo-corrected images to retrieve and map aerosol optical thickness (AOT) values relative to a reference image assumed to be clean of pollution with a homogeneous atmosphere. The comparison of satellite retrieved AOT against PM10 data measured at ground level showed a high positive correlation particularly for the AOT values calculated using the 5th MERIS’ spectral band (R2=0.83). These first results suggest that the application of the DTA code on cloud free areas of MERIS images can be used to provide AOT related to air quality in this urban region. The accuracy of retrieved AOT mainly depends on the overall quality, the pollution cleanness and the atmospheric homogeneity of the reference image.  相似文献   

15.
使用1986年航摄的1:10000比例尺自然彩色负片,放大制作1:1000比例尺苏州市拙政园彩色图像,对园内土地利用现状和绿化覆盖范围进行解译、调查和制图,在解译图上量测各类用地及绿化覆盖的面积,计算出拙政园内绿地率为52.50%,绿化覆盖率为81.36%,为园林、绿化管理部门提供了准确的数据和资料。据解译图上各类用地的平面格局总结了拙政园的园林结构特征集中体现了理水、叠山、建筑、绿化、装修、陈设等综合手法建园之精粹,是我国南方园林艺术之最。因此,在古典园林景点调查中推广运用遥感方法是可行的。  相似文献   

16.
Ziyuan-3 (ZY-3) satellite is the first civilian stereo mapping satellite in China and was designed to achieve the 1: 50,000 scale mapping for land and ocean. Rigorous sensor model (RSM) is required to build the relationship between the three-dimensional (3D) object space and two-dimensional (2D) image space of ZY-3 satellite imagery. However, each satellite sensor has its own imaging system with different physical sensor models, which increase the difficulty of geometric integration of multi-source images with different sensor models. Therefore, it is critical to generate generic model, especially rational polynomial coefficients (RPCs) of optical imagery. Recently, relatively a few researches have been conducted on RPCs generation to ZY-3 satellite. This paper proposes an approach to evaluate the performance of RPCs generation from RSM of ZY-3 imagery. Three scenario experiments with different terrain features (such as ocean, hill, city and grassland) are designed and conducted to comprehensively evaluate the replacement accuracies of this approach and analyze the RPCs fitting error. All the experimental results demonstrate that the proposed method achieved the encouraging accuracy of better than 1.946E?04 pixel in both x-axis direction and y-axis direction, and it indicates that the RPCs are suitable for ZY-3 imagery and can be used as a replacement for the RSM of ZY-3 imagery.  相似文献   

17.
All space-geodetic techniques are now organized as separate services of the International Association of Geodesy (IAG), supporting the first pilot project “Global Geodetic Observing System (GGOS)”. The International DORIS (Détermination d’Orbite et Radiopositionnement Intégrés par Satellite) Service (IDS) was created in mid-2003 to organize a DORIS contribution to this project and to foster a larger international cooperation on this topic. The goal of this paper is to summarize the key steps that were taken to create this structure and to present its current organization and recent results. At present, more than 50 groups from 35 different countries participate in the IDS at various levels, including 43 groups hosting DORIS stations in 32 countries all around the globe. Four Analysis Centres (ACs) provide results, such as estimates of weekly or monthly station coordinates, geocentre variations or Earth polar motion, that will soon be used to generate IDS-combined products for geodesy and geodynamics. As a first test, a preliminary combination was performed for all the 2004 data from these four ACs. Three of them show RMS of weighted station residuals with respect to this combination solution between 1 and 2 cm. The main topic under investigation is a discrepancy in the scale factor of the terrestrial reference frame (TRF) to map the individual solutions into the combination solution, which reaches 6 cm (multiplying the unit-less scale factor by the Earth radius to get convert scale to millimetre in vertical at the Earth’s surface). Finally, foreseen improvements of the DORIS technology are discussed as well as future improvements concerning the service organization itself and the accuracy and reliability of its scientific products.  相似文献   

18.
Abstract

This paper is an elaboration of the theses proposed in ‘Cartographic presentation of forms and degradation of the natural environment: sozological map on a scale of 1∶50?000’ (), where a sozological map of Poland was presented. The said map contained comprehensive cartographic information on the forms of environmental protection and degradation, made to a scale of 1∶50?000. The thematic scope of the map has already been modified twice: in 1997 and in 2005, with the ensuing changes presented in corresponding manuals: Sozological Map on a Scale of 1∶50?000, in an Analogue and Digital Form (Chief National Geodesist, 1997) and Technical Guidelines GIS-4. Sozological Map of Poland, Scale of 1∶50?000, in an Analogue and Digital Form (2005). Many years’ worth of experience gained since the launch of this cartographic system points out to the need for broadening the presented content and improving the map’s scale. Thus, attempts have been made at rescaling the map to 1∶10?000. Increasing the degree of detail is particularly necessary for presenting areas of intensive human activity. In this paper, the authors propose technical and graphical solutions for the 1∶10?000 scale.  相似文献   

19.
In this study, the multi-resolution Kalman filter (MKF) algorithm, which can handle multi-resolution problems with high computational efficiency, was used to blend two emissivity products: the Global LAnd Surface Satellite (GLASS) (BBE) product and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) narrowband emissivity (NBE) product. The ASTER NBE product was first converted into a BBE product. A new detrending method was used to transfer the BBEs into a process suitable for the MKF. The new detrending method was superior to the two existing methods. Finally, both the de-trended GLASS and ASTER BBE products were incorporated into the MKF framework to obtain the optimal estimation at each scale. Field measurements collected in North America were used to validate the integrated BBEs. Visually, the fusion map showed good continuity, with the exception of the border areas, and the quality of the fusion map was better than that of the original maps. The validation results indicate that the MKF improved the BBE product accuracy at the coarse scale. In addition, the MKF was capable of recovering missing pixels at a finer scale.  相似文献   

20.
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