共查询到20条相似文献，搜索用时 31 毫秒
1.
Pete Fisher 《地球空间信息科学学报》2004,7(1):58-66
2.
基于多尺度特征融合和支持向量机的高分辨率遥感影像分类 总被引：10，自引：1，他引：10
相对传统的中低分辨率遥感数据而言,高空间分辨率遥感影像同一地物内部丰富的细节得到表征,空间信息更加丰富,地物的尺寸、形状以及相邻地物的关系得到更好的反映,但其光谱统计特性不如中低分辨率影像稳定,类内光谱差异较大,而传统分类方法仅依据像元的光谱值,因此在高分辨率影像分类中,传统方法往往不能获得好的结果。在此背景下,提出了一种多尺度空间特征融合的分类方法,旨在利用不同尺度的空间邻域特征弥补传统方法的不足。其基本过程是：首先针对不同尺度特点,用小波变换压缩空间邻域特征,并结合支持向量机得到不同尺度下的分类结果,然后根据尺度选择因子为每个像元选择最佳的类别。文中QuickBird和IKONOS影像实验证明该算法能有效提高高分辨率影像解译的精度。 相似文献
3.
G. Ducher 《The Photogrammetric Record》1985,11(66):671-689
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
4.
The loss of natural habitats and the loss of biological diversity is a global problem affecting all ecosystems including agricultural landscapes. Indicators of biodiversity can provide standardized measures that make it easier to compare and communicate changes to an ecosystem. In agricultural landscapes the amount and variety of available habitat is directly correlated with biodiversity levels. Linear woody features (LWF), including hedgerows, windbreaks, shelterbelts as well as woody shrubs along fields, roads and watercourses, play a vital role in supporting biodiversity as well as serving a wide variety of other purposes in the ecosystem. Earth observation can be used to quantify and monitor LWF across the landscape. While individual features can be manually mapped, this research focused on the development of methods using line intersect sampling (LIS) for estimating LWF as an indicator of habitat availability in agricultural landscapes. The methods are accurate, efficient, repeatable and provide robust results. Methods were tested over 9.5 Mha of agricultural landscape in the Canadian Mixedwood Plains ecozone. Approximately 97,000 km of LWF were estimated across this landscape with results useable both at a regional reporting scale, as well as mapped across space for use in wildlife habitat modelling or other landscape management research. The LIS approach developed here could be employed at a variety of scales in particular for large regions and could be adapted for use as a national scale indicator of habitat availability in heavily disturbed agricultural landscape. 相似文献
5.
尺度变化对城市生态环境与人类活动关系的影响研究 总被引：1，自引：0，他引：1
针对空间尺度对城市生态环境与人类活动影响的研究,以南昌市为研究区,划分了300×300、500×500、700×700共3种格网尺度。使用遥感生态指数RSEI（目标向量）量化城市生态环境质量,结合POI点、微博签到点与道路网数据（特征向量）,利用随机森林回归模型分析不同尺度下两者之间的拟合效果。结果表明：①3种尺度下RSEI与POI点、微博签到点与道路网均呈现较强的负相关性;且负相关性最优的为RSEI和微博签到点数据,最差的为RSEI和道路网数据。②300×300尺度下随机森林回归模型的拟合效果最好。随着尺度的变大,拟合的效果会越来越差。③无论尺度如何变化,利用随机森林回归拟合的标准化残差ε均呈正态分布;且随着尺度的变大,ε值空间分布的随机性也逐渐增大。随机森林回归模型为度量尺度对城市生态环境与人类活动的关系研究提供了有效的途径,也为城市生态文明建设提供了科学的依据和参考。 相似文献
6.
7.
8.
郭继发 《武汉大学学报(信息科学版)》2011,36(12)
根据区间II型模糊集理论研究了高阶模糊地理实体的方向表示方法,提出以方向场描述其方向隶属度,以分区方向场代替原始方向场,研究了高阶模糊地理实体的方向关系分析方法,给出了方向场的隶属度误差和方向关系的隶属度误差表示方法。 相似文献
9.
This paper investigates the spatial heterogeneity of three landscapes along an altitudinal gradient and different human land use. The main aim was the identification of appropriate landscape indicators using different extents. ASTER image was used to create a land cover map consisting of three landscapes which differed in altitude and land use. A number of landscape metrics quantifying patch complexity, configuration, diversity and connectivity were derived from the thematic map at the landscape level. There were significant differences among the three landscapes regarding these four aspects of landscape heterogeneity. The analysis revealed a specific pattern of land use where lowlands are being increasingly utilized by humans (percentage of agricultural land = 65.84%) characterized by physical connectedness (high values of Patch Cohesion Index) and relatively simple geometries (low values of fractal dimension index). The landscape pattern of uplands was found to be highly diverse based upon the Shannon Diversity index. After selecting the scale (600 ha) where metrics values stabilized, it was shown that metrics were more correlated at the small scale of 60 ha. From the original 24 metrics, 14 individual metrics with high Spearman correlation coefficient and Variance Inflation Factor criterion were eliminated, leaving 10 representative metrics for subsequent analysis. Data reduction analysis showed that Patch Density, Area-Weighted Mean Fractal Dimension Index and Patch Cohesion Index are suitable to describe landscape patterns irrespective of the scale. A systematic screening of these metrics could enhance a deeper understanding of the results obtained by them and contribute to a sustainable landscape management of Mediterranean landscapes. 相似文献
10.
11.
This article examines the relationship between scale of observation and landform features and their representation in map form. The research is premised on the idea that large scale features are defined by the smaller features that comprise them (that mountain ranges are a collection of clustered yet individually identifiable mountains or hills). In preference to subjective selection of the higher order features, we propose a methodology for automatically discerning mountain ranges as well as the smaller hills that constitute them. A mountainous region can be defined by its prominence (relative height among surrounding features) and various morphological characteristics including the variability in morphology. The algorithm presented here uses derivatives of elevation and the density of morphological properties in order to automatically identify individual hills or mountains and ranges together with their extents. Being able to create generalised views of landscape morphology is considered to be part of the model generalisation process and is an essential prerequisite to spatial query and to the cartographic portrayal of these features at a range of scales (levels of detail). For the purposes of evaluation the algorithm was applied to the hills around Edinburgh city and the hills and ranges around Fort William, Scotland. The research reflects on the challenge of defining the subjective nature of what is a ‘hill’ or a ‘mountain’, but reminds us that a map seeks to capture the essence and characteristic form of the landscape – something that is necessarily fuzzy and scale dependent. 相似文献
12.
Daniel A. Griffith 《Journal of Geographical Systems》2002,4(1):43-51
As either the spatial resolution or the spatial scale for a geographic landscape increases, both latent spatial dependence
and spatial heterogeneity also will tend to increase. In addition, the amount of georeferenced data that results becomes massively
large. These features of high spatial resolution hyperspectral data present several impediments to conducting a spatial statistical
analysis of such data. Foremost is the requirement of popular spatial autoregressive models to compute eigenvalues for a row-standardized
geographic weights matrix that depicts the geographic configuration of an image's pixels. A second drawback arises from a
need to account for increased spatial heterogeneity. And a third concern stems from the usefulness of marrying geostatistical
and spatial autoregressive models in order to employ their combined power in a spatial analysis. Research reported in this
paper addresses all three of these topics, proposing successful ways to prevent them from hindering a spatial statistical
analysis. For illustrative purposes, the proposed techniques are employed in a spatial analysis of a high spatial resolution
hyperspectral image collected during research on riparian habitats in the Yellowstone ecosystem.
Received: 25 February 2001 / Accepted: 2 August 2001 相似文献
13.
掩星观测能够提供地面到低轨卫星轨道高度处的整个电离层电子密度剖面,对于顶部电离层的研究有重要的作用。本文利用COSMIC(constellation observing system for meteorology ionosphere and climate)掩星数据反演了电子密度剖面,提取了F2层峰值高度(hmF2)、F2层峰值密度(NmF2)、垂直标尺高(vertical scale height,VSH)等电离层参数,研究了南极地区的F2层在太阳活动周期内的变化、年际变化、周日变化等,并且重点分析了南极地区的顶部电离层的垂直结构特征,尤其是威德尔海异常在垂直方向上的变化。结果表明,整个南极的hmF2每日均值在250~300 km左右,NmF2每日均值在1~8×1011 el/m3之间,VSH每日均值在100~250 km,威德尔海异常主要表现在顶部电子密度的增强和底部电子密度的减少。 相似文献
14.
G. Obenson 《Journal of Geodesy》1972,46(4):425-429
Two methods of mean gravity anomaly prediction are studied. In predicting the 5°×5° accuracies, covariance functions of 1°×1°
blocks are used. The 1°×1° covariance functions are derived from the covariance function of point anomalies. It is found that
though each method gives different accuracy values for different 1°×1° block configurations, the arithmetic mean method of
prediction gives practically the same results as the minimum variance method if the number of known 1°×1° blocks is more than
Ten.
Computations carried out at different latitudes using appropriate covariance functions gave similar results. 相似文献
15.
Ye. V. Glushko 《地理信息系统科学与遥感》2013,50(4):253-261
Space photography at 1:2,400,000 scale from the “Salyut-6” space station was used to compile maps on the evolution of arid landscapes in the Late Pleistocene and Holocene in western Iraq. The imagery made it possible to trace the development of many ancient natural features and to formulate an interpretation key of landscape elements—formed under a variety of past climatic environments, but subsequently evolving under common, somewhat similar natural conditions. This provides a basis for improved understanding the present state, history of formation, and future transformations of arid landscapes. Translated by Edward Torrey, Alexandria, VA 22308 from: Izvestiya Vsesoyuznogo Geograficheskogo Obshchestva, 1990, No. 3, pp. 255–260. 相似文献
16.
Analysis on the global morphology of stratospheric gravity wave activity deduced from the COSMIC GPS occultation profiles 总被引：5，自引：0，他引：5
Monthly mean global morphologies of potential energy density E
p
from stratospheric gravity waves are revealed by observations of COSMIC GPS radio occultation. The E
p
is obtained from vertical wavelengths ranging from 2 to 10 km over cells of 1° × 2° in latitude and longitude. The computed
values confirm previous results and obtain new ones. The large gravity wave E
p
values found in the tropics between 25°N and 25°S could be mainly due to the strong tropical cumulus convection; July values
are larger than those for January (2007). In mid and high latitudes, the most prominent features of the northern winter hemisphere
are the enhanced densities above the Eurasian continent and the North Atlantic and the depressed E
p
values above the North Pacific and North America for which topography, wind sources and wind filtering may be responsible.
In southern winter hemisphere, large E
p
values are found around 180° and 300° longitudes that are likely due to the topography of the Antarctic plateau, the Antarctic
Peninsula and South America. Enhanced E
p
values are found over Scandinavia. However, there is no clear evidence to show that gravity waves are localized over the
Rocky Mountains, the Himalayas and the Andes. Topography and planetary wave modulations are proposed to interpret the large-scale
longitudinal variations and inter-hemisphere asymmetry of the GW activity. 相似文献
17.
Hypsometric analysis is an important tool to identify and justify the erosional status, erosional processes, geologic and tectonic influences, and stage of landscape development of a basin. In this study, scale dependence of hypsometric integral (Ea) and hypsometric curve parameters were derived and analysed for various order sub-basins of Sirsa river. Here, Ea of higher order sub-basins are quite scale dependent and controlled by lithology; albeit Ea of all order sub-basins is independent of tectonic uplift. Based on Ea, all fourth and fifth order sub-basins were categorised in three classes. The analysis of hypsometric curve parameters showed that sub-basins of first category (Ea < 0.35) is characterised by upward-concave curve, fluvial process dominated and early old stage landscape. Sub-basins of second category (0.35 < Ea < 0.45) reflects concave-convex curve, dominance of fluvial process and mature landscape; whereas third category sub-basins (Ea > 0.45) are diffusive process dominated and belong to late youth to early mature stage. 相似文献
18.
以辽宁省沈抚新城区为研究对象,选择2006、2010及2014年Landsat影像为数据源,利用面向对象方法提取城市生态空间信息,并对研究区内的景观格局动态特征和多方向变化特征进行了相关计算和分析。结果表明:1)多方向变化分析研究区南部城市增长最多,沈抚新城发展中抚顺区域推进较快,不断向沈阳方向发展;2)绿地整体的增加和城市建筑增加呈显著正相关,沈抚新城生态空间结构逐渐靠拢,并向着规划中的打造浑河景观带的目标努力;3)2006~2014年期间,平均斑块面积和最大斑块指数呈增加趋势,散布与并列指数和蔓延度指数逐年递减,说明沈抚同城化过程中景观具有均衡性和规划性。 相似文献
19.
ABSTRACT Visibility determination is a key requirement in a wide range of national and urban applications, such as national security, landscape management, and urban design. Mobile LiDAR point clouds can depict the urban built environment with a high level of details and accuracy. However, few three-dimensional visibility approaches have been developed for the street-level point-cloud data. Accordingly, an approach based on mobile LiDAR point clouds has been developed to map the three-dimensional visibility at the street level. The method consists of five steps: voxelization of point-cloud data, construction of lines-of-sight, construction of sectors of sight, construction of three-dimensional visible space, and calculation of volume index. The proposed approach is able to automatically measure the volume of visible space and openness at any viewpoint along a street. This approach has been applied to three study areas. The results indicated that the proposed approach enables accurate simulation of visible space as well as high-resolution (1 m × 1 m) mapping of the visible volume index. The proposed approach can make a contribution to the improvement of urban planning and design processes that aim at developing more sustainable built environments. 相似文献