共查询到20条相似文献，搜索用时 31 毫秒
1.
AmirReza SHAHTAHMASSEBI YANG Ning WANG Ke Nathan MOORE SHEN Zhangquan 《中国地理科学(英文版)》2013,23(4):403-420
Shadow is one of the major problems in remotely sensed imagery which hampers the accuracy of information extraction and change detection.In these images,shadow is generally produced by different objects,namely,cloud,mountain and urban materials.The shadow correction process consists of two steps:detection and de-shadowing.This paper reviews a range of techniques for both steps,focusing on urban regions(urban shadows),mountainous areas(topographic shadow),cloud shadows and composite shadows.Several issues including the problems and the advantages of those algorithms are discussed.In recent years,thresholding and recovery techniques have become important for shadow detection and de-shadowing,respectively.Research on shadow correction is still an important topic,particularly for urban regions(in high spatial resolution data) and mountainous forest(in high and medium spatial resolution data).Moreover,new algorithms are needed for shadow correction,especially given the advent of new satellite images. 相似文献
2.
植物吸收性光合有效辐射分量（FPAR）的遥感反演是生态环境领域的核心研究内容之一,但在复杂地形山区,其估算精度严重受到地形效应的影响（包括本影与落影）。本文利用能够消除地形阴影影响的阴影消除植被指数（SEVI）对山区遥感影像进行FPAR反演,并分别与基于不同影像预处理程度计算的归一化植被指数（NDVI）、比值型植被指数（RVI）反演的FPAR做对比分析,以评估复杂山区反演FPAR存在的地形效应。结果表明：在不做地形校正的情况下,基于NDVI与RVI反演FPAR会使得本影及落影区域的值远小于非阴影区域的值,它们的相对误差均大于70%;基于C校正后的NDVI与RVI反演FPAR可以较好地校正本影区域,相对误差降至约6.974%,但落影处的校正效果不明显,相对误差约为48.133 %;而基于SEVI反演FPAR无需DEM数据的支持,可以达到经FLAASH+C组合校正后NDVI与RVI反演FPAR相似的结果,且能改善落影区域的地形校正效果,相对误差降至约2.730%。 相似文献
3.
Most existing classification studies use spectral information and those were adequate for cities or plains.This paper explores classification method suitable for the ALOS(Advanced Land Observing Satellite) in mountainous terrain.Mountainous terrain mapping using ALOS image faces numerous challenges.These include spectral confusion with other land cover features,topographic effects on spectral signatures(such as shadow).At first,topographic radiometric correction was carried out to remove the illumination effects of topography.In addition to spectral features,texture features were used to assist classification in this paper.And texture features extracted based on GLCM(Gray Level Cooccurrence Matrix) were not only used for segmentation,but also used for building rules.The performance of the method was evaluated and compared with Maximum Likelihood Classification(MLC).Results showed that the object-oriented method integrating spectral and texture features has achieved overall accuracy of 85.73% with a kappa coefficient of 0.824,which is 13.48% and 0.145 respectively higher than that got by MLC method.It indicated that texture features can significantly improve overall accuracy,kappa coefficient,and the classification precision of existing spectrum confusion features.Object-oriented method Integrating spectral and texture features is suitable for land use extraction of ALOS image in mountainous terrain. 相似文献
4.
Payment for ecosystem services (PES) has become an increasingly popular means of ecosystem conservation. Opportunity cost is an important factor to increase the investment efficiency of PES projects. However, the distribution of opportunity cost is usually unclear in mountainous regions due to the obvious environment changes. In this study, we developed a framework to assess the distribution of agricultural opportunity costs in mountainous regions and applied this method to Baoxing County, a typical mountainous county in Sichuan Province of southwest China. Planting suitability of 17 crops was assessed based on agricultural statistics and natural conditions data within a GIS environment. Agricultural opportunity cost was quantified with a weighted summation of farmers’ willingness to cultivate and each crop’s opportunity cost. Finally, specific agricultural opportunity cost was obtained according to the spatial areas of the protection programs and land use status. The results showed that agricultural opportunity costs of PES in Baoxing County were estimated to be more than $30 million, with a mean of 400.85 $/ha. Agricultural opportunity costs in mountainous regions displayed some obvious spatial variation and areas with lower agricultural opportunity costs could be selected as priority areas for PES. Our findings revealed that the planting suitability evaluation can make agricultural opportunity costs mapping more reasonable. It will be helpful for the PES programs implementation in mountainous regions. 相似文献
5.
1INTRODUCTION Snow is an important component of the Earth's surface. Up to 50×106km2(34%) ofthe Earth's land surface is sea- sonally snow-covered (VIKHAMAR and SOLBERG, 2002).Comparedtootherlandcovers,snowcoverextent varies dramatically on very short time scales (hours- months). Its presence affects physical, chemical and bio- logical processes at many spatial scales and has impor- tant social impacts. At the global scale, its high albedo strongly influences the Earth's radiation … 相似文献
6.
Global climate change is having long-term impacts on the geographic distribution of forest species. However, the response of vertical belts of mountain forests to climate change is still little known. The vertical distribution of forest vegetation(vertical vegetation belt) on Gongga Mountain in Southwest China has been monitored for 30 years. The forest alternation of the vertical vegetation belt under different climate conditions was simulated by using a mathematical model GFSM(the Gongga Forest Succession Model). Three possible Intergovernmental Panel on Climate Change(IPCC) climate scenarios(increase of air temperature and precipitation by 1.8℃/5%, 2.8℃/10% and 3.4℃/15% for B_1, A_1B and A_2 scenarios, respectively) were chosen to reflect lower, medium and higher changes of global climate. The vertical belts of mountainous vegetation will shift upward by approximately 300 m, 500 m and 600 m in the B_1, A_1B and A_2 scenarios, respectively, according to the simulated results. Thus, the alpine tree-line will move to a higher altitude. The simulation also demonstrated that, in a changing climate, the shift in the vegetation community will be a slow and extended process characterized by two main phases. During the initial phase, trees of the forest community degrade or die, owing to an inability to adapt to a warmer climate. This results in modest environment for the introduction of opportunistic species, consequently, the vegetation with new dominant tree species becomes predominant in the space vacated by the dead trees at the expense of previously dominated original trees as the succession succeed and climate change advance. Hence, the global climate change would dramatically change forest communities and tree species in mountainous regions because that the new forest community can grow only through the death of the original tree. Results indicated that climate change will cause the change of distribution and composition of forest communities on Gongga Mountain, and this change may enhance as the intensity of climate change increases. As a result, the alternation of death and rebirth would finally result in intensive landscape changes, and may strongly affect the eco-environment of mountainous regions. 相似文献
7.
城市绿地信息在城市研究中的重要作用。但由于各种因素的影响,城市绿地信息提取的精度受到很大的限制,其中,城市中建筑物的阴影是城市绿地信息提取的一个重要限制因素。本研究选取呼和浩特市城区的QuickBird影像,在获取最佳波段组合的基础上,利用多种方法对遥感影像的阴影信息进行提取和消除,以期获得最佳的阴影消除方法,高效地提取城市绿地信息。首先,通过比值运算、波段重组,增强处理影像阴影信息,用最佳指数法分析QuickBird影像阴影提取的最佳波段组合;然后,根据阴影在近红外波段的最小亮度值与最大亮度值的范围建立掩膜,成功提取影像的阴影信息;最后,将色彩空间变换分别与同态滤波和Gamma矫正结合以消除影像阴影,并与其他方法进行对比。研究结果表明,QuickBird影像阴影提取的最佳波段组合为3/4、4、2波段组合,最佳亮度值范围为70-165;色彩空间变换与Gamma矫正相结合的方法可更好地消除阴影,并能较好地保留影像的彩色信息,是消除阴影的最佳方案。 相似文献
8.
Yong Yang Ren-sheng Chen Yao-xuan Song Jun-feng Liu Chun-tan Han Zhang-wen Liu 《山地科学学报》2017,14(12):2471-2483
Land surface temperature(LST) causes the phase change of water, links to the partitioning of surface water and energy budget, and becomes an important parameter to hydrology, meteorology, ecohydrology, and other researches in the high mountain cold regions. Unlike air temperature, which has common altitudinal lapse rates in the mountainous regions, the influence of terrain leads to complicated estimation for soil LST. This study presents two methods that use air temperature and solar position,to estimate bare LST with high temporal resolution over horizontal sites and mountainous terrain with a random slope azimuth. The data from three horizontal meteorological stations and fourteen LST observation fields with different aspects and slopes were used to test the proposed LST methods. The calculated and measured LST were compared in a range of statistical analysis, and the analysis showed that the average RMSE(root mean square error),MAD(mean absolute deviation), and R~2(correlation coefficient) for three horizontal sites were 5.09℃,3.66℃, 0.92, and 5.03℃, 3.52℃, 0.85 for the fourteen complex terrain sites. The proposed methods showed acceptable accuracy, provide a simple way to estimate LST, and will be helpful for simulating the water and energy cycles in alpine mountainous terrain. 相似文献
9.
YANG Ying-hui CHEN Qiang LIU Guo-xiang Li Zhi-lin CHENG Hai-qin Liu Li-yao 《山地科学学报》2013,10(5):790-800
In order to overcome the limitation of cross correlation coregistration method for Synthetic Aperture Radar(SAR) interferometric pairs with low coherence,a new image coregistration algorithm based on Fringe Definition Detection(FDD) is presented in this paper.The Fourier transformation was utilized to obtain spectrum characteristics of interferometric fringes.The ratio between spectrum mean and peak was proposed as the evaluation index for identifying homologous pixels from interferometric images.The satellites ERS-1/2 C-band SAR acquisitions covering the Yangtze River plain delta,eastern China and ALOS/PALSAR L-band images over the Longmen Shan mountainous area,southwestern China were respectively employed in the experiment to validate the proposed coregistration method.The testing results suggested that the derived Digital Elevation Model(DEM) from FDD method had good agreement with that from the cross correlation method as well as the reference DEM at high coherence area.However,The FDD method achieved a totally improved topographic mapping accuracy by 24 percent in comparison to the cross correlation method.The FDD method also showed better robustness and achieved relatively higher performance for SAR image coregistration in mountainous areas with low coherence. 相似文献
10.
To provide scientific basis for appraising natural resources in Mt. Namjagbarwa area, the migration characteristics of geochemical microelements, such as Zn, V, Ti, Pb, Ni, Cu, Cr, Co, Be and Ba, in the landscape zones of alpine scrub and meadow, the mountainous dark coniferous forest, the mountainous mixed broadleaf and coniferous forest, the mountainous quasi-subtropical semi-evergreen broadleaf forest, the mountainous subtropical evergreen broadleaf forest, and the valley quasi-tropical monsoon rainforest have been described in the paper. 相似文献
11.
南方山地丘陵土地利用类型的地形影响GIS分析——以江西省为例 总被引：2，自引：0，他引：2
分布广泛的山地丘陵,地形复杂多样,生态环境脆弱,不合理的土地利用方式会造成生态环境的破坏,导致严重的水土流失。分析山地丘陵区土地利用的地形控制机制,对于山地丘陵区土地利用开发与水土保持等生态保护之间权衡提供科学依据而具有重要现实意义。因此,本文以南方山地丘陵分布较广泛的江西省为例,在SRTM数字高程模型(DEM)的支持下,利用中国资源环境数据中心基于Landsat遥感解译的2000年土地利用数据,分析了江西省土地利用结构与高程、坡度和坡向等地形因子的关系。结果表明地形因子是影响江西省土地利用方式的一个重要因素,具体表现在:(1)随着高程和坡度的增加,耕地面积及占土地总面积的比例都呈下降趋势,南坡耕地面积和比例都大于北坡的耕地面积和比例;(2)在低海拔区,林地面积占土地总面积比例随着海拔高程的增加而增加,当海拔高于400米时,基本稳定;(3)居民点和工矿用地受高程和坡度的影响较大,受坡向影响较小;(4)草地的面积随着海拔的增加呈下降趋势,但其面积比随着高程增加呈缓慢增加,受坡度和坡向的影响较小。 相似文献
12.
本研究以地质灾害频发的神农架林区为研究区域,以崩塌、滑坡、泥石流3种相关性较高的灾害为研究对象,基于GIS技术进行区域崩滑流灾害的综合风险评价,以辅助城乡规划及相关工作。评价基于研究区地形、地质、灾害点等基础数据,选取崩滑流灾害影响因子,利用Arc GIS空间分析功能,结合SPSS软件进行Binary Logistic回归分析,构建灾害风险评价模型,编制基于模型的研究区崩滑流风险评价图,得到相应评价结果,获知灾害孕育发生的主要影响因素及区域内崩滑流灾害高风险区分布情况。并探讨评价结果在辅助防灾减灾专项规划编制、城乡发展方向确定、重大基础设施选址等规划重点工作方面的应用,以期通过规划,防治和规避崩滑流地质灾害,保障山区人民群众的生命财产安全。 相似文献
13.
面向对象的方法提取湖泊,常常面临边界识别不精确的问题。本研究在面向对象方法的基础上,利用分水岭算法,解决湖泊边界识别问题。该方法初步将遥感影像划分为确定湖泊区域、潜在湖泊区域和背景;然后通过分水岭算法对潜在湖泊区域进行二次提取。研究选择昆仑-喀喇和喜马拉雅山脉区域的3个山地湖泊发育良好的区域作为实验区,利用Landsat系列影像验证该算法。实验结果表明该算法的用户精度、生产者精度和总体精度分别高达99.59%、98.47%和96.53%。相比于单一的面向对象方法,本文方法更适合于山地湖泊提取,能够更加准确地描绘湖泊的实际边界,也能够减弱面向对象方法中分割尺度和分类阈值对提取结果的影响。 相似文献
14.
分别利用Helmert和KTH法模拟试算了不同地形起伏区域内横向密度扰动对于大地水准面的影响。结果表明,在地形起伏较小的平原或丘陵地带,横向密度扰动的影响一般不会超过cm级,在精度允许的范围内可以忽略其影响;在地形起伏较大的山区,横向密度扰动的影响可达cm甚至dm级,对于cm级大地水准面精化而言,需要考虑其影响。此外,基于Helmert与KTH法解算的结果在地形起伏剧烈的山区差异较大,由于Helmert法计算地形效应时忽略了外区地形质量的影响,其解算结果可能存在偏差。总体而言,在地形起伏剧烈的山区建模时,需利用多种计算方法基于实测数据分别进行试算,通过计算的变密度大地水准面与实测的GPS水准数据进行比较分析,得到适合该区域的大地水准面建模方法。 相似文献
15.
Kai Liu Hu Ding Guoan Tang A-Xing Zhu Xin Yang Sheng Jiang Jianjun Cao 《中国地理科学(英文版)》2017,27(3):415-430
Gully feature mapping is an indispensable prerequisite for the motioning and control of gully erosion which is a widespread natural hazard. The increasing availability of high-resolution Digital Elevation Model (DEM) and remote sensing imagery, combined with developed object-based methods enables automatic gully feature mapping. But still few studies have specifically focused on gully feature mapping on different scales. In this study, an object-based approach to two-level gully feature mapping, including gully-affected areas and bank gullies, was developed and tested on 1-m DEM and Worldview-3 imagery of a catchment in the Chinese Loess Plateau. The methodology includes a sequence of data preparation, image segmentation, metric calculation, and random forest based classification. The results of the two-level mapping were based on a random forest model after investigating the effects of feature selection and class-imbalance problem. Results show that the segmentation strategy adopted in this paper which considers the topographic information and optimal parameter combination can improve the segmentation results. The distribution of the gully-affected area is closely related to topographic information, however, the spectral features are more dominant for bank gully mapping. The highest overall accuracy of the gully-affected area mapping was 93.06% with four topographic features. The highest overall accuracy of bank gully mapping is 78.5% when all features are adopted. The proposed approach is a creditable option for hierarchical mapping of gully feature information, which is suitable for the application in hily Loess Plateau region. 相似文献
16.
Sami Ullah Muhammad Farooq Muhammad Shafique Muhammad Afra Siyab Fazli Kareem Matthias Dees 《山地科学学报》2016,13(7):1229-1237
Anthropogenic activities and natural processes are continuously altering the mountainous environment through deforestation, forest degradation and other land-use changes. It is highly important to assess, monitor and forecast forest cover and other land-use changes for the protection and conservation of mountainous environment. The present study deals with the assessment of forest cover and other land-use changes in the mountain ranges of Dir Kohistan in northern Pakistan, using high resolution multi-temporal SPOT-5 satellite images. The SPOT-5 satellite images of years 2004, 2007, 2010 and 2013 were acquired and classified into land-cover units. In addition, forest cover and land-use change detection map was developed using the classified maps of 2004 and 2013. The classified maps were verified through random field samples and Google Earth imagery (Quick birds and SPOT-5). The results showed that during the period 2004 to 2013 the area of forest land decreased by 6.4%, however, area of range land and agriculture land have increased by 22.1% and 2.9%, respectively. Similarly, barren land increased by 1.1%, whereas, area of snow cover/glacier is significantly decreased by 21.3%. The findings from the study will be useful for forestry and landscape planning and can be utilized by the local, provincial and national forest departments; and REDD+ policy makers in Pakistan. 相似文献
17.
The degeneration of forest landscapes is mainly caused by human impact on the natural environment, which is posing a great
threat to biodiversity. We studied the relationship between forest landscapes and birds in mountain regions of Xishuangbanna,
Yunnan Province. In Jinuo ethnic region, forest landscape is degenerating, and bird diversity is reducing as a result of human
influence. However, in Hani ethnic region of Mengsong area, a comparative study area, there are also traditional practices
of agriculture and forestry. The traditional practices are dynamically adaptive to local geographic environment and social
economic conditions. A great deal of biodiversity exists in the place where people have lived for many generations and use
the resources of environment in a sustainable manner. Considering bird diversity and forest landscape of mountainous area,
both economic and ecological benefits should be taken into account, which relate to land use and landscape protection. Biodiversity
conservation, resource management and policy making should pay much attention to the best interconnection of land use and
landscapes protection. 相似文献
18.
王直军 《中国地理科学(英文版)》1999,(2)
１ＧＥＮＥＲＡＬＳＩＴＵＡＴＩＯＮＯＦＴＨＥＳＴＵＤＩＥＤＡＲＥＡ１．１ＮａｔｕｒａｌＥｎｖｉｒｏｎｍｅｎｔＴｈｅｓｔｕｄｙｗａｓｃｏｎｄｕｃｔｅｄｉｎｔｈｅＪｉｎｕｏＭｏｕｎｔａｉｎ（２０°５３′１１″－２２°９′５９″Ｎ,１００°５５′３３″－１... 相似文献
19.
在基于高分辨率遥感影像的道路提取中,阴影遮挡是导致提取的部分或整段道路缺失的重要因素,严重制约了道路提取的自动化过程,因此探索适用性强的阴影情况下道路提取方法对地图数据生产和地理大数据研究具有重要意义。本文针对传统的阴影系数修正方法难以消除植被、建筑上的阴影对道路提取带来的干扰,选用路面颜色不一、地物干扰少的郊区影像与地物丰富、路面地物阴影干扰严重的市区影像开展研究,提出了基于亮度补偿的阴影遮挡道路的提取方法。首先,在图像预处理的基础上,利用HSI阈值分割获取阴影区域;其次,在削弱蓝色分量信息后采用亮度补偿方法实现像素点空间域增强以及阴影区信息的恢复,在增大道路面阴影与周围环境差异的基础上,借助高效的分割算法实现阴影道路提取;最后,通过和由K-means聚类分割获取的非阴影道路进行合并,经细化处理最终实现阴影遮挡道路的完整提取。实验结果表明,此方法提取郊区与市区影像中阴影道路的正确率在80%以上,该方法能有效地提取阴影遮挡道路,消除其他阴影的干扰,降低阴影道路提取时的斑块破碎度,较好的保留道路的主体。 相似文献
20.
Mapping and Assessing Typhoon-induced Forest Disturbance in Changbai Mountain National Nature Reserve Using Time Series Landsat Imagery 总被引：1，自引：0，他引：1
Monitoring forest disturbances is important for understanding changes in ecosystems. The 1986 Typhoon Vera was a serious disturbance that severely impacted the forest ecosystems of Changbai Mountain National Nature Reserve. Although the typhoon disturbance occurred more than two decades ago, the effects of the typhoon still remain within the study area. Few studies have focused on mapping and assessing disturbances across broad spatial and temporal scales. For this study, we first generated a map of forest composition prior to the typhoon disturbance, which served as a baseline data for the extraction of disturbed area. Then, the Disturbance Index(DI) method was tested for mapping the extent and magnitude of disturbance in the study area by applying a Tasseled Cap transformation to the Landsat imagery. The Landsatbased DI method estimated that an area of 13,764.78 ha of forest was disturbed by the typhoon. Based on visual assessments, these results correspond closely with the reference map derived from ground surveys. These results also revealed the influence of local topographic features on the distribution of windthrow areas. Windthrow areas were more pronounced inareas with elevations ranging from 1,000 to 2,000 m, slopes of less than 10 degrees, and southwestern to northwestern aspects. In addition, the relatively long(25 years) post-typhoon recovery period assessed by this study provided a more comprehensive analysis of the dynamics of forest recovery processes over time. Windthrow areas did not recover immediately after the typhoon, likely due to forest management practices enacted at the time. So far, forest recovery has proceeded more rapidly at elevations below 1,400 m, particularly on western slopes within the study area. Finally, a time series of DI values within the study period suggests a secondary disturbance may have occurred between 2000 and 2001. 相似文献