共查询到20条相似文献，搜索用时 46 毫秒
1.
CHEN Xiaoling CHEN Xiaoling Associate professor National Laboratory for momation Engi-neering in Surveying Mapping Remote Sensing WTUSM Luoyu Road Wuhan China 《地球空间信息科学学报》1999,2(1):35-41
The coastal lowlands in northern Jiangsu Province, China, is characterized by low relief and low water surface gradient in streams. The flooding stages are commonly lower than the high-tide level and the tidal range is relatively small. All these factors prohibit rapid discharge of floodwater and make the flood regimes here extremely sensitive to the sea level rise. The 1991 Plum Rain was examined, when precipitation was significantly higher than normal. The one-dimensional open-channel non-conservative flow model was used to simulate the stream flow in the channel network of studied area. GIS technology was used to delineate the maximum in undated area by analyzing the DEMs. 相似文献
2.
XianWen Ding XiaoFeng Li 《International Journal of Applied Earth Observation and Geoinformation》2011
As an active microwave remote sensing sensor, synthetic aperture radar (SAR) can image the Earth surface with high spatial resolution in both day and night under all weather conditions. In this paper, a digital image processing technique was implemented to extract water area information from SAR images and the result is used to monitor the water area variation of Lake Dongting, the second largest freshwater lake in China. 8-year time series of European Space Agency's ENVISAT ASAR (Advanced Synthetic Aperture Radar) images acquired between 2002 and 2009 were obtained and a land-water classification scheme was implemented. Using independent in situ water level data measured at a lake-side hydrologic station during study period, we derived the relationship between water level and water area of Lake Dongting. The results show that, (1) during dry seasons, the water area is 518 km2 larger than that in the 1990s reported by Yangtze BHYRWRC (Bureau of Hydrology and Yangtze River Water Resources Commission), 2000; (2) the water area of Lake Dongting increased significantly in the 2000s after the Chinese Government's “return land to lake” policy took effect in 1998; (3) the water level of Lake Dongting could be low during a rainy season due to drought; but could be high in a dry season due to discharges from the upstream Three Gorges Dam. In addition, the relationship between water storage change and water area/level change is obtained. 相似文献
3.
基于DMSP/OLS夜间灯光数据的居住区指数模型（HSI）广泛应用于区域尺度城市不透水面扩张监测。但是,在干旱区由于受到裸岩、沙漠、戈壁等低植被覆盖区干扰,HSI算法的精度和适应性受到了一定的影响。为解决这一问题,本文利用植被覆盖度作为调节系数,对灯光数据与植被指数进行动态调整,构建了适用于干旱区的城市植被调节不透水指数（VAISI）;然后采用SVR模型,通过机器学习的方法构建了城市不透率参考数据与VAISI之间的非线性关系模型,实现对干旱区区域尺度不透水面覆盖率估算;最后,对模型估算结果进行了精度验证和比较分析。试验结果表明：在干旱区,VAISI解决了由于灯光溢出问题及城市周边裸土等低植被覆盖等因素导致的城市周边裸土像元不透率估算过高问题,一定程度上提高了城市内部不透水面空间分布信息的表达能力,有效克服了非灯光区估算结果高于背景值的现象。平均相关系数R由0.69提升到0.79,RMSE由0.17降至0.14。 相似文献
4.
李玉平 《测绘与空间地理信息》2020,(1):192-195
针对新疆某河地质断面测量范围大、测区通行困难、测量部位分散、传统控制测量方法工作量大且效率低的问题,在测区每条断面上布设断面基点作为控制点并用GNSS接收机静态观测(无需同步),选用武汉大学开发的Trip2.0软件加载事后精密星历和精密钟差等信息解算静态观测数据得到ITRF框架下的三维坐标,然后采用TBC软件加载EGM2008超高阶地球重力场模型点校正得到控制点的国家平面坐标和正常高。结果表明,Trip2.0软件计算的三维点位中误差最大为0.066 m,点校正坐标转换残差与已知点差值均满足限差要求;该方法平面控制测量工作量比传统方案减少46%,五等水准测量比传统方案减少98%,节约工期约56%。实践表明,采用该方法可快速地实现测区面积大、测点分散、控制点稀少区域的平面及高程控制测量。 相似文献
5.
以三峡库区沙镇溪镇-泄滩乡为研究区,探索基于最短描述长度原则的信息增益法对滑坡连续型因子进行离散的效果,计算皮尔森系数去除高相关因子。利用信息量法预测的极低、低易发区随机抽取非滑坡样本点。通过迭代计算袋外误差估计确定较优的随机特征及其数目,将优化后的随机森林对研究区滑坡进行易发性评价,并与逻辑回归等方法进行比较。绘制各算法预测结果的接收灵敏度曲线,其中优化后的随机森林预测结果的曲线下面积较高,达91.8%,表明优化随机森林模型在滑坡易发性评价中具有较高的预测能力。 相似文献
6.
Monitoring growth of built-up areas in indo-gangetic plain using multi-sensor remote sensing data 总被引：1，自引：0，他引：1
This paper provides an approach for rapid and accurate estimation of built-up areas on a per pixel-basis using a integration
of two coarse spatial resolution remote sensing data namely DMSP-OLS and MODIS NDVI. The DMSP-OLS data due to its free availability,
high temporal resolution and wide swath was used for regional level mapping of built-up areas. However, due to its low radiometric
resolution, the built-up areas cannot be estimated accurately from the DMSP-OLS data. In present study, the DMSP-OLS data
was combined with MODIS NDVI data to develop an Human Settlement Index (HSI) image, which estimated the fraction of built-up
area on a per pixel basis. The resultant HSI image conveys more information than both the individual datasets. These temporal
HSI images were then used for monitoring urban growth in Indo-Gangetic plains during the 2001–2007 time period. Thus, the
present research can be very useful for regional level monitoring of built-up areas from coarse resolution data within limited
time and minimal cost. 相似文献
7.
玛河流域景观生态风险评价与时空分异 总被引：1，自引：0，他引：1
高雅 《测绘与空间地理信息》2021,44(1):86-89
以玛纳斯河流域作为研究区,结合特殊的干旱区山地-绿洲-荒漠系统(Mountain-Oasis-Desert System简称MODS),综合考虑遥感影像数据光谱信息和纹理特征,将研究区分为耕地、林地、草地、水体、裸地、居民地、工业用地和冰川/永久积雪等8个景观类型,利用FRAGSTATS软件计算景观指数,引入生态风险的指数,将研究区划为低、较低、中、较高、高生态风险区五级,评估其景观格局的生态风险时空变化特征。结果表明:1)1990—2015年间,玛纳斯河流域景观变化主要表现为耕地、建设用地的增加以及水体、冰川/永久积雪面积的缩减;2)玛纳斯河流域的景观生态风险等级空间分布具有明显的差异,较低风险区的面积变化较为明显,低、较低生态的风险区比重有所上升,除此以外,林、草地类型各生态风险的等级所占比重的起伏波动具有明显的差异。建议应当合理地利用土地资源,尽量保护林地、草地等景观脆弱行较低的原生景观类型,禁止为开垦耕地而破坏林地、草地;增加土地的利用效率,更要对高等、较高生态风险区加强监管。 相似文献
8.
泰安市区不透水面覆盖度遥感估算研究 总被引：2，自引：1，他引：1
区域不透水面覆盖度是该区域城镇化程度、生态环境状况的重要指示因子。针对传统线性混合像元分解丰度图经常出现负值或者大于1的情况,采用完全约束最小二乘混合像元分解方法,利用泰安市市区Landsat8 OLI遥感影像提取了其不透水面分布状况,运用高分辨率遥感影像随机采样进行了精度检验,并对该区域不透水面空间特征进行了分析。结果表明:该文方法对泰安市市区不透水面分布提取的精度较高;植被、水体、高和低反照率不透水面4种光谱端元的线性组合,可以较好地模拟OLI影像的波谱特征;高、低反照率不透水面两种光谱端元可以很好地表达泰安市市区不透水面信息。 相似文献
9.
Yogesh Kant B. D. Bharath Javed Mallick Clement Atzberger Norman Kerle 《Journal of the Indian Society of Remote Sensing》2009,37(2):201-214
The knowledge of the surface temperature is important to a range of issues and themes in earth sciences central to urban climatology,
global environmental change and human-environment interactions. The study analyses land surface temperature (LST) estimation
using temporal ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) datasets (day time and night time) over
National Capital Territory Delhi using the surface emissivity information at pixel level. The spatial variations of LST over
different land use/land cover (LU/LC) at day time and night time were analysed and relationship between the spatial distribution
of LU/LC and vegetation density with LST was developed. Minimum noise fraction (MNF) was used for LU/LC classification which
gave better accuracy than classification with original bands. The satellite derived emissivity values were found to be in
good agreement with literature and field measured values. It was observed that fallow land, waste land/bare soil, commercial/industrial
and high dense built-up area have high surface temperature values during day time, compared to those over water bodies, agricultural
cropland, and dense vegetation. During night time high surface temperature values are found over high dense built-up, water
bodies, commercial/industrial and low dense built-up than over fallow land, dense vegetation and agricultural cropland. It
was found that there is a strong negative correlation between surface temperature and NDVI over dense vegetation, sparse vegetation
and low dense built-up area while with fraction vegetation cover, it indicates a moderate negative correlation. The results
suggest that the methodology is feasible to estimate NDVI, surface emissivity and surface temperature with reasonable accuracy
over heterogeneous urban area. The analysis also indicates that the relationship between the spatial distribution of LU/LC
and vegetation density is closely related to the development of urban heat islands (UHI). 相似文献
10.
济南市是中国雾霾最严重的城市之一,探究该地区大气污染的时空分布及影响机制具有重要意义。利用地统计插值分析了济南市主城区AQI的时空分布特征,并利用地理探测器定量分析了AQI的风险因子及影响机制。研究结果表明,年际尺度上,济南市主城区AQI在时间上呈逐年降低趋势,在空间上大致呈现出东南低西北高的分布态势;季节尺度上,济南市主城区AQI在时间上具有鲜明的季节性差异,从高到低依次为冬季、春季、秋季、夏季,在空间上则呈现出春季和冬季东南低北部高、夏季整个主城区均低、秋季南低北高的分布态势;月尺度上,济南市主城区AQI呈现出典型的“U”形分布特征,最高值为1月和12月、最低值为8月;各因子交互作用的影响力远大于单因子的影响力,其中,土地利用类型∩年均降水量的交互作用对济南市主城区AQI的影响力最大。研究显示,济南市主城区AQI受土地利用类型和年均降水量的共同影响最大。 相似文献
11.
针对含雾遥感影像在军事航空侦查、地物判读等方面使用率低、有效性差的问题,以及现有去雾算法中存在计算复杂耗时、色彩失真的弊端,结合遥感影像景深变化小、不含天空背景等特点,本文提出一种改进的暗原色先验去雾算法。首先,对影像中白色场景灰度值进行统计并设定阈值划分为失效区,分离水域与非水域减少蓝色波段在水域的占比,合成新的蓝色波段,以改进暗通道值的获取方法;其次,采用导向滤波替代软抠图法优化透射率提升处理时间;然后,对关键参数进行适应性改进试验并采用自动色阶恢复去雾后的影像色彩;最后,利用含雾的无人机影像和GF-2影像进行了试验,并进行了定量评价。试验结果表明,在同等试验条件下,本文方法处理单幅影像的时间比暗原色先验去雾算法的提升4倍以上,且去雾后影像的灰度均值、标准差、信息熵、平均梯度等指标比暗原色先验去雾算法得到的值均有提高,能有效提高有雾影像的清晰度,增强影像色彩和细节。 相似文献
12.
现有像元二分模型MODIS植被覆盖度模型因其形式简单、适用性较强的特点被广泛应用于区域植被覆盖度（FVC）的估算。然而,研究表明在沙漠和低植被覆盖的西部干旱区,从250 m的影像上很难精准地获取NDVIveg（全植被覆盖植被指数）和NDVIsoil（全裸土区植被指数）参数。利用常用的直方图累计法获取模型所需参数NDVIveg和NDVIsoil,估算结果存在普遍高估现象。为此,本文首先引入同期获取的GF-2号卫星数据,从GF-2号影像上提取植被覆盖像元;然后,利用Pixel Aggregate方法重采样至250 m分辨率,获取250 m空间分辨率下纯植被和纯裸土像元;最后,将纯植被和纯裸土像元各自空间位置相对应的MODIS NDVI数据最大值作为模型所需NDVIveg和NDVIsoil参数,实现研究区内植被覆盖度的估算。试验通过与线性回归法、多项式回归法和直方图累计像元二分模型法估算结果进行精度对比,结果表明：利用GF-2影像辅助的像元二分模型,精准地获取了低植被覆盖区NDVIveg和NDVIsoil模型参数,提高了干旱区植被覆盖度的估算精度,并有效地抑制了受稀疏植被影响NDVI在干旱区普遍偏高问题导致的FVC高估的现象。 相似文献
13.
一种改进的近似等面积QTM剖分模型 总被引：1，自引：1，他引：0
为克服传统QTM格网面积变形较大的缺陷,在"纬线法"剖分的基础上,引入变经纬度等面积剖分的思想,提出了一种新的等面积改进剖分模型。该模型通过调整纬线的位置,确保两条相邻纬线间的格网面积总和无变化,从而达到控制QTM格网面积变化及变化积累的目的。试验结果表明,该改进模型在保留了"纬线法"QTM剖分的优点(如计算简单、与经纬度格网间的对应关系明确等)以外,还具有以下优势:1模型的收敛性更好,格网单元面积最大、最小比最终收敛到1.38,远小于"纬线法"的1.73;2中低纬度区的格网单元面积变化较小,分布连续,且随剖分层次的增加,变化大的格网区域逐渐向两极移动集中;3格网单元的面积变化不会随层次的增加而累积增大。 相似文献
14.
《International Journal of Digital Earth》2013,6(9):1046-1066
ABSTRACTTo analyze the efficiency of area estimations (i.e. estimation accuracy and variation of estimation) impacted by crop mapping error, we simulated error at eight levels for thematic maps using a stratified sampling estimation methodology. The results show that the estimation efficiency is influenced by the combination of the sample size and the error level. Evaluating the trade-offs between sample size and error level showed that reducing the crop mapping error level provides the most benefit (i.e. higher estimation efficiency). Further, sampling performance differed based on the heterogeneity of the crop area. The results demonstrated that the influence of increasing the error level on estimation efficiency is more detrimental in heterogeneous areas than in homogeneous ones. Therefore, to obtain higher estimation efficiency, a larger sample size and lower error level or both are needed, especially in heterogeneous areas. We suggest that existing land-cover maps should first be used to determine the heterogeneity of the area. The appropriate sample size for these areas then can be determined according to all three factors: heterogeneity, expected estimation efficiency, and sampling budget. Overall, extending our understanding of the impacts of crop mapping error is necessary for decision making to improve our ability to effectively estimate crop area. 相似文献
15.
S. P. Rajaveni K. Brindha R. Rajesh L. Elango 《Journal of the Indian Society of Remote Sensing》2014,42(4):765-776
Drainage and lineaments play an important role in the flow of groundwater. The objective of this study is to assess the groundwater level and its relation to drainage and lineaments in a hard rock region of a part of Nalgonda district, Andhra Pradesh, southern India. The region predominantly comprise of granites and gneisses. Groundwater level was measured in 42 representative wells in this study area from March 2008 to January 2010 once in every two months. Observed groundwater levels were compared with drainage and dyke density. Groundwater level fluctuation in low drainage density region is generally greater than those in moderate and high drainage density regions. The dykes do not act as barriers for groundwater flow as they are highly weathered. The quantity and flow of groundwater in this region is predominantly controlled by drainage density, intensity of weathering and presence of fractures. Thus the study indicate that the drainage density play a major role in groundwater level fluctuation and as the dykes are weathered, they do not affect the groundwater flow in this shallow unconfined aquifer. 相似文献
16.
GIS中折线元及面元置信水平的随机模拟 总被引：2，自引：1，他引：2
置信水平是描述GIS中线元素与面元素的位置不确定性的重要指标之一。文中应用MonteCarlo方法，利用C 中的rand()函数，经过转换，首先产生符合对点误差分布的节点坐标，再按照置信域的构建规则生成大量的随机区域，通过数值判断，算出区域覆盖要素真值的频率，以此频率作为置信水平的近似值，克服了用解析证明方法研究置信水平时结果往往过于保守这一缺陷。本模拟方法有较大的适用范围，为类似的置信水平研究提供了一般方法。 相似文献
17.
遥感影像的计算机解译已广泛地应用于许多领域，但要达到完全自动地解译的目标仍然存在不少问题。本文研究的问题是，在统计分类的基础上，引入空间推理方法，对遥感影像进行专题解译，直至最后自动地输出专题图。据此，文中提出了按专题影像分析需要所形成的由原始影像、分割影像、等质区影像、分类解译影像和功能区影像等构成的表达法层次。在低层次影像分析中，影像按照统计属性被分割；在中间层次和高层次的影像分析中，与地物和专题有关的结构和空间知识被利用。本文说明了四叉树生成、复合形标记、复合形归并和匹配等在沟通不同的表达法中的作用。设计了应用于专题影像解译的差别图。介绍了与差别图和空间分析有关的规则。最后，上述技术已被有效地应用于中国吉林省双阳县的植被调查。 相似文献
18.
以松滋市2000年和2010年Landsat TM影像为基础,利用CA-Markov模型并引入土地利用总体规划限制因素,预测松滋市2020年土地利用情况。构建土地利用生态风险指数,运用4 km×4 km的网格模型采样,采用普通克里金插值法进行插值,引入密度分割法进行归一化等级划分,利用GIS工具进行空间叠加分析并制作土地利用生态风险分级图,实现土地利用变化生态风险动态评价,揭示生态风险变化趋势。模拟预测及评价结果显示:1松滋市2000~2020年土地利用结构发生较大变化,耕地、水域和未利用地面积减少,林地和建设用地面积增加。2土地利用生态风险呈逐步升高趋势,由2000年的21.95升高到2020年的88.53,分布以中部及南部较高,西部及东北部较低。32000~2020年分级结果主要以低风险、较低风险及次中风险为主,特高风险区域逐渐增多,生态风险等级以中心城区为中心呈圈层分布,且距离越远生态风险等级越低。 相似文献
19.
SVM多窗口纹理土地利用信息提取技术 总被引：2，自引：0，他引：2
针对单一窗口纹理分类时地物破碎,分类精度不高等问题,提出了一种基于支持向量机多窗口纹理的遥感图像分类方法。该方法在对SPOT5遥感影像进行纹理特征提取的基础上,构建了结合多窗口纹理的SVM模型。以陕西省佛坪县长角坝乡为试验区,利用此模型对该区域的土地利用类型进行分类研究,并将分类结果与单一窗口纹理SVM分类和单元数据(光谱)SVM分类结果进行了比较分析。结果表明:多窗口纹理参与的土地利用分类总精度达到85.33%,比单一窗口纹理分类提高了13.11%,而与单元数据SVM分类相比提高了近24.10%,取得了较好的分类效果,有效地解决了单一窗口纹理分类时地物破碎、分类精度不高等问题。 相似文献
20.
斯里兰卡亚洲象栖息地是全球重要的亚洲象保护区,象群分布密度约为其他地区的10倍,但由于生境破碎与丧失以及人象冲突等原因导致亚洲象数量急剧下降。对斯里兰卡亚洲象栖息地的生境质量监测与评估能够为亚洲象及其栖息地的保护政策制定与规划提供理论依据,并在全球物种多样性保护中具有重要意义。为评估斯里兰卡亚洲象栖息地的生境质量,综合考虑亚洲象栖息地需求以及影响亚洲象栖息地的关键要素,应用InVEST-HQ模型来估算生境质量指数,同时分析亚洲象栖息地生境质量在海拔梯度及植被覆盖梯度上的分布状况;随后引入空间自相关分析方法在像元尺度上探讨亚洲象栖息地生境质量的空间分布模式与时间演化过程,进而分析栖息地内不同保护区和气候分区的生境质量所存在的空间分异特征。研究结果表明：在空间分布上,斯里兰卡亚洲象栖息地生境质量具有高度聚集性,空间异常值不显著。生境质量高值区主要集中在中低海拔、植被覆盖情况较好、保护区范围密集的区域;生境质量低值区集中于耕地面积大、海拔偏高的区域。在梯度分布上,斯里兰卡亚洲象栖息地生境质量对海拔和植被覆盖度均具有显著线性相关关系,且在较低海拔和较高植被覆盖度梯度上存在聚集现象。在区域尺度上,斯里兰卡亚洲象栖息地生境质量存在显著的地域差异性。栖息地内自然保护区的生境质量明显高于非自然保护区,其中严格自然保护区的生境质量相对较高;热带雨林气候带的生境质量高值聚类大于其余气候分区,而热带疏林草原气候带与热带季风气候带生境质量受到季节性降水的影响较大,高值像元占比偏少。在时间尺度上,斯里兰卡亚洲象栖息地的生境质量总体呈现先降低后趋于平缓的态势。1995年—2010年,生境质量高值聚类占比明显减少,低值聚类占比缓慢上升;2010年—2020年生境质量低值占比有小幅度下降,高值聚类逐渐增加,生境质量逐渐稳定并呈缓慢上升的趋势。 相似文献