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排序方式: 共有147条查询结果,搜索用时 15 毫秒
1.
Wayne S. Walker Josef M. Kellndorfer Michael Hoppus 《Remote sensing of environment》2007,109(4):482-499
Exploiting synergies afforded by a host of recently available national-scale data sets derived from interferometric synthetic aperture radar (InSAR) and passive optical remote sensing, this paper describes the development of a novel empirical approach for the provision of regional- to continental-scale estimates of vegetation canopy height. Supported by data from the 2000 Shuttle Radar Topography Mission (SRTM), the National Elevation Dataset (NED), the LANDFIRE project, and the National Land Cover Database (NLCD) 2001, this paper describes a data fusion and modeling strategy for developing the first-ever high-resolution map of canopy height for the conterminous U.S. The approach was tested as part of a prototype study spanning some 62,000 km2 in central Utah (NLCD mapping zone 16). A mapping strategy based on object-oriented image analysis and tree-based regression techniques is employed. Empirical model development is driven by a database of height metrics obtained from an extensive field plot network administered by the USDA Forest Service-Forest Inventory and Analysis (FIA) program. Based on data from 508 FIA field plots, an average absolute height error of 2.1 m (r = 0.88) was achieved for the prototype mapping zone. 相似文献
2.
为研究漓江流域近15年植被覆盖度变化情况,以1991、2000、2006年3个时相的TM/ETM+影像为基础,采用基于归一化植被指数(NDVI)的像元二分模型对漓江流域植被覆盖度进行估算,分析了植被覆盖度时空变化特征;结合研究区地质数据,进一步分析地质条件对植被覆盖度的影响。结果表明:①受气候和人类活动的影响,1991—2000年漓江流域植被覆盖度有所增加,表现为高和较高植被覆盖区面积增加,中度、较低和低植被覆盖区面积减少;2000—2006年漓江流域植被覆盖度略有降低,表现为高植被覆盖区面积减少,较高和中度植被覆盖区增加,较低和低植被覆盖区面积减少;②由于地质条件的影响,非岩溶区的平均植被覆盖度高于岩溶区,两者的变化趋势与流域整体变化基本一致;③从空间分布上看,1991—2006年漓江流域植被覆盖度的变化较显著。 相似文献
3.
Validation of GOES and MODIS active fire detection products using ASTER and ETM+ data 总被引:2,自引:0,他引:2
Wilfrid Schroeder Elaine Prins Louis Giglio Ivan Csiszar Christopher Schmidt Jeffrey Morisette Douglas Morton 《Remote sensing of environment》2008,112(5):2711-2726
In this study we implemented a comprehensive analysis to validate the MODIS and GOES satellite active fire detection products (MOD14 and WFABBA, respectively) and characterize their major sources of omission and commission errors which have important implications for a large community of fire data users. Our analyses were primarily based on the use of 30 m resolution ASTER and ETM+ imagery as our validation data. We found that at the 50% true positive detection probability mark, WFABBA requires four times more active fire area than is necessary for MOD14 to achieve the same probability of detection, despite the 16× factor separating the nominal spatial resolutions of the two products. Approximately 75% and 95% of all fires sampled were omitted by the MOD14 and WFABBA instantaneous products, respectively; whereas an omission error of 38% was obtained for WFABBA when considering the 30-minute interval of the GOES data. Commission errors for MOD14 and WFABBA were found to be similar and highly dependent on the vegetation conditions of the areas imaged, with the larger commission errors (approximately 35%) estimated over regions of active deforestation. Nonetheless, the vast majority (> 80%) of the commission errors were indeed associated with recent burning activity where scars could be visually confirmed in the higher resolution data. Differences in thermal dynamics of vegetated and non-vegetated areas were found to produce a reduction of approximately 50% in the commission errors estimated towards the hours of maximum fire activity (i.e., early-afternoon hours) which coincided with the MODIS/Aqua overpass. Lastly, we demonstrate the potential use of temporal metrics applied to the mid-infrared bands of MODIS and GOES data to reduce the commission errors found with the validation analyses. 相似文献
4.
Li Luo 《Remote sensing of environment》2010,114(6):1220-3019
With the constant proliferation of computational power, our ability to develop hybrid classifiers has improved. Hybrid classifiers integrate results from multiple algorithms and often improve classification accuracy. In this paper, a hybrid classification framework was used to evaluate two research hypotheses: i) can manipulated results from prior classifiers (“intermediate inputs” (IIs)) improve classification accuracy in subsequent classification steps. and ii) is there an optimal dataset proportion for creation and usage of intermediate inputs. These additional intermediate inputs were based on spatial and texture statistics calculated on a partially classified image. The implementation of intermediate inputs on an impervious surface classification task using a 2001 Landsat ETM+ image from central New York was demonstrated. The results suggested that there was an average accuracy improvement of 3.6% (maximum 6.6%) by using intermediate inputs. These improvements were proved statistically significant by a Z-test and tended to increase as classification difficulty increased. The experiments in this paper also showed that there was an optimal point that balanced the number of pixels and pixel classification accuracy from prior steps used to produce intermediate inputs. Additionally, some traditional problems such as separation of impervious surfaces and soil were successfully tackled through intermediate inputs. The concept of the intermediate inputs may easily apply to other sensors and/or ground features. 相似文献
5.
ETM+和ASTER数据在遥感信息提取中的对比研究 总被引:3,自引:0,他引:3
遥感蚀变信息提取是找矿的一个重要技术手段。本文选择位于秘鲁南部阿雷基帕(AREQUIPA)省境内的萨卡纳(CERCANA)和伊卡(ICA)省境内的Moarcona铁矿区作为本文的两个研究区,从分析地物光谱出发,利用ETM+和ASTER卫星影像数据,通过主成份分析法和比值分析法分别对两个研究区进行泥化蚀变信息提取和铁染蚀变信息提取,并对两者的提取结果进行对比分析。最后结果表明,相较于ETM+数据,ASTER数据在矿化蚀变信息的提取方面具有更大的优势。 相似文献
6.
7.
John C. Price 《Remote sensing of environment》2003,86(4):491-499
Nearly simultaneous reflectance data sets from the Landsat 7 Enhanced Thematic Mapper Plus (ETM+), at 30-m resolution, and the Terra satellite instrument MODIS, at 500-m resolution, are compared for their ability to map fractional coverage of surface types over large areas. Lower spatial resolution MODIS classification results are generally comparable those of ETM+, with discrepancies for some regions with mixed surface types. Analysis of laboratory and field spectra suggests an ambiguity, the “brightness ambiguity”, which can prevent accurate area estimation of pixels having two or more surface types. This ambiguity, plus general mathematical inversion issues, can account for the discrepancy. Thus, occasional high-resolution measurements, as from Landsat 7, are necessary to refine estimations of large area surface types from MODIS and similar lower spatial resolution instruments. 相似文献
8.
Using lidar and effective LAI data to evaluate IKONOS and Landsat 7 ETM+ vegetation cover estimates in a ponderosa pine forest 总被引:1,自引:0,他引:1
Structural and functional analyses of ecosystems benefit when high accuracy vegetation coverages can be derived over large areas. In this study, we utilize IKONOS, Landsat 7 ETM+, and airborne scanning light detection and ranging (lidar) to quantify coniferous forest and understory grass coverages in a ponderosa pine (Pinus ponderosa) dominated ecosystem in the Black Hills of South Dakota. Linear spectral mixture analyses of IKONOS and ETM+ data were used to isolate spectral endmembers (bare soil, understory grass, and tree/shade) and calculate their subpixel fractional coverages. We then compared these endmember cover estimates to similar cover estimates derived from lidar data and field measures. The IKONOS-derived tree/shade fraction was significantly correlated with the field-measured canopy effective leaf area index (LAIe) (r2=0.55, p<0.001) and with the lidar-derived estimate of tree occurrence (r2=0.79, p<0.001). The enhanced vegetation index (EVI) calculated from IKONOS imagery showed a negative correlation with the field measured tree canopy effective LAI and lidar tree cover response (r2=0.30, r=−0.55 and r2=0.41, r=−0.64, respectively; p<0.001) and further analyses indicate a strong linear relationship between EVI and the IKONOS-derived grass fraction (r2=0.99, p<0.001). We also found that using EVI resulted in better agreement with the subpixel vegetation fractions in this ecosystem than using normalized difference of vegetation index (NDVI). Coarsening the IKONOS data to 30 m resolution imagery revealed a stronger relationship with lidar tree measures (r2=0.77, p<0.001) than at 4 m resolution (r2=0.58, p<0.001). Unmixed tree/shade fractions derived from 30 m resolution ETM+ imagery also showed a significant correlation with the lidar data (r2=0.66, p<0.001). These results demonstrate the power of using high resolution lidar data to validate spectral unmixing results of satellite imagery, and indicate that IKONOS data and Landsat 7 ETM+ data both can serve to make the important distinction between tree/shade coverage and exposed understory grass coverage during peak summertime greenness in a ponderosa pine forest ecosystem. 相似文献
9.
梧桐井地区处于塔里木板块一级构造单元,具体位于敦煌地块三级构造单元里。具有优越的成矿地质背景和巨大成矿潜力,已发现一批金、银、铜找矿靶区。该区属于甘肃北山区,地貌属于低山丘陵区,基岩出露,因此在该地区开展遥感找矿的研究是一种便捷、有效、经济的勘查手段。利用ETM遥感数据提取与矿化有关的异常信息,并结合地质资料,区划成矿远景区和圈定找矿靶区,取得了很好的应用效果。 相似文献
10.
电子俘获材料是一类有着巨大应用潜力的光存储材料,它能将写入光照射材料后产生的电子(空穴)束缚在材料的某些稳定的高能级(陷阱)上。只有经过合适的读出光照射,被束缚住的电子(空穴)才能脱离陷阱复合发光。发光在空间的强度分布与写入光的分布一致,即再现了写入光的信息。电子俘获材料的种类很多,研究进展各不相同。其中,以作为X光影像存储材料的BaFBr:Eu为代表的碱土金属氟卤化物已经广泛应用于医疗诊断方面。本文分类介绍了近年来几种典型的电子俘获材料在发光机理和应用方面的最新进展,尤其重点介绍了新兴的玻璃陶瓷型电子俘获材料的研究工作情况。 相似文献