首页期刊导航|International journal of applied earth observation and geoinformation
期刊信息/Journal information
International journal of applied earth observation and geoinformation
International Institute for Aerospace Survey and Earth Sciences
International Institute for Aerospace Survey and Earth Sciences
1569-8432
International journal of applied earth observation and geoinformation/Journal International journal of applied earth observation and geoinformationISTPSCIAHCI
Olpenda, Alex S.Sterenczak, KrzysztofBedkowski, Krzysztof
17页
查看更多>>摘要：Monitoring and quantification of sunlight in the forest is important for silviculture and management as well as an input for modeling, among others, forest regeneration, species composition, soil condition or micro-climate. For consistency, otherwise specified, the term sunlight, referring to solar radiation below canopy within the 400-700 nm wavelength, will be used throughout this paper. This study is presenting application of airborne light detection and ranging (LiDAR) technology in modeling sunlight conditions in the managed mixed stands of Bialowieia Forest (BF). During the summer of 2015, mean daily sunlight in the form of photosynthetically active radiation (PAR) from 100 random circular plots of BF were measured using hemispherical photography (HP). This technique uses photos to capture canopy structures and indirectly estimates understory solar radiation. A total of 5 acquisitions per plot (center and cardinal points) were taken before averaging. Various LiDAR related metrics were generated from point clouds of airborne laser scanning (ALS) acquired on the same area. These metrics were used as predictors in regression models with the direct, diffuse and global radiation. Ratio-based metrics were highly correlated across all components of sunlight. Laser penetration index (LPI) alone was able to predict effectively the amount of sunlight (R-2 = 0.78 for diffuse). A multiple regression improved the model (R-2 = 0.83) with up to 4 predictors. Other contributing metrics included in the model were: mean height of all returns, the median height of returns below diameter at breast height (DBH) and the percentage of the first returns. Results from the research confirmed that LiDAR can be a suitable tool for modeling solar radiation at various levels and producing continuous information across large forested areas with complicated structure and species composition.
Hecker, Christophvan Ruitenbeek, Frank J. A.Bakker, Wim H.Fagbohun, Babatunde J....
8页
查看更多>>摘要：The Wavelength Mapper is an algorithm that searches for the deepest absorption feature in each pixel of a hyperspectral image. On a per pixel basis, it extracts the wavelength position, which serves as a proxy of the mineralogy and the feature depth as a proxy for the relative abundance. This algorithm has been used with near and shortwave infrared data, but has not yet been tested on hyperspectral thermal infrared images. It is unclear what results are expected when the Wavelength Mapper algorithm is applied to hyperspectral thermal infrared data since reststrahlen features characteristically overlap in emissivity spectra. In this paper, the Wavelength Mapper is tested on a multi-flightline airborne hyperspectral TIR dataset acquired over the Yerington Batholith, Nevada. Observations were made in the 8.05-11.65 mu m wavelength range to include thermal spectral features of major rock-forming minerals, and a new color ramp is created to separate quartz-rich rocks from plagioclase-rich rocks. Our results indicate that the Wavelength Mapper creates coherent spatial patterns across flightlines. The results displayed represent different types of igneous and sedimentary rocks, as well as the products of hydro thermal alteration via different colors, mainly based on the relative abundance of quartz, feldspar and garnet, as well as mica and epidote. Comparison with published maps indicate that the Wavelength Mapper represents for each pixel a parameter value that can be linked to the spectrally dominate rock-forming mineral of that area, as mapped with traditional fieldwork methods. In conclusion, the Wavelength Mapper can be applied to airborne hyperspectral TIR data to achieve a simple, repeatable, per-pixel overview map of the dominating rock-forming mineral occurrences.
查看更多>>摘要：High quality land use/land cover (LULC) data with fine spatial resolution and frequent temporal coverage are indispensable for revealing detail information of the Earth's surface, characterizing LULC of the area, predicting the plausible land use changes, and assessing the viability and impacts of any development plans. While airborne imagery has high spatial resolution, it only provides limited temporal coverage over time. The LULC data from historical remote sensing images, such as those from Landsat, have frequent coverages over a long temporal period, but their spatial resolutions are low.
Gomes Costa, Carlos AlexandreFoerster, SaskiaBrosinsky, ArlenaSoares Pereira, Francisco Jairo...
9页
查看更多>>摘要：There is a shortage of sediment-routing monitoring worldwide, despite its relevance to environmental processes. In drylands, where water resources are more vulnerable to the sediment dynamics, this flaw is even more harmful. In the semi-arid Caatinga biome in the North-east of Brazil, rivers are almost all intermittent and hydro-sedimentological monitoring is scarce. In the biome, water supply derives from thousands of surface reservoirs, whose water availability is liable to be reduced by siltation and sediment-related pollution. The goal of this research was to evaluate the potential of multi-temporal high-resolution satellite imagery (RapidEye) to assess the suspended sediment concentration (SSC) in the medium-sized intermittent Jaguaribe River, Brazil, during a 5-year period. We validated 15 one-, two- and three-band indices for SSC estimation based on RapidEye spectral bands deduced in the context of the present investigation and nine indices proposed in the literature for other optical sensors, by comparing them with in-situ concentration data. The in-situ SSC data ranged from 67 mg.L-1 to 230 mg.L-1. We concluded that RapidEye images can assess moderate SSC of intermittent rivers, even when their discharge is low. The RapidEye indices performed better than those from literature. The spectral band that best represented SSC was the near infrared, whose performance improved when associated with the green band. This conclusion agrees with literature findings for diverse sedimentological contexts. The three-band spectral indices performed worse than those with only one or two spectral bands, showing that the use of a third band did not enhance the model ability. Besides, we show that the hydrological characteristics of semi-arid intermittent rivers generate difficulties to monitor SSC using optical satellite remote sensing, such as time-concentrated sediment yield; and its association with recent rainfall events and, therefore, with cloudy sky.
查看更多>>摘要：Building simplification is an important research area in automated map generalization. In the last several decades, various methods for building simplification have been proposed by scholars, most of which have concentrated on vector data. However, with the continuous development of computer vision and artificial intelligence technology, some advanced technologies, such as unstructured image analysis and processing, have provided new opportunities and challenges for map generalization. Therefore, in this paper, we propose a new algorithm called superpixel building simplification (SUBS), for simplifying buildings based on image data. In this method, the buildings are first divided into two types by corner detection: buildings with orthogonal features and buildings with non-orthogonal features. Then, the buildings are globally simplified using a superpixel segmentation algorithm for superpixel extraction via energy-driven sampling. Finally, the buildings are locally simplified to preserve their geometric features. For the purpose of evaluation, we used a total of 285 buildings at scales of 1:5000 and 1:10,000 to perform the simplification. Compared with traditional algorithms, the results indicate that the proposed method can produce satisfactory results for the simplification of buildings with both orthogonal and non-orthogonal features and effectively preserve the area and centre of mass of the buildings. In addition, the SUBS method can generate different representation styles of buildings while effectively avoiding self-intersection.
Topouzelis, KonstantinosPapakonstantinou, ApostolosGaraba, Shungudzemwoyo P.
9页
查看更多>>摘要：A rapidly rising amount of plastic litter on land and at sea is becoming a global wicked environmental problem. Here, we present an innovative exploratory application of unmanned aerial systems (UAS) and open-access satellite imagery in remote detection of floating plastics in natural seawater, through a dedicated aquatic environment experiment. We aimed to extract meaningful spectral measurements in near-real scenarios and to compare the geospatial information ranging from moderate to very high resolution. A set of three artificial floating plastic targets were setup for remote detection in the waters close to Tsamakia beach of Mytilene on Lesvos Island, Greece. These floating targets consisted of 100 m(2) PET-11.5 L water bottles, LDPE plastic bags and nylon fishing ghost nets. Spectral properties of the controlled targets as well as surrounding seawater were investigated for Sentinel-2A satellite data. We demonstrate how UAS very high geospatial resolution images can be useful in improving geo-referencing of satellite images and how UAS can be used to assess the plastic percentage coverage of satellite images. We observed very weak to strong relationships between percentage pixel coverage and the spectral reflectance at p-value < 0.1 significance level. Effects of atmospheric correction algorithms was evaluated using Sen2Cor and ACOLITE, derive unbiased percentage differences were less than 65%. Our feasibility study demonstrated the importance of very high geo-spatial resolution UAS datasets in validating and enhancing the geo-spatial accuracy of satellite data for monitoring plastics in the aquatic environment. Monitoring and identifying plastics needs an integrated suite of sensors, we therefore present how available tools can be utilized to improve current efforts and contribute to advancing relevant future remote sensing technologies.
查看更多>>摘要：Land surface albedo is a key radiative forcing factor in Earth radiation budget, and its variation is highly related to land surface processes, such as land cover change. This study aimed to identify the contribution of human induced albedo to regional land surface albedo change by analyzing the relationship between albedo and land cover change in northern China from 1992 to 2012. We first employed the time series decomposition method (TSDM) to decompose the satellite-based albedo to three components: seasonal cycle, trend, and residual information. We then analyzed the regional albedo characters over different land cover types and their corresponding variations induced by land cover conversion. The multi-year averaged albedo in northern China was 0.2285 +/- 0.0646. The albedo over changed and unchanged area was 0.2435 +/- 0.0840 and 0.2276 +/- 0.0633, respectively. The contribution of human-induced albedo change to overall changes reached about 86%, which was mainly due to cultivation and urbanization. Trend analysis indicated that the albedo slightly increased in northern China, which may decrease regional solar radiation absorption. Fractional increases in croplands showed a positive correlation with albedo variation (R-2 = 0.51). Human-induced albedo change would cause negative radiative forcing (-0.705 W/m(2)) and thus further promote cooling effects in northern China.
Almeida, D. R. A.Broadbent, E. N.Zambrano, A. M. A.Wilkinson, B. E....
7页
查看更多>>摘要：We are in an unprecedented moment for promoting forest restoration globally, with international and regional pledges to restore at least 350 million hectares by 2030. To achieve these ambitious goals, it is necessary to go beyond traditional plot-scale assessments and develop cost-effective technologies that can monitor the structure and function of restored forests at much broader scales. Lidar remote sensing in unmanned aerial vehicle (UAV) platforms can be an agile and autonomous method for monitoring forest restoration projects, especially under conditions when information updates are frequently needed in relatively small areas or, when using an airplane borne lidar system may be not financially viable. Here, we explored the potential of an UAV-borne lidar system to assess the outcomes of a mixed-species restoration plantation experiment, designed to maximize aboveground biomass (AGB) accumulation. The experiment was established in Brazil's Atlantic Forest, with 20 native tree species, by combining two levels of planting density and two management levels, totaling four treatment combinations and one control (plots left over for natural regeneration). We analyzed three structural variables from lidar data (canopy height, gap fraction and leaf area index) and one from field inventory data (AGB). Structural differences between the treatments and the control plots were reliably distinguished by the UAV-borne lidar system. AGB was strongly correlated with canopy height, allowing us to elaborate a predictive equation to use the UAV-borne lidar system for monitoring structural features in other restoration plantations in the region. UAV-borne lidar systems showed enormous potential for monitoring relatively broad-scale (thousands of hectares) forest restoration projects, providing an important tool to aid decision making and accountability in forest landscape restoration.
NSTL
Elsevier