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991.
Recently, a particular statistical method - spatial point pattern analysis (SPPA) - has been introduced as an effective means by which qualitative, observable variations in polygonal terrain network arrangements on Earth and Mars can be quantified. A number of ground- and aerial-based techniques are available from which to derive the required input data: the spatial (x-y) coordinates of all polygon trough intersections within the site. However, each of the data collection methods may contain some level of error. Thus, the overarching question addressed by this research is: “how are the results of SPPA affected by the method by which the input data were generated?” At two polygonal terrain sites in the Canadian High Arctic, we performed ground-based surveys using differential and non-differential Global Positioning Systems (GPS) as well as photogrammetric analysis of aerial and satellite images of varying resolution to determine the trough intersection coordinates. It was found that the most robust statistical results were produced when using data from a combination of differential GPS surveys and high-resolution (∼0.25 m/pixel) aerial images. Images of pixel size ≥1 m were found to be unsuitable for this type of analysis. With respect to the investigation of similar Martian landforms, HiRISE and MOC images of polygonal terrain sites in southwestern Utopia Planitia were analyzed. Our results show that it is strongly preferable to perform SPPA using HiRISE images, though an empirical model is outlined that could be used to correct for errors arising from the reduced resolution inherent to MOC images. 相似文献
992.
利用新源县风电场周边气象站及测风塔观测资料、ERA5-Land再分析资料和数值模拟结果,分析新源县风电场的风场结构特征。结果表明:(1)风电场周边气象站的逐小时10m风速均呈现出早、晚偏低,中午偏高的变化规律。喀拉布拉镇站和公安农场站的风向主要以东风和南风为主,肖尔布拉克沟站的风向则以南风为主。测风塔4302的风速随着高度变化不明显。测风塔4301-4306均存在南风和北风,但各风向占比有一定差异。随高度升高,测风塔南风风向呈现出东南转西南的趋势。(2)ERA5-Land资料不能很好地再现研究区域风场变化。(3)数值模拟的风场变化具有一定山谷风特征。夜间的风向以东南风为主,白天则低海拔河谷地带风吹向山顶,北部谷风逐渐主导东北风向。20时,风电场区域主要以西北风为主。 相似文献
993.
Alaura C. Singleton Gordon R. Osinski Claire Samson Scott Holladay 《Planetary and Space Science》2010,58(4):472-481
Polygonal terrain is found in a variety of polar environments on Earth and Mars. As a result, many areas of northern Canada may represent ideal terrestrial analogues for specific regions of Mars - in particular the northern plains. In the Canadian Arctic, polygon troughs are commonly underlain by wedges of massive ice, with rare examples of other wedge types. If the same is true for Mars, this raises interesting implications for the processes that concentrate H2O at the Martian poles. This study uses an electromagnetic induction sensor to investigate the electromagnetic characteristics of terrestrial polar ice-wedge polygons. Surveys were conducted in two regions of the Canadian Arctic using a DUALEM-1S dual-geometry electromagnetic induction sensor, which measures electrical conductivity in the first 1.5-2 m of the subsurface. At locations where strong geomorphological evidence of ice was found, polygon troughs corresponded to local conductive anomalies. Trenching confirmed the presence of ice wedges at one site and allowed ground-truthing and calibration of the geophysical data. Previously unknown bodies of massive ice were also identified through the use of this geophysical technique. This study shows that an electromagnetic induction sounder is a useful instrument for detecting and mapping out the presence of subsurface ice in the Canadian Arctic. Taking together with its small size, portability and ruggedness, we suggest that this would also be a useful instrument for any future missions to Mars’ polar regions. 相似文献
994.
正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.) 相似文献
995.
This study demonstrates the potential value of a combined unmanned aerial vehicle (UAV) Photogrammetry and ground penetrating radar (GPR) approach to map snow water equivalent (SWE) over large scales. SWE estimation requires two different physical parameters (snow depth and density), which are currently difficult to measure with the spatial and temporal resolution desired for basin-wide studies. UAV photogrammetry can provide very high-resolution spatially continuous snow depths (SD) at the basin scale, but does not measure snow densities. GPR allows nondestructive quantitative snow investigation if the radar velocity is known. Using photogrammetric snow depths and GPR two-way travel times (TWT) of reflections at the snow-ground interface, radar velocities in snowpack can be determined. Snow density (RSN) is then estimated from the radar propagation velocity (which is related to electrical permittivity of snow) via empirical formulas. A Phantom-4 Pro UAV and a MALA GX450 HDR model GPR mounted on a ski mobile were used to determine snow parameters. A snow-free digital surface model (DSM) was obtained from the photogrammetric survey conducted in September 2017. Then, another survey in synchronization with a GPR survey was conducted in February 2019 whilst the snowpack was approximately at its maximum thickness. Spatially continuous snow depths were calculated by subtracting the snow-free DSM from the snow-covered DSM. Radar velocities in the snowpack along GPR survey lines were computed by using UAV-based snow depths and GPR reflections to obtain snow densities and SWEs. The root mean square error of the obtained SWEs (384 mm average) is 63 mm, indicating good agreement with independent SWE observations and the error lies within acceptable uncertainty limits. 相似文献
996.
997.
对洼地积水问题进行了深入研究,从洼地处理和平地处理着手提出了新的解决思路,并在Visual Studio2005平台下,采用ArcGIS Engine组件开发了试验模块,并通过试验数据进行水系的提取。对比发现,算法提取的水系比ArcGIS填平预处理后提取的水系更加连续,且与原始DEM地形在三维显示状态下可以很好地拟合。 相似文献
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999.
1000.
NASA World Wind海量离散地形显示技术研究 总被引:1,自引:0,他引:1
虚拟数字地球需要解决大范围海量地形快速显示问题。本文在对World Wind海量地形显示机理和地形数据LOD分层组织深入研究基础上,提出了基于ArcMap的离散地形分层切割流程,开发了与World Wind三维地形显示数据模型匹配的分层切割软件,对海量离散地形按不同分块大小和层次切割后的显示效率和效果进行了分析,结果表明World Wind能实现不同尺度地形数据的快速三维可视化。 相似文献