نتایج جستجو برای: digitial elevation model dem
تعداد نتایج: 2176518 فیلتر نتایج به سال:
the universal thermal climate index (utci) addresses these shortcomings by using an advanced thermo-physiological model. the aim of this study was to investigate and prepare zoning of thermal comfort condition using utci. meteorological data including temperature, wind speed, cloudiness and relative humidity were obtained on a daily time scale from 10 synoptic stations during (2004-2013) period...
This paper presents a procedure for assessing the quality of a digital elevation model (DEM) which has been applied to the output of a normalized cross correlation based stereomatching algorithm. Using semimetric photography of natural gravel river bed surfaces acquired in the field, digital photogrammetry was used to extract DEMs automatically for use in characterizing surface roughness proper...
Mathematical problems of digital terrain analysis include interpolation of digital elevation models (DEMs), DEM generalization and denoising, and computation of morphometric variables by calculation of partial derivatives of elevation. Traditionally, these procedures are based on numerical treatments of two-variable discrete functions of elevation. We developed a spectral analytical method and ...
The Orbiting Carbon Observatory (OCO), scheduled for launch in December 2008, will make the first space-based measurements of atmospheric CO2 with the precision, spatial and temporal resolution needed to characterize CO2 sources and sinks on regional spatial scales and seasonal to interannual time scales. Variations in surface topography have a direct impact on the retrieval of the columnaverag...
The use of aerial photographs, satellite images, scanned maps and digital elevation models necessitates the setting up of strategies for the storage and visualization of these data in an interactive way. In order to obtain a three dimensional visualization it is necessary to map the images, called textures, onto the terrain geometry computed with Digital Elevation Model (DEM). Practically, all ...
This paper describes a method to automatically construct a 3D geometric model of an urban area by merging features extracted from a cadastral map of the area and from the corresponding digital elevation model (Dem). The cadastral map and the Dem are both transformed into two sets of contour segments: The segments extracted from the map represent contours of buildings and blocks of buildings, wh...
For regional models, the shallow water table surface is often used as a source/sink boundary condition, as model grid scale precludes simulation of the water table aquifer. This approach is appropriate when the water table surface is relatively stationary. Since water table surface maps are not readily available, the elevation of the water table used in model cells is estimated via a two-step p...
ASTER is a high-spatial resolution, multispectral imaging system flying aboard TERRA, a satellite launched in December 1999 as part of NASA’s Earth Observing System (EOS). An ASTER scene covering 61.5 km x 63 km contains data from 14 spectral bands. An ASTER Digital Elevation Model (DEM) is generated using bands 3N (nadir) and 3B (backward) level 1A images acquired by the Visible Near Infra-red...
The hydrodynamics of low-lying riverine floodplains and wetlands play a critical role in hydrology and ecosystem processes. Because small topographic features affect floodplain storage and flow velocity, a hydrodynamic model setup of these regions imposes more stringent requirements on the input Digital Elevation Model (DEM) compared to upland regions with comparatively high slopes. This curren...
Users of GIS are faced with the ongoing and difficult problem of estimating the validity of a GIS output given the uncertainty of the quality of cLgital mapped data. This research project examines the manner in which error from a digital elevation model (DEM) results in error in an estimate of a viewshed. The data set includes two DEMs for the same study area. A 10-metre DEM serves as the contr...
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