Investigation of elevation bias of the SRTM C- and X-band digital elevation models
Altitude ; Australia ; Digital elevation model ; Land utilisation ; Plant canopy ; Queensland ; Radar imagery ; Remote sensing ; Sar imagery ; Statistical bias ; Vegetation
This paper presents results of a comparative study of the vegetation-caused elevation bias of the space shuttle topographic mission data product, both C- and X-band (SRTM.C/X). The SRTM.C/X bands data were compared against a high-resolution digital
relating the elevation bias to the percentage of the vegetation cover of a given land parcel. This model, once verified on varieties of vegetation types, could be utilised to estimate and eliminate the elevation bias from the InSAR elevation model.
Information values of absolute elevation and elevation difference for illustration of thermal belt
This paper estimates the information gain and the information gain ratio, which are usually used in machine-learning processes, to assess which data layer – absolute elevation or elevation difference – better reflects the topoclimatic
Mass elevation effect and its forcing on timberline altitude
Altitudinal zonation ; Base level ; Concept ; Eurasia ; Impact ; Latitude ; Longitude ; Mass elevation ; Model ; Mountain ; Multiple regression ; Tree line
The concept of mass elevation effect (massenerhebungseffect, MEE) was introduced by A. de Quervain about 100 years ago. It has been usually completely neglected in developing fitting models of timberline elevation, with only longitude or latitude
considered as impacting factors. This paper tries to quantify the contribution of MEE to timberline elevation. Considering that the more extensive the land mass and especially the higher the mountain base in the interior of land mass, the greater the mass
elevation effect, this paper takes mountain base elevation (MBE) as the magnitude of MEE. The AA. collect 157 data points of timberline elevation, and use their latitude, longitude and MBE as independent variables to build a multiple linear regression
equation for timberline elevation in the southeastern Eurasian continent. The results show that MBE, serving as a proxy indicator of MEE, is a significant factor determining the elevation of alpine timberline.
The production of digital elevation models for experimental model landscapes
Comparative study ; Digital elevation model ; Experimentation ; Geomorphology ; Model ; Photogrammetry ; Rainfall simulation ; Soil erosion ; Watershed
Automated digital photogrammetry was used to produce digital elevation models of experimental model landscapes under controlled laboratory conditions as part of a series of rainfall erosion experiments looking at the evolution of landforms
in response to erosion. The method allowed the elevations of the experimental landscapes to be studied in great detail on a regular grid digital terrain map. Digital photogrammetry produced elevation data at a resolution of 6 mm with a standard deviation
Méthode de représentation de données thématiques en perspective avec représentation des parties cachées. Modèle d'élévation numérisé, contrôle du tracé en huit couleurs. Exemples sur l'utilisation du sol et de la température moyenne annuelle
La représentation de la géographie pour les élèves de CM2-6
Premiers résultats d'une enquête INRP qui se propose de mettre en relation les contrats didactiques à l'oeuvre en CM2 et en 6 et l'évolution des compétences des élèves.
Analysis of digital elevation data for palaeosurfaces in south-western Sweden
The aim of this study is to describe the gross morphology of the joint-aligned valley landscape, trace the sub-Cambrian peneplain as far as possible in the summits, ascertain the present elevated areas and investigate the cause of fragmentation
Carte ; Elève ; Enseignement de la géographie ; Enseignement secondaire ; Géographie humaine ; Perception
Les élèves rencontrent de complexes problèmes de perception devant les cartes géographiques. Pourtant les plus communément utilisées omettent de nombreux détails notamment ceux concernant le modelé ou la couverture végétale. Cette étude montre
comment des élèves interprètent ces cartes en l'absence de légende.
Main features of geomorphology of the Sudetes re-assessed in the light of digital elevation model
Czech Republic ; Digital elevation model ; Geomorphology ; Mountain ; Sudety ; Tectonics
The Sudetes as a geomorphological region are distinguished by complicated spatial pattern of high- and low-altitude terrains and variable mean slope gradients across the range. An analysis of a digital elevation model and maps derived from the model
Elevation, age, soil development, and chemical weathering at Storbreen, Jotunheimen, Norway
This paper demonstrates that on the glacial foreland at Storbreen, chemical weathering and associated soil development trends show significant elevational influences. Thus the research objectives in this study were to determine the effects
on weathering and soil development of : 1) elevation on materials from the same dated moraine, and 2) longer exposure of similar materials by comparison to a 9000-year-old site.
Channel head location and characteristics using digital elevation models
Australia ; Digital elevation model ; Drainage network ; Hydrology ; Northern Territory ; Slope gradient ; Spatial distribution ; Watershed
extent channel head location can be predicted by the area-slope relationship and the cumulative area distribution. The effect of digital elevation model grid resolution on the ability to locate channel head position and assess hillslope length will also
Geomorphometric mapping of Asia Minor from GLOBE digital elevation model
Anatolia ; Asia ; Cartography ; Cluster analysis ; Digital elevation model ; Geomorphometry ; Mountain ; Peneplain ; South-Eastern Asia ; Turkey
This paper focuses on the mapping of landscapes in Asia Minor on the basis of the moderate resolution digital elevation model GLOBE that provides a regional relief representation. Finally, the classification identifies 2 branches. In between
Impacts of surface elevation on the growth and scaling properties of simulated river networks
The AA. investigate the connection between surface elevation and the growth and scaling of river networks. Three planar models (Scheidegger, Eden, and invasion percolation) are first considered. The AA. show that none of these planar growth models
produces scaling results consistent with observations for natural river basins. The AA. then modify the models to include elevation, simulating the effects of fluvial erosion by enforcing the slope-area relationship. The AA. conclude that inclusion
A comparison of interpolation methods for producing digital elevation models at the field scale
Comparative study ; Digital elevation model ; Geographical information system ; Geostatistics ; Interpolation ; Methodology ; Slope gradient ; Topography ; Turkey
In this study, the magnitudes and spatial patterning of elevation errors were examined, using the effects of interpolation methods. Measurements were performed with theodolite and levelling. Previous research has demonstrated the effects
of interpolation methods and the nature of errors in digital elevation models obtained with indirect survey methods for small-scale areas. The purpose of this study was therefore to investigate the size and spatial patterning of errors in digital elevation models
obtained with direct survey methods for large-scale areas, comparing Inverse Distance Weighting, Radial Basis Functions and Kriging interpolation methods to generate digital elevation models. This study is important because it shows how the accuracy
of the digital elevation model is related to data density and the interpolation algorithm used. Cross validation, split sample and jack-knifing validation methods were used to evaluate the errors. Global and local spatial auto-correlation indices were then used
A study of the contribution of mass elevation effect to the altitudinal distribution of timberline in the Northern Hemisphere
This paper collects 516 data sites of timberline, and takes latitude, continentality and mass elevation effect (MEE) as independent variables and timberline elevation as dependent variable to develop a ternary linear regression model. Continentality
is calculated using the meteorological data released by WorldClim and mountain base elevation (as a proxy of mass elevation effect) is extracted on the basis of SRTM 90-meter resolution elevation data. The results show that MEE is simply the primary factor
contributing to the elevation distribution of timberline on the continental and hemispherical scales. The contribution rate of MEE to timberline altitude differs in North America, eastern Eurasia and in the western Eurasia, but it is usually very high.