scholarly journals Introducing QuickChi, a web application for near-global, exploratory, longitudinal river profile analysis

2021 ◽  
Author(s):  
Gregory Ruetenik
Keyword(s):  
Steady State ◽  
Open Source ◽  
Web Application ◽  
Profile Analysis ◽  
Digital Elevation Models ◽  
Global Scale ◽  
Exploratory Analysis ◽  
Tectonic Geomorphology ◽  
The Past ◽  
Digital Elevation

Stream profile analysis has been used extensively in the field of tectonic geomorphology. In the past, exploration of stream profiles, including χ-elevation profiles, has required downloading and processing Digital Elevation Models for specific areas, which limits the scope of exploratory analysis. Presented here is a web application designed to analyze stream profiles at 90m resolution at a near-global scale. Based on the Hydrosheds (Wickel et al., 2007) 90m drainage direction, as well as computed d8 drainage direction and void-filled DEMs, the app allows users to quickly query downstream from selected points anywhere within ±60 degrees latitude, in order to interactively analyze corresponding stream profiles in both distance and χ space, where χ is a metric that is proportional to the presumed steady-state shape of the stream profile (Perron and Royden, 2013). QuickChi is open source, and although currently it is designed as an exploratory tool, more functions can be easily added via community contributions and/or from existing toolsets.

scholarly journals Assessment of open source digital elevation models (SRTM-30, ASTER, ALOS) for erosion processes modeling

2019 ◽  
Vol 28 (1) ◽  
pp. 95-105 ◽  
Author(s):  
I. P. Kovalchuk ◽  
K. A. Lukianchuk ◽  
V. A. Bogdanets
Keyword(s):  
Open Source ◽  
Correlation Coefficient ◽  
Root Mean Square ◽  
Digital Elevation Models ◽  
Mean Square ◽  
Erosion Processes ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Vertical Accuracy ◽  
Mean Square Errors

The relief has a major impact on the landscape`s hydrological, geomorphological and biological processes. Many geographic information systems used elevation data as the primary data for analysis, modeling, etc. A digital elevation model (DEM) is a modern representation of the continuous variations of relief over space in digital form. Digital Elevation Models (DEMs) are important source for prediction of soil erosion parameters. The potential of global open source DEMs (SRTM, ASTER, ALOS) and their suitability for using in modeling of erosion processes are assessed in this study. Shumsky district of Ternopil region, which is located in the Western part of Ukraine, is the area of our study. The soils of Shumsky district are adverselyaffected by erosion processes. The analysis was performed on the basis of the characteristics of the hydrological network and relief. The reference DEM was generated from the hypsographic data(contours) on the 1:50000 topographical map series compiled by production units of the Main Department of Geodesy and Cartography under the Council of Ministers. The differences between the reference DEM and open source DEMs (SRTM, ASTER and ALOS) are examined. Methods of visual detection of DEM defects, profiling, correlation, and statistics were used in the comparative analysis. This research included the analysis oferrors that occurred during the generation of DEM. The vertical accuracy of these DEMs, root mean square error (RMSE), absolute and relative errors, maximum deviation, and correlation coefficient have been calculated. Vertical accuracy of DEMs has been assessed using actual heights of the sample points. The analysis shows that SRTM and ALOS DEMs are more reliable and accurate than ASTER GDEM. The results indicate that vertical accuracy of DEMs is 7,02m, 7,12 m, 7,60 mand 8,71 m for ALOS, SRTM 30, SRTM 90 and ASTER DEMs respectively. ASTER GDEM had the highest absolute, relative and root mean square errors, the highest maximum positive and negative deviation, a large difference with reference heights, and the lowest correlation coefficient. Therefore, ASTER GDEM is the least acceptable for studying the intensity and development of erosion processes. The use of global open source DEMs, compared with the vectorization of topographic maps,greatly simplifies and accelerates the modeling of erosion processes and the assessment of the erosion risk in the administrative district.

scholarly journals Validation of digital elevation models (DEMs) and comparison of geomorphic metrics on the southern Central Andean Plateau

2017 ◽  
Vol 5 (2) ◽  
pp. 211-237 ◽  
Author(s):  
Benjamin Purinton ◽  
Bodo Bookhagen
Keyword(s):  
Standard Deviation ◽  
Profile Analysis ◽  
Digital Elevation Models ◽  
Frequency Noise ◽  
Differential Gps ◽  
Fourier Frequency ◽  
Digital Elevation ◽  
Southern Central ◽  
Standard Deviations ◽  
Terrain Elevation

Abstract. In this study, we validate and compare elevation accuracy and geomorphic metrics of satellite-derived digital elevation models (DEMs) on the southern Central Andean Plateau. The plateau has an average elevation of 3.7 km and is characterized by diverse topography and relief, lack of vegetation, and clear skies that create ideal conditions for remote sensing. At 30 m resolution, SRTM-C, ASTER GDEM2, stacked ASTER L1A stereopair DEM, ALOS World 3D, and TanDEM-X have been analyzed. The higher-resolution datasets include 12 m TanDEM-X, 10 m single-CoSSC TerraSAR-X/TanDEM-X DEMs, and 5 m ALOS World 3D. These DEMs are state of the art for optical (ASTER and ALOS) and radar (SRTM-C and TanDEM-X) spaceborne sensors. We assessed vertical accuracy by comparing standard deviations of the DEM elevation versus 307 509 differential GPS measurements across 4000 m of elevation. For the 30 m DEMs, the ASTER datasets had the highest vertical standard deviation at > 6.5 m, whereas the SRTM-C, ALOS World 3D, and TanDEM-X were all < 3.5 m. Higher-resolution DEMs generally had lower uncertainty, with both the 12 m TanDEM-X and 5 m ALOS World 3D having < 2 m vertical standard deviation. Analysis of vertical uncertainty with respect to terrain elevation, slope, and aspect revealed the low uncertainty across these attributes for SRTM-C (30 m), TanDEM-X (12–30 m), and ALOS World 3D (5–30 m). Single-CoSSC TerraSAR-X/TanDEM-X 10 m DEMs and the 30 m ASTER GDEM2 displayed slight aspect biases, which were removed in their stacked counterparts (TanDEM-X and ASTER Stack). Based on low vertical standard deviations and visual inspection alongside optical satellite data, we selected the 30 m SRTM-C, 12–30 m TanDEM-X, 10 m single-CoSSC TerraSAR-X/TanDEM-X, and 5 m ALOS World 3D for geomorphic metric comparison in a 66 km2 catchment with a distinct river knickpoint. Consistent m∕n values were found using chi plot channel profile analysis, regardless of DEM type and spatial resolution. Slope, curvature, and drainage area were calculated and plotting schemes were used to assess basin-wide differences in the hillslope-to-valley transition related to the knickpoint. While slope and hillslope length measurements vary little between datasets, curvature displays higher magnitude measurements with fining resolution. This is especially true for the optical 5 m ALOS World 3D DEM, which demonstrated high-frequency noise in 2–8 pixel steps through a Fourier frequency analysis. The improvements in accurate space-radar DEMs (e.g., TanDEM-X) for geomorphometry are promising, but airborne or terrestrial data are still necessary for meter-scale analysis.

scholarly journals Assessment of vertical accuracy of open source 30m resolution space-borne digital elevation models

2021 ◽  
Vol 12 (1) ◽  
pp. 939-960
Author(s):  
Rocky Talchabhadel ◽  
Hajime Nakagawa ◽  
Kenji Kawaike ◽  
Kazuki Yamanoi ◽  
Bhesh Raj Thapa
Keyword(s):  
Open Source ◽  
Digital Elevation Models ◽  
Digital Elevation ◽  
Vertical Accuracy

scholarly journals A Contour-Directional Detection for Deriving Terrace Ridge From Open Source Images and Digital Elevation Models

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 129215-129224 ◽  
Author(s):  
Wen Dai ◽  
Guanghui Hu ◽  
Nan Huang ◽  
Peng Zhang ◽  
Xin Yang ◽  
...  
Keyword(s):  
Open Source ◽  
Digital Elevation Models ◽  
Directional Detection ◽  
Digital Elevation

scholarly journals The generation of digital elevation models using open source images

2021 ◽  
Author(s):  
Nithin Santosh Kumar
Keyword(s):  
Open Source ◽  
Spatial Resolution ◽  
Digital Elevation Models ◽  
Landsat 8 ◽  
Web Mapping ◽  
Digital Elevation ◽  
Satellite Sensors ◽  
Global Coverage ◽  
Comparable Accuracy ◽  
Sentinel 2

Digital Elevation Models are a representation of Earth’s surface and are used in many areas of research. There are a number of freely available DEMs with near-global coverage, which have elevation accuracies ranging between 10 to 25 m. This project attempts to generate DEMs of comparable accuracy using open source images from satellite sensors and web mapping services. Images from Landsat 8, ASTER, and Sentinel-2 satellites, and from Microsoft’s Bing Maps were used to generate DEMs for a 6.633 km2 area in Oshawa, Canada. It was found that it is key that when combining images from different spaceborne sensors, the spatial resolution should be within 10 m of one another. Additionally, the radiometry of the images, in terms of intensity and contrast, must be similar. The highest accuracies of DEMs had RMSE values of 20.047 m and 20.579 m, when combining images from Sentinel-2 with ASTER and Landsat 8, respectively.

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