Matters of choosing the pixel size in topographic aerial photography

2021 ◽  
Vol 977 (11) ◽  
pp. 27-39
Author(s):  
V.I. Yurchenko
Keyword(s):  
Aerial Photography ◽  
Input Data ◽  
Large Scale ◽  
Aerial Survey ◽  
Minimum Size ◽  
Digital Cameras ◽  
Pixel Size ◽  
Digital Elevation ◽  
Elevation Model ◽  
Navigation Equipment

The existing regulatory documents on photogrammetric works are technologically outdated. They neither take into account the peculiarities of aerial photography with digital cameras, the navigation equipment used and modern image processing methods, nor regulate the technique of calculating the pixel size on the ground. In order to select the pixel size in the terrain for aerial photography with topographic requirements concerning to the results, the method of multivariate analysis of the input data is proposed. It is supposed to ensure the minimum pixel size on the ground according to such criteria as the accuracy of the aerial triangulation results, the accuracy of building a digital elevation model for orthotransformation, the possibility of the objects interpretation with a specified minimum size and consideration of camera exposure parameters. To determine the accuracy criteria, we used formulas for pre- calculation of spatial phototriangulation accuracy with multiple choice of parameters. Examples of pixel size selection in the terrain at designing aerial photography by an amateur camera for the purposes of large-scale mapping are considered. Conclusions on the necessity of solving the issues of selecting parameters of large scale aerial photography, taking into account multiple input data and used aerial survey equipment are made.

STUDY OF THE LANDSLIDE MORPHOLOGY BASED ON GNSS DATA AND AIRBORNE SOUNDING (ON THE EXAMPLE OF A SECTION OF THE PROTVA RIVER VALLEY)

2018 ◽  
Vol 12 (5-6) ◽  
pp. 50-57 ◽  
Author(s):  
I. S. Voskresensky ◽  
A. A. Suchilin ◽  
L. A. Ushakova ◽  
V. M. Shaforostov ◽  
A. L. Entin ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Geodetic Network ◽  
Aerial Survey ◽  
River Valley ◽  
Ease Of Use ◽  
Digital Elevation ◽  
Loose Deposits ◽  
Positioning Method ◽  
Landslide Body ◽  
Elevation Model

To use unmanned aerial vehicles (UAVs) for obtaining digital elevation models (DEM) and digital terrain models (DTM) is currently actively practiced in scientific and practical purposes. This technology has many advantages: efficiency, ease of use, and the possibility of application on relatively small area. This allows us to perform qualitative and quantitative studies of the progress of dangerous relief-forming processes and to assess their consequences quickly. In this paper, we describe the process of obtaining a digital elevation model (DEM) of the relief of the slope located on the bank of the Protva River (Satino training site of the Faculty of Geography, Lomonosov Moscow State University). To obtain the digital elevation model, we created a temporary geodetic network. The coordinates of the points were measured by the satellite positioning method using a highprecision mobile complex. The aerial survey was carried out using an unmanned aerial vehicle from a low altitude (about 40–45 m). The processing of survey materials was performed via automatic photogrammetry (Structure-from-Motion method), and the digital elevation model of the landslide surface on the Protva River valley section was created. Remote sensing was supplemented by studying archival materials of aerial photography, as well as field survey conducted immediately after the landslide. The total amount of research results made it possible to establish the causes and character of the landslide process on the study site. According to the geomorphological conditions of formation, the landslide refers to a variety of landslideslides, which are formed when water is saturated with loose deposits. The landslide body was formed with the "collapse" of the blocks of turf and deluvial loams and their "destruction" as they shifted and accumulated at the foot of the slope.

scholarly journals Erosion Prediction Model using Fractional Vegetation Cover

2020 ◽  
Vol 5 (1) ◽  
pp. 125-132
Author(s):  
Nursida Arif ◽  
Projo Danoedoro ◽  
Hartono Hartono ◽  
Andrew Mulabbi
Keyword(s):  
Prediction Model ◽  
Vegetation Cover ◽  
Input Data ◽  
Medium Density ◽  
Vegetation Density ◽  
Erosion Model ◽  
Fractional Vegetation Cover ◽  
Erosion Prediction ◽  
Digital Elevation ◽  
Elevation Model

The purpose of this study was to  create an erosion prediction model in Serang Watershed, Indonesia. The erosion model used two input data, namely the slope derivied from Digital Elevation Model (DEM) data, and Fractional Vegetation Cover (FVC) from SPOT images. Assessment of the model was carried out using questionnaires and interviews with several experts by presenting the results of the model and its supporting data. Based on the DEM data, the level of slope steepness in the study area is very varied namely; flat (52.77%), sloping (7.62%), and rather steep to very steep (39.59%). Vegetation density according to the FVC results is dominated by medium density. The results of the analysis of the two input models can provide predictions of the level of erosion with an accuracy of 67.92%. Evaluation of the model was done by experts with conclusions that the method was very flexible and can be adapted to similar watersheds elsewhere.

scholarly journals Fusion Analysis of Optical Satellite Images and Digital Elevation Model for Quantifying Volume in Debris Flow Disaster

2019 ◽  
Vol 11 (9) ◽  
pp. 1096 ◽  
Author(s):  
Hiroyuki Miura
Keyword(s):  
Debris Flow ◽  
Digital Elevation Model ◽  
Large Scale ◽  
Satellite Images ◽  
Erosion Depth ◽  
Digital Elevation ◽  
Elevation Model ◽  
Fusion Analysis ◽  
Optical Satellite Images ◽  
Debris Flow Disaster

Rapid identification of affected areas and volumes in a large-scale debris flow disaster is important for early-stage recovery and debris management planning. This study introduces a methodology for fusion analysis of optical satellite images and digital elevation model (DEM) for simplified quantification of volumes in a debris flow event. The LiDAR data, the pre- and post-event Sentinel-2 images and the pre-event DEM in Hiroshima, Japan affected by the debris flow disaster on July 2018 are analyzed in this study. Erosion depth by the debris flows is empirically modeled from the pre- and post-event LiDAR-derived DEMs. Erosion areas are detected from the change detection of the satellite images and the DEM-based debris flow propagation analysis by providing predefined sources. The volumes and their pattern are estimated from the detected erosion areas by multiplying the empirical erosion depth. The result of the volume estimations show good agreement with the LiDAR-derived volumes.

A new method for supporting interpretation of paleochannels in a large scale — Detrended Digital Elevation Model Interpretation

Geomorphology ◽  
2020 ◽  
Vol 369 ◽  
pp. 107374
Author(s):  
Shuyan Zhang ◽  
Yong Ma ◽  
Fu Chen ◽  
Jianbo Liu ◽  
Fulong Chen ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Large Scale ◽  
New Method ◽  
Model Interpretation ◽  
Digital Elevation ◽  
Elevation Model

scholarly journals A Semiautomatic Pixel-Object Method for Detecting Landslides Using Multitemporal ALOS-2 Intensity Images

2020 ◽  
Vol 12 (3) ◽  
pp. 561 ◽  
Author(s):  
Bruno Adriano ◽  
Naoto Yokoya ◽  
Hiroyuki Miura ◽  
Masashi Matsuoka ◽  
Shunichi Koshimura
Keyword(s):  
Disaster Response ◽  
Large Scale ◽  
Reference Data ◽  
Mass Movement ◽  
Recovery Planning ◽  
Additional Information ◽  
Digital Elevation ◽  
Before And After ◽  
Intensity Images ◽  
Elevation Model

The rapid and accurate mapping of large-scale landslides and other mass movement disasters is crucial for prompt disaster response efforts and immediate recovery planning. As such, remote sensing information, especially from synthetic aperture radar (SAR) sensors, has significant advantages over cloud-covered optical imagery and conventional field survey campaigns. In this work, we introduced an integrated pixel-object image analysis framework for landslide recognition using SAR data. The robustness of our proposed methodology was demonstrated by mapping two different source-induced landslide events, namely, the debris flows following the torrential rainfall that fell over Hiroshima, Japan, in early July 2018 and the coseismic landslide that followed the 2018 Mw6.7 Hokkaido earthquake. For both events, only a pair of SAR images acquired before and after each disaster by the Advanced Land Observing Satellite-2 (ALOS-2) was used. Additional information, such as digital elevation model (DEM) and land cover information, was employed only to constrain the damage detected in the affected areas. We verified the accuracy of our method by comparing it with the available reference data. The detection results showed an acceptable correlation with the reference data in terms of the locations of damage. Numerical evaluations indicated that our methodology could detect landslides with an accuracy exceeding 80%. In addition, the kappa coefficients for the Hiroshima and Hokkaido events were 0.30 and 0.47, respectively.

Evaluation of Low Cost Digital Cameras for Producing Photogrammetric Output from UAV

2018 ◽  
Vol 7 (2.29) ◽  
pp. 792 ◽  
Author(s):  
Syafiq Sukor ◽  
Anuar Ahmad
Keyword(s):  
Global Positioning System ◽  
Mean Squared Error ◽  
Low Cost ◽  
Control Point ◽  
Ground Control ◽  
Digital Cameras ◽  
Squared Error ◽  
Digital Elevation ◽  
Global Positioning ◽  
Elevation Model

Recently there a lot of improvement in digital photogrammetry and this allow photogrammetry to become faster and cheaper . This study discuss about two type of low cost camera which is the compact camera (Canon Power Shot SX230 ) and action camera (Xiaomi yi) where both of them have different lens distortion. This study is conducted within UTM (Universiti Teknologi Malaysia) Skudai campus at Kolej  Tun Razak. Both of the Canon Power Shot SX230 and Xiaomi yi camera would be attach to the UAV  to take aerial photo with three different altitude which is 60 meter, 80 meter and 100 meter with a similar flight path. Check point (CPs) and Ground control point (GCPs) were also established using rapid static technique of Global Positioning System (GPS) and Total Station. The Canon Power Shot SX230 and Xiaomi yi camera is then calibrated using checkboard calibration this is done by using Agisoft  Lens software. Then all of the pictures that been taken by the Canon Power Shot SX230 and the Xiaomi yi would be processed by using Agisoft Photoscan software to generate Digital Elevation Model (DEM), orthophoto and contour line. The accuracy of DEM was determined based on Root Mean Squared Error (RMSE) value. Both of the result is then analyze visually and statically. Overall both of the camera gives a slight different in accuracy. 

scholarly journals A new 100-m Digital Elevation Model of the Antarctic Peninsula derived from ASTER Global DEM: methods and accuracy assessment

2012 ◽  
Vol 4 (1) ◽  
pp. 129-142 ◽  
Author(s):  
A. J. Cook ◽  
T. Murray ◽  
A. Luckman ◽  
D. G. Vaughan ◽  
N. E. Barrand
Keyword(s):  
Digital Elevation Model ◽  
Antarctic Peninsula ◽  
Accuracy Assessment ◽  
Correction Method ◽  
Pixel Size ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Vertical Accuracy ◽  
Elevation Model ◽  
The Antarctic

Abstract. A high resolution surface topography Digital Elevation Model (DEM) is required to underpin studies of the complex glacier system on the Antarctic Peninsula. A complete DEM with better than 200 m pixel size and high positional and vertical accuracy would enable mapping of all significant glacial basins and provide a dataset for glacier morphology analyses. No currently available DEM meets these specifications. We present a new 100-m DEM of the Antarctic Peninsula (63–70° S), based on ASTER Global Digital Elevation Model (GDEM) data. The raw GDEM products are of high-quality on the rugged terrain and coastal-regions of the Antarctic Peninsula and have good geospatial accuracy, but they also contain large errors on ice-covered terrain and we seek to minimise these artefacts. Conventional data correction techniques do not work so we have developed a method that significantly improves the dataset, smoothing the erroneous regions and hence creating a DEM with a pixel size of 100 m that will be suitable for many glaciological applications. We evaluate the new DEM using ICESat-derived elevations, and perform horizontal and vertical accuracy assessments based on GPS positions, SPOT-5 DEMs and the Landsat Image Mosaic of Antarctica (LIMA) imagery. The new DEM has a mean elevation difference of −4 m (± 25 m RMSE) from ICESat (compared to −13 m mean and ±97 m RMSE for the original ASTER GDEM), and a horizontal error of less than 2 pixels, although elevation accuracies are lower on mountain peaks and steep-sided slopes. The correction method significantly reduces errors on low relief slopes and therefore the DEM can be regarded as suitable for topographical studies such as measuring the geometry and ice flow properties of glaciers on the Antarctic Peninsula. The DEM is available for download from the NSIDC website: http://nsidc.org/data/nsidc-0516.html (doi:10.5060/D47P8W9D).

Food Submergence Calculation and Analysis Using Digital Elevation Model and Geographical Information System

2014 ◽  
Vol 571-572 ◽  
pp. 792-795
Author(s):  
Xiao Qing Zhang ◽  
Kun Hua Wu
Keyword(s):  
Information System ◽  
Digital Elevation Model ◽  
Flood Control ◽  
Large Scale ◽  
Geographical Information ◽  
Economic Losses ◽  
Model Data ◽  
Digital Elevation ◽  
Elevation Model ◽  
Digital Elevation Model Data

Floods usually cause large-scale loss of human life and wide spread damage to properties. Determining flood zone is the core of flood damage assessment and flood control decision. The aim of this paper is to delineate the flood inundation area and estimate economic losses arising from flood using the digital elevation model data and geographic information system techniques. Flood extent estimation showed that digital elevation model data is very precious to model inundation, however, in order to be spatially explicit flood model, high resolution DEM is necessary. Finally, Analyses for the submergence area calculation accuracy.

scholarly journals Morphotectonic analysis of Kozani Basin (Western Macedonia, Greece)

2017 ◽  
Vol 47 (2) ◽  
pp. 657
Author(s):  
E. Simou ◽  
V. Karagkouni ◽  
G. Papantoniou ◽  
D. Papanikolaou ◽  
P. Nomikou
Keyword(s):  
Large Scale ◽  
Drainage Pattern ◽  
Tectonic Structure ◽  
Tectonic Structures ◽  
River Terraces ◽  
Digital Elevation ◽  
Combined Use ◽  
Digital Modelling ◽  
Elevation Model ◽  
Topographic Relief

Kozani Basin is located in northern-central Greece and constitutes the southernmost of the Plio-Pleistocene basins of western Macedonia. Quantitative and qualitative analysis of morphological slope values, as well as the analysis of the drainage pattern in Kozani Basin confirms that the current topographic relief reflects intense neotectonic activity. Synthetic Morphotectonic Map of the under study area was carried out by means of the combined use of: (a) Digital Elevation Model (DEM), (b) Slope Distribution Map, (c) Morphological Slope Map and (d) Drainage Pattern Map. The composition of the digital modelling in conjunction with the regional geological setting, allows the identification of the main morphological discontinuities and lineaments that result from morphotectonic interpretation. The high morphological slope values indicate well-defined morphotectonic features, which mainly trend NE - SW and, secondarily, NW - SE. Distinct tectonic structures are mostly recognized in the SE margin of Kozani Basin, which is characterized by intense topographic relief. The main large-scale tectonic structure trends NE - SW and corresponds to the major Aliakmonas marginal fault zone that bounds the Kozani basin to the south. On the other hand, the NW margin’s features are indiscernible; thus, the criteria for their recognition are based on the existence of the river terraces, which reflect the tectonic control. The results of our studies are presented on the Morphotectonic Map, which is followed by our 3D model of Kozani Basin.

scholarly journals Global analysis of the slope of forest land

2020 ◽  
Author(s):  
Mikael Lundbäck ◽  
Henrik Persson ◽  
Carola Häggström ◽  
Tomas Nordfjell
Keyword(s):  
Large Scale ◽  
Forest Cover ◽  
Global Analysis ◽  
Forest Area ◽  
Forest Land ◽  
Digital Elevation ◽  
Total Forest Area ◽  
Cent Point ◽  
Elevation Model ◽  
Country Specific

Abstract Forests of the world constitute one-third of the total land area and are critical for e.g. carbon balance, biodiversity, water supply and as source for bio-based products. Although the terrain within forest land has a great impact on accessibility, there is a lack of knowledge about the distribution of its variation in slope. The aim was to address that knowledge gap and create a globally consistent dataset of the distribution and area of forest land within different slope classes. A Geographic Information System (GIS) analysis was performed using the open-source QGIS, GDAL and R software. The core of the analysis was a digital elevation model and a forest cover mask, both with a final resolution of 90 m. The total forest area according to the forest mask was 4.15 billion hectares whereof 82 per cent was on slope < 15°. The remaining 18 per cent was distributed over the following slope classes, with 6 per cent on a 15–20° slope, 8 per cent on a 20–30° slope and 4 per cent on a slope > 30°. Out of the major forestry countries, China had the largest proportion of forest steeper than 15° followed by Chile and India. A sensitivity analysis with 20 m resolution resulted in increased steep areas by 1 per cent point in flat Sweden and by 11 per cent points in steep Austria. In addition to country-specific and aggregated results of slope distribution and forest area, a global raster dataset is also made freely available to cover user-specific areas that are not necessarily demarcated by country borders. Apart from predicting the regional possibilities for different harvesting equipment, which was the original idea behind this study, the results can be used to relate geographical forest variables to slope. The results could also be used in strategic forest fire fighting and large-scale planning of forest conservation and management.

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