scholarly journals ANALYSIS OF INFLUENCE OF TERRAIN RELIEF ROUGHNESS ON DEM ACCURACY GENERATED FROM LIDAR IN THE CZECH REPUBLIC TERRITORY

2016 ◽  
Vol XLI-B4 ◽  
pp. 25-30 ◽  
Author(s):  
M. Hubacek ◽  
V. Kovarik ◽  
V. Kratochvil
Keyword(s):  
Czech Republic ◽  
Laser Scanning ◽  
Vegetation Coverage ◽  
The Czech Republic ◽  
Digital Elevation ◽  
Lower Accuracy ◽  
Check Points ◽  
Elevation Data ◽  
Dem Accuracy ◽  
Elevation Model

Digital elevation models are today a common part of geographic information systems and derived applications. The way of their creation is varied. It depends on the extent of area, required accuracy, delivery time, financial resources and technologies available. The first model covering the whole territory of the Czech Republic was created already in the early 1980's. Currently, the 5th DEM generation is being finished. Data collection for this model was realized using the airborne laser scanning which allowed creating the DEM of a new generation having the precision up to a decimetre. Model of such a precision expands the possibilities of employing the DEM and it also offers new opportunities for the use of elevation data especially in a domain of modelling the phenomena dependent on highly accurate data. The examples are precise modelling of hydrological phenomena, studying micro-relief objects, modelling the vehicle movement, detecting and describing historical changes of a landscape, designing constructions etc. <br><br> Due to a nature of the technology used for collecting data and generating DEM, it is assumed that the resulting model achieves lower accuracy in areas covered by vegetation and in built-up areas. Therefore the verification of model accuracy was carried out in five selected areas in Moravia. The network of check points was established using a total station in each area. To determine the reference heights of check points, the known geodetic points whose heights were defined using levelling were used. Up to several thousands of points were surveyed in each area. Individual points were selected according to a different configuration of relief, different surface types, and different vegetation coverage. The sets of deviations were obtained by comparing the DEM 5G heights with reference heights which was followed by verification of tested elevation model. Results of the analysis showed that the model reaches generally higher precision than the declared one in majority of areas. This applies in particular to areas covered by vegetation. By contrast, the larger deviations occurred in relation to the slope of the terrain, in particular in the micro-relief objects. The results are presented in this article.

scholarly journals ANALYSIS OF INFLUENCE OF TERRAIN RELIEF ROUGHNESS ON DEM ACCURACY GENERATED FROM LIDAR IN THE CZECH REPUBLIC TERRITORY

2016 ◽  
Vol XLI-B4 ◽  
pp. 25-30 ◽  
Author(s):  
M. Hubacek ◽  
V. Kovarik ◽  
V. Kratochvil
Keyword(s):  
Czech Republic ◽  
Laser Scanning ◽  
Vegetation Coverage ◽  
The Czech Republic ◽  
Digital Elevation ◽  
Lower Accuracy ◽  
Check Points ◽  
Elevation Data ◽  
Dem Accuracy ◽  
Elevation Model

Digital elevation models are today a common part of geographic information systems and derived applications. The way of their creation is varied. It depends on the extent of area, required accuracy, delivery time, financial resources and technologies available. The first model covering the whole territory of the Czech Republic was created already in the early 1980's. Currently, the 5th DEM generation is being finished. Data collection for this model was realized using the airborne laser scanning which allowed creating the DEM of a new generation having the precision up to a decimetre. Model of such a precision expands the possibilities of employing the DEM and it also offers new opportunities for the use of elevation data especially in a domain of modelling the phenomena dependent on highly accurate data. The examples are precise modelling of hydrological phenomena, studying micro-relief objects, modelling the vehicle movement, detecting and describing historical changes of a landscape, designing constructions etc. &lt;br&gt;&lt;br&gt; Due to a nature of the technology used for collecting data and generating DEM, it is assumed that the resulting model achieves lower accuracy in areas covered by vegetation and in built-up areas. Therefore the verification of model accuracy was carried out in five selected areas in Moravia. The network of check points was established using a total station in each area. To determine the reference heights of check points, the known geodetic points whose heights were defined using levelling were used. Up to several thousands of points were surveyed in each area. Individual points were selected according to a different configuration of relief, different surface types, and different vegetation coverage. The sets of deviations were obtained by comparing the DEM 5G heights with reference heights which was followed by verification of tested elevation model. Results of the analysis showed that the model reaches generally higher precision than the declared one in majority of areas. This applies in particular to areas covered by vegetation. By contrast, the larger deviations occurred in relation to the slope of the terrain, in particular in the micro-relief objects. The results are presented in this article.

Designing on the New Elevation Database of the Czech Republic

2017 ◽  
Vol 755 ◽  
pp. 333-339 ◽  
Author(s):  
Jan Sobotka
Keyword(s):  
Czech Republic ◽  
Laser Scanning ◽  
Airborne Laser Scanning ◽  
The Czech Republic ◽  
Airborne Laser ◽  
Digital Elevation ◽  
Elevation Data

The article presents new possibilities of earthworks designing on new elevation data of the Czech Republic. These new elevation data are the result of the airborne laser scanning of the Czech Republic, which replace the old one. The new digital elevation database is another source of elevation data, which can be used during earthworks designing. Furthermore, the paper presents two projects, where new elevation data were used in practice.

scholarly journals Quality parameters of digital aerial survey and airborne laser scanning covering the entire area of the Czech Republic

2013 ◽  
Vol 10 ◽  
pp. 15-26 ◽  
Author(s):  
Jiří Šíma
Keyword(s):  
Czech Republic ◽  
Laser Scanning ◽  
Aerial Survey ◽  
Systematic Investigation ◽  
Quality Parameters ◽  
Entire Area ◽  
The Czech Republic ◽  
Digital Elevation ◽  
Land Survey ◽  
The University

The paper illustrates the development of digital aerial survey and digital elevation models covering the entire area of the Czech Republic at the beginning of 21st century. It also presents some results of systematic investigation of their quality parameters reached by the author in cooperation with Department of Geomatics at the Faculty of Applied Sciences of the University of Western Bohemia in Pilsen and the Land Survey Office.

scholarly journals A Workflow to Estimate Topographic and Volumetric Changes and Errors in Channel Sedimentation after Disturbance

2019 ◽  
Vol 11 (5) ◽  
pp. 586 ◽  
Author(s):  
Samira Nourbakhshbeidokhti ◽  
Alicia Kinoshita ◽  
Anne Chin ◽  
Joan Florsheim
Keyword(s):  
Laser Scanning ◽  
Point Clouds ◽  
Multiple Model ◽  
Stream Channels ◽  
Change Analysis ◽  
Volumetric Change ◽  
Analytic Methods ◽  
Digital Elevation ◽  
Elevation Data ◽  
Elevation Model

Light Detection and Ranging (LiDAR) methods, such as ground-based Terrestrial Laser Scanning (TLS), have enabled collection of high-resolution point clouds of elevation data to calculate changes in fluvial systems after disturbance, but are often accompanied by uncertainty and errors. This paper reviews and compares TLS analysis methods and develops a workflow to estimate topographic and volumetric changes in channel sedimentation after disturbance. Four analytic methods to estimate topographic and volumetric changes were compared by quantifying the uncertainty in TLS-derived products: Digital Elevation Model (DEM) of difference (DOD), Cloud to Cloud (C2C), Cloud to Mesh (C2M), and Multiple Model to Model Cloud Comparison (M3C2). Mean errors across surfaces within each dataset contributed to a propagation error of 0.015–0.016 m and 0.017–0.018 m for the point clouds and derived DEMs, respectively. The estimated error of the total volumetric change implied increased errors in the conversion of point clouds into a surface by C2M and DOD; whereas C2C and M3C2 were generally simpler, efficient, and accurate techniques for evaluating topographic changes. The comparison of methods to analyze TLS data will contribute to applications of remote sensing of hydro-geomorphic processes in stream channels after disturbance. The workflow presented also aids in estimating uncertainties inherent in data collection and analytic methods for topographic and volumetric change analysis.

Analysis of the potential evapotranspiration demands in the Czech Republic between 1961–1990

Biologia ◽  
2006 ◽  
Vol 61 (19) ◽  
Author(s):  
Jan Pivec ◽  
Václav Brant ◽  
Dalibor Moravec
Keyword(s):  
Czech Republic ◽  
Potential Evapotranspiration ◽  
Area Ratio ◽  
Climatic Data ◽  
The Czech Republic ◽  
Cylindrical Projection ◽  
Digital Elevation ◽  
Previous Decade ◽  
Elevation Model ◽  
The Many

AbstractDynamics of the evapotranspirational demands in the Czech Republic within three decades from 1961 to 1990 has been studied. The determination of the levels of influence of the respective natural components depends on the regionalized modelling techniques. The project of regionalized modelling is theoretically based on the potential evapotranspiration values (ET 0) calculated by FAO methodology (eqs. 1, 2) and the series of temperature and rainfall observations obtained by climatologic stations during a 30-year period from 1961 to 1990 and its relation to the absolute altimetric. The DMR-2 military digital elevation model of the Czech Republic relief consisting of a regular network of points with their altitudes specified in meters was used for the purpose of regionalized modelling. One step of the network in the S-42 coordinate system with the Gauss conforms cylindrical projection is equal to 100 meters; this implies that the smallest area for which the data can be processed is 1 hectare. The digital relief model can be linked to both direct (temperature, precipitation) and derived (evapotranspiration) quantities, which is one of the many novelties of regionalized modelling. The climatic data used in regionalized modelling records daily measurements were obtained by 85 climatologic and rainfall-monitoring stations from 1961 to 1990. Our results showed an appreciable decrease of the most drying area (ratio P/ET0 up to 0.755) in the last decade 1981–90; half as less amounts compared with the previous decade 1971–80 (about 500,000 hectares). On the other hand, an apparent increase (more than 500,000 hectares in comparison with the previous decade 1971–80) of the wettest area (ratio P/ET0 over 1.508) through the last decade was observed. Both first decades 1961–70 and 1971–80 look similar. The project mentioned in this article has made it possible to create models for the different time intervals which have showed higher reliability for heterogeneous application.

scholarly journals The Use of UAV in Cadastral Mapping of the Czech Republic

2021 ◽  
Vol 10 (6) ◽  
pp. 380
Author(s):  
Václav Šafář ◽  
Markéta Potůčková ◽  
Jakub Karas ◽  
Jan Tlustý ◽  
Eva Štefanová ◽  
...  
Keyword(s):  
Czech Republic ◽  
Real Estate ◽  
Point Cloud ◽  
Laser Scanning ◽  
Point Clouds ◽  
Maximum Efficiency ◽  
Image Point ◽  
The Czech Republic ◽  
Main Challenge ◽  
Check Points

The main challenge in the renewal and updating of the Cadastre of Real Estate of the Czech Republic is to achieve maximum efficiency but to retain the required accuracy of all points in the register. The paper discusses the possibility of using UAV photogrammetry and laser scanning for cadastral mapping in the Czech Republic. Point clouds from images and laser scans together with orthoimages were derived over twelve test areas. Control and check points were measured using geodetic methods (RTK-GNSS and total stations). The accuracy of the detailed survey based on UAV technologies was checked on hundreds of points, mainly building corners and fence foundations. The results show that the required accuracy of 0.14 m was achieved on more than 80% and 98% of points in the case of the image point clouds and orthoimages and the case of the LiDAR point cloud, respectively. Nevertheless, the methods lack completeness of the performed survey that must be supplied by geodetic measurements. The paper also provides a comparison of the costs connected to traditional and UAV-based cadastral mapping, and it addresses the necessary changes in the organisational and technological processes in order to utilise the UAV based technologies.

scholarly journals Impact of interpolation techniques on the accuracy of large-scale digital elevation model

2020 ◽  
Vol 12 (1) ◽  
pp. 190-202 ◽  
Author(s):  
Maan Habib ◽  
Yazan Alzubi ◽  
Ahmad Malkawi ◽  
Mohammad Awwad
Keyword(s):  
Digital Elevation Model ◽  
Construction Projects ◽  
Large Scale ◽  
Digital Elevation ◽  
Distance Weighted ◽  
Elevation Data ◽  
Data Capturing ◽  
Dem Accuracy ◽  
Elevation Model ◽  
The Impact

AbstractThere is no doubt that the tremendous development of information technology was one of the driving factors behind the great growth of surveying and geodesy science. This has spawned modern geospatial techniques for data capturing, acquisition, and visualization tools. Digital elevation model (DEM) is the 3D depiction of continuous elevation data over the Earth’s surface that is produced through many procedures such as remote sensing, photogrammetry, and land surveying. DEMs are essential for various surveying and civil engineering applications to generate topographic maps for construction projects at a scale that varies from 1:500 to 1:2,000. GIS offers a powerful tool to create a DEM with high resolution from accurate land survey measurements using interpolation methods. The aim of this research is to investigate the impact of estimation techniques on generating a reliable and accurate DEM suitable for large-scale mapping. As a part of this study, the deterministic interpolation algorithms such as ANUDEM (Topo to Raster), inverse distance weighted (IDW), and triangulated irregular network (TIN) were tested using the ArcGIS desktop for elevation data obtained from real total station readings, with different landforms to show the effect of terrain roughness, data density, and interpolation process on DEM accuracy. Furthermore, comparison and validation of each interpolator were carried out through the cross-validation method and numerous graphical representations of the DEM. Finally, the results of the investigations showed that ANUDEM and TIN models are similar and significantly better than those attained from IDW.

scholarly journals A Comparative Study of Three Non-Geostatistical Methods for Optimising Digital Elevation Model Interpolation

2018 ◽  
Vol 7 (8) ◽  
pp. 300 ◽  
Author(s):  
Serajis Salekin ◽  
Jack Burgess ◽  
Justin Morgenroth ◽  
Euan Mason ◽  
Dean Meason
Keyword(s):  
Digital Elevation Model ◽  
Spatial Resolution ◽  
Laser Scanning ◽  
Interpolation Method ◽  
Digital Elevation Models ◽  
Global Navigation Satellite Systems ◽  
Digital Elevation ◽  
Dem Accuracy ◽  
Elevation Model ◽  
Gnss Data

It is common to generate digital elevation models (DEMs) from aerial laser scanning (ALS) data. However, cost and lack of knowledge may preclude its use. In contrast, global navigation satellite systems (GNSS) are seldom used to collect and generate DEMs. These receivers have the potential to be considered as data sources for DEM interpolation, as they can be inexpensive, easy to use, and mobile. The data interpolation method and spatial resolution from this method needs to be optimised to create accurate DEMs. Moreover, the density of GNSS data is likely to affect DEM accuracy. This study investigates three different deterministic approaches, in combination with spatial resolution and data thinning, to determine their combined effects on DEM accuracy. Digital elevation models were interpolated, with resolutions ranging from 0.5 m to 10 m using natural neighbour (NaN), topo to raster (ANUDEM), and inverse distance weighted (IDW) methods. The GNSS data were thinned by 25% (0.389 points m−2), 50% (0.259 points m−2), and 75% (0.129 points m−2) and resulting DEMs were contrast against a DEM interpolated from unthinned data (0.519 points m−2). Digital elevation model accuracy was measured by root mean square error (RMSE) and mean absolute error (MAE). It was found that the highest resolution, 0.5 m, produced the lowest errors in resulting DEMs (RMSE = 0.428 m, MAE = 0.274 m). The ANUDEM method yielded the greatest DEM accuracy from a quantitative perspective (RMSE = 0.305 m and MAE = 0.197 m); however, NaN produced a more visually appealing surface. In all the assessments, IDW showed the lowest accuracy. Thinning the input data by 25% and even 50% had relatively little impact on DEM quality; however, accuracy decreased markedly at 75% thinning (0.129 points m−2). This study showed that, in a time where ALS is commonly used to generate DEMs, GNSS-surveyed data can be used to create accurate DEMs. This study confirmed the need for optimization to choose the appropriate interpolation method and spatial resolution in order to produce a reliable DEM.

scholarly journals Detection of Microrelief Objects to Impede the Movement of Vehicles in Terrain

2019 ◽  
Vol 8 (3) ◽  
pp. 101 ◽  
Author(s):  
Filip Dohnal ◽  
Martin Hubacek ◽  
Katerina Simkova
Keyword(s):  
Czech Republic ◽  
Laser Scanning ◽  
Large Scale ◽  
High Reliability ◽  
Digital Elevation Models ◽  
Modeling Tools ◽  
The Czech Republic ◽  
Technical Parameters ◽  
Gis Tools ◽  
Digital Elevation

Relief of terrain as a part of the landscape greatly affects the possibilities of vehicles moving off the road. The main influence on the movement is the slope of terrain and the occurrence of microrelief objects. While the slope limits can be easily modeled in the GIS environment, it is difficult to express the effect of the microrelief on the possibilities of moving vehicles. The aim of this work was to find procedures for identification of impassable microrelief objects using GIS tools and precise digital elevation models. Technical parameters defining the ability of a vehicle to overcome microrelief objects are known and these are mainly defined by the dimensions of the vehicle such as a wheel base, a ground clearance, approach angle, and others. Large-scale digital elevation models have not been able to reliably express the location and shape of microrelief objects until recently. Their accuracy of height in nodes achieved meter or decimeter values. The change occurred with the use of airborne laser scanning technology for digital elevation model creation. The accuracy of models created using this technology achieves centimeter values. These can be used for detection of microrelief objects. One of these models is the DMR5 from the territory of the Czech Republic. Its declared total mean height error is 0.18 meters. This model, together with the GIS tools and the technical parameters of individual vehicles, was used to search for such microrelief objects that act as a barrier to movement. Procedures for detecting impassable microrelief objects were created by ArcGIS tools. Modeling tools and mathematical methods were used to create procedures for detection of microrelief objects. These have been applied to selected locations in the Czech Republic. Raster layers representing individual impassable microrelief objects are the result of modeling. The modeling results were verified in the terrain using military vehicles. Field tests confirmed the high reliability of the proposed procedure. Therefore, the calculation process was optimized and will be introduced in the future as one of the input calculations of the complex model of passability in the Army of the Czech Republic.

scholarly journals PREPARATION OF THE DIGITAL ELEVATION MODEL FOR ORTHOPHOTO CR PRODUCTION

2016 ◽  
Vol XLI-B3 ◽  
pp. 107-113
Author(s):  
Z. Švec ◽  
K. Pavelka
Keyword(s):  
Czech Republic ◽  
Rural Areas ◽  
Laser Scanning ◽  
The State ◽  
Image Correlation ◽  
Aerial Photographs ◽  
Surface Model ◽  
Entire Area ◽  
The Czech Republic ◽  
Elevation Model

The Orthophoto CR is produced in co-operation with the Land Survey Office and the Military Geographical and Hydrometeorological Office. The product serves to ensure a defence of the state, integrated crisis management, civilian tasks in support of the state administration and the local self-government of the Czech Republic as well. It covers the whole area of the Republic and for ensuring its up-to-datedness is reproduced in the biennial period. As the project is countrywide, it keeps the project within the same parameters in urban and rural areas as well. Due to economic reasons it can´t be produced as a true ortophoto because it requires large side and forward overlaps of the aerial photographs and a preparation of the digital surface model instead of the digital terrain model. Use of DTM without some objects of DSM for orthogonalization purposes cause undesirable image deformations in the Orthophoto. There are a few data sets available for forming a suitable elevation model. The principal source should represent DTMs made from data acquired by the airborne laser scanning of the entire area of the Czech Republic that was carried out in the years 2009-2013, the DMR4G in the grid form and the DMR5G in TIN form respectively. It can be replenished by some vector objects (bridges, dams, etc.) taken from the geographic base data of the Czech Republic or obtained by new stereo plotting. It has to be taken into account that the option of applying DSM made from image correlation is also available. The article focuses on the possibilities of DTM supplement for ortogonalization. It looks back to the recent transition from grid to hybrid elevation models, problems that occurred, its solution and getting some practical remarks. Afterwards it assesses the current state and deals with the options for updating the model. Some accuracy analysis are included.

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