Avalanche Starting-Zone Analysis by use of a Knowledge-Based System

This paper presents the first step in the development of a new kind of computer-based tool which can help a specialist consultant in avalanche path analysis, a knowledge-based or expert system. In considering an avalanche path, the specialist often needs a simulation of possible avalanches on this path in order to obtain data for probable velocities and pressures. Use of classical numerical tools by an engineer requires a great deal of experience and knowledge. Such knowledge exists, but until the development of knowledge-based systems no computer-based tool was available. After a short review of such systems, we describe a knowledge-based system currently being developed in CEMAGREF. Its problem-solving environment includes methods of analysis developed by a senior consultant, and also numerical and qualitative models. In the first step, which is presented here, it analyses the starting zone of an avalanche path. By means of a digital terrain model and a description of vegetation and main ridges (a model which still needs to be improved) this system can make use of the experience of specialists to produce an avalanche-starting simulation based on specified meteorological conditions. Quite simple rules are employed in order to take into account snow drift. First results are shown on accompanying maps of this qualitative modelling and these will need to be tested for validity.

Download Full-text

Avalanche Starting-Zone Analysis by use of a Knowledge-Based System

Annals of Glaciology ◽

10.3189/s0260305500007588 ◽

1989 ◽

Vol 13 ◽

pp. 27-30 ◽

Cited By ~ 3

Author(s):

Laurent Buisson ◽

Claude Charlier

Keyword(s):

Digital Terrain Model ◽

Short Review ◽

Knowledge Based System ◽

Terrain Model ◽

Knowledge Based ◽

Digital Terrain ◽

Snow Drift ◽

First Results ◽

Qualitative Models ◽

Computer Based

This paper presents the first step in the development of a new kind of computer-based tool which can help a specialist consultant in avalanche path analysis, a knowledge-based or expert system. In considering an avalanche path, the specialist often needs a simulation of possible avalanches on this path in order to obtain data for probable velocities and pressures. Use of classical numerical tools by an engineer requires a great deal of experience and knowledge. Such knowledge exists, but until the development of knowledge-based systems no computer-based tool was available.After a short review of such systems, we describe a knowledge-based system currently being developed in CEMAGREF. Its problem-solving environment includes methods of analysis developed by a senior consultant, and also numerical and qualitative models. In the first step, which is presented here, it analyses the starting zone of an avalanche path. By means of a digital terrain model and a description of vegetation and main ridges (a model which still needs to be improved) this system can make use of the experience of specialists to produce an avalanche-starting simulation based on specified meteorological conditions. Quite simple rules are employed in order to take into account snow drift. First results are shown on accompanying maps of this qualitative modelling and these will need to be tested for validity.

Download Full-text

MODELING CITIES FOR 3D_GIS PURPOSES

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-4-135-2018 ◽

2018 ◽

Vol XLII-4 ◽

pp. 135-142

Author(s):

E. G. V. de Jesus ◽

A. L. de Amorim ◽

N. J. Groetelaars ◽

V. O. Fernandes

Keyword(s):

Data Model ◽

Geometric Modeling ◽

Laser Scanning ◽

Semantic Representation ◽

Digital Terrain Model ◽

Surface Model ◽

Geography Markup Language ◽

Terrain Model ◽

Digital Terrain ◽

First Results

<p><strong>Abstract.</strong> 3D Geographic Information Systems (3D GIS) are systems that are capable of making spatial analyses that consider the tridimentional and semantic representation of objects. These systems make these analyses through its planialtimetric coordinates. The City Geography Markup Language (CityGML) is used for the representation of cities and urban applications. The CityGML is an international standardized data model based on XML used to store and exchange information through 3D representation of cities. This standardized data model has 5 Levels of Detail – LOD, varying from LOD 0 (least detailed) to 4 (most detailed). The main challenges for the implementation of these systems refer to the techniques used for obtaining data and the data format, and also all the software used in the geometric modeling of the urban model. The data related to the buildings were manipulated with the QGIS software in this study. This made it possible to obtain the height of the buildings by the elevation difference between the Digital Surface Model and the Digital Terrain Model. This paper presents and discusses the first results of the geometric modeling made in the campus of the Federal University of Bahia (UFBA), by using airborne laser scanning data, integrating QGIS, Rhinoceros and CityGML.</p>

Download Full-text

Terrain modelling by kinematical GPS survey

Natural Hazards and Earth System Science ◽

10.5194/nhess-5-293-2005 ◽

2005 ◽

Vol 5 (2) ◽

pp. 293-299 ◽

Cited By ~ 7

Author(s):

G. Nico ◽

P. Rutigliano ◽

C. Benedetto ◽

F. Vespe

Keyword(s):

Digital Terrain Model ◽

Monte Carlo Analysis ◽

Sampling Procedure ◽

Archaeological Sites ◽

Kinematic Gps ◽

Terrain Model ◽

Gps Survey ◽

Digital Terrain ◽

First Results ◽

The Stability

Abstract. This work presents the first results of an experiment aiming to derive a high resolution Digital Terrain Model (DTM) by kinematic GPS surveying. The accuracy of the DTM depends on both the operational GPS precision and the density of GPS samples. The operational GPS precision, measured in the field, is about 10cm. A Monte Carlo analysis is performed to study the dependence of the DTM error on the sampling procedure. The outcome of this analysis is that the accuracy of the topographic reconstruction is less than 1m even in areas with a density of samples as low as one sample per 100m2, and becomes about 30cm in areas with at least one sample per 10m2. The kinematic GPS technique gives a means for a fast and accurate mapping of terrain surfaces with an extension of a few km2. Examples of application are the investigation of archaeological sites and the stability analysis of landslide prone areas.

Download Full-text

Geographic information system (GIS) procedure for preliminary delineation of debris-flow hazard areas from a digital terrain model, Madison County, Virginia

Open-File Report ◽

10.3133/ofr99336 ◽

1999 ◽

Author(s):

R.H. Campbell ◽

P.G. Chirico

Keyword(s):

Information System ◽

Geographic Information System ◽

Debris Flow ◽

Digital Terrain Model ◽

Geographic Information ◽

Terrain Model ◽

Madison County ◽

Digital Terrain ◽

Debris Flow Hazard

Download Full-text

The Effect of LiDAR Sampling Density on DTM Accuracy for Areas with Heavy Forest Cover

Forests ◽

10.3390/f12030265 ◽

2021 ◽

Vol 12 (3) ◽

pp. 265

Author(s):

Mihnea Cățeanu ◽

Arcadie Ciubotaru

Keyword(s):

Forest Cover ◽

Initial Point ◽

Ground Surface ◽

Digital Terrain Model ◽

Morphological Data ◽

Sampling Density ◽

Terrain Model ◽

Digital Terrain ◽

Point Density ◽

The Impact

Laser scanning via LiDAR is a powerful technique for collecting data necessary for Digital Terrain Model (DTM) generation, even in densely forested areas. LiDAR observations located at the ground level can be separated from the initial point cloud and used as input for the generation of a Digital Terrain Model (DTM) via interpolation. This paper proposes a quantitative analysis of the accuracy of DTMs (and derived slope maps) obtained from LiDAR data and is focused on conditions common to most forestry activities (rough, steep terrain with forest cover). Three interpolation algorithms were tested: Inverse Distance Weighted (IDW), Natural Neighbour (NN) and Thin-Plate Spline (TPS). Research was mainly focused on the issue of point data density. To analyze its impact on the quality of ground surface modelling, the density of the filtered data set was artificially lowered (from 0.89 to 0.09 points/m2) by randomly removing point observations in 10% increments. This provides a comprehensive method of evaluating the impact of LiDAR ground point density on DTM accuracy. While the reduction of point density leads to a less accurate DTM in all cases (as expected), the exact pattern varies by algorithm. The accuracy of the LiDAR-derived DTMs is relatively good even when LiDAR sampling density is reduced to 0.40–0.50 points/m2 (50–60 % of the initial point density), as long as a suitable interpolation algorithm is used (as IDW proved to be less resilient to density reductions below approximately 0.60 points/m2). In the case of slope estimation, the pattern is relatively similar, except the difference in accuracy between IDW and the other two algorithms is even more pronounced than in the case of DTM accuracy. Based on this research, we conclude that LiDAR is an adequate method for collecting morphological data necessary for modelling the ground surface, even when the sampling density is significantly reduced.

Download Full-text

DTM-based analysis of the spatial distribution of topolineaments

Open Geosciences ◽

10.1515/geo-2020-0059 ◽

2020 ◽

Vol 12 (1) ◽

pp. 1185-1199

Author(s):

Mirosław Kamiński

Keyword(s):

Laser Scanning ◽

Digital Terrain Model ◽

Research Area ◽

Tectonic Structures ◽

Empirical Bayesian ◽

Scanning Method ◽

Empirical Bayesian Kriging ◽

Terrain Model ◽

Digital Terrain ◽

Airborne Laser

AbstractThe research area is located on the boundary between two Paleozoic structural units: the Radom–Kraśnik Block and the Mazovian–Lublin Basin in the southeastern Poland. The tectonic structures are separated by the Ursynów–Kazimierz Dolny fault zone. The digital terrain model obtained by the ALS (Airborne Laser Scanning) method was used. Classification and filtration of an elevation point cloud were performed. Then, from the elevation points representing only surfaces, a digital terrain model was generated. The model was used to visually interpret the course of topolineaments and their automatic extraction from DTM. Two topolineament systems, trending NE–SW and NW–SE, were interpreted. Using the kernel density algorithm, topolineament density models were generated. Using the Empirical Bayesian Kriging, a thickness model of quaternary deposits was generated. A relationship was observed between the course of topolineaments and the distribution and thickness of Quaternary formations. The topolineaments were compared with fault directions marked on tectonic maps of the Paleozoic and Mesozoic. Data validation showed consistency between topolineaments and tectonic faults. The obtained results are encouraging for further research.

Download Full-text

Production, Validation and Morphometric Analysis of a Digital Terrain Model for Lake Trichonis Using Geospatial Technologies and Hydroacoustics

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi10020091 ◽

2021 ◽

Vol 10 (2) ◽

pp. 91

Author(s):

Triantafyllia-Maria Perivolioti ◽

Antonios Mouratidis ◽

Dimitrios Terzopoulos ◽

Panagiotis Kalaitzis ◽

Dimitrios Ampatzidis ◽

...

Keyword(s):

Morphometric Analysis ◽

Ad Hoc ◽

Regional Scale ◽

Digital Terrain Model ◽

Relevant Information ◽

Relative Difference ◽

Systematic Observation ◽

Qualitative And Quantitative ◽

Terrain Model ◽

Digital Terrain

Covering an area of approximately 97 km2 and with a maximum depth of 58 m, Lake Trichonis is the largest and one of the deepest natural lakes in Greece. As such, it constitutes an important ecosystem and freshwater reserve at the regional scale, whose qualitative and quantitative properties ought to be monitored. Depth is a crucial parameter, as it is involved in both qualitative and quantitative monitoring aspects. Thus, the availability of a bathymetric model and a reliable DTM (Digital Terrain Model) of such an inland water body is imperative for almost any systematic observation scenario or ad hoc measurement endeavor. In this context, the purpose of this study is to produce a DTM from the only official cartographic source of relevant information available (dating back approximately 70 years) and evaluate its performance against new, independent, high-accuracy hydroacoustic recordings. The validation procedure involves the use of echosoundings coupled with GPS, and is followed by the production of a bathymetric model for the assessment of the discrepancies between the DTM and the measurements, along with the relevant morphometric analysis. Both the production and validation of the DTM are conducted in a GIS environment. The results indicate substantial discrepancies between the old DTM and contemporary acoustic data. A significant overall deviation of 3.39 ± 5.26 m in absolute bottom elevation differences and 0.00 ± 7.26 m in relative difference residuals (0.00 ± 2.11 m after 2nd polynomial model corrector surface fit) of the 2019 bathymetric dataset with respect to the ~1950 lake DTM and overall morphometry appear to be associated with a combination of tectonics, subsidence and karstic phenomena in the area. These observations could prove useful for the tectonics, geodynamics and seismicity with respect to the broader Corinth Rift region, as well as for environmental management and technical interventions in and around the lake. This dictates the necessity for new, extensive bathymetric measurements in order to produce an updated DTM of Lake Trichonis, reflecting current conditions and tailored to contemporary accuracy standards and state-of-the-art research in various disciplines in and around the lake.

Download Full-text

Refinement of interferometric SAR parameters using digital terrain model as an external reference

ISPRS Journal of Photogrammetry and Remote Sensing ◽

10.1016/j.isprsjprs.2021.02.017 ◽

2021 ◽

Vol 175 ◽

pp. 34-43

Author(s):

Jyunpei Uemoto

Keyword(s):

Digital Terrain Model ◽

Terrain Model ◽

Digital Terrain ◽

External Reference ◽

Interferometric Sar

Download Full-text

Modeling Streamflow and Sediment Loads with a Photogrammetrically Derived UAS Digital Terrain Model: Empirical Evaluation from a Fluvial Aggregate Excavation Operation

Drones ◽

10.3390/drones5010020 ◽

2021 ◽

Vol 5 (1) ◽

pp. 20

Author(s):

Joseph P. Hupy ◽

Cyril O. Wilson

Keyword(s):

Soil Erosion ◽

Point Cloud ◽

Empirical Evaluation ◽

Digital Terrain Model ◽

Surface Flow ◽

Sediment Loading ◽

Terrain Model ◽

Digital Terrain ◽

Statistical Measures ◽

Geospatial Datasets

Soil erosion monitoring is a pivotal exercise at macro through micro landscape levels, which directly informs environmental management at diverse spatial and temporal scales. The monitoring of soil erosion can be an arduous task when completed through ground-based surveys and there are uncertainties associated with the use of large-scale medium resolution image-based digital elevation models for estimating erosion rates. LiDAR derived elevation models have proven effective in modeling erosion, but such data proves costly to obtain, process, and analyze. The proliferation of images and other geospatial datasets generated by unmanned aerial systems (UAS) is increasingly able to reveal additional nuances that traditional geospatial datasets were not able to obtain due to the former’s higher spatial resolution. This study evaluated the efficacy of a UAS derived digital terrain model (DTM) to estimate surface flow and sediment loading in a fluvial aggregate excavation operation in Waukesha County, Wisconsin. A nested scale distributed hydrologic flow and sediment loading model was constructed for the UAS point cloud derived DTM. To evaluate the effectiveness of flow and sediment loading generated by the UAS point cloud derived DTM, a LiDAR derived DTM was used for comparison in consonance with several statistical measures of model efficiency. Results demonstrate that the UAS derived DTM can be used in modeling flow and sediment erosion estimation across space in the absence of a LiDAR-based derived DTM.

Download Full-text