scholarly journals CLOSE RANGE DIGITAL PHOTOGRAMMETRY APPLIED TO TOPOGRAPHY AND LANDSLIDE MEASUREMENTS

2016 ◽  
Vol XLI-B5 ◽  
pp. 875-880 ◽  
Author(s):  
Wen-Cheng Liu ◽  
Wei-Che Huang
Keyword(s):  
Low Cost ◽  
Digital Terrain Model ◽  
Landslide Monitoring ◽  
Digital Photogrammetry ◽  
Terrain Model ◽  
Digital Terrain ◽  
Gps Measurement ◽  
Before And After ◽  
Close Range ◽  
Central Taiwan

Landslide monitoring is a crucial tool for the prevention of hazards. It is often the only solution for the survey and the early-warning of large landslides cannot be stabilized. The objective of present study is to use a low-cost image system to monitor the active landslides. We adopted the direct linear transformation (DLT) method in close range digital photogrammetry to measure terrain of landslide at the Huoyen Shan, Miaoli of central Taiwan and to compare measured results with e-GPS. The results revealed that the relative error in surface area was approximately 1.7% as comparing the photogrammetry with DLT method and e-GPS measurement. It showed that the close range digital photogrammetry with DLT method had the availability and capability to measure the landslides. The same methodology was then applied to measure the terrain before landslide and after landslide in the study area. The digital terrain model (DTM) was established and then was used to calculate the volume of the terrain before landslide and after landslide. The volume difference before and after landslides was 994.16 m<sup>3</sup>.

scholarly journals CLOSE RANGE DIGITAL PHOTOGRAMMETRY APPLIED TO TOPOGRAPHY AND LANDSLIDE MEASUREMENTS

2016 ◽  
Vol XLI-B5 ◽  
pp. 875-880
Author(s):  
Wen-Cheng Liu ◽  
Wei-Che Huang
Keyword(s):  
Low Cost ◽  
Digital Terrain Model ◽  
Landslide Monitoring ◽  
Digital Photogrammetry ◽  
Terrain Model ◽  
Digital Terrain ◽  
Gps Measurement ◽  
Before And After ◽  
Close Range ◽  
Central Taiwan

Landslide monitoring is a crucial tool for the prevention of hazards. It is often the only solution for the survey and the early-warning of large landslides cannot be stabilized. The objective of present study is to use a low-cost image system to monitor the active landslides. We adopted the direct linear transformation (DLT) method in close range digital photogrammetry to measure terrain of landslide at the Huoyen Shan, Miaoli of central Taiwan and to compare measured results with e-GPS. The results revealed that the relative error in surface area was approximately 1.7% as comparing the photogrammetry with DLT method and e-GPS measurement. It showed that the close range digital photogrammetry with DLT method had the availability and capability to measure the landslides. The same methodology was then applied to measure the terrain before landslide and after landslide in the study area. The digital terrain model (DTM) was established and then was used to calculate the volume of the terrain before landslide and after landslide. The volume difference before and after landslides was 994.16 m<sup>3</sup>.

scholarly journals Assessment of the Role of Snowmelt in a Flood Event in a Gauged Catchment

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 506 ◽  
Author(s):  
Jesús Mateo-Lázaro ◽  
Jorge Castillo-Mateo ◽  
José Sánchez-Navarro ◽  
Víctor Fuertes-Rodríguez ◽  
Alejandro García-Gil ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Digital Terrain Model ◽  
Terrain Model ◽  
Rain Gauges ◽  
Digital Terrain ◽  
Before And After ◽  
Thawing Process ◽  
Rainfall Model

An actual event that happened in the Roncal valley (Spain) is investigated and the results are compared between models with and without snowmelt. A distributed rainfall model is generated with the specific data recorded by the rain gauges of the catchment during the episode. To describe the process of water routing in the hydrological cycle of the basin, a model is used based on combinations of parallel linear reservoirs (PLR model), distribution by the basin, and tip-out into its drainage network configured using a digital terrain model (DTM). This PLR model allows simulation of the different actual reservoirs of the basin, including the snow and the contribution due to its melting which, in the model, depends on the temperature. The PLR model also allows for a water budget of the episode where, in addition to the effective rainfall contribution, the water that comes from the thaw is taken into account. The PLR model also allows determination of the amount of water that exists in the basin before and after the episode, data of great interest. When comparing the simulations with and without taking into account the thawing process, it is evident that the intervention of the snow reservoir has been decisive in causing a flood to occur.

A Method to Calculate Porosity of Loess Based SEM and its Application

2012 ◽  
Vol 256-259 ◽  
pp. 179-182
Author(s):  
Peng Ran Song ◽  
Chang Ming Wang
Keyword(s):  
Three Dimensional ◽  
Digital Terrain Model ◽  
Sem Images ◽  
Preparation Methods ◽  
Terrain Model ◽  
Double Peaks ◽  
Digital Terrain ◽  
Structure Changes ◽  
Before And After ◽  
Large Distribution

Research the structure changes before and after collapsible experiment of loess microstructure. Using artificial preparation methods prepared different moisture samples of Liaoxi loess. Do collapsible test and Scanning electron microscope test with the prepared samples. According to Digital Terrain Model theory, three-dimensional porosities were calculated based on gray scale information from the SEM images extracted by MATLAB. The results are shown following as: the microstructure of loess samples is getting dense, the average number of pore of samples obviously increases and the pore area decreases after the sample is collapsed. The distribution before and after the collapsibility of gray value has certain regularity. The before one has double peaks, large distribution. The after one has single peak, concentrate distribution and meets normal distribution.

scholarly journals ACCURACY ANALYSIS OF MEASURING CLOSE-RANGE IMAGE POINTS USING MANUAL AND STEREO MODES

2013 ◽  
Vol 39 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Jūratė Sužiedelytė-Visockienė
Keyword(s):  
3D Model ◽  
Digital Terrain Model ◽  
Image Point ◽  
Range Image ◽  
Control Points ◽  
Image Transformation ◽  
Terrain Model ◽  
Digital Terrain ◽  
Close Range ◽  
Manual Mode

The performed investigations are aimed at estimating the accuracy of image processing using different image point measurements. For this purpose, digital close-range images were processed applying photogrammetric software PhotoMod. The measurements have been made employing two methods: stereo and manual mode. Two or more overlapping images are matched when control and tie points are estimated. The images of two objects have been taken for experimental investigation. Control points and tie points were measured switching either to stereo or manual mode applying the required software. The control points of the first object are distributed on the surface of a smooth facade and on the surface of different (a few) levels. The process of image matching includes the calculation of the correlation coefficient, vertical parallax residuals and the root mean square of the object. Following image transformation (adjustment processes) to the created 3D model, the accuracy of the measured points is determined. All these values show the precision of close-range photogrammetric processes. Such accuracy satisfies requirements for creating a proper digital terrain model and orthophoto generation.

Aerial thermography from low-cost UAV for the generation of thermographic digital terrain models

2015 ◽  
Vol 23 (1) ◽  
Author(s):  
S. Lagüela ◽  
L. Díaz−Vilariño ◽  
D. Roca ◽  
H. Lorenzo
Keyword(s):  
Low Cost ◽  
Digital Terrain Model ◽  
Thermal Response ◽  
Energy Performance ◽  
Medium Size ◽  
Heat Islands ◽  
Terrain Model ◽  
Digital Terrain ◽  
Terrain Models ◽  
Aerial Vehicle

AbstractAerial thermography is performed from a low−cost aerial vehicle, copter type, for the acquisition of data of medium−size areas, such as neighbourhoods, districts or small villages. Thermographic images are registered in a mosaic subsequently used for the generation of a thermographic digital terrain model (DTM). The thermographic DTM can be used with several purposes, from classification of land uses according to their thermal response to the evaluation of the building prints as a function of their energy performance, land and water management. In the particular case of buildings, apart from their individual evaluation and roof inspection, the availability of thermographic information on a DTM allows for the spatial contextualization of the buildings themselves and the general study of the surrounding area for the detection of global effects such as heat islands.

scholarly journals DTM GENERATION WITH UAV BASED PHOTOGRAMMETRIC POINT CLOUD

2017 ◽  
Vol XLII-4/W6 ◽  
pp. 77-79 ◽  
Author(s):  
N. Polat ◽  
M. Uysal
Keyword(s):  
Low Cost ◽  
Laser Scanner ◽  
Digital Camera ◽  
Digital Terrain Model ◽  
Field Work ◽  
Generation Process ◽  
Control Points ◽  
Terrain Model ◽  
Digital Terrain ◽  
Ground Control Points

Nowadays Unmanned Aerial Vehicles (UAVs) are widely used in many applications for different purposes. Their benefits however are not entirely detected due to the integration capabilities of other equipment such as; digital camera, GPS, or laser scanner. The main scope of this paper is evaluating performance of cameras integrated UAV for geomatic applications by the way of Digital Terrain Model (DTM) generation in a small area. In this purpose, 7 ground control points are surveyed with RTK and 420 photographs are captured. Over 30 million georeferenced points were used in DTM generation process. Accuracy of the DTM was evaluated with 5 check points. The root mean square error is calculated as 17.1&amp;thinsp;cm for an altitude of 100 m. Besides, a LiDAR derived DTM is used as reference in order to calculate correlation. The UAV based DTM has o 94.5&amp;thinsp;% correlation with reference DTM. Outcomes of the study show that it is possible to use the UAV Photogrammetry data as map producing, surveying, and some other engineering applications with the advantages of low-cost, time conservation, and minimum field work.

scholarly journals The validation of hydrodynamic modelling for 2014 flood in Kuala Krai, Kelantan

2018 ◽  
Vol 250 ◽  
pp. 04005
Author(s):  
Syaza Faiqah Maruti ◽  
Shahabuddin Amerudin ◽  
Wan Hazli Wan Kadir ◽  
Zainab Mohamed Yusof
Keyword(s):  
Cross Sections ◽  
Digital Terrain Model ◽  
Shuttle Radar Topography Mission ◽  
Roughness Coefficient ◽  
Hydrodynamic Modelling ◽  
Terrain Model ◽  
Flood Depth ◽  
Digital Terrain ◽  
Average Accuracy ◽  
Before And After

Flood catastrophe that struck Kelantan in 2014 has marked as the worst in history. The absence of structural approach such as dam has increased the risks of the flood to this state. In this paper, the simulation of 2014 flood event focuses in Kuala Krai area has been carried out before and after the occurrence of the proposed dams along Galas and Lebir rivers, respectively using hydrodynamic model. The Digital Terrain Model (DTM) from Airborne Light Detection and Ranging (LiDAR) combining with Shuttle Radar Topography Mission (SRTM) data resources have been used for hydrodynamic modelling. The flow hydrograph and water level are generated as input data for initial and boundary conditions. River cross-sections and Manning’s roughness coefficient values that been estimated based on landcover map obtained in 2010 also used in the model. The model produces the outputs of flood depth and velocity. To validate the simulation results, the flood depths were compared against the flood marks depth from field survey at 16 locations collected by researchers from Disaster Prevention Research Institute, Kyoto University, Japan and Department of Irrigation and Drainage (DID). From the validation, it reveals that the average accuracy percentage obtained was about 90% and it can be said that the flood model was acceptable.

scholarly journals Point Cloud Generation from sUAS-Mounted iPhone Imagery: Performance Analysis

2014 ◽  
Vol XL-1 ◽  
pp. 201-205 ◽  
Author(s):  
A. D. Ladai ◽  
J. Miller
Keyword(s):  
Visual Analysis ◽  
Low Cost ◽  
Digital Terrain Model ◽  
Point Clouds ◽  
Quality Analysis ◽  
Main Question ◽  
Terrain Model ◽  
Digital Terrain ◽  
Geodetic Surveying

The rapidly growing use of sUAS technology and fast sensor developments continuously inspire mapping professionals to experiment with low-cost airborne systems. Smartphones has all the sensors used in modern airborne surveying systems, including GPS, IMU, camera, etc. Of course, the performance level of the sensors differs by orders, yet it is intriguing to assess the potential of using inexpensive sensors installed on sUAS systems for topographic applications. This paper focuses on the quality analysis of point clouds generated based on overlapping images acquired by an iPhone 5s mounted on a sUAS platform. To support the investigation, test data was acquired over an area with complex topography and varying vegetation. In addition, extensive ground control, including GCPs and transects were collected with GSP and traditional geodetic surveying methods. The statistical and visual analysis is based on a comparison of the UAS data and reference dataset. The results with the evaluation provide a realistic measure of data acquisition system performance. The paper also gives a recommendation for data processing workflow to achieve the best quality of the final products: the digital terrain model and orthophoto mosaic. <br><br> After a successful data collection the main question is always the reliability and the accuracy of the georeferenced data.

scholarly journals Digital Terrain Models Generated with Low-Cost UAV Photogrammetry: Methodology and Accuracy

2021 ◽  
Vol 10 (5) ◽  
pp. 285
Author(s):  
Sergio Iván Jiménez-Jiménez ◽  
Waldo Ojeda-Bustamante ◽  
Mariana Marcial-Pablo ◽  
Juan Enciso
Keyword(s):  
Land Surface ◽  
Survey Methods ◽  
Low Cost ◽  
Digital Terrain Model ◽  
High Accuracy ◽  
Digital Cameras ◽  
Ground Sample ◽  
Terrain Model ◽  
Digital Terrain ◽  
Dense Point

Digital terrain model (DTM) generation is essential to recreating terrain morphology once the external elements are removed. Traditional survey methods are still used to collect accurate geographic data on the land surface. Given the emergence of unmanned aerial vehicles (UAVs) equipped with low-cost digital cameras and better photogrammetric methods for digital mapping, efficient approaches are necessary to allow rapid land surveys with high accuracy. This paper provides a review, complemented with the authors’ experience, regarding the UAV photogrammetric process and field survey parameters for DTM generation using popular commercial photogrammetric software to process images obtained with fixed-wing or multicopter UAVs. We analyzed the quality and accuracy of the DTMs based on four categories: (i) the UAV system (UAV platforms and camera); (ii) flight planning and image acquisition (flight altitude, image overlap, UAV speed, orientation of the flight line, camera configuration, and georeferencing); (iii) photogrammetric DTM generation (software, image alignment, dense point cloud generation, and ground filtering); (iv) geomorphology and land use/cover. For flat terrain, UAV photogrammetry provided a horizontal root mean square error (RMSE) between 1 to 3 × the ground sample distance (GSD) and a vertical RMSE between 1 to 4.5 × GSD, and, for complex topography, a horizontal RMSE between 1 to 7 × GSD and a vertical RMSE between 1.5 to 5 × GSD. Finally, we stress that UAV photogrammetry can provide DTMs with high accuracy when the photogrammetric process variables are optimized.

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