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.

scholarly journals Photogrammetric surveying forests and woodlands with UAVs: techniques for automatic removal of vegetation and digital terrain model production for hydrological applications

2019 ◽  
Vol 7 (1) ◽  
pp. 1-20
Author(s):  
Fotis Giagkas ◽  
Petros Patias ◽  
Charalampos Georgiadis
Keyword(s):  
Vegetation Type ◽  
Digital Terrain Model ◽  
Point Clouds ◽  
Aerial Images ◽  
Surface Model ◽  
Terrain Model ◽  
Vegetation Height ◽  
Digital Terrain ◽  
Dense Point ◽  
Height Model

The purpose of this study is the photogrammetric survey of a forested area using unmanned aerial vehicles (UAV), and the estimation of the digital terrain model (DTM) of the area, based on the photogrammetrically produced digital surface model (DSM). Furthermore, through the classification of the height difference between a DSM and a DTM, a vegetation height model is estimated, and a vegetation type map is produced. Finally, the generated DTM was used in a hydrological analysis study to determine its suitability compared to the usage of the DSM. The selected study area was the forest of Seih-Sou (Thessaloniki). The DTM extraction methodology applies classification and filtering of point clouds, and aims to produce a surface model including only terrain points (DTM). The method yielded a DTM that functioned satisfactorily as a basis for the hydrological analysis. Also, by classifying the DSM–DTM difference, a vegetation height model was generated. For the photogrammetric survey, 495 aerial images were used, taken by a UAV from a height of ∼200 m. A total of 44 ground control points were measured with an accuracy of 5 cm. The accuracy of the aerial triangulation was approximately 13 cm. The produced dense point cloud, counted 146 593 725 points.

scholarly journals Evaluation of GIS techniques in digital terrain model with temporal data: an approach based in the slope of the land surface

2015 ◽  
Vol 11 (1) ◽  
Author(s):  
Luiz Gilberto Bertotti ◽  
Mauricio Camargo Filho ◽  
Marcos Aurélio Pelegrina ◽  
Marquiana Freitas Vilas Boas Gomes ◽  
Bruno Henrique Costa Toledo ◽  
...  
Keyword(s):  
Land Surface ◽  
Digital Terrain Model ◽  
Temporal Data ◽  
Terrain Model ◽  
Gis Techniques ◽  
Digital Terrain

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 EVALUATING STEREO DTM QUALITY AT JEZERO CRATER, MARS WITH HRSC, CTX, AND HIRISE IMAGES

2020 ◽  
Vol XLIII-B3-2020 ◽  
pp. 1129-1136
Author(s):  
R. L. Kirk ◽  
R. L. Fergason ◽  
B. Redding ◽  
D. Galuszka ◽  
E. Smith ◽  
...  
Keyword(s):  
High Resolution ◽  
Digital Terrain Model ◽  
Landing Site ◽  
Horizontal Resolution ◽  
Ground Sample ◽  
Gale Crater ◽  
Terrain Model ◽  
Digital Terrain ◽  
Spatial Registration ◽  
Imaging Science

Abstract. We have used a high-precision, high-resolution digital terrain model (DTM) of the NASA Mars 2020 rover Perseverance landing site in Jezero crater based on mosaicked images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (MRO HiRISE) camera as a reference dataset to evaluate DTMs based on Mars Express High Resolution Stereo Camera (MEX HRSC) and MRO Context camera (CTX) images. Results are consistent with our earlier HRSC-HiRISE comparisons at the Mars Science Laboratory (MSL) Curiosity landing site in Gale crater, confirming that those results were not compromised by the small area compared and potential problems with spatial registration. Specifically, height errors are on the order of half a pixel and correspond to an image matching error of 0.2–0.3 pixel but estimates of horizontal resolution are 10–20 pixels. Products from the HRSC team pipeline at DLR are smoother but more precise vertically than those produced by using the commercial stereo package SOCET SET®. The DLR products are also homogenous in quality, whereas the SOCET products are less smoothed and have higher errors in rougher terrain. Despite this weak variation, our results are consistent with a rule of thumb of 0.2–0.3 pixel matching precision based on many prior studies. Horizontal resolution is significantly coarser than the DTM ground sample distance (GSD), which is typically 3–5 pixels.

scholarly journals Digital Modeling Phenomenon Of Surface Ground Movement

2016 ◽  
Vol 73 (2) ◽  
pp. 342
Author(s):  
Ioan Voina ◽  
Maricel Palamariu ◽  
Iohan Neuner ◽  
Tudor Salagean ◽  
Dumitru Onose ◽  
...  
Keyword(s):  
Land Surface ◽  
Interpolation Method ◽  
Digital Terrain Model ◽  
Industrial Applications ◽  
Ground Movement ◽  
Terrain Model ◽  
Software Applications ◽  
Specialized Software ◽  
Digital Terrain ◽  
Work Area

With the development of specialized software applications it was possible to approach and resolve complex problems concerning automating and process optimization for which are being used field data. Computerized representation of the shape and dimensions of the Earth requires a detailed mathematical modeling, known as "digital terrain model". The paper aims to present the digital terrain model of Vulcan mining, Hunedoara County, Romania. Modeling consists of a set of mathematical equations that define in detail the surface of Earth and has an approximate surface rigorously and mathematical, that calculated the land area. Therefore, the digital terrain model means a digital representation of the earth's surface through a mathematical model that approximates the land surface modeling, which can be used in various civil and industrial applications in. To achieve the digital terrain model of data recorded using linear and nonlinear interpolation method based on point survey which highlights the natural surface studied. Given the complexity of this work it is absolutely necessary to know in detail of all topographic elements of work area, without the actions to be undertaken to project and manipulate would not be possible. To achieve digital terrain model, within a specialized software were set appropriate parameters required to achieve this case study. After performing all steps we obtained digital terrain model of Vulcan Mine. Digital terrain model is the complex product, which has characteristics that are equivalent to the specialists that use satellite images and information stored in a digital model, this is easier to use.

scholarly journals Effects of Structure from Motion Data Density, Interpolation Method and Grid Size on Micro Topography Digital Terrain Model Accuracy

2019 ◽  
Author(s):  
Francisco Agüera-Vega ◽  
Marta Agüera-Puntas ◽  
Francesco Mancini ◽  
Patricio Martínez-Carricondo ◽  
Fernando Carvajal-Ramírez
Keyword(s):  
Structure From Motion ◽  
Point Cloud ◽  
Interpolation Method ◽  
Digital Terrain Model ◽  
Grid Size ◽  
Ground Sample ◽  
Terrain Model ◽  
Digital Terrain ◽  
Cloud Density ◽  
Sample Distance

The objective of this study is to evaluate the effects of the 3D point cloud density derived from unmanned aerial vehicle (UAV) photogrammetry and structure from motion (SfM) and multi-view stereopsis (MVS) techniques, the interpolation method for generating a digital terrain model (DTM), and the resolution (grid size) of the derived DTM on the accuracy of estimated heights in small areas, where a very accurate high spatial resolution is required. A UAV-photogrammetry project was carried out on a bare soil of 13 × 13 m with a rotatory wing UAV at 10 m flight altitude (equivalent ground sample distance = 0.4 cm). The 3D point cloud was derived, and five sample replications representing 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80 and 90% of the original cloud were extracted to analyze the effect of cloud density on DTM accuracy. For each of these samples, DTMs were derived using four different interpolation methods (Inverse Distance Weighted (IDW), Multiquadric Radial Basis Function (MRBF), Kriging (KR), and Triangulation with Linear Interpolation (TLI)) and 15 DTM grid size (GS) values (20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.67, 0.5, and 0.4 cm). Then, 675 DTMs were analyzed. The results showed, for each interpolation method and each density, an optimal GS value (most of the cases equal to 1 cm) for which the Root Mean Square Error (RMSE) is minimum. IDW was the interpolator which yielded best accuracies for all combination of densities and GS. Its RMSE, considering the raw cloud, was 1.054 cm. The RMSE increased 3% when a point cloud with 80% extracted from the raw cloud was used to generate the DTM. When the point cloud included the 40% of the raw cloud, RMSE increased 5%. For densities lower than 15%, RMSE increased exponentially (45% for 1% of raw cloud). The grid size minimizing RMSE for densities of 20% or higher was 1 cm, which represents 2.5 times the ground sample distance of the pictures used for developing the photogrammetry project.

Automated method of а topographic plan creation based on survey from a drone

2018 ◽  
Vol 939 (9) ◽  
pp. 30-36 ◽  
Author(s):  
D.V. Beregovoi ◽  
M.G. Mustafin
Keyword(s):  
Digital Terrain Model ◽  
Field Work ◽  
Optimal Number ◽  
Reference Points ◽  
Surface Model ◽  
Speed Increase ◽  
Terrain Model ◽  
Digital Terrain ◽  
Automated Method ◽  
Dense Point

The authors show an automated method for performing the main stages of creating a topographic plan. The optimal number and location of the reference points for creation a digital terrain model using drones is determined. The necessary components of a multi-rotor helicopter are described. They are required for lifting the camera into the air and increasing the duration of the flight. On the basis of the research, a significant speed increase of the field work was achieved using effective satellite and linear-angular measurements for determination of the reference points’ coordinates and productive survey from anunmanned aerial vehicle. Algorithms forconstructing an orthophoto and a digital terrain model as well as automated filtering of the resulting dense point cloud for creating a digital surface model are presented. The high-accurate modification of the OBIA (Object-Based Image Analysis) algorithm for classification of ground objects is determined. At the end of the article, the algorithm for automated vectorization of the raster classification using the ArcGIS geoinformation software and converting of the received objects to convention for creating an electronic topographic plan is given.

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 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 % 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.

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.

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