scholarly journals Accuracy Assessment of Post-processing Kinematic Georeferencing Based on Real-time Kinematic Unmanned Aerial Vehicle and Structure-from-motion Photogrammetry: Topographic Measurements of a Riverbed in a Small Watershed with a Check Dam

2021 ◽  
Author(s):  
Masato Hayamizu ◽  
Yasutaka Nakata
Keyword(s):  
Structure From Motion ◽  
Working Time ◽  
Surface Model ◽  
Digital Surface Model ◽  
Check Dam ◽  
Post Processing ◽  
Small Watershed ◽  
Total Station ◽  
Vertical Error ◽  
Aerial Vehicle

<p><a>To obtain an accurate digital surface model of the small watershed topography of a forested area while reducing time and labor costs, we used a consumer-grade unmanned aerial vehicle (UAV) with a build-in real-time kinematic global navigation satellite system. The applicability of structure-from-motion (SfM) multi-view stereo processing with post-processing kinematic (PPK) correction of the positional coordinate data (the UAV-PPK-SfM method) was tested. Nine verification points were set up in a small (0.5 km<sup>2</sup>) watershed, based on a check dam in the headwaters of a forest area. The location information of the verification points extracted from the digital surface model acquired by UAV-PPK-SfM and the overall working time were compared with the corresponding location information and working time of a traditional field survey using a total station. The results showed that the vertical error between the total station and each verification point at an altitude of 150 m ranged from 0.006 to 0.181 m. The working time of the UAV-PK-SfM survey was 10 % of that of the total station survey (30 min). The UAV-PPK-SfM workflow proposed in this study shows that wide-area, non-destructive topographic surveying, including fluvial geomorphological mapping, is possible with a vertical error of ±0.2 m in small watersheds (<0.5 km<sup>2</sup>). This method will be useful for rapid topographic surveying in inaccessible areas during disasters, such as monitoring debris flow at check dam sites, and for efficient topographic mapping of steep valleys in forested areas where the positioning of ground control points is a laborious task.</a></p>

scholarly journals Accuracy Assessment of Post-processing Kinematic Georeferencing Based on Real-time Kinematic Unmanned Aerial Vehicle and Structure-from-motion Photogrammetry: Topographic Measurements of a Riverbed in a Small Watershed with a Check Dam

2021 ◽  
Author(s):  
Masato Hayamizu ◽  
Yasutaka Nakata
Keyword(s):  
Structure From Motion ◽  
Working Time ◽  
Surface Model ◽  
Digital Surface Model ◽  
Check Dam ◽  
Post Processing ◽  
Small Watershed ◽  
Total Station ◽  
Vertical Error ◽  
Aerial Vehicle

<p><a>To obtain an accurate digital surface model of the small watershed topography of a forested area while reducing time and labor costs, we used a consumer-grade unmanned aerial vehicle (UAV) with a build-in real-time kinematic global navigation satellite system. The applicability of structure-from-motion (SfM) multi-view stereo processing with post-processing kinematic (PPK) correction of the positional coordinate data (the UAV-PPK-SfM method) was tested. Nine verification points were set up in a small (0.5 km<sup>2</sup>) watershed, based on a check dam in the headwaters of a forest area. The location information of the verification points extracted from the digital surface model acquired by UAV-PPK-SfM and the overall working time were compared with the corresponding location information and working time of a traditional field survey using a total station. The results showed that the vertical error between the total station and each verification point at an altitude of 150 m ranged from 0.006 to 0.181 m. The working time of the UAV-PK-SfM survey was 10 % of that of the total station survey (30 min). The UAV-PPK-SfM workflow proposed in this study shows that wide-area, non-destructive topographic surveying, including fluvial geomorphological mapping, is possible with a vertical error of ±0.2 m in small watersheds (<0.5 km<sup>2</sup>). This method will be useful for rapid topographic surveying in inaccessible areas during disasters, such as monitoring debris flow at check dam sites, and for efficient topographic mapping of steep valleys in forested areas where the positioning of ground control points is a laborious task.</a></p>

Evaluation of various setups of hydraulic structures in wild creek by River Flow2D

2020 ◽  
Author(s):  
Chin-Hsiang Tu ◽  
Hung-Pin Huang
Keyword(s):  
Unmanned Aerial Vehicle ◽  
River Flow ◽  
Rainfall Data ◽  
Hydraulic Structures ◽  
Surface Model ◽  
Digital Surface Model ◽  
Check Dam ◽  
Aerial Photos ◽  
Aerial Vehicle ◽  
Movable Bed

&lt;p&gt;In Taiwan, the hydraulic structures of groundsill, check dam and embankment are frequently used in wild creek in order to prevent longitudinal and lateral scour. The benefit of these structures could not be numerically evaluated before construction without movable bed computational software. In recent years, the downstream scour-and-fill of hydraulic structures in wild creek could be carried out by software of River Flow 2D. This study used this software to evaluate the various setups of hydraulic structures in Jianshi, Hsinchu. Before carrying out software, the unmanned aerial vehicle (UAV) was operated to capture aerial photos of watershed. Then, the digital surface model (DSM) and orthomosaic photos were produced by Pix4Dmapper. Because most of wild creeks have no vegetation on their own creek bed, the DTM could be replaced by DSM. Associated with the various setups of hydraulic structures, Global mapper, QGIS and designed rainfall data, the software of River Flow 2D could give the downstream scour-and-fill of various setups of hydraulic structures. And, the convenient setup could be selected after evaluating the various setups of hydraulic structures.&lt;/p&gt;

Combined aerial and ground-based Structure-from-Motion modelling for a vertical rock wall face to estimate volume of failure

2020 ◽  
Author(s):  
Helge Smebye
Keyword(s):  
High Resolution ◽  
Structure From Motion ◽  
Software Package ◽  
Standoff Distance ◽  
Ground Control ◽  
Surface Model ◽  
Digital Surface Model ◽  
Failure Model ◽  
Volume Estimate ◽  
Rock Wall

&lt;p&gt;Combined aerial and ground-based Structure-from-Motion modelling for a vertical rock wall face to estimate volume of failure&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Helge C. Smebye,&lt;sup&gt;a,* &lt;/sup&gt;Sean E. Salazar,&lt;sup&gt;a&lt;/sup&gt; Asgeir O. K. Lysdahl,&lt;sup&gt;a&lt;/sup&gt;&lt;/p&gt;&lt;p&gt;aNorwegian Geotechnical Institute, Sognsveien 72, 0855 Oslo, Norway&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Abstract&lt;/strong&gt;. &amp;#160;The A rock wall failure occurred along a major highway in south-eastern Norway, shutting down two lanes of traffic for an extended period of time while the road authority inspected and repaired the wall. It was desired to have a high-resolution digital surface model along a 215-m long section of the 34-m tall vertical rock wall that included the failure zone.&lt;/p&gt;&lt;p&gt;A Structure-from-Motion (SfM)-based methodology was selected to achieve the desired resolution on the rock wall face, as well as below the foot and above the head of the wall. Due to the proximity of the wall face to the remaining open lanes of traffic, it was not possible to survey the face of the wall using a remotely piloted aircraft system (RPAS). Therefore, a combined platform photogrammetric surveying technique was employed to ensure optimal photographic coverage and to generate the best possible model. Ground control points (GCP) were distributed and surveyed along the bottom and top of the wall and an RPAS was flown manually over the head of the wall to capture downward facing (nadir) images. A lift crane was also employed to capture images from elevations varying between 20&amp;#8211;30 meters with a standoff distance of 15 meters from the wall. Finally, ground-based images were captured using a camera equipped with real-time GNSS from the top of the opposite rock wall (across the highway) with standoff distance of approximately 65 meters.&lt;/p&gt;&lt;p&gt;In total, over 800 images were ingested into a commercial SfM software package. The bundle adjustments were assisted by the GNSS-equipped camera locations and the surveyed GCP were imported to georeference the resulting model. The dense point cloud product was exported to a separate meshing software package for comparison with a second dense surface model that was derived from pre-existing images of the as-built condition of same rock wall face (prior to failure). By subtracting the post-failure model from the pre-failure model, a volume estimate of the material, that was mobilized during the failure, was determined.&lt;/p&gt;&lt;p&gt;The utility of the multi-platform survey technique was demonstrated. The combination of aerial and ground-based photographic surveying techniques provided optimal photographic coverage of the entire length of the rock wall to successfully derive high-resolution surface models and volume estimates.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords&lt;/strong&gt;: Structure-from-Motion, photogrammetry, digital surface model, natural hazards, ground control.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;*&lt;/strong&gt;Helge C. Smebye, E-mail: [email protected]&lt;/p&gt;

STRUCTURE-FROM-MOTION PHOTOGRAMMETRY TECHNIQUES AND DIGITAL SURFACE MODEL CREATION FOR GEOSCIENCE APPLICATIONS

2017 ◽  
Author(s):  
Brian M. Webb ◽  
◽  
Jason D. McClaughry ◽  
Robert Hairston-Porter ◽  
Ian P. Madin
Keyword(s):  
Structure From Motion ◽  
Surface Model ◽  
Digital Surface Model

scholarly journals UAV Application for Landslide Mapping in Kuningan Regency, West Java

2019 ◽  
Vol 125 ◽  
pp. 03011 ◽  
Author(s):  
Humam Abdurrasyid Afif ◽  
Rokhmatuloh ◽  
Ratna Saraswati ◽  
Revi Hernina
Keyword(s):  
High Rate ◽  
Surface Model ◽  
Digital Surface Model ◽  
Landslide Area ◽  
West Java ◽  
Factors Affecting ◽  
Study Results ◽  
Aerial Vehicle ◽  
Landslide Mapping ◽  
Cracked Soil

Kuningan Regency is one of the districts in West Java Province with a high rate of landslide events, especially in the southern part where its hilly landscape is dominated with a steep slope. Due to its vulnerability because of cracked soil after the landslide events, landslide locations in Kuningan Regency might only be safe if surveyed using the unmanned aerial vehicle (UAV). Therefore, in this study, DJI Phantom 4 Pro was flown to capture images of landslide locations with a 10 cm spatial resolution. Image processing was conducted to generate Orthophoto and Digital Surface Model (DSM) to give information about the direction and area of landslides. Two sub-districts where landslides occurred, namely Darma and Selajambe, were chosen for landslide mapping using UAV. Results show that in Darma Sub-district, the landslide area is approximately 7,026 m2, while in Selajambe Sub-district is around 8,699 m2. The study results are very useful to analyze the factors affecting landslide events such as slope.

scholarly journals Accuracy assessment of open - pit mine’s digital surface models generated using photos captured by Unmanned Aerial Vehicles in the post - processing kinematic mode

2021 ◽  
Vol 62 (4) ◽  
pp. 38-47
Author(s):  
Long Quoc Nguyen ◽  
Keyword(s):  
Accuracy Assessment ◽  
Open Pit ◽  
Ground Control ◽  
Surface Model ◽  
Control Points ◽  
Post Processing ◽  
Ground Control Points ◽  
Satellite Positioning ◽  
Surface Models ◽  
Aerial Vehicle

To evaluate the accuracy of the digital surface model (DSM) of an open-pit mine produced using photos captured by the unmanned aerial vehicle equipped with the post-processing dynamic satellite positioning technology (UAV/PPK), a DSM model of the Deo Nai open-pit coal mine was built in two cases: (1) only using images taken from UAV/PPK and (2) using images taken from UAV/PPK and ground control points (GCPs). These DSMs are evaluated in two ways: using checkpoints (CPs) and comparing the entire generated DSM with the DSM established by the electronic total station. The obtained results show that if using CPs, in case 1, the errors in horizontal and vertical dimension were 6.8 and 34.3 cm, respectively. When using two or more GCPs (case 2), the horizontal and vertical errors are at the centimetre-level (4.5 cm and 4.7 cm); if using the DSM comparison, the same accuracy as case 2 was also obtained.

scholarly journals Accuracy of DSM By Using Unmanned Aerial Vehicles on the Downstream of Welang Riverbank, District of Pasuruan, Jawa Timur

UKaRsT ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 49
Author(s):  
Dian Wahyu Khaulan ◽  
Entin Hidayah ◽  
Gusfan Halik
Keyword(s):  
High Resolution ◽  
Vertical Direction ◽  
Sufficient Accuracy ◽  
Ground Control ◽  
Surface Model ◽  
Control Points ◽  
Digital Surface Model ◽  
Ground Control Points ◽  
Aerial Vehicle ◽  
Topography Data

The Digital Surface Model (DSM) is commonly used in studies on flood map modeling. The lack of accurate, high-resolution topography data has hindered flood modeling. The use of the Unmanned Aerial Vehicle (UAV) can help data acquisition with sufficient accuracy. This research aims to provide high-resolution DSM-generated maps by Ground Control Points (GCPs) settings. Improvement of the model's accuracy was pursued by distributing 20 GCPs along the edges of the study area. Agrisoft software was used to generate the DSM. The generated DSM can be used for various planning purposes. The model's accuracy is measured in Root Mean Square Error (RMSE) based on the generated DSM. The RMSE values are 0.488 m for x-coordinates and y-coordinates (horizontal direction) and 0.161 m for z-coordinates (vertical direction).

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