scholarly journals Ground-Control Networks for Image Based Surface Reconstruction: An Investigation of Optimum Survey Designs Using UAV Derived Imagery and Structure-from-Motion Photogrammetry

2016 ◽  
Vol 8 (9) ◽  
pp. 786 ◽  
Author(s):  
Toby Tonkin ◽  
Nicholas Midgley
Keyword(s):  
Surface Reconstruction ◽  
Structure From Motion ◽  
Ground Control ◽  
Control Networks ◽  
Survey Designs

scholarly journals PRECISION POTENTIAL OF UNDERWATER NETWORKS FOR ARCHAEOLOGICAL EXCAVATION THROUGH TRILATERATION AND PHOTOGRAMMETRY

2019 ◽  
Vol XLII-2/W10 ◽  
pp. 175-180 ◽  
Author(s):  
D. Skarlatos ◽  
F. Menna ◽  
E. Nocerino ◽  
P. Agrafiotis
Keyword(s):  
Standard Deviation ◽  
Structure From Motion ◽  
Control Point ◽  
Archaeological Site ◽  
3D Models ◽  
Ground Control ◽  
Control Points ◽  
Archaeological Excavation ◽  
Control Networks ◽  
Ground Control Points

<p><strong>Abstract.</strong> Given the rise and wide adoption of Structure from Motion (SfM) and Multi View Stereo (MVS) in underwater archaeology, this paper investigates the optimal option for surveying ground control point networks. Such networks are the essential framework for coregistration of photogrammetric 3D models acquired in different epochs, and consecutive archaeological related study and analysis. Above the water, on land, coordinates of ground control points are determined with geodetic methods and are considered often definitive. Other survey works are then derived from by using those coordinates as fixed (being ground control points coordinates considered of much higher precision). For this reason, equipment of proven precision is used with methods that not only compute the most correct values (according to the least squares principle) but also provide numerical measures of their precisions and reliability. Under the water, there are two options for surveying such control networks: trilateration and photogrammetry, with the former being the choice of the majority of archaeological expeditions so far. It has been adopted because of ease of implementation and under the assumption that it is more reliable and precise than photogrammetry.</p><p>This work aims at investigating the precision of network establishment by both methodologies by comparing them in a typical underwater archaeological site. Photogrammetric data were acquired and analysed, while the trilateration data were simulated under certain assumptions. Direct comparison of standard deviation values of both methodologies reveals a clear advantage of photogrammetry in the vertical (Z) axis and three times better results in horizontal precision.</p>

scholarly journals A New Fast and Low-Cost Photogrammetry Method for the Engineering Characterization of Rock Slopes

2019 ◽  
Vol 11 (11) ◽  
pp. 1267 ◽  
Author(s):  
Francioni ◽  
Simone ◽  
Stead ◽  
Sciarra ◽  
Mataloni ◽  
...  
Keyword(s):  
Structure From Motion ◽  
Engineering Geology ◽  
Survey Methods ◽  
Digital Camera ◽  
3D Models ◽  
Ground Control ◽  
Control Points ◽  
Digital Photogrammetry ◽  
Ground Control Points ◽  
The Creation

Digital photogrammetry (DP) represents one of the most used survey techniques in engineering geology. The availability of new high-resolution digital cameras and photogrammetry software has led to a step-change increase in the quality of engineering and structural geological data that can be collected. In particular, the introduction of the structure from motion methodology has led to a significant increase in the routine uses of photogrammetry in geological and engineering geological practice, making this method of survey easier and more attractive. Using structure from motion methods, the creation of photogrammetric 3D models is now easier and faster, however the use of ground control points to scale/geo-reference the models are still required. This often leads to the necessity of using total stations or Global Positioning System (GPS) for the acquisition of ground control points. Although the integrated use of digital photogrammetry and total station/GPS is now common practice, it is clear that this may not always be practical or economically convenient due to the increase in cost of the survey. To address these issues, this research proposes a new method of utilizing photogrammetry for the creation of georeferenced and scaled 3D models not requiring the use of total stations and GPS. The method is based on the use of an object of known geometry located on the outcrop during the survey. Targets located on such objects are used as ground control points and their coordinates are calculated using a simple geological compass and trigonometric formula or CAD 3D software. We present three different levels of survey using (i) a calibrated digital camera, (ii) a non-calibrated digital camera and (iii) two commercial smartphones. The data obtained using the proposed approach and the three levels of survey methods have been validated against a laser scanning (LS) point cloud. Through this validation we highlight the advantages and limitations of the proposed method, suggesting potential applications in engineering geology.

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;

scholarly journals Microscopic Structure from Motion (SfM) for Microscale 3D Surface Reconstruction

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5599
Author(s):  
Dugan Um ◽  
Sangsoo Lee
Keyword(s):  
Surface Reconstruction ◽  
Structure From Motion ◽  
Imaging Technique ◽  
Confocal Imaging ◽  
Reconstruction Method ◽  
Accuracy Analysis ◽  
Ambient Light ◽  
Solid Objects ◽  
Transparent Objects ◽  
Novel Method

In microscale photogrammetry, the confocal microscopic imaging technique has been the dominant trend. Unlike the confocal imaging mostly for transparent objects, we propose a novel method to construct a 3D shape in microscale for various micro-sized solid objects in a broad spectrµm of applications. Recently, the structure from motion (SfM) demonstrated reliable 3D reconstruction capability for macroscale objects. In this paper, we discuss the results of a novel micro-surface reconstruction method using the Structure from Motion in microscale. The proposed micro SfM technique utilizes the photometric stereovision via microscopic photogrammetry. The main challenges lie in the scanning methodology, ambient light control, and light conditioning for microscale object photography. Experimental results of the microscale SfM, as well as the modeling accuracy analysis of a reconstructed micro-object, are shared in the paper.

scholarly journals Recovering three-dimensional structure from motion with surface reconstruction

1995 ◽  
Vol 35 (1) ◽  
pp. 117-137 ◽  
Author(s):  
Ellen C. Hildreth ◽  
Hiroshi Ando ◽  
Richard A. Andersen ◽  
Stefan Treues
Keyword(s):  
Surface Reconstruction ◽  
Structure From Motion ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure

Airborne Structure-from-Motion modelling for avalanche and debris flow paths in steep terrain with limited ground control

2020 ◽  
Author(s):  
Sean Salazar ◽  
Helge Smebye ◽  
Regula Frauenfelder ◽  
Frank Miller ◽  
Emil Solbakken ◽  
...  
Keyword(s):  
High Resolution ◽  
Debris Flow ◽  
Case Studies ◽  
Structure From Motion ◽  
Ground Control ◽  
Surface Model ◽  
Flight Plan ◽  
Surface Models ◽  
Steep Terrain

&lt;p&gt;The availability of consumer remotely piloted aircraft systems (RPAS) has enabled rapidly deployable airborne surveys for civilian applications. Combined with photogrammetric reconstruction techniques, such as Structure-from-Motion (SfM), it has become increasingly feasible to survey large areas with very high resolution, especially when compared with other airborne or spaceborne surveying techniques. A pair of case studies, using an RPAS-based field surveying technique for establishing baseline surface models in steep terrain, are presented for two different natural hazard applications.&lt;/p&gt;&lt;p&gt;The first case study involved a survey over the entire 1000-m length of a snow-free avalanche path on S&amp;#230;treskarsfjellet in Stryn municipality in Norway. A terrain-aware, multi-battery flight plan was designed to ensure good photographic coverage over the entire avalanche path and 21 ground control points (GCP) were distributed evenly across the path and subsequently surveyed. More than 400 images were collected over a 0.5 km&lt;sup&gt;2&lt;/sup&gt; area, which were processed using a commercial SfM software package. Two digital surface models were reconstructed, each utilizing a different ground control scenario: the first one with the full count of GCP, while the second used only a limited count of GCP, which is more feasible for a repeat survey when avalanche hazard is high. Comparison with data from a pre-existing, airborne LiDAR survey over the avalanche path revealed that the SfM-derived model that utilized only a limited number of GCP diverged significantly from the model that utilized all available GCP. Further differences between the SfM- and LiDAR-derived surface models were observed in areas with very steep slopes and vegetative cover. The same methodology can subsequently be applied during the winter season, after extensive snowfall and/or avalanche events, to deduce relevant avalanche parameters such as snow height, snow distribution and drift, opening of cracks in the snow surface (e.g. for glide avalanches), and avalanche outlines.&lt;/p&gt;&lt;p&gt;The second case study involved a survey over the entire 1000-m length of a debris flow path at &amp;#197;rnes in J&amp;#248;lster, Norway. The &amp;#197;rnes flow, which caused one fatality, was one of the largest of several tens of debris flows that occurred on July 30, 2019. The flows were triggered by an extreme precipitation event around the J&amp;#248;lstravatnet area. Like with the S&amp;#230;treskarsfjellet avalanche path case study, a terrain-aware flight plan was established and 24 GCP were distributed and surveyed along the debris flow path. Over 400 images were collected over a 0.3 km&lt;sup&gt;2&lt;/sup&gt; area, which were used to reconstruct a high-resolution surface model. Like with the avalanche case study, the SfM-derived model was compared with a pre-existing LiDAR survey-derived digital terrain model. Altitude and volume changes, due to the debris flow event, were calculated using GIS analysis tools.&lt;/p&gt;&lt;p&gt;The utility of the RPAS survey technique was demonstrated in both case studies, despite difficult accessibility for ground control. It is suggested that a real-time-kinematic (RTK)-enabled workflow may significantly reduce survey time and increase personnel safety by minimizing the number of required GCP.&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;

scholarly journals OPTIMIZATION OF GROUND CONTROL POINT (GCP) CONFIGURATION FOR UNMANNED AERIAL VEHICLE (UAV) SURVEY USING STRUCTURE FROM MOTION (SFM)

2019 ◽  
Vol XLII-4/W12 ◽  
pp. 167-174 ◽  
Author(s):  
J. K. S. Villanueva ◽  
A. C. Blanco
Keyword(s):  
Structure From Motion ◽  
Reference Data ◽  
Control Point ◽  
Ground Control ◽  
Ground Control Point ◽  
Center Configuration ◽  
Digital Elevation ◽  
Aerial Vehicle ◽  
Elevation Model ◽  
The Impact

<p><strong>Abstract.</strong> This research presents a method in assessing the impact of Ground Control Point (GCP) distribution, quantity, and inter-GCP distances on the output Digital Elevation Model (DEM) by utilizing SfM and GIS. The study was carried out in a quarry site to assess the impacts of these parameters on the accuracy of accurate volumetric measurements UAV derivatives. Based on GCP Root Mean Square Error (RMSE) and surface checkpoint error (SCE), results showed that the best configuration is the evenly distributed GCP set (1.58&amp;thinsp;m average RMSE, 1.30&amp;thinsp;m average SCE). Configurations clumped to edge and distributed to edge follow suit with respective RMSE (SCE) of 2.53&amp;thinsp;m (2.13&amp;thinsp;m) and 3.11&amp;thinsp;m (2.54&amp;thinsp;m). The clumped to center configuration yielded 6.23&amp;thinsp;m RMSE and 4.66&amp;thinsp;m SCE. As the number of GCPs used increase, the RMSE and SCE are observed to decrease consistently for all configurations. Further iteration of the best configuration showed that from RMSE of 4.11&amp;thinsp;m when 4 GCPs are used, there is a drastic decrease to 0.86&amp;thinsp;m once 10 GCPs are used. From that quantity, only centimeter differences can be observed until the full set of 24 GCPs have been used with a 0.012&amp;thinsp;m error. This is reflected in the stockpile measurement when the iteration results are compared to the reference data. The dataset processed with a minimum of 4 GCPs have a 606,991.43&amp;thinsp;m<sup>3</sup> difference, whereas the dataset processed with 23 out of 24 has a 791.12&amp;thinsp;m<sup>3</sup> difference from the reference data. The accuracy of the SfM-based DEM increases with the quantity of the GCPs used with an even distribution.</p>

scholarly journals Mapping snow-depth from manned-aircraft on landscape scales at centimeter resolution using Structure-from-Motion photogrammetry

2015 ◽  
Vol 9 (1) ◽  
pp. 333-381 ◽  
Author(s):  
M. Nolan ◽  
C. F. Larsen ◽  
M. Sturm
Keyword(s):  
Structure From Motion ◽  
Snow Depth ◽  
Digital Camera ◽  
Field Measurements ◽  
Airborne Lidar ◽  
Ground Control ◽  
Barriers To Entry ◽  
Dual Frequency ◽  
Ground Sample ◽  
Landscape Scales

Abstract. Airborne photogrammetry is undergoing a renaissance: lower-cost equipment, more powerful software, and simplified methods have significantly lowered the barriers-to-entry and now allow repeat-mapping of cryospheric dynamics at spatial resolutions and temporal frequencies that were previously too expensive to consider. Here we apply these techniques to the measurement of snow depth from manned aircraft. The main airborne hardware consists of a consumer-grade digital camera coupled to a dual-frequency GPS. The photogrammetric processing is done using a commercially-available implementation of the Structure from Motion (SfM) algorithm. The system hardware and software, exclusive of aircraft, costs less than USD 30 000. The technique creates directly-georeferenced maps without ground control, further reducing costs. To map snow depth, we made digital elevation models (DEMs) during snow-free and snow-covered conditions, then subtracted these to create difference DEMs (dDEMs). We assessed the accuracy (geolocation) and precision (repeatability) of our DEMs through comparisons to ground control points and to time-series of our own DEMs. We validated these assessments through comparisons to DEMs made by airborne lidar and by another photogrammetric system. We empirically determined an accuracy of ± 30 cm and a precision of ± 8 cm (both 95% confidence) for our methods. We then validated our dDEMs against more than 6000 hand-probed snow depth measurements at 3 test areas in Alaska covering a wide-variety of terrain and snow types. These areas ranged from 5 to 40 km2 and had ground sample distances of 6 to 20 cm. We found that depths produced from the dDEMs matched probe depths with a 10 cm standard deviation, and these depth distributions were statistically identical at 95% confidence. Due to the precision of this technique, other real changes on the ground such as frost heave, vegetative compaction by snow, and even footprints become sources of error in the measurement of thin snow packs (< 20 cm). The ability to directly measure such small changes over entire landscapes eliminates the need to extrapolate isolated field measurements. The fact that this mapping can be done at substantially lower costs than current methods may transform the way we approach studying change in the cryosphere.

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