scholarly journals Hardly Accessible Morphological Structures – Geological Mapping and Accuracy Analysis of SfM and TLS Surveying Technologies

2020 ◽  
pp. 479-493
Keyword(s):  
Laser Scanning ◽  
Point Clouds ◽  
Geological Mapping ◽  
High Temporal Resolution ◽  
Remotely Piloted Aircraft ◽  
Close Range ◽  
Mutual Comparison ◽  
Aircraft System ◽  
Map Data

The aim of geological field mapping is to collect and interpret data on the relief of the Earth's surface. From thus created geological maps, we can obtain information about mineral units and their structure – rock and mineral types, their thickness, lithological deposits, faults, folds, fractures, and thus interpret information as they originated over time. However, the accessibility of such structures is affected by various morphological elements – terrain notches, watercourses, but also by vegetation. Simultaneous geodetic and geological mapping could be a solution for surveying hardly accessible morphological structures. Non-contact surveying technologies – terrestrial laser scanning (TLS) and close-range photogrammetry (terrestrial and remotely piloted aircraft system (RPAS) photogrammetry) provide reliable, high-quality and accurate data on the topographic surface with a high temporal resolution, as the spatial accuracy of the measured point can be mXYZ ≤ 10 mm at an imaging distance of about 20 – 30 m. From the measured data, it is possible to generate point clouds, digital terrain models, and orthophoto maps based on automated data processing. However, the disadvantage of photogrammetric imaging is a proportional decrease in accuracy with increasing imaging distance. The accuracy of TLS is not significantly affected by increasing distance. The paper presents a case study of the use and comparison of non-contact surveying technologies and their application for in-situ mapping of hardly accessible geological structures in the area of Spišská Magura (Slovak-Polish border). The results are given for two localities on two outcrops - Jurgów (PL) and Bachledova valley (SK), while analyzing the usability of TLS and RPAS photogrammetry, with and without the use of artificial ground control points (GCP). The paper presents a mutual comparison of all obtained graphical outputs in terms of 1D and 2D quality depending on the type of GCPs used, depending on the terrain and accessibility. The results show that by using photogrammetry when creating map data, in comparison with TLS, we are able to get sufficient accuracy of outputs for in-situ geological mapping.

scholarly journals Fusion of 3D models derived from TLS and image-based techniques for CH enhanced documentation

2014 ◽  
Vol II-5 ◽  
pp. 73-80 ◽  
Author(s):  
P. Bastonero ◽  
E. Donadio ◽  
F. Chiabrando ◽  
A. Spanò
Keyword(s):  
Cultural Heritage ◽  
Laser Scanning ◽  
Point Clouds ◽  
3D Models ◽  
Aerial Survey ◽  
Test Case ◽  
Medieval Architecture ◽  
Relevant Evidence ◽  
Remotely Piloted Aircraft ◽  
Aircraft System

Recognizing the various advantages offered by 3D new metric survey technologies in the Cultural Heritage documentation phase, this paper presents some tests of 3D model generation, using different methods, and their possible fusion. With the aim to define potentialities and problems deriving from integration or fusion of metric data acquired with different survey techniques, the elected test case is an outstanding Cultural Heritage item, presenting both widespread and specific complexities connected to the conservation of historical buildings. The site is the Staffarda Abbey, the most relevant evidence of medieval architecture in Piedmont. This application faced one of the most topical architectural issues consisting in the opportunity to study and analyze an object as a whole, from twice location of acquisition sensors, both the terrestrial and the aerial one. <br><br> In particular, the work consists in the evaluation of chances deriving from a simple union or from the fusion of different 3D cloudmodels of the abbey, achieved by multi-sensor techniques. The aerial survey is based on a photogrammetric RPAS (Remotely piloted aircraft system) flight while the terrestrial acquisition have been fulfilled by laser scanning survey. Both techniques allowed to extract and process different point clouds and to generate consequent 3D continuous models which are characterized by different scale, that is to say different resolutions and diverse contents of details and precisions. Starting from these models, the proposed process, applied to a sample area of the building, aimed to test the generation of a unique 3Dmodel thorough a fusion of different sensor point clouds. <br><br> Surely, the describing potential and the metric and thematic gains feasible by the final model exceeded those offered by the two detached models.

Optical methods and wireless sensors for monitoring of bridges

2019 ◽  
Author(s):  
Cosmin Popescu ◽  
Björn Täljsten ◽  
Thomas Blanksvärd ◽  
Gabriel Sas ◽  
Alexander Jimenez ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Crack Opening ◽  
Point Clouds ◽  
Base Station ◽  
Optical Methods ◽  
Railway Bridges ◽  
Wireless Monitoring ◽  
Building Information ◽  
Close Range ◽  
Traffic Disturbance

<p>Six railway bridges have been scanned using infrared scanning (IR), close range photogrammetry (CRP) and terrestrial laser scanning (TRS) to reconstruct point clouds and evaluate the potential of the technologies for building information modelling (BIM) and assessment purposes. The results may also help to improve bridge inspection routines. This is done by evaluating the accuracy and quality of the point clouds, time consumption, safety and traffic disturbance.</p><p>Wireless Monitoring has been used in a demonstration project in Sweden. It consists of a base station and nodes. The base station receives signals from the node antennas and transmits the signals to the cloud. The nodes are equipped with strain gauges, crack opening devices, temperature sensors or other suitable sensors for the investigation purpose. Results from the methods and conclusions regarding further use will be presented.</p>

Application of close range photogrammetry in structural health monitoring by processing generated point cloud datasets

2021 ◽  
Author(s):  
Ali Mirzazade ◽  
Cosmin Popescu ◽  
Thomas Blanksvärd ◽  
Björn Täljsten
Keyword(s):  
Health Monitoring ◽  
Point Cloud ◽  
Laser Scanning ◽  
Point Clouds ◽  
Optical Data ◽  
Small Scale ◽  
Relevant Parameter ◽  
Bridge Inspection ◽  
Close Range Photogrammetry ◽  
Close Range

<p>In bridge inspection, vertical displacement is a relevant parameter for both short and long-term health monitoring. Assessing change in deflections could also simplify the assessment work for inspectors. Recent developments in digital camera technology and photogrammetry software enables point cloud with colour information (RGB values) to be generated. Thus, close range photogrammetry offers the potential of monitoring big and small-scale damages by point clouds. The current paper aims to monitor geometrical deviations in Pahtajokk Bridge, Northern Sweden, using an optical data acquisition technique. The bridge in this study is scanned two times by almost one year a part. After point cloud generation the datasets were compared to detect geometrical deviations. First scanning was carried out by both close range photogrammetry (CRP) and terrestrial laser scanning (TLS), while second scanning was performed by CRP only. Analyzing the results has shown the potential of CRP in bridge inspection.</p>

scholarly journals Combined Use of Terrestrial Laser Scanning and UAV Photogrammetry in Mapping Alpine Terrain

2019 ◽  
Vol 11 (18) ◽  
pp. 2154 ◽  
Author(s):  
Ján Šašak ◽  
Michal Gallay ◽  
Ján Kaňuk ◽  
Jaroslav Hofierka ◽  
Jozef Minár
Keyword(s):  
High Resolution ◽  
Point Cloud ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Point Clouds ◽  
Mutual Orientation ◽  
Close Range Photogrammetry ◽  
Combined Use ◽  
Wide Range ◽  
Close Range

Airborne and terrestrial laser scanning and close-range photogrammetry are frequently used for very high-resolution mapping of land surface. These techniques require a good strategy of mapping to provide full visibility of all areas otherwise the resulting data will contain areas with no data (data shadows). Especially, deglaciated rugged alpine terrain with abundant large boulders, vertical rock faces and polished roche-moutones surfaces complicated by poor accessibility for terrestrial mapping are still a challenge. In this paper, we present a novel methodological approach based on a combined use of terrestrial laser scanning (TLS) and close-range photogrammetry from an unmanned aerial vehicle (UAV) for generating a high-resolution point cloud and digital elevation model (DEM) of a complex alpine terrain. The approach is demonstrated using a small study area in the upper part of a deglaciated valley in the Tatry Mountains, Slovakia. The more accurate TLS point cloud was supplemented by the UAV point cloud in areas with insufficient TLS data coverage. The accuracy of the iterative closest point adjustment of the UAV and TLS point clouds was in the order of several centimeters but standard deviation of the mutual orientation of TLS scans was in the order of millimeters. The generated high-resolution DEM was compared to SRTM DEM, TanDEM-X and national DMR3 DEM products confirming an excellent applicability in a wide range of geomorphologic applications.

scholarly journals TLS and SfM Approach for Bulk Density Determination of Excavated Heterogeneous Raw Materials

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 174 ◽  
Author(s):  
Peter Blistan ◽  
Stanislav Jacko ◽  
Ľudovít Kovanič ◽  
Julián Kondela ◽  
Katarína Pukanská ◽  
...  
Keyword(s):  
Bulk Density ◽  
Laser Scanning ◽  
Large Scale ◽  
Raw Materials ◽  
Terrestrial Laser Scanning ◽  
Mineral Resources ◽  
Point Clouds ◽  
Raw Material

A frequently recurring problem in the extraction of mineral resources (especially heterogeneous mineral resources) is the rapid operative determination of the extracted quantity of raw material in a surface quarry. This paper deals with testing and analyzing the possibility of using unconventional methods such as digital close-range photogrammetry and terrestrial laser scanning in the process of determining the bulk density of raw material under in situ conditions. A model example of a heterogeneous deposit is the perlite deposit Lehôtka pod Brehmi (Slovakia). Classical laboratory methods for determining bulk density were used to verify the results of the in situ method of bulk density determination. Two large-scale samples (probes) with an approximate volume of 7 m3 and 9 m3 were realized in situ. 6 point samples (LITH) were taken for laboratory determination. By terrestrial laser scanning (TLS) measurement from 2 scanning stations, point clouds with approximately 163,000/143,000 points were obtained for each probe. For Structure-from-Motion (SfM) photogrammetry, 49/55 images were acquired for both probes, with final point clouds containing approximately 155,000/141,000 points. Subsequently, the bulk densities of the bulk samples were determined by the calculation from in situ measurements by TLS and SfM photogrammetry. Comparison of results of the field in situ measurements (1841 kg∙m−3) and laboratory measurements (1756 kg∙m−3) showed only a 4.5% difference in results between the two methods for determining the density of heterogeneous raw materials, confirming the accuracy of the used in situ methods. For the determination of the loosening coefficient, the material from both large-scale samples was transferred on a horizontal surface. Their volumes were determined by TLS. The loosening coefficient for the raw material of 1.38 was calculated from the resulting values.

Terrestrial laser scanning and structure-from-motion photogrammetry concordance analysis for describing the surface layer of gravel beds

2019 ◽  
Vol 43 (2) ◽  
pp. 260-281 ◽  
Author(s):  
Andrew J Neverman ◽  
Ian C Fuller ◽  
Jon N Procter ◽  
Russell G Death
Keyword(s):  
Surface Layer ◽  
Structure From Motion ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Point Clouds ◽  
Survey Method ◽  
Gravel Beds ◽  
Non Invasive ◽  
Sampling Biases

Terrestrial laser scanning (TLS) and structure-from-motion photogrammetry (SfMp) offer rapid, non-invasive surveying of in situ gravels. Numerous studies have used the point clouds derived from TLS or SfMp to quantify surface layer characteristics, but direct comparison of the methods for grain-scale analysis has received relatively little attention to date. Comparing equivalent products of different data capture methods is critical as differences in errors and sampling biases between the two methods may produce different outputs, effecting further analysis. The sampling biases and errors related to SfMp and TLS lead to differences in the point clouds produced by each method. The metrics derived from the point clouds are therefore likely to differ, potentially leading to different inputs for entrainment threshold models, different trends in surface layer development being identified and different trajectories for physical processes and habitat quality being predicted. This paper provides a direct comparison between TLS and SfMp surveys of an exposed gravel bar for three different survey periods following inundation and reworking of the bar surface during high flow events. The point clouds derived from the two methods are used to describe changes in the character of the surface layer between bar inundation events, and comparisons are made with descriptions derived from conventional pebble counts. The results found differences in the metrics derived using each method do exist, but the grid resolution used to detrend the surfaces and identify spatial variations in surface layer characteristics had a greater impact than survey method. Further research is required to understand the significance of these variations for quantifying surface texture and structure and for predicting entrainment thresholds and transport rates.

scholarly journals Workflow: From photo-based 3-D reconstruction of remotely piloted aircraft images to a 3-D geological model

Geosphere ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 1393-1408 ◽  
Author(s):  
Reuben J. Hansman ◽  
Uwe Ring
Keyword(s):  
Remote Sensing ◽  
United Arab Emirates ◽  
Low Cost ◽  
Three Dimensional ◽  
Point Clouds ◽  
Geological Mapping ◽  
Geological Model ◽  
Geological Processes ◽  
Aerial Imaging ◽  
Remotely Piloted Aircraft

AbstractGeological field mapping is a vital first step in understanding geological processes. During the 20th century, mapping was revolutionized through advances in remote sensing technology. With the recent availability of low-cost remotely piloted aircraft (RPA), field geologists now routinely carry out aerial imaging without the need to use satellite, helicopter, or airplane systems. RPA photographs are processed by photo-based three-dimensional (3-D) reconstruction software, which uses structure-from-motion and multi-view stereo algorithms to create an ultra-high-resolution, 3-D point cloud of a region or target outcrop. These point clouds are analyzed to extract the orientation of geological structures and strata, and are also used to create digital elevation models and photorealistic 3-D models. However, this technique has only recently been used for structural mapping. Here, we outline a workflow starting with RPA data acquisition, followed by photo-based 3-D reconstruction, and ending with a 3-D geological model. The Jabal Hafit anticline in the United Arab Emirates was selected to demonstrate this workflow. At this anticline, outcrop exposure is excellent and the terrain is challenging to navigate due to areas of high relief. This makes for an ideal RPA mapping site and provides a good indication of how practical this method may be for the field geologist. Results confirm that RPA photo-based 3-D reconstruction mapping is an accurate and cost-efficient remote sensing method for geological mapping.

scholarly journals ONLY IMAGE BASED FOR THE 3D METRIC SURVEY OF GOTHIC STRUCTURES BY USING FRAME CAMERAS AND PANORAMIC CAMERAS

2016 ◽  
Vol XLI-B5 ◽  
pp. 363-370 ◽  
Author(s):  
A. Pérez Ramos ◽  
G. Robleda Prieto
Keyword(s):  
Laser Scanning ◽  
Imaging Techniques ◽  
Laser Scanner ◽  
Point Clouds ◽  
Office Work ◽  
Light Conditions ◽  
External Quality ◽  
Panoramic Cameras ◽  
Dense Point ◽  
Close Range

Indoor Gothic apse provides a complex environment for virtualization using imaging techniques due to its light conditions and architecture. Light entering throw large windows in combination with the apse shape makes difficult to find proper conditions to photo capture for reconstruction purposes. Thus, documentation techniques based on images are usually replaced by scanning techniques inside churches. Nevertheless, the need to use Terrestrial Laser Scanning (TLS) for indoor virtualization means a significant increase in the final surveying cost. So, in most cases, scanning techniques are used to generate dense point clouds. However, many Terrestrial Laser Scanner (TLS) internal cameras are not able to provide colour images or cannot reach the image quality that can be obtained using an external camera. Therefore, external quality images are often used to build high resolution textures of these models. This paper aims to solve the problem posted by virtualizing indoor Gothic churches, making that task more affordable using exclusively techniques base on images. It reviews a previous proposed methodology using a DSRL camera with 18-135 lens commonly used for close range photogrammetry and add another one using a HDR 360° camera with four lenses that makes the task easier and faster in comparison with the previous one. Fieldwork and office-work are simplified. The proposed methodology provides photographs in such a good conditions for building point clouds and textured meshes. Furthermore, the same imaging resources can be used to generate more deliverables without extra time consuming in the field, for instance, immersive virtual tours. In order to verify the usefulness of the method, it has been decided to apply it to the apse since it is considered one of the most complex elements of Gothic churches and it could be extended to the whole building.

scholarly journals DOCUMENTATION OF HISTORICAL UNDERGROUND OBJECT IN SKORKOV VILLAGE WITH SELECTED MEASURING METHODS, DATA ANALYSIS AND VISUALIZATION

2016 ◽  
Vol XLI-B5 ◽  
pp. 251-254
Author(s):  
A. Dlesk
Keyword(s):  
Laser Scanning ◽  
3D Model ◽  
Local Development ◽  
Radar Data ◽  
Surface Model ◽  
Measuring Methods ◽  
Advantages And Disadvantages ◽  
Remotely Piloted Aircraft ◽  
Historical Objects ◽  
Aircraft System

The author analyzes current methods of 3D documentation of historical tunnels in Skorkov village, which lies at the Jizera river, approximately 30 km away from Prague. The area is known as a former military camp from Thirty Years’ War in 17th Century. There is an extensive underground compound with one entrance corridor and two transverse, situated approximately 2 to 5 m under the local development. The object has been partly documented by geodetic polar method, intersection photogrammetry, image-based modelling and laser scanning. Data have been analyzed and methods have been compared. Then the 3D model of object has been created and compound with cadastral data, orthophoto, historical maps and digital surface model which was made by photogrammetric method using remotely piloted aircraft system. Then the measuring has been realized with ground penetrating radar. Data have been analyzed and the result compared with real status. All the data have been combined and visualized into one 3D model. Finally, the discussion about advantages and disadvantages of used measuring methods has been livened up. The tested methodology has been also used for other documentation of historical objects in this area. This project has been created as a part of research at EuroGV. s.r.o. Company lead by Ing. Karel Vach CSc. in cooperation with prof. Dr. Ing. Karel Pavelka from Czech Technical University in Prague and Miloš Gavenda, the renovator.

scholarly journals THE COMBINATION OF THE IMAGE AND RANGE-BASED 3D ACQUISITION IN ARCHAEOLOGICAL AND ARCHITECTURAL RESEARCH IN THE ROYAL CASTLE IN WARSAW

2019 ◽  
Vol XLII-2/W15 ◽  
pp. 177-184
Author(s):  
A. Bocheńska ◽  
J. Markiewicz ◽  
S. Łapiński
Keyword(s):  
Laser Scanning ◽  
Retaining Wall ◽  
Weather Conditions ◽  
Point Clouds ◽  
Sensor Data ◽  
Data Sets ◽  
Multi Temporal ◽  
Close Range ◽  
3D Acquisition ◽  
Architectural Research

<p><strong>Abstract.</strong> The paper presents archaeological and architectural research in the Royal Castle in Warsaw where a combination of image- and range-based 3D acquisition was applied. The area examined included excavations situated inside the Tower and near its outer western wall. The work was carried out at various periods and in different weather conditions. As part of the measurements, laser scanning was performed (with a Z+F 5006h scanner) and a series of close-range images were taken. It was important to integrate the data acquired to create a comprehensive documentation of archaeological excavations. When data was acquired from TLS together with photogrammetric data (in different measurement periods), the points' displacements were controlled and analysed. The process of orienting and processing the terrestrial images included photographs taken during the inventory of the tower (Canon 5D Mark II) and photographs provided by the Castle's employees (Canon PowerShot G5 X). Agisoft PhotoScan software was used to orient and process the terrestrial images, and LupoScan for the TLS data. In order to integrate the TLS data and the clouds of points from the photographs from the various stages, they were processed into a raster form; our own software (based on the OpenCV library and the Structure-from-Motion method) and LupoScan software were used to interconnect the multi-temporal and multi-sensor data sets. As a result of processing photographs and TLS data, point clouds in an external reference system were obtained. This data was then used to study the thickness of the walls of the Justice Court Tower, to analyse the course of the retaining wall, and to generate the orthoimages necessary for chronological analysis.</p>

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