Role of Ground Control Points (GCPs) in Integration of Terrestrial Laser Scanner (TLS) and Close-range Photogrammetry (CRP)

In this study, an analysis of the capabilities of unmanned aerial vehicle (UAV) photogrammetry to obtain point clouds from areas with a near-vertical inclination was carried out. For this purpose, 18 different combinations were proposed, varying the number of ground control points (GCPs), the adequacy (or not) of the distribution of GCPs, and the orientation of the photographs (nadir and oblique). The results have shown that under certain conditions, the accuracy achieved was similar to those obtained by a terrestrial laser scanner (TLS). For this reason, it is necessary to increase the number of GCPs as much as possible in order to cover a whole study area. In the event that this is not possible, the inclusion of oblique photography ostensibly improves results; therefore, it is always advisable since they also improve the geometric descriptions of break lines or sudden changes in slope. In this sense, UAVs seem to be a more economic substitute compared to TLS for vertical wall surveying.

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PRECISION OF VISUAL LOCALIZATION USING DYNAMIC GROUND CONTROL POINTS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xliii-b1-2020-363-2020 ◽

2020 ◽

Vol XLIII-B1-2020 ◽

pp. 363-370

Author(s):

P. Trusheim ◽

C. Heipke

Keyword(s):

Rapid Development ◽

Sliding Window ◽

Bundle Adjustment ◽

Ground Control ◽

Visual Localization ◽

Control Points ◽

Automated Driving ◽

Sliding Windows ◽

Ground Control Points

Abstract. Localization is one of the first steps in navigation. Especially due to the rapid development in automated driving, a precise and reliable localization becomes essential. In this paper, we report an investigation of the usage of dynamic ground control points (GCP) in visual localization in an automotive environment. Instead of having fixed positions, dynamic GCPs move together with the camera. As a measure of quality, we employ the precision of the bundle adjustment results. In our experiments, we simulate and investigate different realistic traffic scenarios. After investigating the role of tie points, we compare an approach using dynamic GCPs to an approach with static GCPs to answer the question how a comparable precision can be reached for visual localization. We show, that in our scenario, where two dynamic GCPs move together with a camera, similar results are indeed obtained to using a number of static GCPs distributed over the whole trajectory. In another experiment, we take a closer look at sliding window bundle adjustments. Sliding windows make it possible to work with an arbitrarily large number of images and to still obtain near real-time results. We investigate this approach in combination with dynamic GCPs and vary the no. of images per window.

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Reconstructing 3D coastal cliffs from airborne oblique photographs without ground control points

ISPRS Annals of Photogrammetry Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsannals-ii-5-113-2014 ◽

2014 ◽

Vol II-5 ◽

pp. 113-116 ◽

Cited By ~ 2

Author(s):

T. J. B. Dewez

Keyword(s):

Laser Scanner ◽

Point Clouds ◽

Ground Control ◽

Control Points ◽

Open Door ◽

View Point ◽

Ground Control Points ◽

3D Point Clouds ◽

Coastal Cliff ◽

Coastal Cliffs

Coastal cliff collapse hazard assessment requires measuring cliff face topography at regular intervals. Terrestrial laser scanner techniques have proven useful so far but are expensive to use either through purchasing the equipment or through survey subcontracting. In addition, terrestrial laser surveys take time which is sometimes incompatible with the time during with the beach is accessible at low-tide. By comparison, structure from motion techniques (SFM) are much less costly to implement, and if airborne, acquisition of several kilometers of coastline can be done in a matter of minutes. In this paper, the potential of GPS-tagged oblique airborne photographs and SFM techniques is examined to reconstruct chalk cliff dense 3D point clouds without Ground Control Points (GCP). The focus is put on comparing the relative 3D point of views reconstructed by Visual SFM with their synchronous Solmeta Geotagger Pro2 GPS locations using robust estimators. With a set of 568 oblique photos, shot from the open door of an airplane with a triplet of synchronized Nikon D7000, GPS and SFM-determined view point coordinates converge to X: ±31.5 m; Y: ±39.7 m; Z: ±13.0 m (LE66). Uncertainty in GPS position affects the model scale, angular attitude of the reference frame (the shoreline ends up tilted by 2°) and absolute positioning. Ground Control Points cannot be avoided to orient such models.

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Accuracy of Unmanned Aerial Vehicle (UAV) and SfM Photogrammetry Survey as a Function of the Number and Location of Ground Control Points Used

Remote Sensing ◽

10.3390/rs10101606 ◽

2018 ◽

Vol 10 (10) ◽

pp. 1606 ◽

Cited By ~ 64

Author(s):

Enoc Sanz-Ablanedo ◽

Jim Chandler ◽

José Rodríguez-Pérez ◽

Celestino Ordóñez

Keyword(s):

Critical Role ◽

Bundle Adjustment ◽

Ground Control ◽

Control Points ◽

Ground Sample ◽

Ground Control Points ◽

Check Points ◽

Aerial Vehicle

The geometrical accuracy of georeferenced digital surface models (DTM) obtained from images captured by micro-UAVs and processed by using structure from motion (SfM) photogrammetry depends on several factors, including flight design, camera quality, camera calibration, SfM algorithms and georeferencing strategy. This paper focusses on the critical role of the number and location of ground control points (GCP) used during the georeferencing stage. A challenging case study involving an area of 1200+ ha, 100+ GCP and 2500+ photos was used. Three thousand, four hundred and sixty-five different combinations of control points were introduced in the bundle adjustment, whilst the accuracy of the model was evaluated using both control points and independent check points. The analysis demonstrates how much the accuracy improves as the number of GCP points increases, as well as the importance of an even distribution, how much the accuracy is overestimated when it is quantified only using control points rather than independent check points, and how the ground sample distance (GSD) of a project relates to the maximum accuracy that can be achieved.

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DIGITAL DOCUMENTATION, BRIDGE DECK LINEARITY DEFORMATION AND DECK THICKNESS MEASUREMENT USING TERRESTRIAL LASER SCANNER (TLS) AND CLOSE RANGE PHOTOGRAMMETRY (CRP)

ISPRS Annals of Photogrammetry Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-annals-iv-5-47-2018 ◽

2018 ◽

Vol IV-5 ◽

pp. 47-51 ◽

Cited By ~ 1

Author(s):

S. K. P. Kushwaha ◽

H. Pande ◽

S. Raghavendra

Keyword(s):

Point Cloud ◽

Bridge Deck ◽

Laser Scanner ◽

Bottom Layer ◽

Thickness Measurement ◽

Terrestrial Laser Scanner ◽

Road Transportation ◽

The Road ◽

Close Range Photogrammetry ◽

Close Range

Abstract. Bridges are one of the vital and valuable engineer structure from decades. As they play a major role in the road transportation sector. Few old bridges lacks its documents about the measurements of the structure. The study has been carried out on three different types of bridges like Truss, Beam and Cable bridges. Documenting these bridges can be utilised to reconstruct or renovate the bridge in case of any disaster or damage. 3D documentation is made from the point cloud Dataset acquired from Terrestrial Laser Scanner – TLS (Riegl VZ 400) and Close Range photogrammetry – CRP (Nikon DSLR 5300). TLS and CRP point cloud are merged together to increase the density of points. Over the duration of time the bridge gets older and due to the load on the bridge deck, linearity in the deck effects and this linearity deformation measurement is important to know the present deformation in the deck. To know exactly at which part there is more linearity deformation, deflection is calculated at sample intervals between the present linearity conditions of the deck to the idle linearity conditions of the deck. The bridge deck thickness is also measured with the point cloud dataset. A slice is cut through the deck of point cloud dataset, the difference between the top and bottom layer of the deck gives us the thickness of the deck including the road. This thickness can be used to measure when a new deck layer is constructed or during filling up of any potholes. This study is mainly focused to help the construction and maintenance authority, bridge monitoring department and researchers.

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The Integration of 3D Survey Technologies for an Accurate Reality-Based Representation

Conservation, Restoration, and Analysis of Architectural and Archaeological Heritage - Advances in Religious and Cultural Studies ◽

10.4018/978-1-5225-7555-9.ch013 ◽

2019 ◽

pp. 321-345

Author(s):

Cecilia Maria Bolognesi ◽

Fausta Fiorillo

Keyword(s):

Feature Extraction ◽

High Resolution ◽

3D Modeling ◽

Laser Scanner ◽

Acquisition Phase ◽

Terrestrial Laser Scanner ◽

Close Range Photogrammetry ◽

Accuracy And Precision ◽

Complex Process ◽

Close Range

The integration of close-range photogrammetry and terrestrial laser scanner enables reality-based modeling procedures that can help BIM modeling for existing buildings. The restitution of virtual models from high-resolution surveys is a complex process that requires much expertise. It incorporates concepts of resolution, accuracy, and precision in the acquisition phase; filtering, registration, and decimation for point cloud elaboration; and meshing, texturing, simplification, segmentation, and feature extraction in the final modeling stage. The previous steps are the same whether the ultimate goal is a classic 2D representation or a 3D one. For BIM modeling, the job becomes challenging because the necessary simplification of the model cannot be automatized and apparently collides with the high resolution and fidelity of original surveyed data. This chapter presents the process of surveying and 3D modeling of the Ghesc village, following the whole path from data acquisition to BIM modeling, discussing strengths and weakness, issues, and recent solutions for restoration interventions.

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Integration of photogrammetric and terrestrial laser scanning techniques for heritage documentation

Virtual Archaeology Review ◽

10.4995/var.2011.4605 ◽

2011 ◽

Vol 2 (3) ◽

pp. 53 ◽

Cited By ~ 7

Author(s):

Javier Cardenal Escarcena ◽

Emilio Mata de Castro ◽

José Luis Pérez García ◽

Antonio Mozas Calvache ◽

Tomás Fernández del Castillo ◽

...

Keyword(s):

Laser Scanning ◽

Laser Scanner ◽

Terrestrial Laser Scanning ◽

Terrestrial Laser Scanner ◽

Research Project ◽

National Programme ◽

Close Range Photogrammetry ◽

Methods And Techniques ◽

Close Range ◽

Single Technique

This paper presents the preliminary works of the Integration of Photogrammetric and Terrestrial Laser Scanner Techniques for Heritage Documentation Research Project (IFOTEL TIN2009-09939; Ministry of Science and Innovation, National Programme R+D+I, 2008-2011). The IFOTEL project aims with the improvement and optimization of heritage documentation by means of combination and integration of different methods and techniques, mainly close range photogrammetry (both terrestrial and aerial with light platforms), terrestrial laser scanner and surveying, joining the advantages of the different methods but also minimizing the disadvantages of each single technique.

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