Rapid mapping accuracy assessment using low-cost UAV and open-source Structure from Motion

Unmanned Aerial Vehicles (UAVs) can be used to acquire highly accurate data in deformation survey, whereby low-cost digital cameras are commonly used in the UAV mapping. Thus, camera calibration is considered important in obtaining high-accuracy UAV mapping using low-cost digital cameras. The main focus of this study was to calibrate the UAV camera at different camera distances and check the measurement accuracy. The scope of this study included camera calibration in the laboratory and on the field, and the UAV image mapping accuracy assessment used calibration parameters of different camera distances. The camera distances used for the image calibration acquisition and mapping accuracy assessment were 1.5&thinsp;metres in the laboratory, and 15 and 25&thinsp;metres on the field using a Sony NEX6 digital camera. A large calibration field and a portable calibration frame were used as the tools for the camera calibration and for checking the accuracy of the measurement at different camera distances. Bundle adjustment concept was applied in Australis software to perform the camera calibration and accuracy assessment. The results showed that the camera distance at 25&thinsp;metres is the optimum object distance as this is the best accuracy obtained from the laboratory as well as outdoor mapping. In conclusion, the camera calibration at several camera distances should be applied to acquire better accuracy in mapping and the best camera parameter for the UAV image mapping should be selected for highly accurate mapping measurement.

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SfM for Orthophoto to Generation: A Winning Approach for Cultural Heritage Knowledge

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

10.5194/isprsarchives-xl-5-w7-91-2015 ◽

2015 ◽

Vol XL-5/W7 ◽

pp. 91-98 ◽

Cited By ~ 29

Author(s):

F. Chiabrando ◽

E. Donadio ◽

F. Rinaudo

Keyword(s):

Cultural Heritage ◽

Structure From Motion ◽

Image Matching ◽

Accuracy Assessment ◽

Low Cost ◽

Survey Techniques ◽

Large Sets ◽

The Rich ◽

Rich Content ◽

Digital Survey

3D detailed models derived from digital survey techniques have increasingly developed and focused in many field of application. The high detailed content and accuracy of such models make them so attractive and usable for large sets of purposes in Cultural Heritage. The present paper focuses on one of the main techniques used nowadays for Cultural Heritage survey and documentation: the image matching approach or Structure from Motion (SfM) technique. According to the low cost nature and the rich content of derivable information, these techniques are extremely strategic in poor available resources sectors such as Cultural Heritage documentation. <br><br> After an overview of the employed algorithms and used approaches of SfM computer vision based techniques, the paper is focused in a critical analysis of the strategy used by two common employed software: the commercial suite Agisoft Photoscan and the open source tool MicMac realized by IGN France. The experimental section is focused on the description of applied tests (from RPAS data to terrestrial acquisitions), purposed to compare different solutions in various featured study cases. Finally, the accuracy assessment of the achieved products is compared and analyzed according to the strategy employed by the studied software.

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INTEGRATED GEOMATIC TECHNIQUES FOR THE LOCALIZATION AND GEOREFERENCING OF ANCIENT HERMITAGES

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

10.5194/isprs-archives-xlvi-m-1-2021-31-2021 ◽

2021 ◽

Vol XLVI-M-1-2021 ◽

pp. 31-37

Author(s):

V. Baiocchi ◽

M. Onori ◽

M. Scuti

Keyword(s):

Structure From Motion ◽

Accuracy Assessment ◽

Low Cost ◽

Second World War ◽

The Other ◽

Geographical Information ◽

World War ◽

Survey Techniques ◽

Second World ◽

Do So

Abstract. Historical maps represent an important source of geographical information. The changes occurred over time can be extrapolated from them, especially if their geometric accuracies match those achievable with modern survey techniques. An 1820 map belonging to the Gregorian Cadastre provides the position of seven hermitages belonging to the monastery of Fara in Sabina (Italy). Just three of them are nowadays visible, while the others may have been covered by thick vegetation or been destroyed during the Second World War. The paper proposes the integration of geomatic techniques for the localization of the lost hermitages. To do so, Structure from Motion (SfM) algorithms were applied to UAV imagery to produce an orthophoto of the area. In addition, a GNSS survey was carried out using a professional and a low-cost receiver to correctly georeference the photogrammetric products. An accuracy assessment was then performed to evaluate the performance of the u-blox board in real applications. The accuracies obtained with the low-cost receiver indicates a possible more widespread utilization of these new devices. Subsequently, the comparison between the orthophoto and the cadastral map have been detailed. A weak correspondence between the position of the hermitages in the two maps have been observed. On the other side, the comparison led to the localization of two lost hermitages, with the other two being still undiscovered. This study has opened the door to an enhancement process of the monastery and to the rediscovery of the religious values of the hermitages.

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Open source structure-from-motion for aerial video

2016 IEEE Winter Conference on Applications of Computer Vision (WACV) ◽

10.1109/wacv.2016.7477659 ◽

2016 ◽

Cited By ~ 2

Author(s):

Matthew J. Leotta ◽

Eric Smith ◽

Matthew Dawkins ◽

Paul Tunison

Keyword(s):

Open Source ◽

Structure From Motion ◽

Source Structure ◽

Aerial Video

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py2DIC: A New Free and Open Source Software for Displacement and Strain Measurements in the Field of Experimental Mechanics

Sensors ◽

10.3390/s19183832 ◽

2019 ◽

Vol 19 (18) ◽

pp. 3832 ◽

Cited By ~ 4

Author(s):

Valeria Belloni ◽

Roberta Ravanelli ◽

Andrea Nascetti ◽

Martina Di Rita ◽

Domitilla Mattei ◽

...

Keyword(s):

Open Source ◽

Template Matching ◽

Accuracy Assessment ◽

Low Cost ◽

Memory Storage ◽

Image Correlation ◽

Digital Cameras ◽

Software Packages ◽

Pros And Cons ◽

University Of Rome

Thanks to the advances in computer power, memory storage and the availability of low-cost and high resolution digital cameras, Digital Image Correlation (DIC) is currently one of the most used optical and non-contact techniques for measuring material deformations. A free and open source 2D DIC software, named py2DIC, was developed at the Geodesy and Geomatics Division of the Sapienza University of Rome. Implemented in Python, the software is based on the template matching method and computes the 2D displacements and strains of samples subjected to mechanical loading. In this work, the potentialities of py2DIC were evaluated by processing two different sets of experimental data and comparing the results with other three well known DIC software packages Ncorr, Vic-2D and DICe. Moreover, an accuracy assessment was performed comparing the results with the values independently measured by a strain gauge fixed on one of the samples. The results demonstrate the possibility of successfully characterizing the deformation mechanism of the investigated materials, highlighting the pros and cons of each software package.

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UAVs for Structure-From-Motion Coastal Monitoring: A Case Study to Assess the Evolution of Embryo Dunes over a Two-Year Time Frame in the Po River Delta, Italy

Sensors ◽

10.3390/s19071717 ◽

2019 ◽

Vol 19 (7) ◽

pp. 1717 ◽

Cited By ~ 7

Author(s):

Yuri Taddia ◽

Corinne Corbau ◽

Elena Zambello ◽

Alberto Pellegrinelli

Keyword(s):

Cross Sections ◽

Structure From Motion ◽

Accuracy Assessment ◽

Low Cost ◽

Three Dimensional ◽

Time Frame ◽

Three Dimensional Model ◽

Dune System ◽

Po River ◽

Time Saving

Coastal environments are usually characterized by a brittle balance, especially in terms of sediment transportation. The formation of dunes, as well as their sudden destruction as a result of violent storms, affects this balance in a significant way. Moreover, the growth of vegetation on the top of the dunes strongly influences the consequent growth of the dunes themselves. This work presents the results obtained through a long-term monitoring of a complex dune system by the use of Unmanned Aerial Vehicles (UAVs). Six different surveys were carried out between November 2015 and December 2017 in the littoral of Rosolina Mare (Italy). Aerial photogrammetric data were acquired during flight repetitions by using a DJI Phantom 3 Professional with the camera in a nadiral arrangement. The processing of the captured images consisted of the reconstruction of a three-dimensional model using the Structure-from-Motion (SfM). Each model was framed in the European Terrestrial Reference System (ETRS) using GNSS geodetic receivers in Network Real Time Kinematic (NRTK). Specific data management was necessary due to the vegetation by filtering the dense cloud. This task was performed by both performing a slope detection and a removal of the residual outliers. The final products of this approach were thus represented by Digital Elevation Models (DEMs) of the sandy coastal section. In addition, DEMs of Difference (DoD) were also computed for the purpose of monitoring over time and detecting variations. The accuracy assessment of the DEMs was carried out by an elevation comparison through especially GNSS-surveyed points. Relevant cross sections were also extracted and compared. The use of the Structure-from-Motion approach by UAVs finally proved to be both reliable and time-saving thanks to quicker in situ operations for the data acquisition and an accurate reconstruction of high-resolution elevation models. The low cost of the system and its flexibility represent additional strengths, making this technique highly competitive with traditional ones.

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Structure from Motion and Archaeological Excavation: Experiences of the Via Consolare Project in Pompeii

Studies in Digital Heritage ◽

10.14434/sdh.v4i2.27260 ◽

2021 ◽

Vol 4 (2) ◽

pp. 78-107

Author(s):

Michael Andrew Anderson

Keyword(s):

Open Source ◽

Structure From Motion ◽

Low Cost ◽

State Level ◽

Point Clouds ◽

Practical Implementation ◽

Digital Cameras ◽

Image Based Modeling ◽

Field Methodology ◽

Practical Field

The last decade of advances in Image-Based Modeling (IBM) data acquisition based on Structure from Motion (SfM) have made it possible as never before to record excavated archaeological deposits, historical architectural remains, artifacts, and geographical surroundings in the field. Armed only with digital cameras and low-cost or open-source software, researchers can now produce accurate point clouds of millions of points, capturing archaeological information in high-resolution detail. But what changes will IBM really bring to the standards, requirements, and expectations of practical field methodology for projects operating on shoe-string budgets? Since 2010, the Via Consolare Project, a small archaeological research project from a State level University, has employed an entirely open-source and “free for academic use” IBM pipeline to record a variety of archaeological features in Insula VII 6 and the “Villa delle Colonne a mosaico” in Pompeii. Ranging from surviving architecture, to rubble fill layers, to the interiors of inaccessible cisterns and drains, this work has been carried out in preparation for the eventual coordination of these data into a 3D GIS of all recorded stratigraphy. Rarely were sufficient resources available for dedicated equipment or personnel to be devoted to this task. While practical implementation, even in a low-budget excavation environment, has confirmed that this technology can indeed augment archaeological field documentation and provide investigation opportunities that would otherwise be impossible, it failed to replace traditional handdrafted recording techniques and was found to present significant challenges and a number of hidden costs. This emphasizes a need for appropriate and cautious planning in implementation, especially in projects with limited means.

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PyDOSS: An open-source Python-based communicable disease outbreak surveillance system designed and used in a COVID-19 community care facility (Preprint)

10.2196/preprints.21760 ◽

2020 ◽

Author(s):

Andrew Fang ◽

Jonathan Kia-Sheng Phua ◽

Terrence Chiew ◽

Daniel De-Liang Loh ◽

Lincoln Ming Han Liow ◽

...

Keyword(s):

Open Source ◽

Surveillance System ◽

Community Care ◽

Communicable Disease ◽

Low Cost ◽

Real Life ◽

Disease Outbreak ◽

Disease Spread ◽

Healthcare Team ◽

Increased Risk

BACKGROUND During the Coronavirus Disease 2019 (COVID-19) outbreak, community care facilities (CCF) were set up as temporary out-of-hospital isolation facilities to contain the surge of cases in Singapore. Confined living spaces within CCFs posed an increased risk of communicable disease spread among residents. OBJECTIVE This inspired our healthcare team managing a CCF operation to design a low-cost communicable disease outbreak surveillance system (CDOSS). METHODS Our CDOSS was designed with the following considerations: (1) comprehensiveness, (2) efficiency through passive reconnoitering from electronic medical record (EMR) data, (3) ability to provide spatiotemporal insights, (4) low-cost and (5) ease of use. We used Python to develop a lightweight application – Python-based Communicable Disease Outbreak Surveillance System (PyDOSS) – that was able perform syndromic surveillance and fever monitoring. With minimal user actions, its data pipeline would generate daily control charts and geospatial heat maps of cases from raw EMR data and logged vital signs. PyDOSS was successfully implemented as part of our CCF workflow. We also simulated a gastroenteritis (GE) outbreak to test the effectiveness of the system. RESULTS PyDOSS was used throughout the entire duration of operation; the output was reviewed daily by senior management. No disease outbreaks were identified during our medical operation. In the simulated GE outbreak, PyDOSS was able to effectively detect an outbreak within 24 hours and provided information about cluster progression which could aid in contact tracing. The code for a stock version of PyDOSS has been made publicly available. CONCLUSIONS PyDOSS is an effective surveillance system which was successfully implemented in a real-life medical operation. With the system developed using open-source technology and the code made freely available, it significantly reduces the cost of developing and operating CDOSS and may be useful for similar temporary medical operations, or in resource-limited settings.

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Implementation of a Six-Layer Smart Factory Architecture with Special Focus on Transdisciplinary Engineering Education

Sensors ◽

10.3390/s21092944 ◽

2021 ◽

Vol 21 (9) ◽

pp. 2944

Author(s):

Benjamin James Ralph ◽

Marcel Sorger ◽

Benjamin Schödinger ◽

Hans-Jörg Schmölzer ◽

Karin Hartl ◽

...

Keyword(s):

Open Source ◽

User Interfaces ◽

Industrial Revolution ◽

Low Cost ◽

Material Behavior ◽

Sensor Data ◽

Management Tool ◽

Special Focus ◽

Programming Environments ◽

Metal Processing

Smart factories are an integral element of the manufacturing infrastructure in the context of the fourth industrial revolution. Nevertheless, there is frequently a deficiency of adequate training facilities for future engineering experts in the academic environment. For this reason, this paper describes the development and implementation of two different layer architectures for the metal processing environment. The first architecture is based on low-cost but resilient devices, allowing interested parties to work with mostly open-source interfaces and standard back-end programming environments. Additionally, one proprietary and two open-source graphical user interfaces (GUIs) were developed. Those interfaces can be adapted front-end as well as back-end, ensuring a holistic comprehension of their capabilities and limits. As a result, a six-layer architecture, from digitization to an interactive project management tool, was designed and implemented in the practical workflow at the academic institution. To take the complexity of thermo-mechanical processing in the metal processing field into account, an alternative layer, connected with the thermo-mechanical treatment simulator Gleeble 3800, was designed. This framework is capable of transferring sensor data with high frequency, enabling data collection for the numerical simulation of complex material behavior under high temperature processing. Finally, the possibility of connecting both systems by using open-source software packages is demonstrated.

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Induction of Neural Plasticity Using a Low-Cost Open Source Brain-Computer Interface and a 3D-Printed Wrist Exoskeleton

Sensors ◽

10.3390/s21020572 ◽

2021 ◽

Vol 21 (2) ◽

pp. 572

Author(s):

Mads Jochumsen ◽

Taha Al Muhammadee Janjua ◽

Juan Carlos Arceo ◽

Jimmy Lauber ◽

Emilie Simoneau Buessinger ◽

...

Keyword(s):

Open Source ◽

Neural Plasticity ◽

Motor Evoked Potentials ◽

Low Cost ◽

True Positive Rate ◽

Positive Rate ◽

3D Printed ◽

Major Factors ◽

And Control ◽

Bci System

Brain-computer interfaces (BCIs) have been proven to be useful for stroke rehabilitation, but there are a number of factors that impede the use of this technology in rehabilitation clinics and in home-use, the major factors including the usability and costs of the BCI system. The aims of this study were to develop a cheap 3D-printed wrist exoskeleton that can be controlled by a cheap open source BCI (OpenViBE), and to determine if training with such a setup could induce neural plasticity. Eleven healthy volunteers imagined wrist extensions, which were detected from single-trial electroencephalography (EEG), and in response to this, the wrist exoskeleton replicated the intended movement. Motor-evoked potentials (MEPs) elicited using transcranial magnetic stimulation were measured before, immediately after, and 30 min after BCI training with the exoskeleton. The BCI system had a true positive rate of 86 ± 12% with 1.20 ± 0.57 false detections per minute. Compared to the measurement before the BCI training, the MEPs increased by 35 ± 60% immediately after and 67 ± 60% 30 min after the BCI training. There was no association between the BCI performance and the induction of plasticity. In conclusion, it is possible to detect imaginary movements using an open-source BCI setup and control a cheap 3D-printed exoskeleton that when combined with the BCI can induce neural plasticity. These findings may promote the availability of BCI technology for rehabilitation clinics and home-use. However, the usability must be improved, and further tests are needed with stroke patients.

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