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Börlin, N., Murtiyoso, A., Grussenmeyer, P., Menna, F. & Nocerino, E. (2019). Flexible Photogrammetric Computations Using Modular Bundle Adjustment: The Chain Rule and the Collinearity Equations. Photogrammetric Engineering and Remote Sensing, 85(5), 361-368
Open this publication in new window or tab >>Flexible Photogrammetric Computations Using Modular Bundle Adjustment: The Chain Rule and the Collinearity Equations
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2019 (English)In: Photogrammetric Engineering and Remote Sensing, ISSN 0099-1112, Vol. 85, no 5, p. 361-368Article in journal (Refereed) Published
Abstract [en]

The main purpose of this article is to show that photogrammetric bundle-adjustment computations can be sequentially organized into modules. Furthermore, the chain rule can be used to simplify the computation of the analytical Jacobians needed for the adjustment. Novel projection models can be flexibly evaluated by inserting, modifying, or swapping the order of selected modules. As a proof of concept, two variants of the pinhole projection model with Brown lens distortion were implemented in the open-source Damped Bundle Adjustment Toolbox and applied to simulated and calibration data for a nonconventional lens system. The results show a significant difference for the simulated, error-free, data but not for the real calibration data. The current flexible implementation incurs a performance loss. However, in cases where flexibility is more important, the modular formulation should be a useful tool to investigate novel sensors, data-processing techniques, and refractive models.

Place, publisher, year, edition, pages
Bethesda, Maryland, USA: American Society of Photogrammetry and Remote Sensing (ASPRS), 2019
Keywords
Bundle adjustment, photogrammetry, chain rule, software
National Category
Computational Mathematics Probability Theory and Statistics
Research subject
computer and systems sciences; Mathematical Statistics
Identifiers
urn:nbn:se:umu:diva-157690 (URN)10.14358/PERS.85.5.361 (DOI)000468866900006 ()
Available from: 2019-04-01 Created: 2019-04-01 Last updated: 2019-06-17Bibliographically approved
Forsman, M., Börlin, N., Olofsson, K., Reese, H. & Holmgren, J. (2018). Bias of cylinder diameter estimation from ground-based laser scanners with different beam widths: a simulation study. ISPRS journal of photogrammetry and remote sensing (Print), 135, 84-92
Open this publication in new window or tab >>Bias of cylinder diameter estimation from ground-based laser scanners with different beam widths: a simulation study
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2018 (English)In: ISPRS journal of photogrammetry and remote sensing (Print), ISSN 0924-2716, E-ISSN 1872-8235, Vol. 135, p. 84-92Article in journal (Refereed) Published
Abstract [en]

In this study we have investigated why diameters of tree stems, which are approximately cylindrical, are often overestimated by mobile laser scanning. This paper analyzes the physical processes when using ground-based laser scanning that may contribute to a bias when estimating cylinder diameters using circle-fit methods. A laser scanner simulator was implemented and used to evaluate various properties, such as distance, cylinder diameter, and beam width of a laser scanner-cylinder system to find critical conditions. The simulation results suggest that a positive bias of the diameter estimation is expected. Furthermore, the bias follows a quadratic function of one parameter - the relative footprint, i.e., the fraction of the cylinder width illuminated by the laser beam. The quadratic signature opens up a possibility to construct a compensation model for the bias.

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2018
Keywords
Mobile laser scanning, Diameter estimation, Cylinder measurement, Simulation, Terrestrial laser scanning, Circle fit methods, Forest measurement, Tree stem diameter
National Category
Computational Mathematics Forest Science
Research subject
Computer and Information Science
Identifiers
urn:nbn:se:umu:diva-142207 (URN)10.1016/j.isprsjprs.2017.11.013 (DOI)000423895100007 ()
Available from: 2017-11-25 Created: 2017-11-25 Last updated: 2018-06-09Bibliographically approved
Menna, F., Nocerino, E., Drap, P., Remondino, F., Murtiyoso, A., Grussenmeyer, P. & Börlin, N. (2018). Improving Underwater Accuracy by Empirical Weighting of Image Observations. In: ISPRS Technical Commission II Symposium 2018: . Paper presented at ISPRS Technical Commission II Symposium 2018, Riva del Garda, Italy, June 3-7, 2018 (pp. 699-705). ISPRS, XLII-2
Open this publication in new window or tab >>Improving Underwater Accuracy by Empirical Weighting of Image Observations
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2018 (English)In: ISPRS Technical Commission II Symposium 2018, ISPRS , 2018, Vol. XLII-2, p. 699-705Conference paper, Published paper (Refereed)
Abstract [en]

An underwater imaging system with camera and lens behind a flat port does not behave as a standard pinhole camera with additional parameters. Indeed, whenever the entrance pupil of the lens is not in contact with the flat port, the standard photogrammetric model is not suited anymore and an extended mathematical model that considers the different media would be required. Therefore, when dealing with flat ports, the use of the classic photogrammetric formulation represents a simplification of the image formation phenomenon, clearly causing a degradation in accuracy. Furthermore, flat ports significantly change the characteristics of the enclosed imaging device and negatively affect the image quality, introducing heavy curvilinear distortions and optical aberrations. With the aim of mitigating the effect of systematic errors introduced by a combination of (i) image quality degradation, induced by the flat ports, and (ii) a non-rigorous modelling of refraction, this paper presents a stochastic model for image observations that penalises those that are more affected by aberrations and departure from the pinhole model. Experiments were carried out at sea and in pools showing that the use of the proposed stochastic model is beneficial for the final accuracy with improvements up to 50 %.

Place, publisher, year, edition, pages
ISPRS, 2018
Series
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, ISSN 1682-1750, E-ISSN 2194-9034
Keywords
underwater photogrammetry, image quality, bundle adjustment, image observation weighting
National Category
Computational Mathematics Probability Theory and Statistics
Research subject
computer and systems sciences; Mathematical Statistics
Identifiers
urn:nbn:se:umu:diva-147868 (URN)10.5194/isprs-archives-XLII-2-699-2018 (DOI)2-s2.0-85048367823 (Scopus ID)
Conference
ISPRS Technical Commission II Symposium 2018, Riva del Garda, Italy, June 3-7, 2018
Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2019-05-22Bibliographically approved
Börlin, N., Murtiyoso, A., Grussenmeyer, P., Menna, F. & Nocerino, E. (2018). Modular Bundle Adjustment for Photogrammeric Computations. In: ISPRS Technical Commission II Symposium 2018: . Paper presented at ISPRS Technical Commission II Symposium 2018, Riva del Garda, Italy, June 3-7, 2018 (pp. 133-140). ISPRS, XLII-2
Open this publication in new window or tab >>Modular Bundle Adjustment for Photogrammeric Computations
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2018 (English)In: ISPRS Technical Commission II Symposium 2018, ISPRS , 2018, Vol. XLII-2, p. 133-140Conference paper, Published paper (Refereed)
Abstract [en]

In this paper we investigate how the residuals in bundle adjustmentcan be split into a composition of simple functions. According to thechain rule, the Jacobian (linearisation) of the residual can be formedas a product of the Jacobians of the individual steps. Whenimplemented, this enables a modularisation of the computation of thebundle adjustment residuals and Jacobians where each component haslimited responsibility. This enables simple replacement of componentsto e.g. implement different projection or rotation models byexchanging a module. The technique has previously been used toimplement bundle adjustment in the open-source package DBAT (Borlinand Grussenmeyer, ¨ 2013) based on the Photogrammetric and ComputerVision interpretations of Brown (1971) lens distortion model. In thispaper, we applied the technique to investigate how affine distortionscan be used to model the projection of a tilt-shift lens. Two extendeddistortion models were implemented to test the hypothesis that theordering of the affine and lens distortion steps can be changed toreduce the size of the residuals of a tilt-shift lens calibration.Results on synthetic data confirm that the ordering of the affine andlens distortion steps matter and is detectable by DBAT. However, whenapplied to a real camera calibration data set of a tilt-shift lens, nodifference between the extended models was seen. This suggests thatthe tested hypothesis is false and that other effects need to bemodelled to better explain the projection. The relatively lowimplementation effort that was needed to generate the models suggestthat the technique can be used to investigate other novel projectionmodels in photogrammetry, including modelling changes in the 3Dgeometry to better understand the tilt-shift lens.

Place, publisher, year, edition, pages
ISPRS, 2018
Series
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, ISSN 1682-1750, E-ISSN 2194-9034
Keywords
Bundle adjustment, Camera model, Analytical Jacobians, Software, Photogrammetry, Tilt-shift lens
National Category
Computational Mathematics Probability Theory and Statistics
Research subject
computer and systems sciences; Mathematical Statistics
Identifiers
urn:nbn:se:umu:diva-147865 (URN)10.5194/isprs-archives-XLII-2-133-2018 (DOI)
Conference
ISPRS Technical Commission II Symposium 2018, Riva del Garda, Italy, June 3-7, 2018
Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2019-06-25Bibliographically approved
Murtiyoso, A., Grussenmeyer, P., Börlin, N., Vandermeerschen, J. & Freville, T. (2018). Open Source and Independent Methods for Bundle Adjustment Assessment in Close-Range UAV Photogrammetry. Drones, 2(1), Article ID 3.
Open this publication in new window or tab >>Open Source and Independent Methods for Bundle Adjustment Assessment in Close-Range UAV Photogrammetry
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2018 (English)In: Drones, ISSN 2504-446X, Vol. 2, no 1, article id 3Article in journal (Refereed) Published
Abstract [en]

Close-range photogrammetry as a technique to acquire reality-based 3D data has, in recenttimes, seen a renewed interest due to developments in sensor technologies. Furthermore, the strong democratization of UAVs (Unmanned Aerial Vehicles) or drones means that close-rangephotogrammetry can now be used as a viable low-cost method for 3D mapping. In terms of software development, this led to the creation of many commercial black-box solutions (PhotoScan, Pix4D, etc.). This paper aims to demonstrate how the open source toolbox DBAT (Damped Bundle AdjustmentToolbox) can be used to generate detailed photogrammetric network diagnostics to help assess the quality of surveys processed by the commercial software, PhotoScan. In addition, the Apero module from the MicMac software suite was also used to provide an independent assessment of the results. The assessment is performed by the careful examination of some of the bundle adjustment metrics generated by both open source solutions. A UAV project was conducted on a historical church in the city center of Strasbourg, France, in order to provide a dataset with a millimetric level of precision. Results showed that DBAT can be used to reprocess PhotoScan projects under similar conditions and derive useful metrics from them, while Apero provides a completely independent verification of the results of commercial solutions. Overall, this paper shows that an objective assessment of photogrammetric results is important. In cases where problems are encountered in the project, this assessment method can be useful to detect errors that may not be explicitly presented by PhotoScan.

Place, publisher, year, edition, pages
Basel: , 2018
Keywords
photogrammetry, UAV, open source, bundle adjustment, quality control
National Category
Computer and Information Sciences Computational Mathematics
Research subject
Computer and Information Science; Computerized Image Analysis
Identifiers
urn:nbn:se:umu:diva-146380 (URN)10.3390/drones2010003 (DOI)
Available from: 2018-04-06 Created: 2018-04-06 Last updated: 2018-06-09Bibliographically approved
Murtiyoso, A., Grussenmeyer, P. & Börlin, N. (2017). Reprocessing Close Range Terrestrial and UAV Photogrammetric Projects with the DBAT Toolbox for Independent Verification and Quality Control. In: T. P. Kersten, F. Remondino (Ed.), LowCost 3D – Sensors, Algorithms, Applications: 5th International Workshop. Paper presented at LowCost 3D 2017, Hamburg, Germany, 28-29 November 2017 (pp. 171-177). , XLII-2/W8
Open this publication in new window or tab >>Reprocessing Close Range Terrestrial and UAV Photogrammetric Projects with the DBAT Toolbox for Independent Verification and Quality Control
2017 (English)In: LowCost 3D – Sensors, Algorithms, Applications: 5th International Workshop / [ed] T. P. Kersten, F. Remondino, 2017, Vol. XLII-2/W8, p. 171-177Conference paper, Published paper (Refereed)
Abstract [en]

Photogrammetry has recently seen a rapid increase in many applications, thanks to developments in computing power and algorithms. Furthermore with the democratisation of UAVs (Unmanned Aerial Vehicles), close range photogrammetry has seen more and more use due to the easier capability to acquire aerial close range images. In terms of photogrammetric processing, many commercial software solutions exist in the market that offer results from user-friendly environments. However, in most commercial solutions, a black-box approach to photogrammetric calculations is often used. This is understandable in light of the proprietary nature of the algorithms, but it may pose a problem if the results need to be validated in an independent manner. In this paper, the Damped Bundle Adjustment Toolbox (DBAT) developed for Matlab was used to reprocess some photogrammetric projects that were processed using the commercial software Agisoft Photoscan. Several scenarios were experimented on in order to see the performance of DBAT in reprocessing terrestrial and UAV close range photogrammetric projects in several configurations of self-calibration setting. Results show that DBAT managed to reprocess PS projects and generate metrics which can be useful for project verification.

Series
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, ISSN 1682-1750, E-ISSN 2194-9034
Keywords
close range, UAV, bundle adjustment, quality control, photogrammetry, software, DBAT
National Category
Computational Mathematics Probability Theory and Statistics
Research subject
Computer and Information Science; Mathematical Statistics
Identifiers
urn:nbn:se:umu:diva-142206 (URN)10.5194/isprs-archives-XLII-2-W8-171-2017 (DOI)
Conference
LowCost 3D 2017, Hamburg, Germany, 28-29 November 2017
Available from: 2017-11-24 Created: 2017-11-24 Last updated: 2018-06-09Bibliographically approved
Forsman, M., Börlin, N. & Holmgren, J. (2016). Estimation of Tree Stem Attributes using Terrestrial Photogrammetry with a Camera Rig. Forests, 7(3), Article ID 61.
Open this publication in new window or tab >>Estimation of Tree Stem Attributes using Terrestrial Photogrammetry with a Camera Rig
2016 (English)In: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 7, no 3, article id 61Article in journal (Refereed) Published
Abstract [en]

We propose a novel photogrammetric method for field plot inventory, designed for simplicity and time efficiency on-site. A prototype multi-camera rig was used to acquire images from field plot centers in multiple directions. The acquisition time on-site was less than two minutes. From each view, a point cloud was generated using a novel, rig-based matching of detected SIFT keypoints. Stems were detected in the merged point cloud, and their positions and diameters were estimated. The method was evaluated on 25 hemi-boreal forest plots of a 10-m radius. Due to difficult lighting conditions and faulty hardware, imagery from only six field plots was processed. The method performed best on three plots with clearly visible stems with a 76% detection rate and 0% commission. Dieameters could be estimated for 40% of the stems with an RMSE of 2.8-9.5 cm. The results are comparable to other camera-based methods evaluated in a similar manner. The results are inferior to TLS-based methods. However, our method is easily extended to multiple station image schemas, something that could significantly improve the results while retaining low commission errors and time on-site. Furthermore, with smaller hardware, we believe this could be a useful technique for measuring stem attributes in the forest.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI (Multidisciplinary Digital Publishing Institute), 2016
Keywords
forest inventory, point cloud, circle estimation, mobile mapping, stem diameter
National Category
Forest Science Computer and Information Sciences Computer Vision and Robotics (Autonomous Systems)
Research subject
Computer and Information Science; Computerized Image Analysis
Identifiers
urn:nbn:se:umu:diva-117957 (URN)10.3390/f7030061 (DOI)000373700800021 ()
Funder
The Kempe Foundations, SMK-1033
Available from: 2016-03-08 Created: 2016-03-08 Last updated: 2018-06-07Bibliographically approved
Börlin, N. & Grussenmeyer, P. (2016). External Verification of the Bundle Adjustment in Photogrammetric Software Using the Damped Bundle Adjustment Toolbox. In: L. Halounova, V. Šafář, F. Remondino, J. Hodač, K. Pavelka, M. Shortis, F. Rinaudo, M. Scaioni, J. Boehm, and D. Rieke-Zapp (Ed.), XXIII ISPRS Congress, Commission V: Volume XLI-B5. Paper presented at ISPRS 2016 Congress, 12–19 July 2016, Prague, Czech Republic (pp. 7-14). International Society of Photogrammetry and Remote Sensing, XLI-B5
Open this publication in new window or tab >>External Verification of the Bundle Adjustment in Photogrammetric Software Using the Damped Bundle Adjustment Toolbox
2016 (English)In: XXIII ISPRS Congress, Commission V: Volume XLI-B5 / [ed] L. Halounova, V. Šafář, F. Remondino, J. Hodač, K. Pavelka, M. Shortis, F. Rinaudo, M. Scaioni, J. Boehm, and D. Rieke-Zapp, International Society of Photogrammetry and Remote Sensing , 2016, Vol. XLI-B5, p. 7-14Conference paper, Published paper (Refereed)
Abstract [en]

The aim of this paper is to investigate whether the Matlab-based Damped Bundle Adjustment Toolbox (DBAT) can be used to provide independent verification of the BA computation of two popular software—PhotoModeler (PM) and PhotoScan (PS).

For frame camera data sets with lens distortion, DBAT is able to reprocess and replicate subsets of PM results with high accuracy. For lens-distortion-free data sets, DBAT can furthermore provide comparative results between PM and PS. Data sets for the discussed projects are available from the authors.

The use of an external verification tool such as DBAT will enable users to get an independent verification of the computations of their software. In addition, DBAT can provide computation of quality parameters such as estimated standard deviations, correlation between parameters, etc., something that should be part of best practice for any photogrammetric software. Finally, as the code is free and open-source, users can add computations of their own.

Place, publisher, year, edition, pages
International Society of Photogrammetry and Remote Sensing, 2016
Series
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, ISSN 2194-9034 ; XLI
Keywords
Software, Bundle adjustment, Accuracy, Quality, Best practice, Distortion, Data sets
National Category
Computer and Information Sciences Mathematics
Research subject
Computer and Information Science; Computerized Image Analysis
Identifiers
urn:nbn:se:umu:diva-122706 (URN)10.5194/isprs-archives-XLI-B5-7-2016 (DOI)
Conference
ISPRS 2016 Congress, 12–19 July 2016, Prague, Czech Republic
Available from: 2016-06-21 Created: 2016-06-21 Last updated: 2018-06-07Bibliographically approved
Börlin, N. & Grussenmeyer, P. (2014). Camera Calibration using the Damped Bundle Adjustment Toolbox. In: F. Remondino and F. Menna (Ed.), ISPRS Annals - Volume II-5, 2014: ISPRS Technical Commission V Symposium 23–25 June 2014, Riva del Garda, Italy. Paper presented at ISPRS Technical Commission V Symposium, 23 – 25 June 2014, Riva del Garda, Italy (pp. 89-96). Copernicus GmbH, II-5
Open this publication in new window or tab >>Camera Calibration using the Damped Bundle Adjustment Toolbox
2014 (English)In: ISPRS Annals - Volume II-5, 2014: ISPRS Technical Commission V Symposium 23–25 June 2014, Riva del Garda, Italy / [ed] F. Remondino and F. Menna, Copernicus GmbH , 2014, Vol. II-5, p. 89-96Conference paper, Published paper (Refereed)
Abstract [en]

Camera calibration is one of the fundamental photogrammetric tasks. The standard procedure is to apply an iterative adjustment to measurements of known control points. The iterative adjustment needs initial values of internal and external parameters. In this paper we investigate a procedure where only one parameter - the focal length is given a specific initial value. The procedure is validated using the freely available Damped Bundle Adjustment Toolbox on five calibration data sets using varying narrow- and wide-angle lenses. The results show that the Gauss-Newton-Armijo and Levenberg-Marquardt-Powell bundle adjustment methods implemented in the toolbox converge even if the initial values of the focal length are between 1/2 and 32 times the true focal length, even if the parameters are highly correlated. Standard statistical analysis methods in the toolbox enable manual selection of the lens distortion parameters to estimate, something not available in other camera calibration toolboxes. A standardised camera calibration procedure that does not require any information about the camera sensor or focal length is suggested based on the convergence results. The toolbox source and data sets used in this paper are available from the authors.

Place, publisher, year, edition, pages
Copernicus GmbH, 2014
Series
ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, ISSN 2194-9050 ; Volume II-5
Keywords
Camera calibration, bundle adjustment, focal length, convergent, initial values, close range photogrammetry
National Category
Computer Vision and Robotics (Autonomous Systems) Computational Mathematics
Research subject
Computer and Information Science
Identifiers
urn:nbn:se:umu:diva-88638 (URN)10.5194/isprsannals-II-5-89-2014 (DOI)
Conference
ISPRS Technical Commission V Symposium, 23 – 25 June 2014, Riva del Garda, Italy
Available from: 2014-05-12 Created: 2014-05-12 Last updated: 2018-06-07Bibliographically approved
Becher, M., Börlin, N. & Klaminder, J. (2014). Measuring soil motion with terrestrial close range photogrammetry in periglacial environments. In: Gonçalo Vieira, Pedro Pina, Carla Mora and António Correia (Ed.), EUCOP 4: Book of Abstracts. Paper presented at EUCOP4, 4th European Conference on Permafrost, 18-21 June 2014, Évora, Portugal (pp. 351-351). University of Lisbon and the University of Évora
Open this publication in new window or tab >>Measuring soil motion with terrestrial close range photogrammetry in periglacial environments
2014 (English)In: EUCOP 4: Book of Abstracts / [ed] Gonçalo Vieira, Pedro Pina, Carla Mora and António Correia, University of Lisbon and the University of Évora , 2014, p. 351-351Conference paper, Oral presentation only (Other academic)
Abstract [en]

Cryoturbation plays an important role in the carbon cycle as it redistributes carbon deeper down in the soil where the cold temperature prevents microbial decomposition. This contribution is also included in recent models describing the long-term build up of carbon stocks in artic soils. Soil motion rate in cryoturbated soils is sparsely studied. This is because the internal factors maintaining cryoturbation will be affected by any excavation, making it impossible to remove soil samples or install pegs without changing the structure of the soil. So far, mainly the motion of soil surface markers on patterned ground has been used to infer lateral soil motion rates. However, such methods constrain the investigated area to a predetermined distribution of surface markers that may result in a loss of information regarding soil motion in other parts of the patterned ground surface.

We present a novel method based on terrestrial close range (<5m) photogrammetry to calculate lateral and vertical soil motion across entire small-scale periglacial features, such as non-sorted circles (frost boils). Images were acquired by a 5-camera calibrated rig from at least 8 directions around a non-sorted circle. During acquisition, the rig was carried by one person in a backpack-like portable camera support system. Natural feature points were detected by SIFT and matched between images using the known epipolar geometry of the calibrated rig. The 3D coordinates of points matched between at least 3 images were calculated to create a point cloud of the surface of interest. The procedure was repeated during two consecutive years to be able to measure any net displacement of soil and calculate rates of soil motion. The technique was also applied to a peat palsa where multiple exposures where acquired of selected areas.

The method has the potential to quantify areas of disturbance and estimate lateral and vertical soil motion in non-sorted circles. Furthermore, it should be possible to quantify peat erosion and rates of desiccation crack formations in peat palsas. This tool could provide new information about cryoturbation rates that could improve existing soil carbon models and increase our understanding about how soil carbon stocks will respond to climate change.

Place, publisher, year, edition, pages
University of Lisbon and the University of Évora, 2014
National Category
Computer Vision and Robotics (Autonomous Systems) Other Earth and Related Environmental Sciences
Research subject
Computer and Information Science; Physical Geography
Identifiers
urn:nbn:se:umu:diva-89591 (URN)
Conference
EUCOP4, 4th European Conference on Permafrost, 18-21 June 2014, Évora, Portugal
Available from: 2014-06-05 Created: 2014-06-05 Last updated: 2018-09-17Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7657-6917

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