scholarly journals Point-clouds as photogrammetric representations of linear objects surfaces: The impact of extrinsic shooting parameters on the change of roughness-quality of their textures

2019 ◽  
Vol 47 (2) ◽  
pp. 316-325
Author(s):  
Đorđe Đorđević ◽  
Gordana Đukanović ◽  
Alina Duta ◽  
Mirjana Devetaković-Radojević ◽  
Nikola Popović
Keyword(s):  
Point Clouds ◽  
The Impact

scholarly journals Quantifying the density-quality of photogrammetrically created point-clouds of linear architectural/urban elements as a function of shooting distances and number of camera positions I.E. shooting-directions

2015 ◽  
Vol 13 (3) ◽  
pp. 257-272 ◽  
Author(s):  
Djordje Djordjevic ◽  
Gordana Djukanovic ◽  
Dusan Filipovic
Keyword(s):  
Software Process ◽  
Point Clouds ◽  
Process Quality ◽  
Density Level ◽  
Coverage Level ◽  
Digital Representations ◽  
Radial Movement ◽  
The Impact ◽  
Movement Angle

This paper examines the impact of various object-to-camera distances and the number of station-points i.e. various shooting directions with regard to the obtained Density-quality of photogrammetrically created Point-clouds - as digital representations of the existent linear architectural/urban objects/elements. According to an artificial (purified) experimental scene used, the conclusion is that with the chosen focal lengths/object-to-camera distances, with shooting directions perpendicular to the axis of that object, with station-points uniformly radially distributed around it (at a circle of 360deg), and with the obtained values of photogrammetric-software process-quality outputs which belong to the recommended ranges, the achieved density-level of the created Point-clouds may be treated as independent on the camera's radial-movement angle but dependent on the percentage of ?Object's Photo-Coverage?: the lower the Coverage, the lower the density. Also, regardless of the Coverage level, the majority of the generated points are generally more "densimetrically" precise than they are "densimetrically" accurate.

scholarly journals Seven Different Lighting Conditions in Photogrammetric Studies of a 3D Urban Mock-Up

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8002
Author(s):  
Katarzyna Bobkowska ◽  
Pawel Burdziakowski ◽  
Jakub Szulwic ◽  
Karolina M. Zielinska-Dabkowska
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Total Error ◽  
Spectral Characteristics ◽  
Point Clouds ◽  
Light Sources ◽  
Experimental Proof ◽  
Lighting Conditions ◽  
The Impact

One of the most important elements during photogrammetric studies is the appropriate lighting of the object or area under investigation. Nevertheless, the concept of “adequate lighting” is relative. Therefore, we have attempted, based on experimental proof of concept (technology readiness level—TRL3), to verify the impact of various types of lighting emitted by LED light sources for scene illumination and their direct influence on the quality of the photogrammetric study of a 3D urban mock-up. An important issue in this study was the measurement and evaluation of the artificial light sources used, based on illuminance (E), correlated colour temperature (CCT), colour rendering index (CRI) and Spectral power distribution (SPD) and the evaluation of the obtained point clouds (seven photogrammetric products of the same object, developed for seven different lighting conditions). The general values of the quality of the photogrammetric studies were compared. Additionally, we determined seventeen features concerning the group of tie-points in the vicinity of each F-point and the type of study. The acquired traits were related to the number of tie-points in the vicinity, their luminosities and spectral characteristics for each of the colours (red, green, blue). The dependencies between the identified features and the obtained XYZ total error were verified, and the possibility of detecting F-points depending on their luminosity was also analysed. The obtained results can be important in the process of developing a photogrammetric method of urban lighting monitoring or in selecting additional lighting for objects that are the subject of a short-range photogrammetric study.

Structural assessment using terrestrial laser scanning point clouds

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Linh Truong-Hong ◽  
Roderik Lindenbergh ◽  
Thu Anh Nguyen
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Noisy Data ◽  
Point Clouds ◽  
Reference Surface ◽  
Content Type ◽  
Mixed Pixels ◽  
Data Points ◽  
The Impact

PurposeTerrestrial laser scanning (TLS) point clouds have been widely used in deformation measurement for structures. However, reliability and accuracy of resulting deformation estimation strongly depends on quality of each step of a workflow, which are not fully addressed. This study aims to give insight error of these steps, and results of the study would be guidelines for a practical community to either develop a new workflow or refine an existing one of deformation estimation based on TLS point clouds. Thus, the main contributions of the paper are investigating point cloud registration error affecting resulting deformation estimation, identifying an appropriate segmentation method used to extract data points of a deformed surface, investigating a methodology to determine an un-deformed or a reference surface for estimating deformation, and proposing a methodology to minimize the impact of outlier, noisy data and/or mixed pixels on deformation estimation.Design/methodology/approachIn practice, the quality of data point clouds and of surface extraction strongly impacts on resulting deformation estimation based on laser scanning point clouds, which can cause an incorrect decision on the state of the structure if uncertainty is available. In an effort to have more comprehensive insight into those impacts, this study addresses four issues: data errors due to data registration from multiple scanning stations (Issue 1), methods used to extract point clouds of structure surfaces (Issue 2), selection of the reference surface Sref to measure deformation (Issue 3), and available outlier and/or mixed pixels (Issue 4). This investigation demonstrates through estimating deformation of the bridge abutment, building and an oil storage tank.FindingsThe study shows that both random sample consensus (RANSAC) and region growing–based methods [a cell-based/voxel-based region growing (CRG/VRG)] can be extracted data points of surfaces, but RANSAC is only applicable for a primary primitive surface (e.g. a plane in this study) subjected to a small deformation (case study 2 and 3) and cannot eliminate mixed pixels. On another hand, CRG and VRG impose a suitable method applied for deformed, free-form surfaces. In addition, in practice, a reference surface of a structure is mostly not available. The use of a fitting plane based on a point cloud of a current surface would cause unrealistic and inaccurate deformation because outlier data points and data points of damaged areas affect an accuracy of the fitting plane. This study would recommend the use of a reference surface determined based on a design concept/specification. A smoothing method with a spatial interval can be effectively minimize, negative impact of outlier, noisy data and/or mixed pixels on deformation estimation.Research limitations/implicationsDue to difficulty in logistics, an independent measurement cannot be established to assess the deformation accuracy based on TLS data point cloud in the case studies of this research. However, common laser scanners using the time-of-flight or phase-shift principle provide point clouds with accuracy in the order of 1–6 mm, while the point clouds of triangulation scanners have sub-millimetre accuracy.Practical implicationsThis study aims to give insight error of these steps, and the results of the study would be guidelines for a practical community to either develop a new workflow or refine an existing one of deformation estimation based on TLS point clouds.Social implicationsThe results of this study would provide guidelines for a practical community to either develop a new workflow or refine an existing one of deformation estimation based on TLS point clouds. A low-cost method can be applied for deformation analysis of the structure.Originality/valueAlthough a large amount of the studies used laser scanning to measure structure deformation in the last two decades, the methods mainly applied were to measure change between two states (or epochs) of the structure surface and focused on quantifying deformation-based TLS point clouds. Those studies proved that a laser scanner could be an alternative unit to acquire spatial information for deformation monitoring. However, there are still challenges in establishing an appropriate procedure to collect a high quality of point clouds and develop methods to interpret the point clouds to obtain reliable and accurate deformation, when uncertainty, including data quality and reference information, is available. Therefore, this study demonstrates the impact of data quality in a term of point cloud registration error, selected methods for extracting point clouds of surfaces, identifying reference information, and available outlier, noisy data and/or mixed pixels on deformation estimation.

scholarly journals UNCERTAINTY PROPAGATION FOR TERRESTRIAL MOBILE LASER SCANNER

2016 ◽  
Vol XLI-B3 ◽  
pp. 331-335 ◽  
Author(s):  
c Mezian ◽  
Bruno Vallet ◽  
Bahman Soheilian ◽  
Nicolas Paparoditis
Keyword(s):  
Uncertainty Analysis ◽  
Covariance Matrix ◽  
Uncertainty Propagation ◽  
Laser Scanner ◽  
Point Clouds ◽  
3D Point Clouds ◽  
Laser Scanners ◽  
Propagation Technique ◽  
The Impact

Laser scanners are used more and more in mobile mapping systems. They provide 3D point clouds that are used for object reconstruction and registration of the system. For both of those applications, uncertainty analysis of 3D points is of great interest but rarely investigated in the literature. In this paper we present a complete pipeline that takes into account all the sources of uncertainties and allows to compute a covariance matrix per 3D point. The sources of uncertainties are laser scanner, calibration of the scanner in relation to the vehicle and direct georeferencing system. We suppose that all the uncertainties follow the Gaussian law. The variances of the laser scanner measurements (two angles and one distance) are usually evaluated by the constructors. This is also the case for integrated direct georeferencing devices. Residuals of the calibration process were used to estimate the covariance matrix of the 6D transformation between scanner laser and the vehicle system. Knowing the variances of all sources of uncertainties, we applied uncertainty propagation technique to compute the variance-covariance matrix of every obtained 3D point. Such an uncertainty analysis enables to estimate the impact of different laser scanners and georeferencing devices on the quality of obtained 3D points. The obtained uncertainty values were illustrated using error ellipsoids on different datasets.

scholarly journals UNCERTAINTY PROPAGATION FOR TERRESTRIAL MOBILE LASER SCANNER

2016 ◽  
Vol XLI-B3 ◽  
pp. 331-335 ◽  
Author(s):  
c Mezian ◽  
Bruno Vallet ◽  
Bahman Soheilian ◽  
Nicolas Paparoditis
Keyword(s):  
Uncertainty Analysis ◽  
Covariance Matrix ◽  
Uncertainty Propagation ◽  
Laser Scanner ◽  
Point Clouds ◽  
3D Point Clouds ◽  
Laser Scanners ◽  
Propagation Technique ◽  
The Impact

Laser scanners are used more and more in mobile mapping systems. They provide 3D point clouds that are used for object reconstruction and registration of the system. For both of those applications, uncertainty analysis of 3D points is of great interest but rarely investigated in the literature. In this paper we present a complete pipeline that takes into account all the sources of uncertainties and allows to compute a covariance matrix per 3D point. The sources of uncertainties are laser scanner, calibration of the scanner in relation to the vehicle and direct georeferencing system. We suppose that all the uncertainties follow the Gaussian law. The variances of the laser scanner measurements (two angles and one distance) are usually evaluated by the constructors. This is also the case for integrated direct georeferencing devices. Residuals of the calibration process were used to estimate the covariance matrix of the 6D transformation between scanner laser and the vehicle system. Knowing the variances of all sources of uncertainties, we applied uncertainty propagation technique to compute the variance-covariance matrix of every obtained 3D point. Such an uncertainty analysis enables to estimate the impact of different laser scanners and georeferencing devices on the quality of obtained 3D points. The obtained uncertainty values were illustrated using error ellipsoids on different datasets.

Self-Compassion and Quality of Life in Adults Who Stutter

2020 ◽  
Vol 29 (4) ◽  
pp. 2097-2108
Author(s):  
Robyn L. Croft ◽  
Courtney T. Byrd
Keyword(s):  
Quality Of Life ◽  
Social Connectedness ◽  
The Self ◽  
Future Research ◽  
Self Compassion ◽  
Adults Who Stutter ◽  
And Gender ◽  
Relationship Of ◽  
The Impact

Purpose The purpose of this study was to identify levels of self-compassion in adults who do and do not stutter and to determine whether self-compassion predicts the impact of stuttering on quality of life in adults who stutter. Method Participants included 140 adults who do and do not stutter matched for age and gender. All participants completed the Self-Compassion Scale. Adults who stutter also completed the Overall Assessment of the Speaker's Experience of Stuttering. Data were analyzed for self-compassion differences between and within adults who do and do not stutter and to predict self-compassion on quality of life in adults who stutter. Results Adults who do and do not stutter exhibited no significant differences in total self-compassion, regardless of participant gender. A simple linear regression of the total self-compassion score and total Overall Assessment of the Speaker's Experience of Stuttering score showed a significant, negative linear relationship of self-compassion predicting the impact of stuttering on quality of life. Conclusions Data suggest that higher levels of self-kindness, mindfulness, and social connectedness (i.e., self-compassion) are related to reduced negative reactions to stuttering, an increased participation in daily communication situations, and an improved overall quality of life. Future research should replicate current findings and identify moderators of the self-compassion–quality of life relationship.

Surgery for Lung Cancer and the Consequences for the Swallow

2016 ◽  
Vol 1 (13) ◽  
pp. 162-168
Author(s):  
Pippa Hales ◽  
Corinne Mossey-Gaston
Keyword(s):  
Lung Cancer ◽  
Treatment Options ◽  
Vocal Cord Palsy ◽  
Subsequent Treatment ◽  
Physiological Reserve ◽  
Palliative Phase ◽  
And Function ◽  
The Impact ◽  
Swallow Function

Lung cancer is one of the most commonly diagnosed cancers across Northern America and Europe. Treatment options offered are dependent on the type of cancer, the location of the tumor, the staging, and the overall health of the person. When surgery for lung cancer is offered, difficulty swallowing is a potential complication that can have several influencing factors. Surgical interaction with the recurrent laryngeal nerve (RLN) can lead to unilateral vocal cord palsy, altering swallow function and safety. Understanding whether the RLN has been preserved, damaged, or sacrificed is integral to understanding the effect on the swallow and the subsequent treatment options available. There is also the risk of post-surgical reduction of physiological reserve, which can reduce the strength and function of the swallow in addition to any surgery specific complications. As lung cancer has a limited prognosis, the clinician must also factor in the palliative phase, as this can further increase the burden of an already compromised swallow. By understanding the surgery and the implications this may have for the swallow, there is the potential to reduce the impact of post-surgical complications and so improve quality of life (QOL) for people with lung cancer.

Health and Quality of Life in PTSD: What is the Impact of Co-Occurring Depression?

2008 ◽  
Author(s):  
Jennifer S. Fabritius ◽  
Lisa S. Doane ◽  
Aileen M. Echiverri ◽  
Shoshana Y. Kahana ◽  
Joshua D. McDavid ◽  
...  
Keyword(s):  
Quality Of Life ◽  
The Impact
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