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Dr. Petra Helmholz
Curtin University

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Research Keywords & Expertise

0 Photogrammetry
0 Remote Sensing
0 Surveying
0 Underwater
0 Geomatics Engineering

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Remote Sensing
Photogrammetry
Underwater
3D Reconstruction
Surveying

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Short Biography

Dr Petra Helmholz, Senior Lecturer Photogrammetry in Spatial Sciences, holds a German Dipl.-Ing. (equivalent: M.Sc) and a German Dr.-Ing. (Ph.D) in Geomatics. She started her research career in 2006 within the fields of digital Photogrammetry, Remote Sensing and Image Analysis as a scientific and research assistant whilst working at the Institute of Photogrammetry and GeoInformation at the Leibniz University Hannover and the Cooperative Research Centre for Spatial Information (CRC SI) at the University of Melbourne. Since 2012 she works at Curtin as academic staff member; her work includes teaching and research. Current research interests include Underwater Photogrammetry, Terrestrial and Airborne Photogrammetry, and applications of Photogrammetry in the areas of health, agriculture, heritage mapping and engineering.

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Journal article
Published: 15 September 2020 in Remote Sensing
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The number of researchers utilising imagery for the 3D reconstruction of underwater natural (e.g., reefs) and man-made structures (e.g., shipwrecks) is increasing. Often, the same procedures and software solutions are used for processing the images as in-air without considering additional aberrations that can be caused by the change of the medium from air to water. For instance, several publications mention the presence of chromatic aberration (CA). The aim of this paper is to investigate CA effects in low-cost camera systems (several GoPro cameras) operated in an underwater environment. We found that underwater and in-air distortion profiles differed by more than 1000 times in terms of maximum displacement and in terms of curvature. Moreover, significant CA effects were found in the underwater profiles that did not exist in-air. Furthermore, the paper investigates the effect of adjustment constraints imposed on the underwater self-calibration and the reliability of the interior orientation parameters. The analysis of the precision shows that in-air RMS values are just due to random errors. In contrast, the underwater calibration RMS values are 3x-6x higher than the exterior orientation parameter (EOP) precision, so these values contain both random error and the systematic effects from the CA. The accuracy assessment shows significant differences.

ACS Style

Petra Helmholz; Derek Lichti. Investigation of Chromatic Aberration and Its Influence on the Processing of Underwater Imagery. Remote Sensing 2020, 12, 3002 .

AMA Style

Petra Helmholz, Derek Lichti. Investigation of Chromatic Aberration and Its Influence on the Processing of Underwater Imagery. Remote Sensing. 2020; 12 (18):3002.

Chicago/Turabian Style

Petra Helmholz; Derek Lichti. 2020. "Investigation of Chromatic Aberration and Its Influence on the Processing of Underwater Imagery." Remote Sensing 12, no. 18: 3002.

Original article
Published: 06 December 2019 in PFG – Journal of Photogrammetry, Remote Sensing and Geoinformation Science
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Recent advances in the ability to capture high spatial resolution images by unmanned aerial vehicles (UAVs) have shown the potential of this technology for a wide range of application including exploring the effects of different external stimuli when monitoring environmental and structural variables. In this paper, we show the application of UAV technology for crop height monitoring and modelling to provide quantitative crop growth data and demonstrate the remote sensing and photogrammetric capabilities of the technology to the farming industry. This study was carried out in a field trial involving a combination of six wheat varieties and three different fungicide treatments. The UAV imagery of the field trial site was captured on five occasions throughout crop development. These were used to create digital surface models from which crop surface models (CSMs) were extracted for the cropped areas. Crop heights are estimated from the photogrammetric derived CSMs and are compared against the reference heights captured using Real-Time Kinematic Global Navigation Satellite System (GNSS) to validate the CSMs. Furthermore, crop growth differences among varieties are analysed; and crop height correlations with grain yield as well as with independently estimated vegetation indices are evaluated. These evaluations show that the technology is suitable (with average bias range 2–10 cm depending on wind conditions relative to GNSS height) and has potential for quantitative and qualitative monitoring of canopy and/or crop height and growth. Überwachung von Getreidehöhen mit einer handelsüblichen Kamera und UAV Technologie. Jüngste Fortschritte bei der Erfassung von Bildern mit hoher Auflösung durch unbemannte Luftfahrzeuge (Unmanned Aerial Vehicles, UAV) haben das Potenzial dieser Technologie für einen breiten Anwendungsbereich aufgezeigt, einschließlich der Untersuchung der Auswirkungen verschiedener externer Reize bei der Überwachung von Umgebungs- und Strukturvariablen. In diesem Artikel zeigen wir die Anwendung der UAV-Technologie zur Überwachung und Modellierung von Getreidehöhen, um quantitative Getreidewachstumshöhen bereitzustellen und die Fernerkundungs- und photogrammetrische Fähigkeiten der Technologie für die Landwirtschaft zu demonstrieren. Diese Studie wurde in einem Feldversuch mit einer Kombination von sechs Weizensorten und drei verschiedenen Pilzbehandlungen durchgeführt. Die UAV-Bilder des Feldversuchsgeländes wurden während der gesamten Ernteentwicklung fünfmal aufgenommen. Diese Bilder wurden verwendet, um digitale Oberflächenmodelle (Digital Surface Models - DSMs) zu erstellen, aus denen Getreideoberflächenmodelle (Crop Surface Models - CSMs) für die Versuchsflächen extrahiert wurden. Die Erntehöhen werden aus den photogrammetrisch abgeleiteten CSMs geschätzt und mit den Referenzhöhen verglichen, die mit dem Global Navigation Satellite System (GNSS) mit Real-Time Kinematic (RTK) zur Validierung der CSMs erfasst wurden. Darüber hinaus werden Unterschiede im Pflanzenwachstum zwischen den Sorten analysiert und die Korrelation der Getreidehöhe mit dem Getreideertrag sowie mit unabhängig geschätzten Vegetationsindizes ausgewertet. Diese Auswertungen zeigen, dass die Technologie geeignet ist (mit einem durchschnittlichen Bias-Bereich von 2 bis 10 cm in Abhängigkeit von den Windverhältnissen in Bezug auf die GNSS-Höhe) und das Potenzial zur quantitativen und qualitativen Überwachung der Getreidehöhe und des Wachstums vorhanden ist.

ACS Style

D. Belton; P. Helmholz; J. Long; A. Zerihun. Crop Height Monitoring Using a Consumer-Grade Camera and UAV Technology. PFG – Journal of Photogrammetry, Remote Sensing and Geoinformation Science 2019, 87, 249 -262.

AMA Style

D. Belton, P. Helmholz, J. Long, A. Zerihun. Crop Height Monitoring Using a Consumer-Grade Camera and UAV Technology. PFG – Journal of Photogrammetry, Remote Sensing and Geoinformation Science. 2019; 87 (5-6):249-262.

Chicago/Turabian Style

D. Belton; P. Helmholz; J. Long; A. Zerihun. 2019. "Crop Height Monitoring Using a Consumer-Grade Camera and UAV Technology." PFG – Journal of Photogrammetry, Remote Sensing and Geoinformation Science 87, no. 5-6: 249-262.

Journal article
Published: 29 November 2019 in The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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Chromatic aberration in colour digital camera imagery can affect the accuracy of photogrammetric reconstruction. Both longitudinal and transverse chromatic aberrations can be effectively modelled by making separate measurements in each of the blue, green and red colour bands and performing a specialized self-calibrating bundle adjustment. This paper presents the results of an investigation with two aims. The first aim is to quantify the presence of chromatic aberration in two sets of cameras: the six individual cameras comprising a Ladybug5 system, calibrated simultaneously in air; and four GoPro Hero 5 cameras calibrated independently under water. The second aim is to investigate the impacts of imposing different constraints in the self-calibration adjustment. To this end, four different adjustment cases were performed for all ten cameras: independent adjustment of the observations from each colour band; combined adjustment of all colour bands’ observations with common object points; combined adjustment of all colour bands with common object points and common exterior orientation parameters for each colour band triplet; and combined adjustment with common object points and certain common interior orientation parameters. The results show that the Ladybug5 cameras exhibit a small (1-2 pixel) amount of transverse chromatic aberration but no longitudinal chromatic aberration. The GoPro Hero 5 cameras exhibit significant (25 pixel) transverse chromatic aberration as well as longitudinal chromatic aberration. The principal distance was essentially independent of the adjustment case for the Ladybug5, but it was not for the GoPro Hero 5. The principal point position and precision were both affected considerably by adjustment case. Radial lens distortion was invariant to the adjustment case. The impact of adjustment case on decentring distortion was minimal in both cases.

ACS Style

D. D. Lichti; D. Jarron; M. Shahbazi; P. Helmholz; R. Radovanovic. INVESTIGATION INTO THE BEHAVIOUR AND MODELLING OF CHROMATIC ABERRATIONS IN NON-METRIC DIGITAL CAMERAS. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2019, XLII-2/W18, 99 -106.

AMA Style

D. D. Lichti, D. Jarron, M. Shahbazi, P. Helmholz, R. Radovanovic. INVESTIGATION INTO THE BEHAVIOUR AND MODELLING OF CHROMATIC ABERRATIONS IN NON-METRIC DIGITAL CAMERAS. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2019; XLII-2/W18 ():99-106.

Chicago/Turabian Style

D. D. Lichti; D. Jarron; M. Shahbazi; P. Helmholz; R. Radovanovic. 2019. "INVESTIGATION INTO THE BEHAVIOUR AND MODELLING OF CHROMATIC ABERRATIONS IN NON-METRIC DIGITAL CAMERAS." The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W18, no. : 99-106.

Review
Published: 01 September 2019 in The Photogrammetric Record
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Registration is one of the most important tasks in mobile laser scanning (MLS) point cloud processing. This paper firstly reviews existing target‐free matching techniques as well as methods to evaluate the quality of the registration. Next, a new error metric is introduced that takes into account the residuals of check planes as well as their orientation. Experiments using real datasets in combination with reference data were performed to evaluate the suitability of these metrics. The proposed error metric proved to be more suitable for evaluating the quality of point cloud registration than state‐of‐the‐art equivalents. The results also indicate that least squares plane fitting is the best technique for MLS point cloud registration.

ACS Style

Hoang Long Nguyen; David Belton; Petra Helmholz. Review of mobile laser scanning target‐free registration methods for urban areas using improved error metrics. The Photogrammetric Record 2019, 34, 282 -303.

AMA Style

Hoang Long Nguyen, David Belton, Petra Helmholz. Review of mobile laser scanning target‐free registration methods for urban areas using improved error metrics. The Photogrammetric Record. 2019; 34 (167):282-303.

Chicago/Turabian Style

Hoang Long Nguyen; David Belton; Petra Helmholz. 2019. "Review of mobile laser scanning target‐free registration methods for urban areas using improved error metrics." The Photogrammetric Record 34, no. 167: 282-303.

Journal article
Published: 04 June 2019 in The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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The diversity and heterogeneity of coastal, estuarine and stream habitats has led to them becoming a prevalent topic for study. Woody ruins are areas of potential riverbed habitat, particularly for fish. Therefore, the mapping of those areas is of interest. However, due to the limited visibility in some river systems, satellites, airborne or other camera-based systems (passive systems) cannot be used. By contrast, sidescan sonar is a popular underwater acoustic imaging system that is capable of providing high- resolution monochromatic images of the seafloor and riverbeds. Although the study of sidescan sonar imaging using supervised classification has become a prominent research subject, the use of composite texture features in machine learning classification is still limited. This study describes an investigation of the use of texture analysis and feature extraction on side-scan sonar imagery in two supervised machine learning classifications: Support Vector Machine (SVM) and Decision Tree (DT). A combination of first- order texture and second-order texture is investigated to obtain the most appropriate texture features for the image classification. SVM, using linear and Gaussian kernels along with Decision Tree classifiers, was examined using selected texture features. The results of overall accuracy and kappa coefficient revealed that SVM using a linear kernel leads to a more promising result, with 77% overall accuracy and 0.62 kappa, than SVM using either a Gaussian kernel or Decision Tree (60% and 73% overall accuracy, and 0.39 and 0.59 kappa, respectively). However, this study has demonstrated that SVM using linear and Gaussian kernels as well as a Decision Tree makes it capable of being used in side-scan sonar image classification and riverbed habitat mapping.

ACS Style

Hendra Febriawan; P. Helmholz; I. M. Parnum. SUPPORT VECTOR MACHINE AND DECISION TREE BASED CLASSIFICATION OF SIDE-SCAN SONAR MOSAICS USING TEXTURAL FEATURES. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2019, XLII-2/W13, 27 -34.

AMA Style

Hendra Febriawan, P. Helmholz, I. M. Parnum. SUPPORT VECTOR MACHINE AND DECISION TREE BASED CLASSIFICATION OF SIDE-SCAN SONAR MOSAICS USING TEXTURAL FEATURES. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2019; XLII-2/W13 ():27-34.

Chicago/Turabian Style

Hendra Febriawan; P. Helmholz; I. M. Parnum. 2019. "SUPPORT VECTOR MACHINE AND DECISION TREE BASED CLASSIFICATION OF SIDE-SCAN SONAR MOSAICS USING TEXTURAL FEATURES." The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W13, no. : 27-34.

Journal article
Published: 04 June 2019 in The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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With recent advancements in UAV based technology the use of airborne photogrammetry and LiDAR poses a new and effective approach for continuous, fast and efficient beach monitoring surveys. This paper aims to compare three platforms (a DJI Phantom Pro 4 using Ground Control Points, a DJI Matrice 200 with built in PPK allowing direct georeferencing and a DJI Matrice 600 with a Riegl Mini-VUX LiDAR system) in order to assess if they enable beach surveys to be performed efficiently, accurately and cost- effectively. A series of beach surveys were performed over a period of 6 months enabling the ability of each UAV surveying technique to be assessed for the identification and evaluation of trends in the changing topography of beaches and shorelines. The study area (Warnbro Sound, Western Australia) is an area that has experienced significant coastal change over the last 20 years as well as several serious weather events in the course of this research. The results show a significant positive bias of a consistent vertical offset to the ground surface by 4–9 cm between the two image based systems in comparison to the LiDAR system. Although these height offsets are significant it is still within the accuracy required to perform successful beach surveys, and all systems were able to quantify the change of the beach shoreline in area (m2) and volume (m3).

ACS Style

L. Shaw; P. Helmholz; David Belton; N. Addy. COMPARISON OF UAV LIDAR AND IMAGERY FOR BEACH MONITORING. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2019, XLII-2/W13, 589 -596.

AMA Style

L. Shaw, P. Helmholz, David Belton, N. Addy. COMPARISON OF UAV LIDAR AND IMAGERY FOR BEACH MONITORING. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2019; XLII-2/W13 ():589-596.

Chicago/Turabian Style

L. Shaw; P. Helmholz; David Belton; N. Addy. 2019. "COMPARISON OF UAV LIDAR AND IMAGERY FOR BEACH MONITORING." The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W13, no. : 589-596.

Journal article
Published: 29 May 2019 in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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With underwater photogrammetric mapping becoming more prominent due to the lower costs for waterproof cameras as well as lower costs for underwater platforms, the aim of this research is to investigate chromatic aberration in underwater environments. Chromatic aberration in in-air applications is to be known to systematically influence the observations of up to a few pixels. In order to achieve pixel-level positioning accuracy, this systematic influence needs further investigation. However, while chromatic aberration studies have been performed for in-air environments, there is a lack of research to quantify the influence of chromatic aberration in underwater environments. Using images captured in a water tank from three different GoPro cameras in five datasets, we investigate possible chromatic aberration by running two different adjustments on the extracted red (R), green (G) and blue (B) bands. The first adjustment is an adjustment that calculates the interior orientation parameters for each set of images independently in a free network adjustment. The second adjustment solves for all interior orientation parameters (for R, G, and B channels) in a combined adjustment per camera, constraining the point observations in object space. We were able to quantify significant chromatic aberrations in our evaluation, with the largest aberrations observed for red band followed by green and blue.

ACS Style

P. Helmholz; D. D. Lichti. ASSESSMENT OF CHROMATIC ABERRATIONS FOR GOPRO 3 CAMERAS IN UNDERWATER ENVIRONMENTS. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2019, IV-2/W5, 575 -582.

AMA Style

P. Helmholz, D. D. Lichti. ASSESSMENT OF CHROMATIC ABERRATIONS FOR GOPRO 3 CAMERAS IN UNDERWATER ENVIRONMENTS. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2019; IV-2/W5 ():575-582.

Chicago/Turabian Style

P. Helmholz; D. D. Lichti. 2019. "ASSESSMENT OF CHROMATIC ABERRATIONS FOR GOPRO 3 CAMERAS IN UNDERWATER ENVIRONMENTS." ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W5, no. : 575-582.

Journal article
Published: 29 May 2019 in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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Road network asset management is a challenging task as many data sources with different road asset location accuracies are available. In Australia and New Zealand transport agencies are investigating into harmonisation of road asset data, whereby two or more data sets are merged to create a new data set. Currently, identifying relations between road assets of the same meaning is not always possible, as road authorities of these countries use their own data structures and standards. This paper employs SemanticWeb Technologies, such as RDF/Turtle ontologies and semantic rules to enable road network conflation (merge multiple data sets without creating a new data set) as a first step towards data harmonisation by means of information exchange, and shifts road network data from intersections and road nodes to data sets considering the accuracy of the data sets in the selected area. The data integration from GeoJSON into RDF/Turtle files is processed with Python. A geographic coordinates shifting algorithm reads unique data entries that have been extracted from RDF/Turtle into JSON-LD and saves the processed data in their origin file format, so that a closed data flow can be approached.

ACS Style

M. G. Niestroj; D. A. McMeekin; P. Helmholz. INTRODUCING A FRAMEWORK FOR CONFLATING ROAD NETWORK DATA WITH SEMANTIC WEB TECHNOLOGIES. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2019, IV-2/W5, 231 -238.

AMA Style

M. G. Niestroj, D. A. McMeekin, P. Helmholz. INTRODUCING A FRAMEWORK FOR CONFLATING ROAD NETWORK DATA WITH SEMANTIC WEB TECHNOLOGIES. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2019; IV-2/W5 ():231-238.

Chicago/Turabian Style

M. G. Niestroj; D. A. McMeekin; P. Helmholz. 2019. "INTRODUCING A FRAMEWORK FOR CONFLATING ROAD NETWORK DATA WITH SEMANTIC WEB TECHNOLOGIES." ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W5, no. : 231-238.

Original article
Published: 26 March 2019 in The Photogrammetric Record
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An automatic method for the regularisation of building outlines is presented, utilising a combination of data‐ and model‐driven approaches to provide a robust solution. The core part of the method includes a novel data‐driven approach to generate approximate building polygons from a list of given boundary points. The algorithm iteratively calculates and stores likelihood values between an arbitrary starting boundary point and each of the following boundary points using a function derived from the geometrical properties of a building. As a preprocessing step, building segments have to be identified using a robust algorithm for the extraction of a digital elevation model. Evaluation results on a challenging dataset achieved an average correctness of 96·3% and 95·7% for building detection and regularisation, respectively.

ACS Style

Yousif A. Mousa; Petra Helmholz; David Belton; Dimitri Bulatov. Building detection and regularisation using DSM and imagery information. The Photogrammetric Record 2019, 34, 85 -107.

AMA Style

Yousif A. Mousa, Petra Helmholz, David Belton, Dimitri Bulatov. Building detection and regularisation using DSM and imagery information. The Photogrammetric Record. 2019; 34 (165):85-107.

Chicago/Turabian Style

Yousif A. Mousa; Petra Helmholz; David Belton; Dimitri Bulatov. 2019. "Building detection and regularisation using DSM and imagery information." The Photogrammetric Record 34, no. 165: 85-107.

Journal article
Published: 20 March 2019 in ISPRS Journal of Photogrammetry and Remote Sensing
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Plane detection and segmentation is one of the most crucial tasks in point cloud processing. The output from this process can be used as input for further processing steps, such as modelling, registration and calibration. However, the sparseness and heterogeneity of Mobile Laser Scanning (MLS) point clouds may lead to problems for existing planar surfaces detection and segmentation methods. This paper proposes a new method that can be applicable to detect and segment planar features in sparse and heterogeneous MLS point clouds. This method utilises the scan profile patterns and the planarity values between different neighbouring scan profiles to detect and segment planar surfaces from MLS point clouds. The proposed method is compared to the three most state-of-the-art segmentation methods (e.g. RANSAC, a robust segmentation method based on robust statistics and diagnostic principal component analysis – RDCPA as well as the plane detection method based on line arrangement). Three datasets are used for the validation of the results. The results show that our proposed method outperforms the existing methods in detecting and segmenting planar surfaces in sparse and heterogeneous MLS point clouds. In some instances, the state-of-the-art methods produce incorrect segmentation results for façade details which have a similar orientation, such as for windows and doors within a façade. While RDCPA produces up to 50% of outliers depending on the neighbourhood threshold, another method could not detect such features at all. When dealing with small features such as a target, some algorithms (including RANSAC) were unable to perform segmentation. However, the propose algorithm was demonstrated to detect all planes in the test data sets correctly. The paper shows that these mis-segmentations in other algorithms may lead to significant errors in the registration process of between 1.047 and 1.614 degrees in the angular parameters, whereas the propose method had only resulted in 0.462 degree angular bias. Furthermore, it is not sensitive to the required method parameters as well as the point density of the point clouds.

ACS Style

Hoang Long Nguyen; David Belton; Petra Helmholz. Planar surface detection for sparse and heterogeneous mobile laser scanning point clouds. ISPRS Journal of Photogrammetry and Remote Sensing 2019, 151, 141 -161.

AMA Style

Hoang Long Nguyen, David Belton, Petra Helmholz. Planar surface detection for sparse and heterogeneous mobile laser scanning point clouds. ISPRS Journal of Photogrammetry and Remote Sensing. 2019; 151 ():141-161.

Chicago/Turabian Style

Hoang Long Nguyen; David Belton; Petra Helmholz. 2019. "Planar surface detection for sparse and heterogeneous mobile laser scanning point clouds." ISPRS Journal of Photogrammetry and Remote Sensing 151, no. : 141-161.

Journal article
Published: 26 September 2018 in The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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As more cities are starting to experience the urban heat islands effect, knowledge about the energy emitted from building roofs is of primary importance. Since this energy depends both on roof orientations and materials, we tackled both issues by analysing sensor data from multispectral, thermal infrared, high-resolution RGB, and airborne laser datasets (each with different spatial resolutions) of a council in Perth, Australia. To localise the roofs, we acquired building outlines that had to be updated using the normalised digital surface model, the NDVI and the planarity. Then, we computed a semantic 3D model of the study area, with roof detail analysis being a particular focus. The main objective of this study, however, was to classify three commonly used roofing materials: Cement tiles, Colorbond and Zincalume by combining the multispectral and thermal infrared image bands while the high-resolution RGB dataset was used to provide additional information about the roof texture. Three types of image segmentation approaches were evaluated to assess any differences while performing the material classification; pixel-wise, superpixel-wise and building-wise image segmentation. Due to the limited amount of labelled data, we extended the dataset by labelling data ourselves and merged Colorbond and Zincalume into one separate class. The supervised classifier Random Forest was applied to all reasonable configurations of segmentation kinds, numbers of classes, and finally, keeping track of the added value of principal component analysis.

ACS Style

R. Ilehag; Dimitri Bulatov; P. Helmholz; David Belton. CLASSIFICATION AND REPRESENTATION OF COMMONLY USED ROOFING MATERIAL USING MULTISENSORIAL AERIAL DATA. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2018, XLII-1, 217 -224.

AMA Style

R. Ilehag, Dimitri Bulatov, P. Helmholz, David Belton. CLASSIFICATION AND REPRESENTATION OF COMMONLY USED ROOFING MATERIAL USING MULTISENSORIAL AERIAL DATA. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2018; XLII-1 ():217-224.

Chicago/Turabian Style

R. Ilehag; Dimitri Bulatov; P. Helmholz; David Belton. 2018. "CLASSIFICATION AND REPRESENTATION OF COMMONLY USED ROOFING MATERIAL USING MULTISENSORIAL AERIAL DATA." The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-1, no. : 217-224.

Journal article
Published: 19 September 2018 in The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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Governmental agencies, companies and other organisations benefit from sharing data effectively using a harmonised data specification. In asset management, data standards exist from the construction phase through to the operation of the building. A gap exists within transport agencies in Australia and New Zealand for the road asset information exchange. The expectation is that by transferring road asset data from one system to another using a commonly accepted data standard, annual cost savings are predicted to be achieved within these countries of between $65 and $130 million. Current developments are investigating standardising road asset data. This research provides a critical review of data standards for vertical and horizontal infrastructure, namely buildings and roads, and reviews current approaches that deal with the challenge of information exchange for the road network.

ACS Style

M. G. Niestroj; D. A. McMeekin; P. Helmholz. OVERVIEW OF STANDARDS TOWARDS ROAD ASSET INFORMATION EXCHANGE. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2018, XLII-4, 443 -450.

AMA Style

M. G. Niestroj, D. A. McMeekin, P. Helmholz. OVERVIEW OF STANDARDS TOWARDS ROAD ASSET INFORMATION EXCHANGE. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2018; XLII-4 ():443-450.

Chicago/Turabian Style

M. G. Niestroj; D. A. McMeekin; P. Helmholz. 2018. "OVERVIEW OF STANDARDS TOWARDS ROAD ASSET INFORMATION EXCHANGE." The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4, no. : 443-450.

Journal article
Published: 19 September 2018 in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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Data harmonisation improves the coherence between data sets within and across themes and is, therefore, a very helpful tool for governmental agencies, companies and other organisations that share their data. This research focuses on horizontal infrastructures, namely roads, and proposes a new strategy to apply Semantic Web Technologies. The aim is to understand if their application is efficient and effective in filling the gap of data harmonisation in Australia’s and New Zealand’s road asset management systems within the definition of location. The proposed strategy has three stages. First, available international data standards for road assets will be analysed to identify the gaps within these standards and create recommendations towards an improved standard. The second stage is for the location aspect within each stage of the life cycle of asset management with respect to existing road asset data standards. Finally, in a third stage Semantic Web Technologies, ontologies and semantic rules will be used to build a prototype solution for road asset data conflation by merging multiple data sources that share no common lineage. The application of these technologies will allow for easier search and discovery of this data as well as facilitate the automated processing and updating of this data over the Web.

ACS Style

M. G. Niestroj; D. A. McMeekin; P. Helmholz; M. Kuhn. A PROPOSAL TO USE SEMANTIC WEB TECHNOLOGIES FOR IMPROVED ROAD NETWORK INFORMATION EXCHANGE. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2018, IV-4, 147 -154.

AMA Style

M. G. Niestroj, D. A. McMeekin, P. Helmholz, M. Kuhn. A PROPOSAL TO USE SEMANTIC WEB TECHNOLOGIES FOR IMPROVED ROAD NETWORK INFORMATION EXCHANGE. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2018; IV-4 ():147-154.

Chicago/Turabian Style

M. G. Niestroj; D. A. McMeekin; P. Helmholz; M. Kuhn. 2018. "A PROPOSAL TO USE SEMANTIC WEB TECHNOLOGIES FOR IMPROVED ROAD NETWORK INFORMATION EXCHANGE." ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences IV-4, no. : 147-154.

Journal article
Published: 01 November 2017 in Journal of Surveying Engineering
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ACS Style

Qian Yu; Petra Helmholz; David Belton. Semantically Enhanced 3D Building Model Reconstruction from Terrestrial Laser-Scanning Data. Journal of Surveying Engineering 2017, 143, 04017015 .

AMA Style

Qian Yu, Petra Helmholz, David Belton. Semantically Enhanced 3D Building Model Reconstruction from Terrestrial Laser-Scanning Data. Journal of Surveying Engineering. 2017; 143 (4):04017015.

Chicago/Turabian Style

Qian Yu; Petra Helmholz; David Belton. 2017. "Semantically Enhanced 3D Building Model Reconstruction from Terrestrial Laser-Scanning Data." Journal of Surveying Engineering 143, no. 4: 04017015.

Journal article
Published: 13 September 2017 in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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The least square plane fitting adjustment method has been widely used for registration of the mobile laser scanning (MLS) point clouds. The inputs for this process are the plane parameters and points of the corresponding planar features. These inputs can be manually and/or automatically extracted from the MLS point clouds. A number of papers have been proposed to automatically extract planar features. They use different criteria to extract planar features and their outputs are slightly different. This will lead to differences in plane parameters values and points of the corresponding features. This research studies and compares the results of the least square plane fitting adjustment process with different inputs obtained by using different segmentation methods (e.g. RANSAC, RDPCA, Cabo, RGPL) and the results from the point to plane approach – an ICP variant. The questions for this research are: (1) which is the more suitable method for registration of MLS sparse point clouds and (2) which is the best segmentation method to obtain the inputs for the plane based MLS point clouds registration? Experiments were conducted with two real MLS point clouds captured by the MDL – Dynascan S250 system. The results show that ICP is less accurate than the least square plane fitting adjustment. It also shows that the accuracy of the plane based registration process is highly correlated with the mean errors of the extracted planar features and the plane parameters. The conclusion is that the RGPL method seems to be the best methods for planar surfaces extraction in MLS sparse point clouds for the registration process.

ACS Style

H. Long Nguyen; D. Belton; P. Helmholz. COMPARATIVE STUDY OF AUTOMATIC PLANE FITTING REGISTRATION FOR MLS SPARSE POINT CLOUDS WITH DIFFERENT PLANE SEGMENTATION METHODS. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2017, IV-2/W4, 115 -122.

AMA Style

H. Long Nguyen, D. Belton, P. Helmholz. COMPARATIVE STUDY OF AUTOMATIC PLANE FITTING REGISTRATION FOR MLS SPARSE POINT CLOUDS WITH DIFFERENT PLANE SEGMENTATION METHODS. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2017; IV-2/W4 ():115-122.

Chicago/Turabian Style

H. Long Nguyen; D. Belton; P. Helmholz. 2017. "COMPARATIVE STUDY OF AUTOMATIC PLANE FITTING REGISTRATION FOR MLS SPARSE POINT CLOUDS WITH DIFFERENT PLANE SEGMENTATION METHODS." ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W4, no. : 115-122.

Journal article
Published: 04 July 2017 in Heritage Science
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ACS Style

Annabelle Davis; David Belton; Petra Helmholz; Paul Bourke; Jo McDonald. Pilbara rock art: laser scanning, photogrammetry and 3D photographic reconstruction as heritage management tools. Heritage Science 2017, 5, 1 .

AMA Style

Annabelle Davis, David Belton, Petra Helmholz, Paul Bourke, Jo McDonald. Pilbara rock art: laser scanning, photogrammetry and 3D photographic reconstruction as heritage management tools. Heritage Science. 2017; 5 (1):1.

Chicago/Turabian Style

Annabelle Davis; David Belton; Petra Helmholz; Paul Bourke; Jo McDonald. 2017. "Pilbara rock art: laser scanning, photogrammetry and 3D photographic reconstruction as heritage management tools." Heritage Science 5, no. 1: 1.

Journal article
Published: 01 July 2017 in Quaternary Science Reviews
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Not availablePeter Veth, Ingrid Ward, Tiina Manne, Sean Ulm, Kane Ditchfield, Joe Dortch, Fiona Hook, Fiona Petchey, Alan Hogg, Daniele Questiaux, Martina Demuro, Lee Arnold, Nigel Spooner, Vladimir Levchenko, Jane Skippington, Chae Byrne, Mark Basgall, David Zeanah, David Belton, Petra Helmholz, Szilvia Bajkan, Richard Bailey, Christa Placzek, Peter Kendric

ACS Style

Peter Veth; Ingrid Ward; Tiina Manne; Sean Ulm; Kane Ditchfield; Joe Dortch; Fiona Hook; Fiona Petchey; Alan Hogg; Daniele Questiaux; Martina Demuro; Lee Arnold; Nigel Spooner; Vladimir Levchenko; Jane Skippington; Chae Byrne; Mark Basgall; David Zeanah; David Belton; Petra Helmholz; Szilvia Bajkan; Richard Bailey; Christa Placzek; Peter Kendrick. Early human occupation of a maritime desert, Barrow Island, North-West Australia. Quaternary Science Reviews 2017, 168, 19 -29.

AMA Style

Peter Veth, Ingrid Ward, Tiina Manne, Sean Ulm, Kane Ditchfield, Joe Dortch, Fiona Hook, Fiona Petchey, Alan Hogg, Daniele Questiaux, Martina Demuro, Lee Arnold, Nigel Spooner, Vladimir Levchenko, Jane Skippington, Chae Byrne, Mark Basgall, David Zeanah, David Belton, Petra Helmholz, Szilvia Bajkan, Richard Bailey, Christa Placzek, Peter Kendrick. Early human occupation of a maritime desert, Barrow Island, North-West Australia. Quaternary Science Reviews. 2017; 168 ():19-29.

Chicago/Turabian Style

Peter Veth; Ingrid Ward; Tiina Manne; Sean Ulm; Kane Ditchfield; Joe Dortch; Fiona Hook; Fiona Petchey; Alan Hogg; Daniele Questiaux; Martina Demuro; Lee Arnold; Nigel Spooner; Vladimir Levchenko; Jane Skippington; Chae Byrne; Mark Basgall; David Zeanah; David Belton; Petra Helmholz; Szilvia Bajkan; Richard Bailey; Christa Placzek; Peter Kendrick. 2017. "Early human occupation of a maritime desert, Barrow Island, North-West Australia." Quaternary Science Reviews 168, no. : 19-29.

Journal article
Published: 30 May 2017 in The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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In this work, a new filtering approach is proposed for a fully automatic Digital Terrain Model (DTM) extraction from very high resolution airborne images derived Digital Surface Models (DSMs). Our approach represents an enhancement of the existing DTM extraction algorithm Multi-directional and Slope Dependent (MSD) by proposing parameters that are more reliable for the selection of ground pixels and the pixelwise classification. To achieve this, four main steps are implemented: Firstly, 8 well-distributed scanlines are used to search for minima as a ground point within a pre-defined filtering window size. These selected ground points are stored with their positions on a 2D surface to create a network of ground points. Then, an initial DTM is created using an interpolation method to fill the gaps in the 2D surface. Afterwards, a pixel to pixel comparison between the initial DTM and the original DSM is performed utilising pixelwise classification of ground and non-ground pixels by applying a vertical height threshold. Finally, the pixels classified as non-ground are removed and the remaining holes are filled. The approach is evaluated using the Vaihingen benchmark dataset provided by the ISPRS working group III/4. The evaluation includes the comparison of our approach, denoted as Network of Ground Points (NGPs) algorithm, with the DTM created based on MSD as well as a reference DTM generated from LiDAR data. The results show that our proposed approach over performs the MSD approach.

ACS Style

Y. A. Mousa; P. Helmholz; D. Belton. NEW DTM EXTRACTION APPROACH FROM AIRBORNE IMAGES DERIVED DSM. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2017, XLII-1/W1, 75 -82.

AMA Style

Y. A. Mousa, P. Helmholz, D. Belton. NEW DTM EXTRACTION APPROACH FROM AIRBORNE IMAGES DERIVED DSM. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. 2017; XLII-1/W1 ():75-82.

Chicago/Turabian Style

Y. A. Mousa; P. Helmholz; D. Belton. 2017. "NEW DTM EXTRACTION APPROACH FROM AIRBORNE IMAGES DERIVED DSM." The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-1/W1, no. : 75-82.

Journal article
Published: 03 May 2017 in Orphanet Journal of Rare Diseases
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New approaches are required to address the needs of complex undiagnosed diseases patients. These approaches include clinical genomic diagnostic pipelines, utilizing intra- and multi-disciplinary platforms, as well as specialty-specific genomic clinics. Both are advancing diagnostic rates. However, complementary cross-disciplinary approaches are also critical to address those patients with multisystem disorders who traverse the bounds of multiple specialties and remain undiagnosed despite existing intra-specialty and genomic-focused approaches. The diagnostic possibilities of undiagnosed diseases include genetic and non-genetic conditions. The focus on genetic diseases addresses some of these disorders, however a cross-disciplinary approach is needed that also simultaneously addresses other disorder types. Herein, we describe the initiation and summary outcomes of a public health system approach for complex undiagnosed patients - the Undiagnosed Diseases Program-Western Australia (UDP-WA). Briefly the UDP-WA is: i) one of a complementary suite of approaches that is being delivered within health service, and with community engagement, to address the needs of those with severe undiagnosed diseases; ii) delivered within a public health system to support equitable access to health care, including for those from remote and regional areas; iii) providing diagnoses and improved patient care; iv) delivering a platform for in-service and real time genomic and phenomic education for clinicians that traverses a diverse range of specialties; v) retaining and recapturing clinical expertise; vi) supporting the education of junior and more senior medical staff; vii) designed to integrate with clinical translational research; and viii) is supporting greater connectedness for patients, families and medical staff. The UDP-WA has been initiated in the public health system to complement existing clinical genomic approaches; it has been targeted to those with a specific diagnostic need, and initiated by redirecting existing clinical and financial resources. The UDP-WA supports the provision of equitable and sustainable diagnostics and simultaneously supports capacity building in clinical care and translational research, for those with undiagnosed, typically rare, conditions.

ACS Style

Gareth Baynam; Stephanie Broley; Alicia Bauskis; Nicholas Pachter; Fiona McKenzie; Sharron Townshend; Jennie Slee; Cathy Kiraly-Borri; Anand Vasudevan; Anne Hawkins; Lyn Schofield; Petra Helmholz; Richard Palmer; Stefanie Kung; Caroline E. Walker; Caron Molster; Barry Lewis; Kym Mina; John Beilby; Gargi Pathak; Cathryn Poulton; Tudor Groza; Andreas Zankl; Tony Roscioli; Marcel Dinger; John Mattick; William Gahl; Stephen Groft; Cynthia Tifft; Domenica Taruscio; Paul Lasko; Kenjiro Kosaki; Helene Wilhelm; Bela Melegh; Jonathan Carapetis; Sayanta Jana; Gervase Chaney; Allison Johns; Peter Wynn Owen; Frank Daly; Tarun Weeramanthri; Hugh Dawkins; Jack Goldblatt. Initiating an undiagnosed diseases program in the Western Australian public health system. Orphanet Journal of Rare Diseases 2017, 12, 1 -8.

AMA Style

Gareth Baynam, Stephanie Broley, Alicia Bauskis, Nicholas Pachter, Fiona McKenzie, Sharron Townshend, Jennie Slee, Cathy Kiraly-Borri, Anand Vasudevan, Anne Hawkins, Lyn Schofield, Petra Helmholz, Richard Palmer, Stefanie Kung, Caroline E. Walker, Caron Molster, Barry Lewis, Kym Mina, John Beilby, Gargi Pathak, Cathryn Poulton, Tudor Groza, Andreas Zankl, Tony Roscioli, Marcel Dinger, John Mattick, William Gahl, Stephen Groft, Cynthia Tifft, Domenica Taruscio, Paul Lasko, Kenjiro Kosaki, Helene Wilhelm, Bela Melegh, Jonathan Carapetis, Sayanta Jana, Gervase Chaney, Allison Johns, Peter Wynn Owen, Frank Daly, Tarun Weeramanthri, Hugh Dawkins, Jack Goldblatt. Initiating an undiagnosed diseases program in the Western Australian public health system. Orphanet Journal of Rare Diseases. 2017; 12 (1):1-8.

Chicago/Turabian Style

Gareth Baynam; Stephanie Broley; Alicia Bauskis; Nicholas Pachter; Fiona McKenzie; Sharron Townshend; Jennie Slee; Cathy Kiraly-Borri; Anand Vasudevan; Anne Hawkins; Lyn Schofield; Petra Helmholz; Richard Palmer; Stefanie Kung; Caroline E. Walker; Caron Molster; Barry Lewis; Kym Mina; John Beilby; Gargi Pathak; Cathryn Poulton; Tudor Groza; Andreas Zankl; Tony Roscioli; Marcel Dinger; John Mattick; William Gahl; Stephen Groft; Cynthia Tifft; Domenica Taruscio; Paul Lasko; Kenjiro Kosaki; Helene Wilhelm; Bela Melegh; Jonathan Carapetis; Sayanta Jana; Gervase Chaney; Allison Johns; Peter Wynn Owen; Frank Daly; Tarun Weeramanthri; Hugh Dawkins; Jack Goldblatt. 2017. "Initiating an undiagnosed diseases program in the Western Australian public health system." Orphanet Journal of Rare Diseases 12, no. 1: 1-8.

Perspective article
Published: 10 April 2017 in Frontiers in Public Health
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Precision public health is a new field driven by technological advances that enable more precise descriptions and analyses of individuals and population groups, with a view to improving the overall health of populations. This promises to lead to more precise clinical and public health practices, across the continuum of prevention, screening, diagnosis and treatment. A phenotype is the set of observable characteristics of an individual resulting from the interaction of a genotype with the environment. Precision (deep) phenotyping, applies innovative technologies to exhaustively and more precisely examine the discrete components of a phenotype, and goes beyond the information usually included in medical charts. This form of phenotyping is a critical component of more precise diagnostic capability and 3D facial analysis (3DFA) is a key technological enabler in this domain. In this paper we examine the potential of 3DFA as a public health tool, by viewing it against the 10 essential public health services of the ‘public health wheel’, developed by the US Centers for Disease Control. This provides an illustrative framework to gauge current and emergent applications of genomic technologies for implementing precision public health.

ACS Style

Gareth Baynam; Alicia Bauskis; Nicholas Pachter; Lyn Schofield; Hedwig Verhoef; Richard L. Palmer; Stefanie Kung; Petra Helmholz; Michael Ridout; Caroline E. Walker; Anne Hawkins; Jack Goldblatt; Tarun S. Weeramanthri; Hugh J. S. Dawkins; Caron M. Molster. 3-Dimensional Facial Analysis—Facing Precision Public Health. Frontiers in Public Health 2017, 5, 1 .

AMA Style

Gareth Baynam, Alicia Bauskis, Nicholas Pachter, Lyn Schofield, Hedwig Verhoef, Richard L. Palmer, Stefanie Kung, Petra Helmholz, Michael Ridout, Caroline E. Walker, Anne Hawkins, Jack Goldblatt, Tarun S. Weeramanthri, Hugh J. S. Dawkins, Caron M. Molster. 3-Dimensional Facial Analysis—Facing Precision Public Health. Frontiers in Public Health. 2017; 5 ():1.

Chicago/Turabian Style

Gareth Baynam; Alicia Bauskis; Nicholas Pachter; Lyn Schofield; Hedwig Verhoef; Richard L. Palmer; Stefanie Kung; Petra Helmholz; Michael Ridout; Caroline E. Walker; Anne Hawkins; Jack Goldblatt; Tarun S. Weeramanthri; Hugh J. S. Dawkins; Caron M. Molster. 2017. "3-Dimensional Facial Analysis—Facing Precision Public Health." Frontiers in Public Health 5, no. : 1.