title: Image processing and machine learning for segmentation and classification of aluminium extrusions

authors: Pehrson, Michelle Josefina

abstract: Inventory management is one of the most important components of administration in a large-scale manufacturing business. Architectural Profile Limited produces tonnes of aluminium profiles every single day and have over one thousand different extrusions available. Many of the profiles look almost identical to each other and are very difficult for even a highly experienced employee to distinguish. Sending out an incorrect extrusion will cost time and money for both the manufacturer and the customer.

Automation using machine vision is already a prominent tool used in factory environments worldwide. The ability to automate repetitive tasks frees up time for higher skill tasks and reduces manual data entry errors. A real time inventory monitoring system would allow for quick and confident decision making and reduce order problems due to out of date stock numbers.

The aim of this project is to explore whether classification of extrusion profiles from images is possible and what factors ensure an accurate classification system. To achieve the aim, new data was acquired that captures a range of variation such as different angles, positions and lighting.

In this thesis two main paths were explored, segmentation followed by classification of binary images using generic Fourier descriptors, and direct classification from colour images. This thesis presents a qualitative and quantitative analysis of the different approaches, and discusses the challenges and limitations found with the data. The methods are compared and recommendations are highlighted regarding the next steps that aid creation of an automated aluminium extrusion inventory management system.

Presented is a pipeline of extracting features using techniques such as Gabor filters, Gaussian blur, and edge detectors. The output filters are used to train a random forest pixel classifier to segment the extrusions. Perfect reference binary images generated via a semi-manual threshold process are used to train a Logistic Regression classifier, and the test images were automatically segmented and classified. This classifier makes predictions on the segmented images, and the testing accuracy achieved was 88%. Instances that were misclassified had poor segmentations, in most cases from uneven illumination on the extrusion end. The other promising method is training convolutional neural networks using transfer learning. VGG-19 was trained with only the dataset acquired and achieved a testing accuracy of 89%, while ResNet-50 was trained using data augmentation and achieved a testing accuracy of 90%. The resulting confusion matrices show misclassifications between extrusions that are very similar in shape and size.

Further work will improve the performance of the classifiers by fine-tuning the parameters and carrying out parameter searching. Further investigation should be carried out given more requirements for the application, such as the processors and exact lighting conditions.

text: Image processing and machine learning for segmentation and classification of aluminium extrusions Inventory management is one of the most important components of administration in a large-scale manufacturing business. Architectural Profile Limited produces tonnes of aluminium profiles every single day and have over one thousand different extrusions available. Many of the profiles look almost identical to each other and are very difficult for even a highly experienced employee to distinguish. Sending out an incorrect extrusion will cost time and money for both the manufacturer and the customer.

Automation using machine vision is already a prominent tool used in factory environments worldwide. The ability to automate repetitive tasks frees up time for higher skill tasks and reduces manual data entry errors. A real time inventory monitoring system would allow for quick and confident decision making and reduce order problems due to out of date stock numbers.

The aim of this project is to explore whether classification of extrusion profiles from images is possible and what factors ensure an accurate classification system. To achieve the aim, new data was acquired that captures a range of variation such as different angles, positions and lighting.

In this thesis two main paths were explored, segmentation followed by classification of binary images using generic Fourier descriptors, and direct classification from colour images. This thesis presents a qualitative and quantitative analysis of the different approaches, and discusses the challenges and limitations found with the data. The methods are compared and recommendations are highlighted regarding the next steps that aid creation of an automated aluminium extrusion inventory management system.

Presented is a pipeline of extracting features using techniques such as Gabor filters, Gaussian blur, and edge detectors. The output filters are used to train a random forest pixel classifier to segment the extrusions. Perfect reference binary images generated via a semi-manual threshold process are used to train a Logistic Regression classifier, and the test images were automatically segmented and classified. This classifier makes predictions on the segmented images, and the testing accuracy achieved was 88%. Instances that were misclassified had poor segmentations, in most cases from uneven illumination on the extrusion end. The other promising method is training convolutional neural networks using transfer learning. VGG-19 was trained with only the dataset acquired and achieved a testing accuracy of 89%, while ResNet-50 was trained using data augmentation and achieved a testing accuracy of 90%. The resulting confusion matrices show misclassifications between extrusions that are very similar in shape and size.

Further work will improve the performance of the classifiers by fine-tuning the parameters and carrying out parameter searching. Further investigation should be carried out given more requirements for the application, such as the processors and exact lighting conditions.

year: 2022

title: Marine wood borers in New Zealand: an interdisciplinary study of their origins, impacts and management

authors: Rayes, Courtney A.

subjects: biological invasion

abstract: Non-indigenous marine species are a major concern worldwide. For some species, insufficient historical and biogeographical data can leave their origin and patterns of dispersal difficult to determine. Among such species are marine wood borers. This thesis uses an interdisciplinary approach, combining both historical and biological methods, to address marine borer impacts, management attempts, and their status in New Zealand. 
This research had two key components. Firstly, a historical review sought to improve the understanding and awareness of the historic impacts and responses to borers, with particular reference to New Zealand between 1850 and 1930. Marine wood borers have had profound impacts throughout history, responsible for significant structural and economic damage to wooden ships and marine infrastructure globally. In New Zealand, trade and economy played an important role in providing both the transportation vectors and infrastructure for marine wood borers to inhabit. Ongoing trialling of timber alternatives and chemicals for the preservation of infrastructure followed, with little success until the introduction of ferro-concrete in the early 1900s. When considered in a global context, the New Zealand case study of borer impacts and management attempts highlights their significant role in environmental history. 
Mitochondrial DNA (COI) sequence analyses were used to examine the questionable invasion histories and status of common marine wood borers in New Zealand. It has been assumed that many marine wood borers invaded New Zealand via wooden ships. However, these purported introductions are historic, and the specific origins of many species are unclear. Species from three families and two phyla were collected around the North Island, New Zealand; Teredinidae (Bivalvia: Mollusca), Sphaeromatidae and Limnoriidae (Isopoda: Arthropoda). Low levels of genetic divergence (0-2%) were found among the New Zealand populations of two species, Limnoria quadripunctata and Sphaeroma quoianum, suggesting a non-indigenous status. Limnoria quadripunctata also showed a close genetic affinity to populations in Chile, supporting a non-indigenous status, with its widespread distribution in New Zealand explained by multiple introductions. For Lyrodus pedicellatus, a lack of genetic affinity to conspecifics sequenced elsewhere (France), greater genetic diversity compared to the native Bankia australis, and evidence of population structuring among New Zealand locations, suggested L. pedicellatus may be native to New Zealand. Lyrodus pedicellatus from New Zealand was highly divergent (>20%) from global L. pedicellatus populations, suggesting that either identifications of specimens on global databases are incorrect, or the New Zealand species represents a morphologically undescribed cryptic congener. In conclusion, COI sequences provided a useful tool in elucidating the status of marine wood borers in New Zealand, and highlighted a need for taxonomic resolution of some species.  
Collectively the two chapters illustrate the knowledge gaps and lack of recognition surrounding marine wood borers, globally and in New Zealand. This research provides an extensive understanding of their significant historical role in marine environmental history and assists in re-evaluation of their current native or non-indigenous status in New Zealand.

text: Marine wood borers in New Zealand: an interdisciplinary study of their origins, impacts and management Non-indigenous marine species are a major concern worldwide. For some species, insufficient historical and biogeographical data can leave their origin and patterns of dispersal difficult to determine. Among such species are marine wood borers. This thesis uses an interdisciplinary approach, combining both historical and biological methods, to address marine borer impacts, management attempts, and their status in New Zealand. 
This research had two key components. Firstly, a historical review sought to improve the understanding and awareness of the historic impacts and responses to borers, with particular reference to New Zealand between 1850 and 1930. Marine wood borers have had profound impacts throughout history, responsible for significant structural and economic damage to wooden ships and marine infrastructure globally. In New Zealand, trade and economy played an important role in providing both the transportation vectors and infrastructure for marine wood borers to inhabit. Ongoing trialling of timber alternatives and chemicals for the preservation of infrastructure followed, with little success until the introduction of ferro-concrete in the early 1900s. When considered in a global context, the New Zealand case study of borer impacts and management attempts highlights their significant role in environmental history. 
Mitochondrial DNA (COI) sequence analyses were used to examine the questionable invasion histories and status of common marine wood borers in New Zealand. It has been assumed that many marine wood borers invaded New Zealand via wooden ships. However, these purported introductions are historic, and the specific origins of many species are unclear. Species from three families and two phyla were collected around the North Island, New Zealand; Teredinidae (Bivalvia: Mollusca), Sphaeromatidae and Limnoriidae (Isopoda: Arthropoda). Low levels of genetic divergence (0-2%) were found among the New Zealand populations of two species, Limnoria quadripunctata and Sphaeroma quoianum, suggesting a non-indigenous status. Limnoria quadripunctata also showed a close genetic affinity to populations in Chile, supporting a non-indigenous status, with its widespread distribution in New Zealand explained by multiple introductions. For Lyrodus pedicellatus, a lack of genetic affinity to conspecifics sequenced elsewhere (France), greater genetic diversity compared to the native Bankia australis, and evidence of population structuring among New Zealand locations, suggested L. pedicellatus may be native to New Zealand. Lyrodus pedicellatus from New Zealand was highly divergent (>20%) from global L. pedicellatus populations, suggesting that either identifications of specimens on global databases are incorrect, or the New Zealand species represents a morphologically undescribed cryptic congener. In conclusion, COI sequences provided a useful tool in elucidating the status of marine wood borers in New Zealand, and highlighted a need for taxonomic resolution of some species.  
Collectively the two chapters illustrate the knowledge gaps and lack of recognition surrounding marine wood borers, globally and in New Zealand. This research provides an extensive understanding of their significant historical role in marine environmental history and assists in re-evaluation of their current native or non-indigenous status in New Zealand.

year: 2014

title: Restorying the individual: The cultural dimension of special education in three Te Arawa sites

authors: Macfarlane, Angus H

subjects: Māori special education

abstract: On the basis of observation of three Te Arawa educational sites, it is argued here that a central characteristic of successful programmes that attend to Māori students with special needs is cultural-centredness. Significant aspects of that culture-centredness are outlined here, aspects that, it is argued, are fundamental to the process of restorying that is, it is argued, critical to the success of many Māori students, particularly those with special needs.

text: Restorying the individual: The cultural dimension of special education in three Te Arawa sites On the basis of observation of three Te Arawa educational sites, it is argued here that a central characteristic of successful programmes that attend to Māori students with special needs is cultural-centredness. Significant aspects of that culture-centredness are outlined here, aspects that, it is argued, are fundamental to the process of restorying that is, it is argued, critical to the success of many Māori students, particularly those with special needs.

year: 2002-09