title: Navigating the noise: evaluating the occurence of vessels and cetaceans within tamatea/dusky sound

authors: Bassett, Oliver

subjects: marine acoustics

abstract: Vessel use associated with recreation and tourism is currently increasing without limits in Dusky Sound. Passive acoustic monitoring was used to investigate spatiotemporal presence and potential cooccurrence of vessels with the endangered resident subpopulation of Fiordland bottlenose dolphins (Tursiops truncatus) and migratory humpback whales (Megaptera novaeangliae) within Tamatea/Dusky Sound, Fiordland Marine Area (FMA). Hydrophones were deployed between February 2022 and November 2023 at three recording sites to collect soundscape data within Dusky Sound. The internal coastline of Five Fingers Peninsula, inside Taumoana Marine Reserve, was identified as a previously unrecognised area of significant usage for Fiordland bottlenose dolphins. Detected humpback whale presence coincided with peaks in migration, and though identified by previous visual surveying efforts, the extent of their presence in the area during their northward migration was previously unreported. Humpback whale presence was significantly higher in June compared with other months, which is consistent with their described increased vocalisation behaviour during the northward migration. 

Vessel presence detected by passive acoustic monitoring was primarily dictated by usage patterns of tourism and recreational vessels and was greatest in the channel south of Anchor Island, a highly utilised access into Dusky Sound from the outer coast. Monthly equivalent continuous sound levels (LEqs), produced using Automatic Identification System vessel records and sound propagation modelling, illustrated that sound exposure levels regularly reached ~150 dB re 1 µPa2.s within the study area. Cruise ship transits were the major contributor to these high levels, with noise levels exceeding the recommended behavioural exposure threshold for continuous sound in much of the area during the late spring and summer months. Proactive management strategies including vessel limits, speed restrictions (slowdowns) and exclusion zones (dolphin protection zones) are likely required in the future to protect these species before the potential impacts from increased tourism is seen in Tamatea/Dusky Sound.

text: Navigating the noise: evaluating the occurence of vessels and cetaceans within tamatea/dusky sound Vessel use associated with recreation and tourism is currently increasing without limits in Dusky Sound. Passive acoustic monitoring was used to investigate spatiotemporal presence and potential cooccurrence of vessels with the endangered resident subpopulation of Fiordland bottlenose dolphins (Tursiops truncatus) and migratory humpback whales (Megaptera novaeangliae) within Tamatea/Dusky Sound, Fiordland Marine Area (FMA). Hydrophones were deployed between February 2022 and November 2023 at three recording sites to collect soundscape data within Dusky Sound. The internal coastline of Five Fingers Peninsula, inside Taumoana Marine Reserve, was identified as a previously unrecognised area of significant usage for Fiordland bottlenose dolphins. Detected humpback whale presence coincided with peaks in migration, and though identified by previous visual surveying efforts, the extent of their presence in the area during their northward migration was previously unreported. Humpback whale presence was significantly higher in June compared with other months, which is consistent with their described increased vocalisation behaviour during the northward migration. 

Vessel presence detected by passive acoustic monitoring was primarily dictated by usage patterns of tourism and recreational vessels and was greatest in the channel south of Anchor Island, a highly utilised access into Dusky Sound from the outer coast. Monthly equivalent continuous sound levels (LEqs), produced using Automatic Identification System vessel records and sound propagation modelling, illustrated that sound exposure levels regularly reached ~150 dB re 1 µPa2.s within the study area. Cruise ship transits were the major contributor to these high levels, with noise levels exceeding the recommended behavioural exposure threshold for continuous sound in much of the area during the late spring and summer months. Proactive management strategies including vessel limits, speed restrictions (slowdowns) and exclusion zones (dolphin protection zones) are likely required in the future to protect these species before the potential impacts from increased tourism is seen in Tamatea/Dusky Sound.

year: 2024

title: Adapting the bidirectional Kalman filter for use in multi-frequency Time-of-flight range imaging

authors: Alqassab, Ali

subjects: Time-of-flight

abstract: Time-of-flight range imaging cameras obtain range by producing amplitude modulated light and measuring the time taken for light to travel to the scene and back to the camera. Time-of-flight cameras require at least three raw measurements to calculate range. Raw frames are captured sequentially, and as such, motion in scenes during capture leads to inconsistent raw frame measurements and erroneous range calculations. Motion error constrains Time-of-flight cameras to non-dynamic scenes and limits their potential applications. The Time-of-flight bidirectional Kalman filter method is a state-of-the-art method known to reduce error due to transverse motion in cameras operating with a single modulation frequency. The method works by treating raw frames as a noisy time series and running the Kalman filter on it to produce a range estimation at every raw frame. The Kalman filter is then reapplied to the data in reverse to produce another set of range estimations, and a composite range is selected from the two set of range estimations. A number of commercial timeof-flight cameras, such as the Microsoft Kinect V2, use multiple modulation frequencies. In this thesis, we adapt the bidirectional Kalman filter method to multi-frequency operated cameras by having the prediction component of the Kalman filter take into account the change in amplitude and phase shift caused by the change in frequency. The amplitude component of the prediction is performed linearly by multiplication, while the phase shift component of the prediction is performed using the ratio of the modulation frequencies. The phase shift prediction across modulation frequencies requires the phase to be unwrapped. The unwrapping is performed between modulation frequencies by selecting the number of phase wraps that best predicts the two following raw frames. Finally, to ensure correct composite phase selection, an alternative method for selecting the composite phase is proposed for the adapted bidirectional Kalman filter. We perform quantitative and qualitative experiments to test the proposed method. In the quantitative experiment, the proposed method produces less error than the classical Discrete Fourier Transform approach in 70% of tested instances. The qualitative experiment shows that the proposed method significantly reduces motion blur.

text: Adapting the bidirectional Kalman filter for use in multi-frequency Time-of-flight range imaging Time-of-flight range imaging cameras obtain range by producing amplitude modulated light and measuring the time taken for light to travel to the scene and back to the camera. Time-of-flight cameras require at least three raw measurements to calculate range. Raw frames are captured sequentially, and as such, motion in scenes during capture leads to inconsistent raw frame measurements and erroneous range calculations. Motion error constrains Time-of-flight cameras to non-dynamic scenes and limits their potential applications. The Time-of-flight bidirectional Kalman filter method is a state-of-the-art method known to reduce error due to transverse motion in cameras operating with a single modulation frequency. The method works by treating raw frames as a noisy time series and running the Kalman filter on it to produce a range estimation at every raw frame. The Kalman filter is then reapplied to the data in reverse to produce another set of range estimations, and a composite range is selected from the two set of range estimations. A number of commercial timeof-flight cameras, such as the Microsoft Kinect V2, use multiple modulation frequencies. In this thesis, we adapt the bidirectional Kalman filter method to multi-frequency operated cameras by having the prediction component of the Kalman filter take into account the change in amplitude and phase shift caused by the change in frequency. The amplitude component of the prediction is performed linearly by multiplication, while the phase shift component of the prediction is performed using the ratio of the modulation frequencies. The phase shift prediction across modulation frequencies requires the phase to be unwrapped. The unwrapping is performed between modulation frequencies by selecting the number of phase wraps that best predicts the two following raw frames. Finally, to ensure correct composite phase selection, an alternative method for selecting the composite phase is proposed for the adapted bidirectional Kalman filter. We perform quantitative and qualitative experiments to test the proposed method. In the quantitative experiment, the proposed method produces less error than the classical Discrete Fourier Transform approach in 70% of tested instances. The qualitative experiment shows that the proposed method significantly reduces motion blur.

year: 2020

title: Māori data sovereignty and privacy

authors: Kukutai, Tahu

abstract: Privacy is a fundamental human right. One of its most important aspects is information privacy – providing individuals with control over the way in which their personal data is collected, used, disclosed and otherwise handled. Existing information privacy regulation neither recognises nor protects the collective privacy rights of Indigenous peoples. This paper explores Indigenous data
privacy, and the challenges and opportunities, in the context of Aotearoa. It has two aims: to identify gaps in existing data privacy approaches with regards to Indigenous data, and to provide a foundation for progressing alternative privacy paradigms. We argue that while personal data protection is necessary, it is insufficient to meet the needs of Māori and Aotearoa more broadly. In so doing, we draw on three areas of research: Indigenous and Māori data sovereignty; data and information privacy,
including collective privacy; and Māori and Indigenous privacy perspectives. We examine key features of the Aotearoa privacy context – including the Privacy Act 2020 (NZ) – and consider the implications of te Tiriti o Waitangi and tikanga Māori for alternative privacy approaches. Future options, including legal and extra-legal measures, are proposed.

text: Māori data sovereignty and privacy Privacy is a fundamental human right. One of its most important aspects is information privacy – providing individuals with control over the way in which their personal data is collected, used, disclosed and otherwise handled. Existing information privacy regulation neither recognises nor protects the collective privacy rights of Indigenous peoples. This paper explores Indigenous data
privacy, and the challenges and opportunities, in the context of Aotearoa. It has two aims: to identify gaps in existing data privacy approaches with regards to Indigenous data, and to provide a foundation for progressing alternative privacy paradigms. We argue that while personal data protection is necessary, it is insufficient to meet the needs of Māori and Aotearoa more broadly. In so doing, we draw on three areas of research: Indigenous and Māori data sovereignty; data and information privacy,
including collective privacy; and Māori and Indigenous privacy perspectives. We examine key features of the Aotearoa privacy context – including the Privacy Act 2020 (NZ) – and consider the implications of te Tiriti o Waitangi and tikanga Māori for alternative privacy approaches. Future options, including legal and extra-legal measures, are proposed.

year: 2023