title: Towards optical flow in time-of-flight range imaging using the continuous wavelet transform

authors: Wise, JJ

abstract: Time-of-flight (ToF) range imaging cameras perform full-field distance measurement, but require multiple frames to be captured sequentially in order to construct a single range image. When motion occurs during data acquisition, artifacts appear that limit the accuracy of range estimates. Analysis of these artifacts finds that they take the form of spatial waves whose frequency encodes motion information. We therefore propose a new technique for measuring motion in Time-of-Flight range imaging based on the continuous wavelet transform (CWT). Synchrosqueezing is explored as a means of improving the accuracy of velocity estimates.

text: Towards optical flow in time-of-flight range imaging using the continuous wavelet transform Time-of-flight (ToF) range imaging cameras perform full-field distance measurement, but require multiple frames to be captured sequentially in order to construct a single range image. When motion occurs during data acquisition, artifacts appear that limit the accuracy of range estimates. Analysis of these artifacts finds that they take the form of spatial waves whose frequency encodes motion information. We therefore propose a new technique for measuring motion in Time-of-Flight range imaging based on the continuous wavelet transform (CWT). Synchrosqueezing is explored as a means of improving the accuracy of velocity estimates.

year: 2024-01-01

title: Colonisation, Fragment Recovery, and Disturbance in Zostera muelleri Beds, Raglan

authors: Cade, Octavia Jane

subjects: Seagrass

abstract: Zostera muelleri is a seagrass currently on the decline in New Zealand. Potential conservation methods rely on accurate information tailored to local sites. This thesis considers the Z. muelleri beds at Raglan harbour, New Zealand. It focuses on their mechanisms for acquiring genetic diversity, and their ability to prove resilient to small-scale disturbance.

Extensive sediment sampling at four different study sites within the Raglan harbour has yielded no evidence of a seed bank. Z. muelleri reproduction at this site is likely therefore vegetative. Without sexual reproduction to increase the genetic diversity (and therefore the resilience) of the beds, this diversity can be increased by the natural mechanism of seagrass fragments or the deliberate transplantation of seeds, seedlings, or adult plants. This, however, raises conservation questions regarding the tension between “original” and “resilient” environmental states. 

Genetic diversity within the seagrass beds may be introduced via the natural dispersal of seagrass fragments. Fragments collected in austral autumn (April) and spring (September) were tested to determine if length of dispersal (floating) time impacted their ability to grow either rhizome length or new shoots. Fragments were randomly assigned to one of five treatments (T0-T4) and left to float for between 0-28 days before planting (T0 = 0 days; T1 = 7 days; T2 = 14 days; T3 = 21 days; T4 = 28 days). After a six-week planting there was no statistically significant difference in rhizome or shoot growth between treatments or between collection times.   

The ability of Z. muelleri to respond to small-scale disturbance was also assessed. The presence of Canada geese (Branta canadensis) has been noted feeding on New Zealand seagrass for the first time, and an experiment mimicking their feeding patterns performed. Z. muelleri proved highly resilient to single-event, small scale disturbance at all tidal levels. However, the rapidly increasing population of geese in the Waikato region is expected to increase the level of disturbance to the Raglan beds, and their ability to respond to repetitive, large-scale disturbance may be crucial to their continued survival.

text: Colonisation, Fragment Recovery, and Disturbance in Zostera muelleri Beds, Raglan Zostera muelleri is a seagrass currently on the decline in New Zealand. Potential conservation methods rely on accurate information tailored to local sites. This thesis considers the Z. muelleri beds at Raglan harbour, New Zealand. It focuses on their mechanisms for acquiring genetic diversity, and their ability to prove resilient to small-scale disturbance.

Extensive sediment sampling at four different study sites within the Raglan harbour has yielded no evidence of a seed bank. Z. muelleri reproduction at this site is likely therefore vegetative. Without sexual reproduction to increase the genetic diversity (and therefore the resilience) of the beds, this diversity can be increased by the natural mechanism of seagrass fragments or the deliberate transplantation of seeds, seedlings, or adult plants. This, however, raises conservation questions regarding the tension between “original” and “resilient” environmental states. 

Genetic diversity within the seagrass beds may be introduced via the natural dispersal of seagrass fragments. Fragments collected in austral autumn (April) and spring (September) were tested to determine if length of dispersal (floating) time impacted their ability to grow either rhizome length or new shoots. Fragments were randomly assigned to one of five treatments (T0-T4) and left to float for between 0-28 days before planting (T0 = 0 days; T1 = 7 days; T2 = 14 days; T3 = 21 days; T4 = 28 days). After a six-week planting there was no statistically significant difference in rhizome or shoot growth between treatments or between collection times.   

The ability of Z. muelleri to respond to small-scale disturbance was also assessed. The presence of Canada geese (Branta canadensis) has been noted feeding on New Zealand seagrass for the first time, and an experiment mimicking their feeding patterns performed. Z. muelleri proved highly resilient to single-event, small scale disturbance at all tidal levels. However, the rapidly increasing population of geese in the Waikato region is expected to increase the level of disturbance to the Raglan beds, and their ability to respond to repetitive, large-scale disturbance may be crucial to their continued survival.

year: 2016

title: Planning for the protection and enhancement of marine environments' wellbeing

authors: Barnsdall, Aaron

subjects: marine

abstract: The wellbeing of marine environments has a direct relationship with the types of whenua (land, placenta) use and management practices that go from the mountains to the sea. In Aotearoa, activities that are carried out in this land-marine interface, including those related to Nature-based Solutions (NbSs), are regulated by national, regional, and district policies (e.g., New Zealand Coastal Policy Statement, regional plans, and district plans). However, due to its novel character, not all current policies account for the realisation of NbSs nor are NbSs’ potential for addressing the wellbeing of our marine environments well understood.

This dissertation focuses on Tauranga Moana (the seas of Tauranga) as the chosen locality for the case study area, to:

i) investigate how the Ngapeke 7 Trust’s community participants in the Ngāti Pūkenga area of Tauranga Moana understand and value NbSs for addressing the wellbeing of their marine systems; and,
ii) review current planning policies and mechanisms to identify barriers, enablers, and gaps that support or hinder the implementation of NbSs in Tauranga Moana, observing through a Kaupapa Māori lens.

Findings emphasize that integrating mātauranga Māori and Māori Ecological Knowledge (MEK) with scientific knowledge offers a holistic approach to environmental management, enhancing decision-making, education, and policy. Key Māori values, including whakapapa, mauri, and kaitiakitanga, are central to this approach.

The research identifies gaps in policies regarding NbS realization and a need for greater understanding of NbS potential and Māori perspectives. Implications include the necessity of integrating MEK into environmental practices and policies, and the value of NbSs for effective and equitable environmental outcomes. Limitations include sample size and scope, which focused on the Ngapeke 7 block. This research contributes valuable insights for environmental planning and management by centring mātauranga Māori and values in NbS implementation for marine health.

text: Planning for the protection and enhancement of marine environments' wellbeing The wellbeing of marine environments has a direct relationship with the types of whenua (land, placenta) use and management practices that go from the mountains to the sea. In Aotearoa, activities that are carried out in this land-marine interface, including those related to Nature-based Solutions (NbSs), are regulated by national, regional, and district policies (e.g., New Zealand Coastal Policy Statement, regional plans, and district plans). However, due to its novel character, not all current policies account for the realisation of NbSs nor are NbSs’ potential for addressing the wellbeing of our marine environments well understood.

This dissertation focuses on Tauranga Moana (the seas of Tauranga) as the chosen locality for the case study area, to:

i) investigate how the Ngapeke 7 Trust’s community participants in the Ngāti Pūkenga area of Tauranga Moana understand and value NbSs for addressing the wellbeing of their marine systems; and,
ii) review current planning policies and mechanisms to identify barriers, enablers, and gaps that support or hinder the implementation of NbSs in Tauranga Moana, observing through a Kaupapa Māori lens.

Findings emphasize that integrating mātauranga Māori and Māori Ecological Knowledge (MEK) with scientific knowledge offers a holistic approach to environmental management, enhancing decision-making, education, and policy. Key Māori values, including whakapapa, mauri, and kaitiakitanga, are central to this approach.

The research identifies gaps in policies regarding NbS realization and a need for greater understanding of NbS potential and Māori perspectives. Implications include the necessity of integrating MEK into environmental practices and policies, and the value of NbSs for effective and equitable environmental outcomes. Limitations include sample size and scope, which focused on the Ngapeke 7 block. This research contributes valuable insights for environmental planning and management by centring mātauranga Māori and values in NbS implementation for marine health.

year: 2025-04-16