title: Determining Canopy Vigour in G3 Kiwifruit using Remote Sensing and Geographic Information Systems

authors: Hull, Graham George

subjects: GIS

abstract: Consumers are increasingly demanding that food producers justify their use of water, fertiliser and agrichemicals. Placing the right inputs, in the right place, at the right time, is sometimes called “Precision Agriculture”. However, the adoption of Precision Agriculture by New Zealand kiwifruit growers, has been constrained in part, by the cost and complexity of monitoring seasonal growth. Therefore, any new technology, that can simply and cost effectively measure canopy vigour in a timely way and relate that to fruit quality and production inputs, will ultimately help improve orchard gate returns and keep consumers happy. Using a multispectral camera and UAV (drone), this study monitored two, G3 kiwifruit orchards over three months. Canopy Chlorophyll Content, was found to be the best proxy for canopy vigour. The vegetation index, EVI2 on its own, explained 67% of the variability in canopy vigour. Adding orchard topography measures, extracted from LIDAR data using GIS software, increased the explanatory power of the best model to 85%. In many respects, remote sensing was found to be superior to historical measurement methods. However, uptake by the kiwifruit industry is likely to be conditional on a better understanding of the relationship between canopy vigour, fruit quality and orchard gate returns. The significant correlations observed between orchard topography and canopy vigour, signal a need for closer integration of Geography and Agricultural Science disciplines, in future kiwifruit research.

text: Determining Canopy Vigour in G3 Kiwifruit using Remote Sensing and Geographic Information Systems Consumers are increasingly demanding that food producers justify their use of water, fertiliser and agrichemicals. Placing the right inputs, in the right place, at the right time, is sometimes called “Precision Agriculture”. However, the adoption of Precision Agriculture by New Zealand kiwifruit growers, has been constrained in part, by the cost and complexity of monitoring seasonal growth. Therefore, any new technology, that can simply and cost effectively measure canopy vigour in a timely way and relate that to fruit quality and production inputs, will ultimately help improve orchard gate returns and keep consumers happy. Using a multispectral camera and UAV (drone), this study monitored two, G3 kiwifruit orchards over three months. Canopy Chlorophyll Content, was found to be the best proxy for canopy vigour. The vegetation index, EVI2 on its own, explained 67% of the variability in canopy vigour. Adding orchard topography measures, extracted from LIDAR data using GIS software, increased the explanatory power of the best model to 85%. In many respects, remote sensing was found to be superior to historical measurement methods. However, uptake by the kiwifruit industry is likely to be conditional on a better understanding of the relationship between canopy vigour, fruit quality and orchard gate returns. The significant correlations observed between orchard topography and canopy vigour, signal a need for closer integration of Geography and Agricultural Science disciplines, in future kiwifruit research.

year: 2017

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: Indigenous children and youth: The case of marae courts in Aotearoa/New Zealand

authors: Toki, Valmaine

abstract: Marae2-based Courts are an initiative of the Judiciary that builds on existing programmes for offenders such as Te Whanau Awhina, and informed by the Koori Courts in Australia.3 This is the first time that a New Zealand court has conducted criminal cases on a Marae within the jurisdiction of the Youth Court. Most offenders referred to the programme are Maori4 and the process incorporates Maori tikanga (Maori customs).

text: Indigenous children and youth: The case of marae courts in Aotearoa/New Zealand Marae2-based Courts are an initiative of the Judiciary that builds on existing programmes for offenders such as Te Whanau Awhina, and informed by the Koori Courts in Australia.3 This is the first time that a New Zealand court has conducted criminal cases on a Marae within the jurisdiction of the Youth Court. Most offenders referred to the programme are Maori4 and the process incorporates Maori tikanga (Maori customs).

year: 2014