title: Adaptive Vision Based Scene Registration for Outdoor Augmented Reality

authors: Catchpole, Jason James

subjects: computer vision

abstract: Augmented Reality (AR) involves adding virtual content into real scenes. Scenes are viewed using a Head-Mounted Display or other display type. In
order to place content into the user's view of a scene, the user's position and orientation relative to the scene, commonly referred to as their pose, must be determined accurately. This allows the objects to be placed in the correct positions and to remain there when the user moves or the scene changes. It is achieved by tracking the user in relation to their environment using a variety of technology. One technology which has proven to provide accurate results is computer vision. Computer vision involves a computer
analysing images and achieving an understanding of them. This may be locating objects such as faces in the images, or in the case of AR, determining the pose of the user.

One of the ultimate goals of AR systems is to be capable of operating under any condition. For example, a computer vision system must be robust under a range of different scene types, and under unpredictable environmental conditions due to variable illumination and weather. The majority of existing literature tests algorithms under the assumption of ideal or 'normal' imaging conditions. To ensure robustness under as many circumstances as possible it is also important to evaluate the systems under adverse conditions.

This thesis seeks to analyse the effects that variable illumination has on computer vision algorithms. To enable this analysis, test data is required to isolate weather and illumination effects, without other factors such as changes in viewpoint that would bias the results. A new dataset is presented which also allows controlled viewpoint differences in the presence of weather and illumination changes. This is achieved by capturing video from a camera undergoing a repeatable motion sequence. Ground truth data is stored per frame allowing images from the same position under differing environmental conditions, to be easily extracted from the
videos.

An in depth analysis of six detection algorithms and five matching techniques demonstrates the impact that non-uniform illumination changes can have on vision algorithms. Specifically, shadows can degrade performance and reduce confidence in the system, decrease reliability, or even completely prevent successful operation.

An investigation into approaches to improve performance yields techniques that can help reduce the impact of shadows. A novel algorithm is presented that merges reference data captured at different times, resulting in reference data with minimal shadow effects. This can significantly improve performance and reliability when operating on images containing shadow effects. These advances improve the robustness of computer vision systems and extend the range of conditions in which they can operate. This can increase the usefulness of the algorithms and the AR systems that employ them.

text: Adaptive Vision Based Scene Registration for Outdoor Augmented Reality Augmented Reality (AR) involves adding virtual content into real scenes. Scenes are viewed using a Head-Mounted Display or other display type. In
order to place content into the user's view of a scene, the user's position and orientation relative to the scene, commonly referred to as their pose, must be determined accurately. This allows the objects to be placed in the correct positions and to remain there when the user moves or the scene changes. It is achieved by tracking the user in relation to their environment using a variety of technology. One technology which has proven to provide accurate results is computer vision. Computer vision involves a computer
analysing images and achieving an understanding of them. This may be locating objects such as faces in the images, or in the case of AR, determining the pose of the user.

One of the ultimate goals of AR systems is to be capable of operating under any condition. For example, a computer vision system must be robust under a range of different scene types, and under unpredictable environmental conditions due to variable illumination and weather. The majority of existing literature tests algorithms under the assumption of ideal or 'normal' imaging conditions. To ensure robustness under as many circumstances as possible it is also important to evaluate the systems under adverse conditions.

This thesis seeks to analyse the effects that variable illumination has on computer vision algorithms. To enable this analysis, test data is required to isolate weather and illumination effects, without other factors such as changes in viewpoint that would bias the results. A new dataset is presented which also allows controlled viewpoint differences in the presence of weather and illumination changes. This is achieved by capturing video from a camera undergoing a repeatable motion sequence. Ground truth data is stored per frame allowing images from the same position under differing environmental conditions, to be easily extracted from the
videos.

An in depth analysis of six detection algorithms and five matching techniques demonstrates the impact that non-uniform illumination changes can have on vision algorithms. Specifically, shadows can degrade performance and reduce confidence in the system, decrease reliability, or even completely prevent successful operation.

An investigation into approaches to improve performance yields techniques that can help reduce the impact of shadows. A novel algorithm is presented that merges reference data captured at different times, resulting in reference data with minimal shadow effects. This can significantly improve performance and reliability when operating on images containing shadow effects. These advances improve the robustness of computer vision systems and extend the range of conditions in which they can operate. This can increase the usefulness of the algorithms and the AR systems that employ them.

year: 2008

title: Acute Assessment of Aggression: Using the Dynamic Appraisal of Situational Aggression (DASA) with New Zealand Offenders

authors: Lang, Veronika

subjects: Aggression

abstract: Institutional violence in prisons and other corrections settings is a hazard to the security and wellbeing of staff and other offenders.  However, the ability to systematically assess for acute, day-to-day aggression in these settings has not been widely developed. Staff assessing aggression in institutional settings ought to use risk assessment measures to aid professional judgement, and this research suggests a need for dynamic, acute risk assessment for aggression amongst New Zealand offenders. The Dynamic Appraisal of Situational Aggression (DASA; Ogloff & Daffern, 2006) was created originally for use amongst psychiatric inpatients. This research aimed to evaluate the use of the DASA for custodial staff in acute risk assessment and offender treatment in different prison units for its potential to fill this niche.
Predictive accuracy of the measure in relation to aggressive behaviour was examined, and custodial staff were surveyed on the ease of administration, their perception of the measure’s effectiveness with their unit, and whether its addition improved offender management. Staff consisted of prison officers and a principle correctional officer in each of the three prison-based units, and custodial management staff at Tai Aroha. These staff nominated offenders (N = 19) on agreement of them being of highest management concern.
Results found the DASA to demonstrate moderate predictive validity, with survival analyses showing high scores on the DASA were associated with highly aggressive offenders. Most staff identified the DASA as assisting in identifying those offenders that were a high risk for aggression. Implications for practice in corrections settings are discussed.

text: Acute Assessment of Aggression: Using the Dynamic Appraisal of Situational Aggression (DASA) with New Zealand Offenders Institutional violence in prisons and other corrections settings is a hazard to the security and wellbeing of staff and other offenders.  However, the ability to systematically assess for acute, day-to-day aggression in these settings has not been widely developed. Staff assessing aggression in institutional settings ought to use risk assessment measures to aid professional judgement, and this research suggests a need for dynamic, acute risk assessment for aggression amongst New Zealand offenders. The Dynamic Appraisal of Situational Aggression (DASA; Ogloff & Daffern, 2006) was created originally for use amongst psychiatric inpatients. This research aimed to evaluate the use of the DASA for custodial staff in acute risk assessment and offender treatment in different prison units for its potential to fill this niche.
Predictive accuracy of the measure in relation to aggressive behaviour was examined, and custodial staff were surveyed on the ease of administration, their perception of the measure’s effectiveness with their unit, and whether its addition improved offender management. Staff consisted of prison officers and a principle correctional officer in each of the three prison-based units, and custodial management staff at Tai Aroha. These staff nominated offenders (N = 19) on agreement of them being of highest management concern.
Results found the DASA to demonstrate moderate predictive validity, with survival analyses showing high scores on the DASA were associated with highly aggressive offenders. Most staff identified the DASA as assisting in identifying those offenders that were a high risk for aggression. Implications for practice in corrections settings are discussed.

year: 2015

title: Wearing moko: Maori facial marking in today’s world

authors: Nikora, Linda Waimarie

subjects: moko

abstract: The early voyagers, missionaries, settlers all reacted to the pukanohi, to the marked faces of the Maori people, during the period of first contact, and the century following it. Their accounts are vivid, judgemental, revealing, telling us as much about them as they do about the people they described.
Curiosity and horror are mixed with a genuine
fascination; where sternly evangelizing words
failed, armed confrontation occurred; and we
now live with the results, te ao hou, a new world. In this world, today, wahine mau kauae, tangata mau moko, pukanohi – wearers – are speaking for themselves, about themselves, and commenting on how others view them. Unanimously, they insist that the decision to take the marking is about continuity, affirmation, identity and commitment. It is also about wearing those ancestors, carrying them into the future; as their moko become a companion, a salient being with its own life force, its own integrity and power, beyond the face.

text: Wearing moko: Maori facial marking in today’s world The early voyagers, missionaries, settlers all reacted to the pukanohi, to the marked faces of the Maori people, during the period of first contact, and the century following it. Their accounts are vivid, judgemental, revealing, telling us as much about them as they do about the people they described.
Curiosity and horror are mixed with a genuine
fascination; where sternly evangelizing words
failed, armed confrontation occurred; and we
now live with the results, te ao hou, a new world. In this world, today, wahine mau kauae, tangata mau moko, pukanohi – wearers – are speaking for themselves, about themselves, and commenting on how others view them. Unanimously, they insist that the decision to take the marking is about continuity, affirmation, identity and commitment. It is also about wearing those ancestors, carrying them into the future; as their moko become a companion, a salient being with its own life force, its own integrity and power, beyond the face.

year: 2004-04-04