title: Resolving Multiple Propagation Paths in Time of Flight Range Cameras using Direct and Global Separation Methods

authors: Whyte, Refael

subjects: time of flight imaging

abstract: Time of flight (ToF) range cameras illuminate the scene with an amplitude-modulated continuous wave light source and measure the returning modulation envelopes: phase and amplitude. The phase change of the modulation envelope encodes the distance travelled. This technology suffers from measurement errors caused by multiple propagation paths from the light source to the receiving pixel. The multiple paths can be represented as the summation of a direct return, which is the return from the shortest path length, and a global return, which includes all other returns. We develop the use of a sinusoidal pattern from which a closed form solution for the direct and global returns can be computed in nine frames with the constraint that the global return is a spatially lower frequency than the illuminated pattern. In a demonstration on a scene constructed to have strong multipath interference, we find the direct return is not significantly different from the ground truth in 33∕136 pixels tested; where for the full-field measurement, it is significantly different for every pixel tested. The variance in the estimated direct phase and amplitude increases by a factor of eight compared with the standard time of flight range camera technique.

text: Resolving Multiple Propagation Paths in Time of Flight Range Cameras using Direct and Global Separation Methods Time of flight (ToF) range cameras illuminate the scene with an amplitude-modulated continuous wave light source and measure the returning modulation envelopes: phase and amplitude. The phase change of the modulation envelope encodes the distance travelled. This technology suffers from measurement errors caused by multiple propagation paths from the light source to the receiving pixel. The multiple paths can be represented as the summation of a direct return, which is the return from the shortest path length, and a global return, which includes all other returns. We develop the use of a sinusoidal pattern from which a closed form solution for the direct and global returns can be computed in nine frames with the constraint that the global return is a spatially lower frequency than the illuminated pattern. In a demonstration on a scene constructed to have strong multipath interference, we find the direct return is not significantly different from the ground truth in 33∕136 pixels tested; where for the full-field measurement, it is significantly different for every pixel tested. The variance in the estimated direct phase and amplitude increases by a factor of eight compared with the standard time of flight range camera technique.

year: 2015

title: Book review: Muhammad: a very short introduction

authors: Pratt, Douglas

subjects: book review

abstract: This article reviews the book: “Muhammad: a very short introduction”, edited by Jonathan A.C. Brown.

text: Book review: Muhammad: a very short introduction This article reviews the book: “Muhammad: a very short introduction”, edited by Jonathan A.C. Brown.

year: 2011

title: Activating whanau (extended family) processes within a community and school literacy partnership

authors: Glynn, Ted

subjects: Maori Education

abstract: "The paper describes the positive outcomes of a home and school literacy partnership in one mainstream primary school where the principal and the large majority of students, teachers, and whānau belong to one Māori hapū (sub-tribe), Ngāti Whakaue. Participating students were identified by teachers as experiencing difficulties with reading and writing. They were assigned randomly to one of two conditions: (1) participating in their school’s regular reading programme (school group) or (2) participating also in the home tutored reading and writing programme (home and school group).

Students in the home and school group improved their reading and writing outcomes over and above the outcomes achieved by students participating only in the regular school programme. There were two key reasons for the success of this partnership. The first was parents and whānau members successful implementation of both a Māori language reading tutoring programme, Tatari, Tautoko Tauawhi, and the two components of the writing programme, Tuhi Atu Tui Mai and Whakaputa Whakaaro. The second was the professional educational and cultural expertise of the home and school liaison worker, Hiro. Because of her language and cultural expertise and her mana (acknowledged authority and standing), Hiro was able to engage Māori parents and whānau actively in the home and school project. The co-constructed narrative between Hiro and Mere (the second author) provided a salient context for understanding the power of culturally preferred pedagogy in establishing effective home and school partnerships."

text: Activating whanau (extended family) processes within a community and school literacy partnership "The paper describes the positive outcomes of a home and school literacy partnership in one mainstream primary school where the principal and the large majority of students, teachers, and whānau belong to one Māori hapū (sub-tribe), Ngāti Whakaue. Participating students were identified by teachers as experiencing difficulties with reading and writing. They were assigned randomly to one of two conditions: (1) participating in their school’s regular reading programme (school group) or (2) participating also in the home tutored reading and writing programme (home and school group).

Students in the home and school group improved their reading and writing outcomes over and above the outcomes achieved by students participating only in the regular school programme. There were two key reasons for the success of this partnership. The first was parents and whānau members successful implementation of both a Māori language reading tutoring programme, Tatari, Tautoko Tauawhi, and the two components of the writing programme, Tuhi Atu Tui Mai and Whakaputa Whakaaro. The second was the professional educational and cultural expertise of the home and school liaison worker, Hiro. Because of her language and cultural expertise and her mana (acknowledged authority and standing), Hiro was able to engage Māori parents and whānau actively in the home and school project. The co-constructed narrative between Hiro and Mere (the second author) provided a salient context for understanding the power of culturally preferred pedagogy in establishing effective home and school partnerships."

year: 2004