Understanding the measurement of forests with waveform lidar

The measurement of forests is essential for monitoring and predicting the role and response of the land surface to global climate change. Globally consistent and frequent measurements can only be made by satellites; unfortunately many current system’s measurements saturate at moderate canopy densities and are not directly related to forest properties, requiring tenuous empirical relationships that are insensitive to many of the Earth’s most important, Carbon rich forests. Lidar (laser radar) is a relatively new technology that offers the potential to make direct measurements of forest height, vertical density and, when ground based, explicit measurements of structure. In addition measurements do not saturate until much higher forest densities. In recent years there has been much interest in the measurement of forests by lidar, with a number of airborne and terrestrial and one spaceborne lidar developed. Measuring a forest leaf by leaf is impractical and very tedious, so more rapid ground based methods are needed to collect data to validate satellite derived estimates. These rapid methods are themselves not directly related to forest properties causing uncertainty in any validation of remotely sensed estimates. This thesis uses Monte Carlo ray tracing to simulate the measurement of forests by full waveform lidars over explicit geometric forest models for both above and below canopy instruments. Existing methods for deriving forest properties from measurements are tested against the known truth of these simulated forests, a process impossible in reality. Causes of disagreements are explored and new methods developed to attempt to overcome any shortcomings. These new methods include dual wavelength lidar for correcting satellite based measurements for topography and a voxel based method for more directly relating terrestrial lidar signals to forest properties

On the hunt for feedback: Vibrotactile feedback in interactive electronic music performances

The expressivity of musical performance is highly dependent on the feedback relationship between the performer and the instrument. Despite current advances in music technology, performers still struggle to retain the same expressive nuances of acoustic instruments. The capacity of performative musical expression in technologically-driven music is mitigated by the limitations of controllers and other sensor-based devices used in the performance of such music. Due to their physical properties, such devices and components are unable to provide mainly the haptic and vibrotactile experience between the instrument and the user, thus breaking the link with traditional musical performance. Such limitations are apparent to performers, suggesting often the existence of an unnatural barrier between the technology and the performer. The thesis proposes the use of vibrotactile feedback as means to enhance performer’s expressivity and creativity in technology mediated performances and situate vibrotactile feedback as part of the tradition of instrumental musical playing. Achieved through the use of small controllable electric motors, vibrotactile feedback can nourish communicative pathways between the performer and technology, a relationship that is otherwise limited or non-existing. The ability to experience an instrument's communicative response can significantly improve the performer-instrument relationship, and in turn the music performed. Through a series of case studies, compositions and performances, the dissertation suggests ways in which vibrotactile feedback may be applied to enhance the experience between the technology and the performer. As a result performers are able to develop expressive nuances and have better control of the technology during performance