Spectral and spatial information from a novel dual-wavelength full-waveform terrestrial laser scanner for forest ecology

The Salford Advanced Laser Canopy Analyser (SALCA) is an experimental terrestrial laser scanner designed and built specifically to measure the structural and biophysical properties of forest canopies. SALCA is a pulsed dual-wavelength instrument with co-aligned laser beams recording backscattered energy at 1063 and 1545 nm; it records full-waveform data by sampling the backscattered energy at 1 GHz giving a range resolution of 150 mm. The finest angular sampling resolution is 1 mrad and around 9 million waveforms are recorded over a hemisphere above the tripod-mounted scanner in around 110 minutes. Starting in 2010, data pre-processing and calibration approaches, data analysis, and information extraction methods, were developed and a wide range of field experiments conducted. The overall objective is to exploit the spatial, spectral and temporal characteristics of the data to produce ecologically useful information on forest and woodland canopies including leaf area index, plant area volume density and leaf biomass, and to explore the potential for tree species identification and classification. This paper outlines the key challenges in instrument development, highlights the potential applications for providing new data for forest ecology, and describes new avenues for exploring information-rich data from the next generation of TLS instruments like SALCA

Authentication Beyond Desktops and Smartphones: Novel Approaches for Smart Devices and Environments

Much of the research on authentication in the past decades focused on developing authentication mechanisms for desktop computers and smartphones with the goal of making them both secure and usable. At the same time, the increasing number of smart devices that are becoming part of our everyday life creates new challenges for authentication, in particular since many of those devices are not designed and developed with authentication in mind. Examples include but are not limited to wearables, AR and VR glasses, devices in smart homes, and public displays. The goal of this workshop is to develop a common understanding of challenges and opportunities smart devices and environments create for secure and usable authentication. Therefore, we will bring together researchers and practitioners from HCI, usable security, and specific application areas (e.g., smart homes, wearables) to develop a research agenda for future approaches to authentication

Terrestrial laser scanning to characterise three-dimensional foliage and woody material distributions in trees

Three-dimensional characterisation of foliage and wood distribution within forests is essential for understanding, managing and monitoring forest ecosystems. The recent advances in terrestrial laser scanning (TLS) technologies have provided new opportunities to measure the 3D structure of forest canopies, which in turn can be correlated to tree attributes. In addition to estimation of variables such as stem density and the diameter at breast height and tree height, dual- and multi-wavelength systems are now being tested to distinguish foliage and wood based on their reflectance properties. Previous studies have suggested that using spectral information to distinguish foliage from wood materials is unlikely to provide an accurate classification on its own. In this thesis, a spectral approach was designed based on the frequency distribution of the reflectance and spectral ratios to distinguish between the foliage and woody materials. Additionally, a spatial classifier (CANUPO) approach was applied to describe the geometric relationships between the points of the TLS point clouds and characterise the local dimensionality at a given location and scale. TLS point cloud data of small broadleaf and needle-leaf trees in the laboratory, three single isolated oak trees with different structure and appearance and a full forest stand plot were used for foliage/wood classification in this research. The spectral and spatial classifications were compared to investigate the compatibility between them for all data sets. The results showed a clear separation of foliage and wood using 1063 nm and NDI data for the broadleaf tree and 1545 nm data for the needle-leaf tree. In contrast, the 1545 nm for the broadleaf and 1063 nm and NDI of the needle-leaf tree produced classification errors. A large number of foliage points were classified as wood for both trees using the spatial approach, with comparative errors of 67.35% and 73.18% for the broadleaf and needle-leaf tree respectively. For the three single trees, the 1545 nm data provide a clear separation for all trees while there was a variation in the classification using 1063 and NDI data for every tree. In general, the spatial classifier showed a clear separation for all of the trees with a few apparent errors in the canopy and on the stems with different results according to their structure and appearance. It was unlikely to be possible to separate foliage and wood using spectral data and ratios for the full forest data at ranges greater than 17m from the scanner. CANUPO classified 15% of the points as foliage and 85% as wood at a range of less than 15m. The classification showed a compatibility of 55.63% for the full stand data. Overall, the results highlight the potential of a dual-wavelength laser scanners for providing a wide range of data for forest ecology

Putting Security on the Table: The Digitalisation of Security Tabletop Games and its Challenging Aftertaste

IT-Security Tabletop Games for developers have been available in analog format; with the COVID-19 pandemic, interest in collaborative remote security games has increased. In this paper, we propose a methodology to evaluate the impact of a (remote) security game-based intervention on developers. The study design consists of the respective intervention, three questionnaires, and a small open interview guide for a focus group. A validated self-efficacy scale is used as a proxy for measuring effects on participants' ability to develop secure software. We tested this design with 9 participants (expert and novice developers and security experts) as part of a small feasibility study to understand the challenges and limitations of remote tabletop games. We describe how we selected and digitalised three security tabletop games, and report the qualitative findings from our evaluation. Setting up and running the virtual tabletop games turned out to be more challenging and complex for both moderator and participants than we expected. Completing the games required patience and persistence, and social interaction was limited. Our findings can be helpful in building and evaluating a better, more comprehensive, technically sound and issue-specific game-based training measure for developers. The methodology can be used by researchers to evaluate existing and new game designs