Calculating and Assessing Mobile Mapping System Point Density for Roadside Infrastructure Surveys

The current generation of Mobile Mapping Systems (MMSs) capture increasingly larger amounts of data in a short time frame. Due to the relative novelty of this technology there is no concrete understanding of the point density that different scanner confgurations and scanner hardware settings will exhibit on objects at specific distances. Depending on the project requirements, obtaining the required point density impacts on survey time, processing time, data storage and is the underlying limit of automated algorithms. Insufficient knowledge of the factors in uencing MMS point density means that defning point density in project specifications is a complicated process. The objectives of this thesis are to calculate point density, to assess MMS laser scanner configuration and hardware settings and to benchmark a selection of MMSs in terms of their point density. The calculation methods involve a combination of algorithms applying 3D surface normals and 2D geometric formulae and outputs profile angle, profile spacing, point spacing and point density. Each of these elements are a major factor in calculating point density on arbitrary objects, such as road signs, poles or buildings - all important features in asset management surveys. These algorithms are combined in a system called the Mobile Mapping Point Density Calculator (MIMIC). MIMIC is then applied in a series of tests identifying the recommended MMS laser scanner configuration and scanner hardware settings for near side infrastructure. The in uence that the scanner orientation and location on the MMS has on point density is quantified, resulting in a recommended MMS laser scanner configuration. A series of benchmarking tests assess the performance of one commercial and two theoretical MMSs in terms of their point density. The recommended configuration identified in the previous tests allows a low specification MMS to increase its performance in relation to a higher specification MMS. The benchmarking tests also highlight that a high pulse repetition rate is preferable to a high mirror frequency for maximising point density. The findings in this thesis enable a MMS to be configured to maximise point density for specific targets. Researchers can utilise MIMIC to tailor their automated algorithm's point density requirements for specific targets

Estimating missing data in hierarchical space-time series with a short temporal extent

A challenging problem exists in the estimation of missing space-time data where the time series are relatively short, and the space series belong to a spatial hierarchy. An example is provided by the population estimates for regions belonging to the NUTS hierarchy which are available from the EUROSTAT data portal. The table demo_r_gind3 provides estimates of the population of NUTS0/1/2/3 regions at the 1st January 2000…2012 inclusive. Inspection of the table reveals that estimates are missing for 2000-2003 for two of the five NUTS3 regions in the NUTS2 region of Liège. There are other instances of missing data at NUTS3 where there are data for the corresponding higher level NUTS regions. The EUROSTAT table demo_r_d2jan provides estimates of the population on the 1st January for a longer time period, 1990…2012 inclusive, but these are only to NUTS2. Again, there is missing data. The question then arises as to whether it is possible to estimate the missing series. The NUTS2 values act as a constraint on the NUTS3 values – the total population of the NUTS3 regions should equal those of the corresponding NUTS2 regions. However, the relative shortness of the available series is a challenge if conventional methods of time series analysis are adopted. Furthermore, the imposition of the spatial constraints is both a check as well as a challenge

Calculating the effect of dual-axis scanner rotations and surface orientation on scan profiles

The large volumes of point cloud data collected by a Mobile Mapping System(MMS) equipped with a laser scanner have attracted the attention of the research community, primarily towards developing automated algorithms to help when processing this data. This has resulted in insufficient attention being paid to quantifying the capabilities of these systems, and due to the relative youth of this technology there is no concrete understanding of the point density that different hardware configurations and operating parameters will exhibit on objects at specific distances. Obtaining the required point density for a project impacts on survey time, processing time, data storage and is the underlying limit of automated algorithms. Lack of understanding of these systems makes defining point density in project specifications a complicated process. We are in the process of developing a method for determining the quantitative resolution of point clouds collected by a MMS with respect to known objects at specified distances. We have previously demonstrated the effect that scanner orientation in one axis, scanner configuration and scanner operating speed have on scan profiles. We have also focused on the effect on scan profiles of the combined vertical and horizontal rotations of the scanner (dual-axis rotations) and also incorporated point spacing for planar surfaces at different scanner mirror speeds, pulse repetition rates and field of view as a function of range into our model. The subject of this paper is to investigate the effect that a dual-axis scanner rotation has on profile spacing and to design a theoretical system to calculate the angular change on profiles exhibited on horizontal and vertical surfaces for different system configurations. The second goal of the research presented in this paper is to include in our calculations a method for incorporating surfaces that are not parallel to the direction of travel or that are not perfectly vertical, such as walls facing away from the road or sloped surfaces. Profile angle impacts on profile spacing and is a major factor in calculating point density on arbitrary objects, such as road signs, poles or buildings, all important features in asset management surveys. A number of tests were designed to investigate these issues and the results show that these tests have justified our methods, but it has been made apparent that vehicle dynamics play a larger role than anticipated

Mathematical Models For The Evolution And Development Of The Cerebral Cortex In Mammals

This is a pivotal time in neuroscience as modern imaging techniques and methods in network reconstruction are elucidating the structure of the brain as never before. Ultimately, our insights into these networks of connections will be the foundation for a better understanding of cognitive function and dysfunction in humans and other species. Comprehending why these structures are as we find them can be helped by knowing their developmental programs. Mathematical models will play a key role in understanding how developmental programs are orchestrated by the genome and refined by evolution to construct the brain. In this thesis I present mathematical models for two early stages of the development of the cerebral cortex in mammals: neurogenesis and the emergence of early network structure. Both models are informed by empirical developmental and anatomical data. The first, an ordinary differential equation model for the kinetics of cortical neurogenesis, shows how those kinetics shape the basic architecture of the cortex. A massive increase in the number of cortical neurons, driving the size of the cortex to increase by 5 orders of magnitude, is a key feature of mammalian evolution. Not only are there systematic variations in the cortical architecture across species, but also within a given cortex (affecting the type of information processing which happens in each part of the cortex). The mathematical model presented here accounts for both the cross-species and within-cortex variation as arising from the same developmental mechanism. For the second model, data from an axon-tracing study in rodents informs a network model of early connectivity between neurons in the cerebral cortex. Analysis of the model shows that early axon out-growth has an anisotropic spatial distribution which reduces the volume occupied by the axons without causing a significant decrease in the efficiency of the resulting network. Moreover, the preferential connectivity observed along the medial-lateral axis of the cortex my seed the emerging layout of the cortical areas which are specialized for various types of information processing

Editorial: Beyond the Factory Paradigm: Digital Nomadism and the Digital Future(s) of Knowledge Work Post-COVID-19

What are the potential futures of knowledge work, given its transformation into almost exclusively digital work during the COVID-19 pandemic crisis? Our ongoing research program on digital nomadism informs a Hegelian dialectical analysis and an envisioning of the future(s) of knowledge work. We contrast the Factory paradigm of work (thesis), exemplified by the “ideal type” of the 9-to-5 corporate worker, with the Hypermobility paradigm of work (antithesis), exemplified by the ideal type of the digital nomad. Reflecting on this contrast, we envision the possible digital futures of knowledge work as a continuous spectrum, ranging from a future based on the Digital Taylorism paradigm of work to a future based on the Worker Autonomy paradigm of work. These futures are discussed in terms of different approaches to organizing work, working with technology, delineating work/life boundaries, and provisioning the social safety net. IS researchers are uniquely positioned to perform research and inform decision-making in all these areas, and thus make a difference in determining whether the future we end up with more closely resembles Digital Taylorism or the Worker Autonomy vision