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Visualisation of Origins, Destinations and Flows with OD Maps
We present a new technique for the visual exploration of origins (O) and destinations (D) arranged in geographic space. Previous attempts to map the flows between origins and destinations have suffered from problems of occlusion usually requiring some form of generalisation, such as aggregation or flow density estimation before they can be visualized. This can lead to loss of detail or the introduction of arbitrary artefacts in the visual representation. Here, we propose mapping OD vectors as cells rather than lines, comparable with the process of constructing OD matrices, but unlike the OD matrix, we preserve the spatial layout of all origin and destination locations by constructing a gridded twoâlevel spatial treemap. The result is a set of spatially ordered small multiples upon which any arbitrary geographic data may be projected. Using a hash grid spatial data structure, we explore the characteristics of the technique through a software prototype that allows interactive query and visualisation of 105â106 simulated and recorded OD vectors. The technique is illustrated using US county to county migration and commuting statistics
Information technology and urban green analysis
It is well recognized that green area plays a pivotal role in improving urban environment, such as preserving water and soil, controlling temperature and humidity of air, preventing pollution, flood prevention, functioning as buffers between incompatible land uses, preserving natural habitat, and providing space for recreation and relaxation. However, due to pressures from new development both in urban fringes and urban centres, urban green and open spaces are seen to be rapidly declining in term of allocated spaces and quality. Without careful urban land use planning, many open spaces will be filled with residential and commercial buildings. Therefore, there is a need for proper planning control to ensure that the provisions of green spaces are adequately being conserved for current and future generations. The need for an urban green information system is particularly important for strategic planning at macro level and local planning at the micro level. The advent of information technology has created an opportunity for the development of new approaches in preserving and monitoring the development of urban green and open spaces. This paper will discuss the use of Geographical Information Systems (GIS) incorporated with other data sources such as remote sensing images and aerial photographs in providing innovative and alternative solutions in the management and monitoring of urban green. GIS is widely accepted in urban landscape planning as it can provide better understanding on the spatial pattern and changes of land use in an area. This paper will primarily focus on digital database that are developed to assist in monitoring urban green and open spaces at regional and local context. The application of GIS in the Klang Valley region or better known as AGISwlk developed since mid-1990's is currently being used by various organisations in the region. The focus of AGISwlk is not merely in providing relevant database to its stakeholders but more importantly, assist in making specific and relevant decisions with regard to spatial planning. It is also used to monitor the loss of green areas by using several temporal data sets. The method of classifying green and open spaces in the region is also being discussed. This paper demonstrates that GIS can be an effective tool in preserving and monitoring green and open spaces in an urban area. The contribution of urban green digital database in someway may leads toward landscape sustainability as to satisfy the ever changing society
Sonification of Network Traffic Flow for Monitoring and Situational Awareness
Maintaining situational awareness of what is happening within a network is
challenging, not least because the behaviour happens within computers and
communications networks, but also because data traffic speeds and volumes are
beyond human ability to process. Visualisation is widely used to present
information about the dynamics of network traffic dynamics. Although it
provides operators with an overall view and specific information about
particular traffic or attacks on the network, it often fails to represent the
events in an understandable way. Visualisations require visual attention and so
are not well suited to continuous monitoring scenarios in which network
administrators must carry out other tasks. Situational awareness is critical
and essential for decision-making in the domain of computer network monitoring
where it is vital to be able to identify and recognize network environment
behaviours.Here we present SoNSTAR (Sonification of Networks for SiTuational
AwaReness), a real-time sonification system to be used in the monitoring of
computer networks to support the situational awareness of network
administrators. SoNSTAR provides an auditory representation of all the TCP/IP
protocol traffic within a network based on the different traffic flows between
between network hosts. SoNSTAR raises situational awareness levels for computer
network defence by allowing operators to achieve better understanding and
performance while imposing less workload compared to visual techniques. SoNSTAR
identifies the features of network traffic flows by inspecting the status flags
of TCP/IP packet headers and mapping traffic events to recorded sounds to
generate a soundscape representing the real-time status of the network traffic
environment. Listening to the soundscape allows the administrator to recognise
anomalous behaviour quickly and without having to continuously watch a computer
screen.Comment: 17 pages, 7 figures plus supplemental material in Github repositor
Global-Scale Resource Survey and Performance Monitoring of Public OGC Web Map Services
One of the most widely-implemented service standards provided by the Open
Geospatial Consortium (OGC) to the user community is the Web Map Service (WMS).
WMS is widely employed globally, but there is limited knowledge of the global
distribution, adoption status or the service quality of these online WMS
resources. To fill this void, we investigated global WMSs resources and
performed distributed performance monitoring of these services. This paper
explicates a distributed monitoring framework that was used to monitor 46,296
WMSs continuously for over one year and a crawling method to discover these
WMSs. We analyzed server locations, provider types, themes, the spatiotemporal
coverage of map layers and the service versions for 41,703 valid WMSs.
Furthermore, we appraised the stability and performance of basic operations for
1210 selected WMSs (i.e., GetCapabilities and GetMap). We discuss the major
reasons for request errors and performance issues, as well as the relationship
between service response times and the spatiotemporal distribution of client
monitoring sites. This paper will help service providers, end users and
developers of standards to grasp the status of global WMS resources, as well as
to understand the adoption status of OGC standards. The conclusions drawn in
this paper can benefit geospatial resource discovery, service performance
evaluation and guide service performance improvements.Comment: 24 pages; 15 figure
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