Lewis, Paul and Fotheringham, Stewart and Winstanley, Adam
Spatial Video and GIS.
International Journal of Geographical Information Science , 25 (5).
GIS elemental unit representations of spatial data are often defined in terms of
points, lines and areas. However, another type of spatial data that is becoming frequently
captured, but as yet is largely ignored in GIS, is that of video. While digital video recording
is a commonly encountered medium in modern society and encompasses many forms, from
simple personal camcorders through to sophisticated survey and surveillance systems, its
geographical representation in a GIS has not been fully examined or realised. In the majority
of cases the video footage is usually captured while the device and/or the objects being
viewed are in motion. What is of particular interest is when video streams can be, or have
been, associated with spatial data such as location and orientation to create geographically
referenced videographic data, which, for simplicity, will be defined as spatial video.
Fundamentally, the nature of video is to record space, so when spatial properties can be
accurately acquired and associated with this footage, an important geographical element can
be considered for integration and analysis within a GIS.
Existing spatial video systems, both commercial and research, are predominantly used in
survey or LBS roles and are usually bespoke and application specific (Kim et al. 2003a; Red
Hen 2005; RouteMapper 2007) . These systems do not model spatial video to any recognised
standards that is generalised to be both data and platform independent. They do not support
GIS integration and/or analysis from a purely spatial content perspective. A videoimage/
remote-sensing centric approach prevails where usage options range from simple
visualisation interfaces to interactive computer vision systems. What has been largely
overlooked is a spatial approach where the inherent geographical extent recorded in each
video frame can be modelled and used in a geo-spatial analysis context. While this modelling
approach has not been fully realised, it does exist in a GIS form based on Open Geospatial
Consortium (OGC) standards, where the spatial context of video is defined in a structure
called a ViewCone (Lewis et al. 2006; OGC OWS-3 2005). However, a ViewCone only
defines a 2D model of the geographical extent of each frame and is restricted to a three-orfive
sided polygon representation.
Thus, this paper examines the potential of modelling spatial video through the use of
elemental data types within GIS; gives some examples of using this approach; describes
some problems in using spatial video within GIS; and then demonstrates how these problems
are being solved. This is done in three stages. Firstly, a detailed overview of spatial video in
its current GIS role is provided - this is achieved through a complete introduction to the
distinct elements of spatial video followed by a review of its use in both commercial and
academic application areas. Secondly, a brief theoretical overview of an alternative GISconstrained
ViewCone data structure is given that defines a more flexible spatial video model
for both 2D and 3D GIS analysis and visualisation. Thirdly, a selective sample of results is
presented based on an implementation of this approach being applied to a constrained spatial
video data source in a specific study area.
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