Geoscience Reference
In-Depth Information
2. Demonstrate the power, flexibility and efficiency of command line tools.
3. Highlight the time savings in geoprocessing by effectively using batch program-
ming.
1.1 Introduction to Geospatial Data
Although the term geospatial was first coined in the late 1980s, the notion of spatially
referenced data and their use has been around for a much longer time. People have
long associated information with places and used it to improve their knowledge
about a location. One of the earliest examples of 'GIS' was used by Dr. Snow during
the 19th century to map the incidence of cholera outbreaks, which allowed him to
deduce that the outbreaks were clustered around water fountains. Although Snow's
study did not utilize specialist software, his approach is still considered as geospatial
analysis. The term Geospatial analysis is frequently used to define the processing and
interpretation of geospatial information. A geographic information system (GIS) can
be defined as an information system that consists of hardware, software, personnel
and geospatial data for the efficient capture, storage, updating, manipulation and
analysis of disparate forms of geospatial data. Some authors define a GIS more
concisely as “a means of checking, manipulating and analyzing data that are spatially
referenced to the Earth's surface” (Burroughs and McDonnell 1998).
The first GIS emerged during the 1960s, but the discipline has developed exponen-
tially over the last decade, primarily due to the availability of Web-based geographic
information systems and image services, such as Google Earth and Bing Imagery.
Furthermore, the widespread use of global positioning devices for location-based
services, such as satellite navigation systems in cars to GPS units integrated into
Smart phones and personal devices has made geospatial data even more common
place.
This shift in data availability has meant that geospatial concepts that had been
reserved for specialists are now deconstructed and made fully accessible to lay,
non-technical people of all ages. With this shift, location based questions can be
solved using an Internet browser or a Smart phone. For instance, examples of these
questions are: what are the geographic coordinates of a city; what is the shortest
path and travel time between two cities or how many restaurants are within walking
distance of a specific location. Furthermore, easy access to satellite imagery means
that one can easily browse and interpret satellite imagery from across the world, with
the possibility of retrospective analysis using historical satellite data archives. In a
similar way, the concept of spatially located data is now taken for granted and almost
expected when visualizing data (over the Web).
Geospatial data consist of geographical entities that can be defined in terms of their
spatial location, dimensions, attributes and temporal definition. These geographic
entities are also commonly referred to as spatial objects. We return to the specifics
of geographic entities in the subsequent chapters.
 
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