Supporting Geospatial Data in the Field
2.1 Field Expectations
Field users have a very simple requirement for the data needed in their computer support.
They simply want access to the data that they need when they need it. Moreover, they
want the access to be seamless. They want access to data that allows them to use their
application programs without worrying about any of the underlying issues of how the
data has been gathered, integrated, and processed.
Unfortunately, these underlying issues can be very complicated for some applications.
The precise data required can be split over several data sources. How to integrate the
data is nontrival in most environments. Ensuring that the correct data is available in the
field when it is needed, can also be a difficult problem.
Using geospatial data in the field increases the difficulty of these problems. First
geospatial data is richer than any alphanumeric data. Figure 1 illustrates the basic data
types of geospatial data. Raster data in particular creates interesting complications. The
number of different formats of raster data that are available is large. Issues like,
resolution, coverage and accuracy make integration a difficult problem. The fact that we
are dealing with images mean that the size of the raster data is staggering for many
applications.
2.2 Field Users
There are several ways to look at the field users. The spatial cognition of a user is briefly
discussed.
Each person has a different ability to make use of geospatial data. Even in something as
basic as using maps to find a location, the difference is striking. Research in spatial
cognition suggests that there are at least three recognizable levels of knowledge that
people use to be able to “use” a map to find their destination. The levels are known as
landmark, route and survey based[6]. A landmark based thinker uses a list of landmarks
to find her/his way around in a new area. This type of individual needs map support to
obtain the list of landmarks needed to navigate the region described by the map.
A route based person uses the map to familiarize themselves with the major routes(roads)
that are available and only supplements with landmarks in regions where roads are very
poorly marked or non-existent. In a heavily populated region a route based thinker
focuses on the major routes and only uses the map for minor roads when they are close to
their destination. This type of user tends to use the map to create a list of written
directions (e.g., turn left on to I-35 North).
A survey based map user tends to see the full extent of the map and uses the map directly
to interpret their navigation needs. When this type of user uses a map in advance of
traveling, it is to familiarize themselves with the map.
2.2 Devices
The range of equipment that is available for using geospatial data in the field continues to
grow every year. The equipment considered in this presentation ranges from laptops to
wearable computers. The characteristics critical to using the devices with geospatial data
are briefly discussed in the remainder of this subsection. Figure 2 illustrates a tablet, a
PDA, and the visual portion of a wearable computer.
2.2.1 Laptops
Today’s laptops are essentially mobile workstations. Only screen size and the need for
battery power in the field separate a high end laptop from a workstation. Most software
developed for a desktop application can be handled by a laptop in the field. In particular
a GIS system developed for a workstation can be used by a laptop in the field. As a result
we only consider the issue of downloading data to laptops in the remainder of this
presentation.
Figure 2. Sample mobile computing devices.
