Geography Reference
In-Depth Information
A Breakdown of the Components
Looking at the diagram in Figure 1, we can see that there are a number of parts that have
specific meanings. We have our inputs (blue), outputs (red), in-place processing (green),
and end processing (purple). At this point you might be asking yourself, "How is this different
from any other data-centric system I deal with?" and you'd be right to do so. The main
difference here is that in a typical GIS, you have to design everything in each component
from the very beginning. With a regular data-centric system, many of the components are
often optional or are combined into multifunctional components.
For a typical GIS, none of what you see in Figure 1 is optional, except for possibly your
inputs. Even then, the components you'll most likely see omitted are manual and historical
data.
So what do these separate entities entail, and why are they often not optional?
External Data Collection
As the name suggests, this is the process of gathering external data specific to the system
being designed. Typically this will come from custom devices running custom software (often
embedded or small scale) designed to create input data in a very specific form for the
system it is being used in. The lack of any in-place processing generally means the data
produced is in a format that is already acceptable in the setup.
This component is typically satisfied by many diverse pieces of technology, and in most
cases requires some training to use correctly. You'll often see things like digital surveying
equipment or specialized GPS devices fitted to vehicles, which in many cases will often feed
data back in real time using some kind of radio connection.
Static Data Production
Like external data, this process normally gathers data in a specific format for the system it is
being used in. Unlike external data however, you will generally find that static data is
produced in-house by scanning existing paper maps or digitizing features from existing
building plans, for instance.
Like external inputs, static data is often produced using custom software and processes
specific to the business.
Historical Data
Because of the size and amount of data produced in a typical GIS setup, there is often a
need to back up data into a separate archival system while still maintaining the ability to
work with it if needed. Often, data of this nature is created by planning authorities showing
things like land use over time or recording where specific points of interest are. This is
treated as a separate input because the data is usually read only, and similarly to external
and static data, was at one time produced specifically for the system.
