Database Analysis & Management
dbf, Excel, Access, Oracle, etc...
ArcInfo, ArcView, AutoCadMap, MapInfo, etc...
AutoCAD, Microstation, ect..
| G.I.S. produces
a “SMART MAP” that is geospatially correct & has data associated
with certain features that can be queried. Each feature in a G.I.S.
map has a corresponding record that stores attributes related to that
feature. When this is implemented correctly it enables the end user
to quickly retrieve information based on attribute data or spatial
location. For example when the city needs to determine how many fire
hydrants have a flow rate greater than 1000 gallons of water a minute,
the G.I.S. can quickly & accurately deliver this information with
just a few clicks of a mouse. However, a database can also produce this
information as quickly. If the city also want to see how many fire hydrants
are within 500' of a building a C.A.D. system would allow for this. Integrating
these two processes is where the G.I.S. differentiates from either a database
or a C.A.D. system. A G.I.S will allow the user to determine how many
buildings greater than 10,000 sq ft have a fire hydrant closer than 500'
with a flow rate greater than 1,000 gallons per minute and also be able
to create an accurate map of these features based on these pre-defined
attributes With the ability to have more information available in a format
that allows for rapid retrieval the G.I.S. allows better decisions to
be made with regards to the planning, implementing, maintaining, &
managing a city.
| There are several
methods of entering information into a G.I.S. First there must be a
good established coordinate system with a set of control points. This
is the basis upon which all other data layers will be referenced, therefore
the accuracy of this dataset is critical. Other data layers can be created,
imported, compiled, scanned, or collected in order to get the information
into the G.I.S. Some examples of this include importing existing digital
plats & plans from engineers, drawing in building footprints from
orthophotography, collecting data in the field with G.P.S., importing
tabular information from existing databases, or drawing features in using
coordinate geometry (COGO). Background images can be imported into
the G.I.S. through either scanning paper drawings or digital photography
& then some degree of rectification (alignment of the image based on
| Map scale
is basically the distance ratio between features on a map & the
corresponding features on the ground. This relationship determines
how much ground area can be portrayed on a specific size of paper. There
are different ways to calculate scale but here are some of the easiest
formulas for simple conversions.