BENEFITS vs COST OF GIS
"Benefits should be measured over time. Proper GIS applications provide intelligent planning for
the most efficient use of resources. Because the information is digital, it also allows for
continuous refinement, enhancement, and increased efficiency."
Richard Chaney, Resource Information Manager, Ouachita National Forest
QUESTIONS THAT GIS CAN ANSWER
Location: What is at...? A GIS can be used to display the features that exist at
a certain location or that are associated with a certain location. For example, a GIS
can be used to map public infrastructure, such as roads, utility lines, and schools.
Trends: What has changed...? By comparing data from two or more time
periods, a GIS can be used to identify trends over time. For example, by looking at
population change between two points in time, high growth areas within a region
can be visually identified.
Condition: Where is the location that meets these criteria...? A GIS can be
used to identify locations that meet certain criteria. Using the query and selection
tools that are available with a GIS, you can perform a series of queries on land
parcel data that would identify those parcels that meet the criteria. The results of
your query can be easily displayed with a map.
Pattern: What is the spatial pattern...? A GIS makes it possible to view and
analyze spatial patterns exhibited by the data. For example, the spatial pattern of
retail establishments relative to population density within the county.
GIS vs CAD
A GIS can be used to emphasize the spatial relationships among the objects being
mapped. While a computer-aided mapping system may represent a road simply as a line, a GIS
may also recognize that road as the boundary between wetland and urban development,
between two census statistical areas, etc.
GIS vs SURVEYING
"GIS provides a graphical representation of the real world. GIS can be used to
perform research and analysis on 'what if' scenarios. Surveying is a profession that involves
more precise measurements of the earth's surface. Surveys also produce a legal document.
GIS should not be used or held as legally authoritative. GIS should only be used to evaluate
a particular problem, and in some cases may provide the need for a survey." Learon Dalby
THE MAJOR COMPONENTS OF GIS
1. Data Entry
2. Data Management
3. Data Manipulation and Analysis
4. Data Output
1. DATA ENTRY Data Entry / Data Conversion stage. Normally, data exists on paper
maps or hand drawn maps, electronic maps such as AutoCAD maps, aerial photographs,
or even satellite images. Data entry or conversion can be the most costly part of your
GIS project. It could take months or even years to initially collect and convert data.
2. DATA MANAGEMENT Data management is the process of storing and retrieving
data from a data base. Once data is captured or converted it must be managed and
maintained. Updates and changes must be made on a regular basis in order to ensure
data integrity. Standards must also be in place so data is always up-to-date.
Data is often forgotten after the initial conversion or collection. When this happens, it
slows or halts GIS projects because users want current data for analysis. Therefore, once
data is captured, converted or entered, it must be maintained and managed. Users who are
responsible for updating and maintaining data should be identified early in the project to
avoid data disasters.
3. DATA MANIPULATION AND ANALYSIS Specific GIS applications are the most
common way to manipulate and analyze geographic data. Simple database queries are
also ways to obtain information stored in a GIS. This component concentrates on what
you want from the data. Data can be manipulated in many ways. It is in this stage that
the people using the data dictate what they want from the data and then applications
are written to perform those functions. Applications can include standard queries, map
generation and production, marketing analysis, reports, data entry forms, work order
tracking, trouble call routing, and dispatching. The applications are limited only by
project budgetary constraints and time.
4. DATA OUTPUT Data output is best defined as data in the form of maps, tables, or
text in both hard copy (paper copies) or soft copy (electronic files). This component is
what most users want first. Understanding that the data collection and conversion is first
will help produce better quality output. Visuals are important tools in business. A GIS
can produce great visuals if the data is accurate and well maintained. Remember,
without data, a GIS can not exist. How do I plan for a GIS? How do I implement a GIS?
These questions are often asked too late in the process. In order to successfully
implement a GIS, you must first spend time planning for what you want your GIS to do.
GIS can perform many functions. It can house a landbase, infrastructure, facilities,
utility lines, and countless other layers of data.