What is GIS?
Geographic Information Systems (GIS) provide a
platform for displaying and analyzing spatial
data. GIS systems allow you to view multiple
layers of data simultaneously. GIS is a
powerful tool for visualization, spatial
analysis, and mapping.
Why is GIS important for engineers?
Engineers must make decisions regarding the
possible alternative locations for a design and
the impact of a particular decision, must model
and analyze geographic data, and must
communicate this information to various
audiences. GIS provides a way for engineers to
overlay all of the data that is important to the
decision, so that they can evaluate alternatives
considering multiple factors. GIS also provides
a platform for spatial modeling. GIS provides a
visual tool for analyzing and presenting
decision criteria.
Software
ArcGIS
– GIS software platform created by
ESRI. We will be using ArcGIS
exclusively this year. ArcGIS contains
several software applications, including
ArcMap and ArcCatalog.
ArcMap
– Mapping, editing, and analysis
software within ArcGIS.
ArcCatalog
– Data management software (create new
files, manage database information,
etc.) within ArcGIS.
Key Terminology
Project
– This is a ‘session’ in ArcMap. You
can save a project so that you can
return to the session and continue
working. The project will contain all
datasets you imported, any maps you have
created in the project, all symbology
(the ‘look’ of your data) changes you
have made, and any new data features you
created through analysis. When you save
a project, it has a .mxd extension.
Feature Class
– Data file containing a group of
geographic data of the same type (point,
line, or polygon). Feature Classes are
contained within a geodatabase.
Shapefile
– A single feature class. These files
can contain either point, line, or
polygon data. The shapefile is actually
a collection of loose files when you
look in the folder where you have saved
the file. It displays as a single .shp
file when using GIS software. The
shapefile format is the format that ESRI
shares in the public domain, and is used
by other GIS software.
Geodatabase
– A database for storing GIS data.
Think of a geodatabase as a ‘container’
for a group of related data. You can
have point, line, and polygon data all
contained within a geodatabase as
separate feature classes. There are two
types of geodatabases:
-
file geodatabase
– can store large datasets and can be
accessed by multiple users at a time;
has .gdb extension
-
personal geodatabase
– smaller datasets up to 2 GB, can only
be accessed by one user at a time; has
a .mdb extension.
Layer File
– A file containing instructions for
displaying a spatial data set (i.e.
symbols, colors, etc.). These files
have a .lyr extension.
Attribute Table
– A table containing data associated
with your geographic files (shapefiles,
feature classes).
Metadata
– Descriptive information about your
data. This is entered and displayed in
ArcCatalog.
This website was originally
developed by
Charles Camp for
CIVL
1101.
This site is
maintained by the
Department of Civil Engineering
at the University of Memphis.
Your comments and questions are welcomed.
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