5. Geographic Information Systems
An organized collection of computer
hardware, software, geographic data,
and personnel designed to effectively
capture, store, manipulate, analyze,
and display all forms of
geographically referenced
information.
22. GIS Life Cycle: Sampling & Data Model
• Data Model: A Conceptual description (Mental Model) of how data
are organized for use by the GIS.
• They are not always designed to deal with the limitations of
computers
GIS Data Models
Attribute Data
Models
Spatial Data
Models
Raster Data
Model
Vector Data
Model
Image Data
Model
23. GIS Life Cycle: Data Transfer
• Data Structures: Methods of representing the data model
from w/in the computer
– Vector [Arc/Nodes] Data Structures
– Raster [Grid] Data Structures
24. GIS Life Cycle: Data Analysis
Spatial Data: Geographically referenced data, identified according to
Location.
Points Lines Polygons
Non-Spatial [Attribute Data ]: The attributes refer to the properties of spatial
entities.
Spatial Data
Community-
developed data
sets
Framework Data
sets
25. GIS Life Cycle: Reports
• Mapping is a key feature of a GIS but it is NOT the whole story.
• Spatially Intelligent Reports : Provides links between point, lines,
areas, grids & Attributes in a database.
– Identify trends on the data.
– Create new relationships from the data.
– View complex relationships between data sets.
– Make better decisions.
28. Weather Dashboard
Objective of the tool?
– Develop a web interface that allows Travelers to visualize the
weather data by day, zoom into areas of significant “Impact” to
provide appropriate metrics related to the weather, policies, and
claims.
Targeted Users
– Application will be utilized primarily by the “CAT Center” to
enhance event response activity.
Generally, a GIS is custom-designed for an organization. Hence, a GIS developed for an application, jurisdiction, enterprise, or purpose may not be necessarily interoperable or compatible with a GIS that has been developed for some other application, jurisdiction, enterprise, or purpose.
GIS is a collection of computer hardware, software, and geographic data for capturing, storing, updating, manipulating, analyzing, and displaying all forms of geographically referenced information.
In the simplest terms, GIS is the merging of cartography, statistical analysis, and database technology.
Organized collection of
Hardware
Software
Network
Data
People
Procedures
Generally, a GIS is custom-designed for an organization. Hence, a GIS developed for an application, jurisdiction, enterprise, or purpose may not be necessarily interoperable or compatible with a GIS that has been developed for some other application, jurisdiction, enterprise, or purpose.
Generally, a GIS is custom-designed for an organization. Hence, a GIS developed for an application, jurisdiction, enterprise, or purpose may not be necessarily interoperable or compatible with a GIS that has been developed for some other application, jurisdiction, enterprise, or purpose.
Field Data Models : Selecting points from a continuous surface.
Object Data Models: Selecting some discrete objects, discarding others.
what is a Data Model?
- The heart of any GIS is the data model.
- A data model is a set of constructions for describing and representing selected aspects of the real world in a computer.
- There is no single type of GIS Data model that is best for all circumstances.
Generally, a GIS is custom-designed for an organization. Hence, a GIS developed for an application, jurisdiction, enterprise, or purpose may not be necessarily interoperable or compatible with a GIS that has been developed for some other application, jurisdiction, enterprise, or purpose.
Vectors can represent point, line & area features very accurately
Raster Model
Advantages
Simple data structure
Efficient for remotely sensed or scanned data
Simple spatial analysis procedures
Disadvantages
Requires greater storage space on computer
Depending on pixel size, graphical output may be less pleasing
Projection transformations are more difficult
More difficult to represent topological relationships
Vector Model
Advantages
Data can be represented in its original resolution without generalisation
Requires less disk storage space
Topological relationships are readily maintained
Graphical output more closely resembles hand-drawn maps
Disadvantages
More complex data structure
Inefficient for remotely sensed data
Some spatial analysis procedures are complex and process intensive
Overlaying multiple vector maps is often time consuming
Geospatial Data:
Community-developed data sets usually derived for a single purpose but made available for potential re-use.
Data sets developed to a common content specification for high re-use potential. these are known as "FrameWork" Data
Generally, a GIS is custom-designed for an organization. Hence, a GIS developed for an application, jurisdiction, enterprise, or purpose may not be necessarily interoperable or compatible with a GIS that has been developed for some other application, jurisdiction, enterprise, or purpose.
Generally, a GIS is custom-designed for an organization. Hence, a GIS developed for an application, jurisdiction, enterprise, or purpose may not be necessarily interoperable or compatible with a GIS that has been developed for some other application, jurisdiction, enterprise, or purpose.
Generally, a GIS is custom-designed for an organization. Hence, a GIS developed for an application, jurisdiction, enterprise, or purpose may not be necessarily interoperable or compatible with a GIS that has been developed for some other application, jurisdiction, enterprise, or purpose.
