University of Texas at Arlington

Geographic Information Systems (GIS)

GIS Definition

  • Geographic Information Systems (GIS) let us visualize, question, analyze, and interpret spatial (location-based) and non-spatial (tabular) data to understand relationships, patterns, and trends.
  • Spatial Data is about location, shape (i.e. Point, Line, Polygon), and associated attribute of geographic features and the relationships between them.
  • Relationships: The arrangement that constrains how point, line, and polygon features share geometry (aka Topology).

GIS Application

GIS has many applications in variety of fields including but not limited to geography, urban planning, architecture, geology, water and soil management/engineering, transportation planning, business, etc. In general we can categorize GIS Analysis into the following, no matter of the field:

3D map

  • 3D Analyses
    • Viewshed: Identify the cells in an input raster that can be seen from one or more observation locations.
    • Build and maintain functional surfaces, such as a terrain dataset constructed from Lidar.
    • Query and analyze surfaces such as Slope, Aspect, and Hillshade.
  • Geostatistical Analyses geostatistical map
    • The mining industry uses Geostatistics to quantify mineral resources and evaluate the project's economic feasibility, then on a daily basis in order to decide which material is routed to the plant and which one is waste.
    • In the environmental sciences, Geostatistics are used to estimate pollutant levels in order to decide if they pose a threat to environmental or human health and warrant remediation.
    • In soil science, Geostatistics are used to map soil nutrient levels (nitrogen, phosphorus, potassium, etc.) and other indicators (e.g. electrical conductivity) in order to study their relationships to crop yield and prescribe precise amounts of fertilizer for each location in the field.
    • Meteorological applications include prediction of temperatures, rainfall, and associated variables (such as acid rain).
    • In public health, Geostatistics are being used for prediction of environmental contaminant levels and their relation to the incidence rates of cancer.
  • Spatial Analyses map layers
    • Create, query, map, and analyze cell-based raster data.
    • Perform integrated raster/vector analysis.
    • Derive new information from existing data.
    • Query information across multiple data layers.
    • Fully integrate cell-based raster data with traditional vector data sources.
    • Derive distance from points, polylines, or polygons.
    • Calculating population density from measured quantities at certain points.
    • Find areas that are the most suitable for particular objectives by combining layers of information (aka Suitability Analysis).
    • Create Euclidean distance surfaces to understand the straight-line distance from one location to another.
    • Create cost-weighted distance surfaces to understand the cost of getting from one location to another based on a set of input criteria.
    • Identify the best path or optimum corridors for roads, pipelines, or animal migration based on economic, environmental, physical/natural factors.
    • Interpolate data values for a study area based on sample points to create continuous raster surfaces from elevation, pollution, noise, etc.
    • Clean up raster datasets that contain data that is either erroneous, irrelevant to the analysis at hand, or more detailed than you need.
  • Network Analyses routing map
    • Route: What's the best (quickest, shortest, or most scenic route) route between Point A and Point B?
    • Service Area: A region that encompasses all accessible streets; streets that lie within a specified impedance (e.g. 10-minute drive).
    • Closest Facility: The closest hospitals to an accident, the closest police cars to a crime scene, and the closest stores to a customer's address.
    • O-D Cost Matrix: An Origin-Destination (O-D) cost matrix is a table that contains the network impedance (e.g. travel time, distance) from each origin to each destination.
    • Vehicle Routing Problem: A dispatcher managing a fleet of vehicles is often required to make decisions about vehicle routing. One such decision involves how to best assign a group of customers to a fleet of vehicles and to sequence and schedule their visits. The objectives are to provide a high level of customer service by honoring any time windows while keeping the overall operating and investment costs for each route as low as possible.
    • Location–Allocation: Helps you to choose which facilities from a set of facilities to operate based on their potential interaction with demand points.
  • Tracking Analyses tracking map
    • Bring geographic data containing dates and times to life.
    • Track objects in real time using GPS.
    • Symbolize temporal data using time windows for viewing data that changes through time.
    • Analyze patterns in temporal data by creating data clocks.