GIS and Geospatial Data: Chapter 5 Overview

• Focus of Chapter 5: Working with Digital Geospatial Data and GIS.

Learning Outcomes

• Define geographic information systems (GIS).
• Describe real-world items represented in GIS.
• Identify the four types of non-spatial data.
• Describe linking non-spatial data to location-based data using GIS.
• Recognize at least three GIS software packages.
• Define how GIS data exists in a geodatabase.
• Demonstrate viewing data, joining tables, and basic measurements in ArcGIS/QGIS.

Geographic Information System (GIS)

• Computer-based mapping, analysis, visualization, and retrieval of location-based data.
• GIS systems are used to compare and analyze locations and their attributes.
• GIS systems allow ability to create, map, and analyze digital geospatial data.
• GIS is 100% computer-based.
• The "S" in GIS stands for "system".
• Software runs on desktop, laptop, mobile devices, or the web

Datasets

• GIS can utilize non-spatial data and link it directly to a location.
• Non-spatial data examples: After-school programs, church populations, and student rosters.
• Spatial data consists of school addresses, ethnic/cultural agencies, and census block data.

GIS Operations

• Geographic information system can perform multiple operations related to geospatial data
• Analyze, capture, create, manipulate, store, and visualize

GIS History

• GIS History began in the 1950s and 1960s with computer-based mapping.
• CGIS (Canadian Geographic Information System): large land inventory system developed in Canada
• The first system to use the term "GIS" (early 1960s).
• Roger Tomlinson is known as the "Father of GIS".

Real-World Item Representation

• GIS applications have multiple applications, data needs representing.
• GIS provides means for representing (modeling) data for analysis and manipulation.

Ways of Viewing

• Two ways of viewing include:
  • Discrete object view: conceptualization of a world where reality is represented by separate objects.
  • Continuous field view: conceptualization where all items vary across the Earth's surface as constant fields.

Discrete Object View

• Real-world items are represented in GIS by vector objects:
  • Points
  • Lines
  • Polygons

Vector Data Model

• Vector data model has a conceptualization of the world which represents spatial data as a series of vector objects (points, lines, and polygons).
• Data availability: data is freely available and accessible (roads, boundaries, utilities, etc.)

Digitizing Data

• Developing new data requires digitizing.
• Digitizing creates vector objects through sketches/tracings from maps/images.
• "Heads-up digitizing": a map/image (aerial photo) shows on screen as a backdrop.
  • Vector data which is drawn on top of the backdrop creates new sets of data

Coordinate System

• If starting with points, points may be created using coordinates

Topology

• Topology helps to understand how objects connect to each other
• Topology defines how vector objects relate (adjacency, connectivity, containment), independently of coordinates.
• Types of topology includes: arc-node, region, polygon, node, route, and point events.
• Adjacency which describes how polygons relate to one another.
• Containment describes how locations sit in polygons boundaries
• Connectivity shows how lines interact with each other
• NHD (National Hydrography Dataset): collection of water resource GIS data for the US.

Continuous Field View

• Variables don't have a set boundary, comprising nearly infinite points.
• Temperature, atmospheric pressure, and elevation are examples.
• In continuous field view real-world phenomenon continuously vary

Raster Data

• Raster Data Model:Utilizes spatial data of equally spaced and sized grid cells
• Grid Cells: Is a square unit representing a real-world size, containing a single value.

National Land Cover Database

• National Land Cover Database maps the land cover types for the entire United States at 30-meter resolution using raster-based GIS.

Non-Spatial Data Handeling

• Attributes: non-spatial data associated to a spatial location.
• Attributes can be nominal, ordinal, interval, or ratio types.

Nominal Data

• Type of data which has a unique identifier of some kind
• If numerical, numerical differences are not significant.
• Examples include: social security numbers, phone numbers, shoe size, names, and descriptive information.

Ordinal Data

• Type of data referring solely to a ranking
• Example: The first, second, and third person in a competition.

Interval Data

• Type of numerical data with significant differences between numbers
• No fixed non-arbitrary zero point associated with the data.

Ratio Data

• Type of numerical data with significant differences between numbers
• Fixed non-arbitrary zero point associates with the data.

Attribute Tables

• Spreadsheet-style form
• Rows contain individual objects
• Columns represents attributes associated with listed objects.
• Objects are stored as records (rows) and fields (columns)

Joining Tables

• Joining method used to link two (or more) tables together
• Can connect non-spatial data to spatial locations
• Possible if both tables share common field
• The key field allows the tables to be be joined

Metadata

• Descriptive information about the data.
• Access to separate file (“readme”.txt or XML document).
• Useful info includes metadata (descriptive info about geospatial data) such as..
  • Coordinate system, projection, and datum of data. When data was created. Source data for product creation How accurate the data is What attributes represents.
• Federal Geographic Data Committee (FGDC) establishes standards for metadata.
• Standards include: Identification, data quality, spatial data organization, spatial reference, entity/attribute, distribution, metadata reference, citation, time period and contact information.

Available GIS Kinds

• Esri is a key developer of and industry leader in GIS products.
• ArcGIS is Esri's GIS platform; as desktop software, a web browser, and tablet app or developer toolkit.
• ArcGIS Pro: standard desktop GIS software from Esri such as the 64-bit architecture, ribbons/tabs/ groups, compatible web-based GIS maps, a 3D visualization and includes a basic, standard and advanced licenses.
• ArcMap is the original component of ArcGIS Desktop used for viewing and analyzing data.
• ArcGIS Online is a cloud-based resource which creates and shares GIS web maps and applications.
• Computer programming:
  • Python: free programming language in ArcGIS. a short piece of computer code.
  • JavaScript: web-based
  • HTML 5 and CSS.
  • SQL: programming with databases.
• Shapefile: a series of files with extensions such as .shp, .shx, and .dbf which make up a vector data layer and consists of multiple files stored together.
• File Geodatabase: a single folder able to hold multiple files and contains nearly unlimited storage located in ArcGIS Pro.
• Feature class: a single data layer in geodatabase. Feature dataset: grouping of multiple feature classes within a geodatabase.

Other Software Products

• GeoMedia, Global Mapper, and Manifold System.
• MapInfoPro, Smallworld, TerrSet, and Google Earth Engine.
• QGIS: open source GIS program.
  • Can handle vector, raster, and image data.
  • Capable of geospatial analysis.