W01 - Introduction Flashcards
geographic information system (GIS)
computer system for capturing, storing, querying, analyzing, and displaying geospatial data
geospatial data
describes both the locations and characteristics of spatial features
what does a GIS require besides geospatial data?
hardware (ex. computers, operating systems, monitors, scanners, GPS receivers, etc), software, people, infrastructure (the physical, organizational, administrative and cultural environments that support GIS operations)
when was the first operational GIS developed and what other events helped with the early development of GIS?
- by Tomlinson in the early 1960s for storing, manipulating and analyzing data collected for the Canada Land Inventory
- in 1964, Fisher founded the Harvard Laboratory for Computer Graphics
- mapping and spatial analysis were introducted at the University of Edinburgh + the Experimental Cartography Unit in the UK
- publication of Ian McHarg’s Design with Nature included map overlay method for suitability analysis
- introduction of an urban street network with topology in the US census bureau’s DIME system
what advancements in technology helped bring GIS to mainstream use by the 1990s?
advent of the GUI, powerful and affordable hardware and software, public digital data
what are 2 trends that have emerged in GIS?
- GIS has been increasingly integrated with other geospatial data such as satellite images and GPS data
- GIS has been linked with web mapping, web service, social media and cloud computing
examples of applications of GIS
- land use planning, natural hazard assessment, wildlife habitat analysis, riptarian zone monitoring, timber management
- emergency planning, crime analysis, public health, land records management, transportation applications, precision farming, economic recovery
examples of the integration with GIS and the internet
online map locators, location based services on phones for location searches, mobile GIS for field workers, mobile resource management, GPS for cars
what are the different data models for GIS data?
vector data or raster data
vector data
- uses points, lines, and polygons to represent spatial features or objects with a clear spatial location and boundary
- can be georelational or object-based, with or without topology, simple or composite
georelational data model
stores geometries and attributes of spatial features separately
object-based data model
stores geometries and attributes of spatial features in a single system
topology
explicitly expresses the spatial relationships between features (ex. 2 lines meeting at a point)
what are composite features?
features that are built on simple features of points, lines, and polygons and are designed for handling complex spatial relationships (ex. triangulated irregular network, dynamic segmentation)
triangulated irregular network (TIN)
model that approximates the terrain with a set of nonoverlapping trianagles
dynamic segmentation
combines 1-D linear measures like mileposts with 2-D projected coordinates
raster data model
- uses a grid and grid cells to represent continuous fields (ex. elevation, precipitation). each cell has a value that captures the magnitiude of the field at that cell location
- requires lots of computer memory
what is attribute data
describes the characteristics of spatial features
what is data exploration
activities of visualizing, manipulating and querying data using maps, tables, and graphs to get a closer look at the data
what are 2 basic data analysis tools for vector data?
- buffering and overlay
- buffering creates buffer zones from select features
- overlay combines the geometries and attributes of the input layers
what are 4 basic data analysis tools for raster data?
- local, neighborhood, zonal, and global operations
- performed at the level of individual cells, groups of cells, or cells within the entire raster
analyzing terrain
- tools to map the terrain in contours, profiles, hill shading, and 3d views
- tools to analyze the terrain’s slope, aspect and surface curvature
- viewshed analysis - determine areas visible from one or more observation points
- watershed analysis - trace water flow to delineate streams and watersheds
spatial interpolation
- use points with known values to estimate values at other points (ex. kriging)
least-cost path analysis
- find the least accumulated cost path in a raster (raster based, works with “virtual” paths
network analysis
- find the shortest path between stops on a topological road network (vector-based, works with an existing road network)
what is “volunteered geographic information” (VGI)
geographic information generated by the public using web applications and services
when VGI comes from a community or a specific group of people, that approach is public participation GIS (PPGIS) and results in community-based geographic information
