Spatial analysis Flashcards
GIS
a system utilized to capture, store, analyze, model and display data associated with its geographic position (x, y, z) on the Earth’s surface (i.e. “spatial” data). Among many other planning uses, GIS can be used to track and analyze land use data, monitor land use trends, model and display future hurricane paths, carry out land use suitability analyses, determine and show buffer areas for environmentally sensitive areas, and track and analyze real-time traffic flow and other “Smart City” information. It generally does this by allowing large amounts of spatial data to be stored and displayed in separate layers:
Spatial Data
themes, layers, coverages. Can be displayed accurately due to georeferencing.
Attributes
Information about object or feature. Attributes of census data include tract number, population, avg HHI, number of HH, etc
Topographic map
a two-dimensional representation of a portion of the three-dimensional surface of the earth
Global Positioning Systems (GPS
Improved the spatial accuracy of planning information. GPS allows the incorporation of the location of features and facilities into databases. This is used frequently in a smartphone and associated apps to show your location or provide directions. It is also used by transportation departments to alert drivers to traffic delays.
TIGER
Topographically Integrated Geographical Encoding and Referencing Map.
Census data. TIGER maps includes streets, RR, zip codes and landmarks.
TIGER maps are used by the U.S. Census Bureau and can be downloaded into a GIS system, where they are often used as base layers upon which local information is added.
Digital Aerial Photography
Digital aerial photography has allowed for increased accuracy to the 0.5-foot resolution.
Digital Elevation Models (DEMs)
how digital data about the elevation of the earth’s surface as it varies across communities allows planners to analyze and map it. DEMs can be used for stormwater management, flood control, land use decisions, and other purposes.
Light Detection and Ranging (LIDAR)
is a new technology using a laser, instead of radio waves, that is mounted in an airplane to provide detailed topographic information. It can provide a dense pattern of data points to create one-foot contours for DEMs for use in watershed mapping and hydrologic modeling for flood control. It can also be used to sense the environment for code violations, such as signs that were not built to comply with code.
UrbanSim
is a simulation software program that models planning and urban development. This free software program is designed to be used by Metropolitan Planning Organizations (MPOs).
CommunityViz
Is an ESRI software environment that allows agencies to analyze land use scenarios and create 3D images. This allows citizens to visualize the potential for development and redevelopment.
Urban Footprint
as developed by Peter Calthorpe and Associates and is a more recent addition to the simulation program options for planners. It uses a library of place types, block types, and building types to support interactive scenario building.
What are the two important aspects of geographic information?
Locational information and attribute (values) information
What are the two dominant data types in GIS?
Raster - grids, pixels
Vector- points, lines, polygons, networks (layers)
What is a datum?
A mathematical approximation of the shape of the earths surface as an ellipsoid to compute location
What are the four characteristics of geographic information that are affected by projections, and what are the corresponding projections?
Shape, distance, direction, land area
Conformal (keeps shape)
Equal area
Equidistant
True Direction
What is the purpose of map classification?
To group the observations into categories that correspond with a given color shade on the map
What is the difference between a map showing equal interval vs. a quantile distribution?
Equal interval has the same value difference between categories but number of observations in each category can differ.
A quantile map has equal number of obs/data in each category but values difference between the categories varies.
Which map classification method is like a histogram?
Equal interval, equal size categories
Which planner is recognized as the pioneer of overlay analysis?
Ian McHarg in Design with Nature
What is a heat map?
A map to show the intensity of events or concentration of points
a system utilizing computer software and tools to create, modify, analyze and optimize a design. It can be used to depict a two or three dimensional physical object or location (building site), engineer drawing, blueprint, or site drawing.
Computer Aided Drafting and Design (CADD)
a system utilized for decision-making, and for the coordination, control, analysis, and visualization of management information in an organization. It can be used to produce regular reports on the ongoing operations and performance in an organization, including its strategic, tactical, financial and operational conditions.
Management Information System (MIS
method used to identify suitable locations for placing land uses to minimize adverse environmental impacts. In his 1969 book Design with Nature, Ian McHarg (sometimes referred to as the “Father of Ecological Planning”) described an overlay procedure involving paper maps, pens, and multiple same-scale transparent mylar sheets, used over a light table, to depict individual shaded layers of concern, such as wetlands, soils, vegetation, slope, floodplains, and aquifer recharge areas. Once all the individual mylar layers were put atop one another for a proposed development location, the area with the lightest or absence of shaded areas would be considered as potentially the most suitable development site. This composite suitability map “layering concept” is fundamental to the analysis and visualization of geographical data layers used in today’s GIS.
Land suitability analysis
Geocoding is the process of transforming a description of a location to an actual location on the earth’s surface. Often this involves converting (i.e. assigning geographic coordinates for) street addresses so that the resulting spatial data can be displayed on a GIS map.
Geocoding
Metadata is data about data. GIS metadata provides information about the GIS dataset including an abstract describing the dataset, the projection system being used, the information included in the dataset, its origin, creation, when last updated and accuracy.
Metadata
A way to display the curved surface of the earth on a flat surface.
Projection
An aerial or satellite raster image photograph with a uniform scale, in a given map projection. An orthophotograph can be used to measure distance as it provides an accurate representation of the Earth’s surface. Often used as a GIS basemap.
Orthophotograph
The grid cells that make up raster images, like in a digital camera. Each cell is the smallest (and identical in size) component of information in an image.
Pixels
Aligning maps, images and databases in a non-projected coordinate system into a coordinate system with a common datum and projection. Registration is required to connect data to specific geographic points on the Earth’s surface in order to accurately locate the information and allow for valid analysis between different GIS layers.
Registration
searching or retrieving GIS data without altering the existing data, based on the specifics asked by the operator:
• Location query – e.g. asking to display or list all commercial land use parcels less than 1 acre in size
• Attribute query – e.g. asking to display or list all commercial parcels owned by John T. Smith
• Boolean query (AND, OR, NOT) – combining location and attribute information in a query:
e.g. asking to display or list all commercial land use parcels less than 1 acre in size “AND” owned by John T. Smith
Query
Buffer
The buffer tool in a GIS is a proximity function that creates a polygon at a set distance surrounding a selected point, line or polygon (e.g. displaying a 200’ buffer around a stream, below).
The GIS tool version of McHarg’s land use suitability analysis, allowing a user to identify the most suitable geographic site from a set of possible sites, through applying a set of individually weighted criteria to identify the “best location”.
Suitability analysis
GENERAL PLANNING USES FOR GIS
• Visualizing and understanding spatial (geographic) data
• Assessing environmental impacts and
• Depicting hazard vulnerabilities
• Municipal and transportation planning
• Marketing analyses
• Modeling and simulations
• Probability analyses
• Trend analyses & Scenario planning
