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112 Cards in this Set
- Front
- Back
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Map
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"a simplified depiction of a space, a navigational aid which highlights relations between objects within that space. Most usually a map is a two-dimensional, geometrically accurate representation of a three-dimensional space. The science and art of mapmaking is cartography." Source:Wikipedia.org
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Cartography
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The science and art of making maps or charts
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Feature
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A type of information that represents natural objects and human defined objects on a GIS map. There are four components to a feature, which are shape, location, symbol, and attributes.
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Layer
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A layer is a group of features that represent the same theme. Layers consist of features with the same shape and set of attributes.
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Scale
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The relationship of the size of a feature on a map and the actual size of the feature in the real world. On a map, scale is fixed. On a GIS map, scale is dynamic.
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Geographic Information Systems (GIS)
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"a computer system for capturing, storing, checking integrating, manipulating, analyzing and displaying data related to positions on the Earth's surface" Source: USGS
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Attribute Data Types
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At each location, we have measurements of various attributes.
There are two broad classes: -Numerical data, which are either ratio or interval -Categorical data, which are either ordinal or nominal |
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True Value
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The known accepted value
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Measured Value
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The individual measurement of a quantifiable property
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Accuracy
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The degree to which information on a map or in a digital database matches true or accepted values
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Precision
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The level of measurement and exactness of description in a GIS database
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Random Errors
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Caused by unknown and unpredictable changes
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Systematic Errors
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Reproducible inaccuracies that are consistently in the same direction.
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Cartographic Scale
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A large-scale map covers a smaller area but generally with more detail and a small-scale map covers a larger area with less detail
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Spatial Extent
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The term scale may be used to denote the spatial extent of a study
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Operational Scale
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The spatial extent to which a phenomenon operates. For example, sediment transport on beaches operates on a beach compartment scale whereas mountain-building processes operate on a larger scale
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Cartography
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The discipline dealing with the conception, production, dissemination and study of maps
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Spatial dimensionality
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Matching the dimensionality of symbols to phenomena they represent
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Categorical data
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Nominal distinctions-distinctions in kind of things; no natural or implied order
Ordinal distinctions-distinctions in order or sequence of things; no numerically defined difference between positions in that order |
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Level of Measurement
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Numerical data-distinctions in order with quantities assigned to the steps in that order; discrete and continuous data
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Remote Sensing
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"The art and science of obtaining information about an object without being in direct contact with the object" Jenson (2000)
Obtaining information about a location without being there; obtaining information without touching it. |
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Electromagnetic Radiation (EMR)
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Radiation that is emitted in wave form by all substances
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Multispectral Image
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Captures data at specific wavelengths; captures data from wavelengths beyond those visible to the naked eye. Such as infrared. Very useful!
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True Colour
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The colour of a target closely matches what would be seen with the naked eye
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False Colour
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The colour of a target in the displayed image does not have any resemblance to its actual colour.
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Passive Sensor
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Most types of sensors that rely on reflected energy. (e.g. Landsat, Spot, AVHRR)
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Active Sensor
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They supply energy into the scene and measure how much it is reflected (e.g. Radar, ERS, JERS SeaWinds)
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Four kinds of resolutiion
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1. Spatial
2. Spectral 3. Radiometric 4. Temporal |
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Spatial Resolution
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A measure of the fineness of detail visible in a remote sensing image. It determines the size of the smallest area that can be resolved by the sensor.
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Spectral Resolution
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The number and dimension of specific wavelength intervals in the electro-magnetic spectrum to which a remote sensing instrument is sensitive.
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Radiometric Resolution
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How good the instrument is at measuring small differences in the magnitude, or brightness, of radiation within the ground area corresponding to a single raster cell.
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Temporal Resolution
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The ability to collect imagery of the same area of the Earth's surface at different periods of time is one of the most important elements for applying remote sensing data. Spectral characteristics of features may change over time and these changes can be detected by collecting and comparing multi-temporal imagery.
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Geosynchronous
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Orbits around the equator; stays in sync with a certain part of the Earth
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Polar
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Zooms around the poles as the Earth turns underneath it.
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Sun Synchrnous
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Follows the sun; images always have light source in same place.
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Georeferencing
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To georeference something means to define its existence in physical space. That is establishing its location in terms of map projections or coordinate systems. Source: wikipedia
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Ground Control Points
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Control points are known locations for a physical feature that can be identified in the image
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Digitising
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Turning something analog into something digital.
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Spherical ("Geographic") Coordinates
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Latitude ranges from 90 degrees North to -90 degrees South. Longitude ranges from 0 degrees to 180 degrees East and from 0 degrees to -180 degrees West.
As latitude increases, the length of parallels decreases to zero at the poles. |
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Ellipsoid
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Earth is not a true sphere, rather is bulging at the equator and flattened at the poles
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Geoid
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If you imagine there are no tides or wind, the geoid would be roughly the level of the average sea level continuing through the earth.
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Map Projection
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A method of representing the earth's three-dimensional surface as a flat two-dimensional surface.
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Four Classes of Map Projections based on Distortion
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1. Conformal- preserves angles and shapes of small objects
2. Equivalent (Equal Area)- preserves the area 3. Equidistant- preserves distance 4. Azimuthal- preserves angles from a specific point |
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Mercator Projection
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Cylindrical projection
Conformal Extreme distortion of area towards the poles Greenland represented about 9 times larger than it actually is |
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UTM Facts
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The Universal Transverse Mercator Coordinate system divides the World into 60 zones, each being 6 degrees longitude wide, and extending from 80 degrees south latitude to 84 degrees north latitude. The polar regions are excluded.
The first zone starts at the International Date Lines proceeding eastward. |
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Spatial Structure of Census
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National --> Territorial Local Authority (thousands to hundreds of thousands) --> Wards (tens of thousands sometimes) --> Census Area Units (low thousands) --> Meshblocks (low hundreds)
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Ecological Fallacy
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A situation that can occur when a researcher or analyst makes an inference about an individual based on aggregate data for a group. The fallacy assumes the group is homogenous and the individual has the characteristics of the group.
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Modifiable Areal Unit Problem
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The same data when aggregated in different ways will yield different results... "geographic manifestation of the ecological fallacy in which conclusions based on data aggregated to a particular set of districts may change if one aggregates the same underlying data to a different set of districts (Waller and Gotway, 2004)"
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Scale Effect
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The scale effect is attributed to variation in numerical results owing strictly to the number of areal units used in the analysis of a given area.
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Zone Effect
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The zonation effect is attributed to changes in numerical results owing strictly to the manner in which a larger number of smaller areal units are grouped into a small number of larger areal units.
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Indices
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A statistical measure of change in representative group of individual data points
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Metadata
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Data about data
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Types of Spatial Data
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Satellite Imagery
Photographic Images Maps Tables Locations of Entities |
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Buffer
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Area of prescribed distance from object
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Address Matching
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Convert addresses to the geospatial location on maps...use for emergency services
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Data Storage
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Data files are often tabular in form:
Entities/objects Attributes |
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Attributes
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characteristics associated with objects
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Spatially explicit simulation model
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predicts locations
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Tobler's First Law of Geography
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generally things closer together are more similar than things farther apart --> spatial autocorrelation
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Point Pattern
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A set of events/objects within a defined region
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Nearest-Neighborhood Distance
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The distance from an event (point) to the nearest event (point) in the pattern.
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Kernel Density Estimation
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Principal concept of KDE: point pattern has an estimated density at any location in the study region, not just where events (points) were observed.
KDE is the transformation from a point feature to a field (continuous surface) representation |
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Contours
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lines of equal density values
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How does GPS work?
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Speed*Time=Distance
m/s*s=m |
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GPS has 3 segments (components)
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1. Space segment: Satellites
2. User segment: Receivers 3. Control segment: Monitor & control stations |
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Atmospheric Delay
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The GPS signal bounces around when traveling through the ionosphere and troposphere. This increases the time it takes to reach the Earth, which alters the calculated position.
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Multipath Problems
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Smooth surfaces act as 'mirrors' to GPS signals
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Obstruction
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Some features of the landscape may block the GPS signals
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Positional Dilution of Precision
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a measure of geometric configuration of satellites used to calculate a fix
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Jitter
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The apparent movement of a GPS receiver due to a location error
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GPS averaging
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Median not affected by outliers.
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Differential GPS
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Correction of location estimates via info from a fixed receiver
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Wide Area Augmentation System (WAAS)
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a network of ground reference stations covering key regions and coastal areas
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Sources of GPS error
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-satellite clock errors
-ephemeris errors -receiver errors -ionosphere -troposphere -multi-path errors -selective availability (when active) -positional dilution of precision |
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Neogeography
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New geography
refers to geography for the masses |
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Data Warehouse
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Online repository of geospatial data
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Data Clearinghouse
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provide catalogues of data, not necessarily the data itself
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Web Mapping
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the process and outputs of designing, implementing, generating and delivering maps on the world wide web
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Web GIS
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similar to web mapping but with an emphasis on analysis, processing of project specific geodata and exploratory analyses
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Sensors
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a device that responds to a stimulus and records a resulting impulse
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Sensor Webs
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"a coordinated observation infrastructure composed of a distributed collection of resources that can collectively behave as a single autonomous, taskable, dynamically adaptive and reconfigurable observing system that provides raw and processed data, along with associated metadata, via a set of standards-based services of oriented interfaces"
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Sap Flow Sensors
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Functions: Measures Sap Velocity (transpiration)
Application: herbs, grasses, trees, shrubs Principle: thermocouples (heat), plant energy balance |
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Radio and Acoustic Telemetry
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Functions: Organism tracking and sensing
Application: birds, bats, fish, reptiles, mammals, large insects Principle: micro-sensors (position, pressure, temp), radio and acoustic waves |
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Minirhizotron
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Function: soil observation
Application: Soils, root studies, soil fauna Principle: video, magnification |
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Ground Penetrating Radar
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Function: 3-D ground mapping
Application: Soils, roots, groundwater, rocks, nests, forests, lakes, deserts, ice... Principle: EM wave propagation |
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Multi-Parameter Sondes
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Function: Measures 15 or more parameters including: temperature, pH, nutrients, gas, chlorophyll
Application: fresh & marine water Principle: sensor cluster & datalogger Pros: multiple parameters simultaneously |
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Acoustic Doppler Current Profiler
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Function: current and wave velocity profiler
Application: oceans, rivers, discharge Principle: Doppler shift |
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Autonomous Underwater Vehicles
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Function: Automated ocean surveyors
Application: Deep Ocean surveys Principle: Video, temp, salinity, magnetometer, optical backscatter, acoustic altimeter |
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Video Plankton Recorder
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Function: Autonomous plankton observatory
Application: Oceans, estuaries, lakes Principle: Video, sensors Pros: plankton imaged & environmental data measured, 'real time' autonomous |
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Digital Whale Tag
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Function: Acoustical, physiological, and environmental data
Application: marine mammals Principle: Micro-sensors |
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Mini-weather stations
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Function: Pressure, temperature, micro-hygrometer, radiation, densitometer, laser doppler anemometer
Application: in-situe microclimate data Principle: micro-sensor clusters Pros: Accuracy, fast response, low mass & volume, cheap |
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Electronic Nose
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Function: ID gases and quantify concentrations
Application: Air, water, soil, plant volatiles |
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Electronic Tongue
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Function: ID chemical composition of liquids
Application: Dissolved organics and inorganics, aquatic mold growth, soil analysis Principle: 100's of microsensors on chip, colors change depending on chemicals, results read by camera on a chip |
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Sensor Webs
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Function: wireless microsensor clusters for spatial and temporal monitoring
Application: terrestrial, atmosphere, gases Principle: Microsensor clusters, RF telemetry |
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Topography
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The study and mapping of land surfaces, including relief and the position of natural and constructed features
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Contour Map
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A map depicting contour lines, for example a topographic map, which shows valleys and hills, and the steepness of slopes
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Contour LIne
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line on a map joining points of equal elevation
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Benchmark
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a stationary object of previously determined position and elevation and used as a reference point
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Contour Interval
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the elevation difference between adjacent contour lines
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Digital Elevation Model (DEM)
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Set or regularly or irregularly spaced height values
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Digital Terrain Model (DTM)
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Set or regularly or irregularly spaced height values but with other information about terrain surface: ridge lines, spot heights, troughs, coast/shore lines, drainage lines, faults, peaks, pits, passes, etc.
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Photogrammetry
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the science of making reliable measurements of physical objects and the environment by measuring & plotting electromagnetic radiation data from aerial photographs & remote-sensing platforms
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Viewshed
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Locations visible from one or more specified points or lines
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Shading
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provides realism and aides interpretation of surfaces and helps choose locations where light levels are important
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Digital Elevation MOdels
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based on data sampled on a regular grid
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Triangular Irregular Networks (TINs)
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based on irregularly sampled data and 'Delaunay' Triangulation
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inverse distance weighting
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one method for interpolation
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Linear Interpolation
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another method of interpolation
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Hypermedia
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an extension to hypertext that supports linking graphics, sound, and video elements in addition to text elements
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Hyperinactivity
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input/output from multiple sensors
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Location-based services
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A location information service accessed through mobile devices
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Augmented Reality
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Combining real and digital worlds
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