# Shared Flashcard Set

GIS Fundamentals
Final Exam
34
Geography
12/11/2011

## Additional Geography Flashcards

Term
 Raster Algebra
Definition
 The cell by cell combination of raster data layers using either local, neighborhood, or in some cases, global functions. Includes Binary and Unary
Term
 Local Raster Functions: Math
Definition
 Apply mathematical functions on a cell by cell basis. Most functions use one input layer and one output payer.
Term
 Local Raster Functions: Boolean
Definition
 Boolean operations place true or false values depending on the input values. The three basic logical operators are AND, OR, NOT
Term
 Local Raster Functions: Reclassification
Definition
 Raster reclassification assigns output values that depend on the specific set of input values. It is based on matching input cell values to a reclassification table. Usually a single output applies to a range of input values.
Term
 Local Raster Functions: Overlay
Definition
 Cell by cell combination of data from two of more input layers. New output values are generated for each unique combination of input values. Typical nominal data (categorical)
Term
 Neighborhood Functions: Moving Window
Definition
 Method of conducting the function. The window is a configuration of cells used to specify the input values for the operation. The function visits each cell in the raster and calculates the specified statistic within the identified neighborhood. The result is usually associated with a cell at the center of the windows position. It then moves to the adjacent cell. Shapes: rectangle, circle, annulus, wedge
Term
 Neighborhood Functions: Zonal Functions
Definition
 Zonal functions apply operations based on defined regions or zones. Zone refers to all the cells in a raster that have the same value (do not have to be contiguous). What
Term
 Neighborhood functions: Zonal statistics
Definition
 A statistic is calculated for each zone of a zone dataset based on values form another dataset.
Term
 Neighborhood Functions: Cost-Distance Analysis
Definition
 A cost surface contains the minimum cost of reaching cells in a layer from one or more source cells. Uniform travel cost - fixed cost per distance. Friction surface
Term
 Neighborhood Functions: Cost-Distance Analysis --> Cost weighting
Definition
 Reclassifying your dataset to a common scale. Weighting datasets according to percent influence
Term
 Spatial Estimation: Spatial Interpolation
Definition
 The procedure of estimating the values of properties at unsampled sites within an area covered by existing observations
Term
 Spatial Estimation: Spatial Interpolation --> Key Methods (1/5)
Definition
 Isarithmic Mapping: (contour map) Created by interpolating a set of isolines between sample points of known values. An isopleth map is a special kind of Isarithmic Map where the sample points are associated with enumeration units
Term
 Spatial Estimation: Spatial Interpolation --> Key Methods (2/5)
Definition
 Thiessen Polygon: This method assumes the values of unsampled areas are equal to the value of the closest sampled point
Term
 Spatial Estimation: Spatial Interpolation --> Key Methods (3/5)
Definition
 TIN (Triangulated Irregular Network): This method is used to construct digital elevation models. Adjacent data points are connected by lines to form a network of irregular triangles.
Term
 Spatial Estimation: Spatial Interpolation --> Key Methods (4/5)
Definition
 Trend Surfaces: This method attempts to fit a mathematically defines surface through all the data points.
Term
 Spatial Estimation: Spatial Interpolation --> Key Methods (5/5)
Definition
 Spatial Moving Average: The most common interpolation method used in GIS. It calculates a value for a location based on the range of values attached to neighboring points that fall within a user defines range.
Term
 Density Analysis
Definition
 Takes known quantities of some phenomena and spreads it across the landscape based on the quantity that is measured at each location and the spatial relationship of the locations of the measured quantities.
Term
 Data Collection
Definition
 Two Methods: Primary Data Collection (direct measurement) Secondary Data Collection (derivation from other sources)
Term
 Primary Data collection
Definition
 Captured specifically for use in GID by direct measurement using hand-held devices often. Raster example: digital satellite Vector example: GPS
Term
 Secondary Data Collection
Definition
 Secondary sources are those reused from earlier studies or obtained from other systems. Data capture refers to direct entry. Data transfer refers to importing existing digital data. Raster example: scanned maps Vector example: existing vector data (Autocad)
Term
 Raster Data Capture (primary)
Definition
 Remote sensing: The measurement of physical, chemical and biological properties of objects without direct contact. Uses satellite imagery and aerial photography
Term
 Considerations when getting raster sensing data onto GIS:
Definition
 Registration: control points in image and on ground or from GIS layer. Projection
Term
 Generating GIS layer with raster sensing
Definition
 Classification results "heads up digitizing"
Term
 Updating GID layer with raster sensing
Definition
 Currency Provides coverage over large spatial areas quickly Editing Use old maps and update them with new remotely sensed data
Term
 Raster Data Capture, Secondary: Scanning
Definition
 Using a scanning device to convert hardcopy analog media into digital images Georeference Geographic wallpaper Template for vectorization
Term
 Why Scan? Benefits:
Definition
 Reduce wear and tear, improve access, provide DB storage Provide geographic context Scan prior to vectorization Creates a raster data set that can be vectorized (both automated & manually)
Term
 Georeferencing (rubbersheeting)
Definition
 When you georeference you dataset, you define its location using map coordinates and assign the coordinate system of the data frame.
Term
 General steps for georeferencing a raster dataset:
Definition
 Add the raster dataset that you want to align with your projected data in ArcMap Add control points that link known dataset poitions to known positions in map coordinates Save the georeferencing information when you're satisfied with the alignment (registration) Optionally permanently transform the raster dataset
Term
 Vector Data Capture (primary)
Definition
 Ground surveying Determined by measuring angles and distances from known points GPS
Term
 Surveying
Definition
 Surveying is the art and science of measuring the surface of the earth and its features
Term
 Types of Surveying:
Definition
 Geodetic surveys: Take into account the true shape of the earth Plane Surveys: Treat the earth as a flat surface Horizontal Surveys: Determine the position of features on the ground Vertical Surveys: Determine the elevation or height of features
Term
 GPS Satellite
Definition
 A minimum of 24 GPS satellites orbit the Earth at an altitude of approximately 11,000 miles. Provide users with accurate information on positions, velocity, and time anywhere in the world and in all weather conditions.
Term
 How does GPS work?
Definition
 Trilateration Geocoding
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