Term
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Definition
| The cell by cell combination of raster data layers using either local, neighborhood, or in some cases, global functions. Includes Binary and Unary |
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Term
Local Raster Functions:
Math |
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Definition
| Apply mathematical functions on a cell by cell basis. Most functions use one input layer and one output payer. |
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Term
Local Raster Functions:
Boolean |
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Definition
| Boolean operations place true or false values depending on the input values. The three basic logical operators are AND, OR, NOT |
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Term
Local Raster Functions:
Reclassification |
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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. |
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Term
Local Raster Functions:
Overlay |
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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) |
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Term
Neighborhood Functions:
Moving Window
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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 |
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Term
Neighborhood Functions:
Zonal Functions |
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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 |
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Term
Neighborhood functions:
Zonal statistics
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Definition
| A statistic is calculated for each zone of a zone dataset based on values form another dataset. |
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Term
Neighborhood Functions:
Cost-Distance Analysis |
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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 |
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Term
Neighborhood Functions:
Cost-Distance Analysis
--> Cost weighting |
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Definition
| Reclassifying your dataset to a common scale. Weighting datasets according to percent influence |
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Term
Spatial Estimation:
Spatial Interpolation |
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Definition
| The procedure of estimating the values of properties at unsampled sites within an area covered by existing observations |
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Term
Spatial Estimation:
Spatial Interpolation
--> Key Methods (1/5) |
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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 |
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Term
Spatial Estimation:
Spatial Interpolation
--> Key Methods (2/5)
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Definition
| Thiessen Polygon: This method assumes the values of unsampled areas are equal to the value of the closest sampled point |
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Term
Spatial Estimation:
Spatial Interpolation
--> Key Methods (3/5)
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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. |
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Term
Spatial Estimation:
Spatial Interpolation
--> Key Methods (4/5)
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Definition
| Trend Surfaces: This method attempts to fit a mathematically defines surface through all the data points. |
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Term
Spatial Estimation:
Spatial Interpolation
--> Key Methods (5/5)
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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. |
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Term
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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. |
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Term
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Definition
Two Methods:
- Primary Data Collection (direct measurement)
- Secondary Data Collection (derivation from other sources)
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Term
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Definition
Captured specifically for use in GID by direct measurement using hand-held devices often.
Raster example: digital satellite
Vector example: GPS |
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Term
| Secondary Data Collection |
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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) |
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Term
| Raster Data Capture (primary) |
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Definition
Remote sensing:
The measurement of physical, chemical and biological properties of objects without direct contact. Uses satellite imagery and aerial photography |
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Term
| Considerations when getting raster sensing data onto GIS: |
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Definition
- Registration: control points in image and on ground or from GIS layer.
- Projection
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Term
| Generating GIS layer with raster sensing |
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Definition
- Classification results
- "heads up digitizing"
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Term
| Updating GID layer with raster sensing |
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Definition
- Currency
- Provides coverage over large spatial areas quickly
- Editing
- Use old maps and update them with new remotely sensed data
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Term
Raster Data Capture, Secondary:
Scanning |
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Definition
- Using a scanning device to convert hardcopy analog media into digital images
- Georeference
- Geographic wallpaper
- Template for vectorization
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Term
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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)
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Term
| Georeferencing (rubbersheeting) |
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Definition
| When you georeference you dataset, you define its location using map coordinates and assign the coordinate system of the data frame. |
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Term
| General steps for georeferencing a raster dataset: |
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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
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Term
| Vector Data Capture (primary) |
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Definition
- Ground surveying
- Determined by measuring angles and distances from known points
- GPS
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Term
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Definition
| Surveying is the art and science of measuring the surface of the earth and its features |
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Term
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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 |
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Term
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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. |
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Term
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Definition
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