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GIS Flashcards Exam 1
Flashcards for a 200 level Geographic Information Systems Course
87
Geography
Undergraduate 4
02/23/2012

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Term
GIS
Definition
A computer system for capturing, storing, querying, analyzing, and displaying geospatial data
Term
geospatial data
Definition
data that describe both the locations and characteristics of spatial features on the Earth's surface
Term
vector data model
Definition
a spatial data model that uses points and their x-y- coordinates to construct spatial features of points, lines, and polygons
Term
georelational data model
Definition
a vector data model that uses a split system to store geometries and attributes
Term
data exploration
Definition
data centered query and analysis
Term
projection
Definition
process of transforming the spatial relationship of features on the Earth's surface to a flat map
Term
reprojection
Definition
projection of spatial data from one spatial coordinate system to another
Term
geographic coordinate system
Definition
a location reference system for spatial features on the earth's surface
Term
latitude
Definition
– the angle north or south of the equatorial plane
Term
longitude
Definition
the angle east or west of the prime meridian
Term
meridians
Definition
line of longitude (East and West)
Term
parallels
Definition
line of latitude (N and S)
Term
sphere
Definition
perfectly round geometric object in 3D space
Term
spheroid/ellipsoid
Definition
a model that approximates the earth
Term
geoid
Definition
closer approximation of earth than a spheroid
Term
Clarke 1866
Definition
a ground measured spheroid which is the basis for NAD27.
Term
NAD 27
Definition
North american datum of 1927... based on clarke 1886. centered in Meades Ranch, Kansas.
Term
NAD 83
Definition
North american datum of 1983... based on the GRS80 spheroid... origin at center of spheroid
Term
GRS 80
Definition
a satellite determined spheroid developed in 1980- Geodetic Reference System 1980
Term
WGS 84
Definition
satellite determined spheroid for the world geodetic system 1984
Term
datum
Definition
the basis for calculating the geographic coordinates of a a location. A spheroid is a required input to the derivation of a datum.
Term
map projection
Definition
a systematic arrangement of parallels and meridians on a plane surface
Term
false easting/northing
Definition
a value applied to the origin of a coordinate system to change the x or y-coordinate readings.
Term
state plane coordinate system
Definition
a coordinate system developed in the 1930s to permanently record original land survey monument locations in the US. Most states have more than one zone based on SPC27 or SPC83
Term
map scale
Definition
ratio of the distance on the map to the actual distance on the ground.
Term
projected coordinate system
Definition
a plane coordinate system based on a map projection
Term
on-the-fly projection
Definition
displaying datasets based on different coordinate systems... a means of using projection files available and converting datasets to common coordinate systems.
Term
Coverage (arcinfo)
Definition
the vector data model associated with the ARCInfo software package. Example of georelational data model, which uses a split system to store geometries and attributes.
Term
shapefile (ArcView)
Definition
the vector data model associated with the ArcView software package. Example of georelational data model, which uses a split system to store geometries and attributes.
Term
geodatabase (ArcGIS)
Definition
the vector data model associated with the ArcGIS software package... an example of object-based data model, which stores geometries and attributes in a single system... AN object-based vector data model developed by Esri
Term
Esri
Definition
environmental systems research institute, developer of ARCGis
Term
Point
Definition
has zero dimension and has only the property of location... example, well, tree, gravel pit... a spatial feature represented by a pair of coordinates and has only the geometric property of location
Term
Line
Definition
A spatial feature that has one dimension and has the property of length in addition to location. Has two end points and points in between to mark the shape of the line. Represented by a series of points
Term
Polygon
Definition
two dimensional shape which has the properties of area and perimeter in addition to location. Made of connected, closed, non intersecting line segments. A spatial feature that is represented by a series of lines and has the geometric properties of location, size, and perimeter
Term
Topology
Definition
A subfield of mathematics that studies the properties of geometric objects that remain invariant under certain transformations such as bending and stretching
Term
TIGER
Definition
an early application of topology in geospatial technology – the Topologically Integrated Geographic Encoding and Referencing database created by the US Census Bureau.
Term
DLG
Definition
another well known example of vector data with built-in topology. Digital representations of point, line, and area features from USGS quadrangle maps.
Term
georelational data model (coverage & shapefile)
Definition
type of model which stores geometries and attributes in a split system – geometries in graphic files and attributes in relational database. GIS data model that stores geometries and attributes n two separated by related file systems
Term
object-based data model (geodatabase)
Definition
type of model which treats geospatial models as objects which can represent spatial features such as a road, or a hydrological unit... a vector data model that uses objects to organize spatial data.
Term
feature class
Definition
a data set that stores features of the same geometry type in a geodatabase... stores spatial features of the same geometry type
Term
feature dataset
Definition
a collection of feature classes in a geodatabase that share the same coordinate system and area extent...stores feature classes that share the same coordinate system and area extent (BOTH FEATURE CLASSES AND FEATURE DATASETS ARE COMPONENTS OF GEODATABASES)
Term
NHDinGEO
Definition
the acronym used by the National Hydrography Dataset program to designate their data in geodatabases
Term
raster data model
Definition
a data model that uses rows, columns, and cells to construct spatial features
Term
cell value
Definition
each cell in a raster contains a value which represents a characteristic of a spatial phenomenon at the location denoted by its row and column
Term
integer (categorical)
Definition
– a raster that contains cell values of integers
Term
floating-point (continuous)
Definition
a raster that contains cells of continuous values
Term
cell size
Definition
– determines the resolution of a raster.
Term
spatial reference –
Definition
a raster model must have a spatial reference information so they can align with other datasets in a GIS. The projection upon which raster data is able to be spatially related.
Term
georeferenced raster –
Definition
a raster that has been processed to align with a projected coordinate system
Term
remote sensing
Definition
– acquisition of information about an object without making physical contact with the object.
Term
Landsat (NASA)
Definition
– an orbiting satellite that provides repeat images of the Earth's surface. Latest landsat launched in 1999.
Term
digital elevation model (DEM)
Definition
– a digital model with an array of uniformly spaced elevation data in raster format
Term
digital orthophoto quad (DOQ)
Definition
a digitized image in which the displacement caused by the camera tilt and terrain relief has been removed from an aerial photograph.
Term
digital raster graphic (DRG) –
Definition
a scanned image of a USGS topographic map.
Term
USGS topographic map (7 1⁄2 minute quads)
Definition
map which stores topographic features at 250
dpi, uses 13 colors.
Term
ESRI Grid –
Definition
format in which ArcGIS stores raster data
Term
cell-by-cell encoding
Definition
– a raster data structure that stores cell value in a matrix by row and column
Term
run-length encoding (RLE)
Definition
– a raster data structure that records the cell values by row and by group. A run-length encoded file is also called a run-length compressed file
Term
quad tree (recursive decomposition)
Definition
– a raster data structure that divides rasters into a hierarchy of quadrants
Term
header file
Definition
– file in which information about the raster, such as data structure, number of bands, and value for no data is stored.
Term
data compression
Definition
– reduction of data volume, especially for raster data
Term
MrSID
Definition
– a compression technique / format which allows for lossless and lossy compression (multiresolution seamless image database). Multiresolution means it can recall the image data at different resolutions or scales.
Term
rasterization
Definition
– converting vector to raster
Term
vectorization
Definition
converting raster to vector
Term
Metadata –
Definition
provide information about geospatial data - an integral part of GIS data and are usually prepared and entered during the data production process
Term
framework data-
Definition
common types of GIS data on the internet that many organizations regularly use for GIS activities, typically consist of seven basic layers
Term
geodetic control
Definition
accurate positional framework for surveying and mapping
Term
orthoimagery
Definition
recertified imagery such as orthophotos
Term
Federal Geographic Data Committee (FGDC)
Definition
an interagency committee that leads development of policies, metadata standards, and training to support NSDI
Term
National Spatial Data Infrastructure (NSDI)
Definition
– aimed at sharing of geospatial data throughout all levels of government, the private and nonprofit sectors, and the academic community.
Term
U.S. Geological Survey (USGS)
Definition
– major provider of GIS data in the US.. offers national mapping and remotely sensed data, and to thematic data clearinghouses on biological, geological, and water resources data.
Term
digital line graphs (DLGs) –
Definition
VECTOR digital representations of point, line, and area features from USGS quadrangle maps, at the scales of 1:24000, 1:100000, and 1:2,000,000
Term
National Land Cover Data (NLDC)
Definition
- one of two datasets... 1992 includes 21 thematic classes compiled from thematic mapper imagery of the early 1990s. 2001 used the Landsat 7 ETM+ imagery to compile land cover data for all states and Puerto Rico.
Term
digital elevation models (DEMs)
Definition
– digital elevation models available at three designated websites... include 7.5 minute, 15 minute and 30 minute DEMS.
Term
National Elevation Dataset (NED) –
Definition
compiled by the USGS – provides 1:24000 scale of DEMS nationwide. A USGS program that uses a seamless system for delivering 1:24000 scale DEMS.
Term
TIGER/Line Files (U.S. Census)
Definition
– offered by the US census bureau – extracts of geographic/ cartographic information from it's MAF/TIGER database. Contain legal and statistical area boundaries such as counties, census tracts, and block groups, which can be linked to the census data, as well as roads, railroads, streams, waterbodies, etc.
Term
Content Standard for Digital Geospatial Metadata (CSDGM)-
Definition
standards published by the FGDC which cover: identification, data quality, spatial data organization, spatial reference, entity and attribute, distribution, metadata reference, citation, time period, and contact. Have been revised in accordance with international standards.
Term
Data conversion
Definition
– mechanism for converting GIS data from one format to another
Term
Autocad's DXF and DWG
Definition
a type of CAD file which can be translated to a GIS format (either shapefile or geodatabase) using ARCToolbox
Term
GPS
Definition
is a space-based satellite navigation system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites. Longitude, latitude, and elevation data for point locations made available through a navigational satellite system and a reciever
Term
NAVSTAR (Navigation Satellite Timing and Ranging)-
Definition
a group of 24 satellites maintained by the US military which play a crucial role in GPS application.
Term
Differential correction
Definition
– reducing noise errors mediated by a reference or base station
Term
reference (base) station
Definition
- stations which allow for differential correction by using a known position that can calculate what the travel time of GPS signals should be.
Term
Digitizing
Definition
– process of converting data from analog to digital format.
Term
Scanning –
Definition
digitizing method which uses a scanner to concert an analog map into a scanned file in raster format, which is then concerted back to vector format through tracing.
Term
Vectorization
Definition
– turns raster files into vector lines via a process called tracing.
Term
on-screen (heads-up digitizing)
Definition
– manual digitizing on the computer monitor using a data source such as DOQ as the background.
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