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GIS Midterm
| Question | Answer |
|---|---|
| GIS | Geographic information system. A computer system used for capturing, storing, query, analyzing, and displaying geospatial data |
| geospatial data | data that describes the locations and characteristics of spatial features on the Earth’s surface |
| vector data model | use of points and x |
| raster data model | use of grid and grid cells to represent continuous features such as elevation and precipitation |
| data exploration | general exploration of data trends and possible relationships among data sets. Can use maps for data classification and comparison. |
| data analysis | 7 classifications: spatial data input, attribute data management, data display, data exploration, data analysis, GIS modeling |
| ESRI | ArcGIS software manufacturer |
| ArcGIS | main ESRI software product. Scalable system with ArcView, ArcEditor, and ArcInfo |
| Projection | The process of transforming the spatial relationship of features on the Earth’s surface to a flat map |
| Reprojection | Projection of spatial data from one projected coordinate system to another |
| geographic coordinate system | A location reference system for spatial features on the Earth’s surface |
| latitude | The angle north or south of the equatorial plane |
| longitude¬ | The angle east or west of the equatorial plane |
| meridians | Lines of longitude that measure locations in the E |
| parallels | Lines of latitude that that measure locations in the N |
| sphere | Earth is NOT a sphere |
| spheroid/ellipsoid | A model that approximates the Earth with the major axis along the equator and the minor axis connecting the north and south poles |
| geoid | irregularly surfaced ellipsoid, better representing the varying elevations of Earth’s surface |
| Clarke 1866 | A ground |
| NAD 27 | North American Datum of 1927, based on Clarke 1866, has center at Meades Ranch, Kansas |
| NAD 83 | North American Datum of 1983, based on the GRS80 spheroid, origin at center of spheroid |
| GRS 80 | A satellite |
| WGS 84 | A satellite |
| Datum | The basis for calculating the geographic coordinates of a location. A spheroid is a required input to the derivation of a datum |
| map projection | A systematic arrangement of parallels and meridians on a plane surface |
| false easting/northing | a value applied to the origin of a coordinate system to change the x |
| projected coordinate system | A plane coordinate system that is based on a map projection |
| map scale | ratio of map distance to the corresponding ground distance |
| state plane coordinate system (SPC) | A coord. system developed in the 1930s to record original land survey monument locations in the US. Most states have >1 zone based on the SPC27 or SPC83 system |
| on | the |
| raster data model | a data model that uses rows, columns, and cells to construct spatial features |
| cell value | spatial characteristics in that cell, changes in cell value reflect spatial variation |
| integer (categorical) | no decimal digit, represents categorical data, such as habitats. |
| floating | point (continuous) |
| cell size | determines the resolution of a raster cell—smaller cell, more detail |
| spatial reference | information that allows raster data to spatially align with other GIS data sets |
| georeferenced raster | a raster that has been processed to match a projected coordinate system |
| remote sensing | acquisition of information without making physical contact |
| Landsat (NASA) | geo |
| digital elevation model (DEM) | array of uniformly spaces elevation data, point based but can be converted to raster |
| digital orthophoto quad (DOQ) | digitized image of an aerial photograph or other remotely sensed data in which the displacement caused by camera tilt and terrain relief has been removed. |
| digital raster graphic (DRG) | scanned image of a USGS topographic map, ground resolution of 2.4 meters |
| USGS topographic map (7 ½ minute quads) | 1:24,000 |
| ESRI Grid | format in which ArcGIS stores raster data |
| cell | by |
| run | length encoding (RLE) |
| quad tree (recursive decomposition) | division of a raster into a hierarchy of quadrants as to make cells smaller and more precise |
| header file | project file for a coordinate system including information about the raster, data structure, area extent, cell size, number of bands, and value for no data |
| data compression | reduction of data volume. Lossless: preserves cell or pixel values and allows the original raster or image to be precisely reconstructed. |
| MrSID | Mulitresolution Seamless Image Database |
| Rasterization | conversion of vector data into raster data |
| Vectorization | conversion of raster data into vector data |
Created by:
caroline.chandler