Accuracy - Degree of conformity with a standard, or the degree of correctness attained in a measure. Accuracy relates to the quality of a result, and is distinguished from precision which relates to the quality of the operation by which the result is obtained.
Attribute - Descriptive characteristics or quality of a feature. An attribute value is a measurement assigned to an attribute for a feature instance.
Computer aided design (CAD) - Software with the capability of assisting the operator in performing standard engineering and architecture design functions.
Computer aided mapping (CAM) - Software with the capability of assisting the operator in performing standard mapping functions.
Coordinate systems - A particular kind of reference frame or system, such as rectangular coordinates or spherical coordinates, that use linear or angular quantities to designate the position of points within that particular reference frame or system.
Data capture - Series of operations required to encode data in a computer-readable digital form (digitizing).
Data topology - Refers to the order or relationship of specific items of data to other items of data.
Digital data - Of or relating to data in the form of digits; data displayed, recorded, or stored in binary notation.
Digital elevation model (DEM) - A file with terrain elevations recorded at the intersections of a fine grid and organized by quadrangle to be the digital equivalent of the elevation data on a topographic base map.
Digital line graph (DLG) data - Digital representations of cartographic information.
Digital orthophoto - A digital image of an aerial photograph in which displacements caused by the camera and the terrain have been removed. It combines the image characteristics of a photograph with the geometric qualities of a map.
Digital raster graphic (DRG) - A scanned image of a U.S. Geological Survey (USGS) topographic map.
Digitizing - Process of converting an analog image or map into a digital format usable by a computer.
Edge matching - The comparison and graphic adjustment of features to obtain agreement along the edges of adjoining map sheets.
Geographic information system (GIS) - Computer system designed to allow users to collect, manage, and analyze large volumes of spatially referenced and associated attribute data.
Grid - A network of uniformly spaced horizontal and perpendicular lines that enclose an area (a cell) with an associated value assigned.
Import - Process of bringing data or software from another system into a system.
Labeling - Process of assigning attributes to polygons.
Map projection - Systematic drawing of lines on a flat surface to represent the parallels of latitude and the meridians of longitude of the spherical earth.
Photogrammetrically digitized - Digitized from aerial photographs and geodetic control data by means of photogrammetric instruments, providing three-dimensional coordinates.
Planimetric data - Spatial data that do not take topographic relief information into account for establishing position.
Raster - A cell-based data structure for storing images that is comprised of columns and rows. Each cell is analogous to a pixel in an image.
Rectification - Process of projecting a titled or oblique image onto a reference plane.
Scanning - Process of using an electronic input device to convert analog information from media such as maps, photographs, or overlays into a digital format usable by a computer.
Shapefiles - The Shapefile spatial data format is open and published
by ESRI. Shapefiles store nontopological geometry and attribute information
for the spatial features in a data set. Shapefiles can support point, line,
and area features. The shapefile concept includes as many as five file types
with specific file extensions. These files should be stored in the same workspace.
Shapefile file extensions and their function:
.shp - the feature geometry
.shx -an index to the feature geometry
.dbf - the associated dBASE file of attribute information
.sbn and .sbx - a spatial index of the features
.ain and .aih - the attribute index of active fields in a table or a theme’s
attribute table
Spatial data - Data pertaining to the location of geographic entities together with their spatial dimensions. Spatial data are classified as point, line, area, or surface.
Topology - A branch of geometric mathematics concerned with order, contiguity, and relative position, rather than actual linear dimensions.
Vector - Directed line segment, with magnitude commonly represented by the coordinates for the pair of end points. Vector data refer to data in the form of an array with one dimension.
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Jerry Weisenfluh / E-mail to jerryw@uky.edu