GIS Dictionary

[physics] Acronym for radio detection and ranging. A device or system that detects surface features on the earth by bouncing radio waves off them and measuring the energy reflected back.

[physics] An instrument that determines elevation, usually from mean sea level, by measuring the amount of time an electromagnetic pulse takes to travel from an aircraft to the ground and … Read more

[remote sensing] The analysis of interferograms that have been created by IFSAR, or artificially. Radar interferometry involves the comparison of two or more images of the same area taken from … Read more

[spatial statistics use for geostatistics] In ArcGIS Geostatistical Analyst, a deterministic interpolation method. The interpolated surface is forced to conform to the sample data points, and the method does not … Read more

[Euclidean geometry] The angle subtended by an arc of a circle that is the same length as the radius of the circle, approximately 57 degrees, 17 minutes, and 44.6 seconds. … Read more

[physics] The emission and propagation of energy through space in the form of waves. Electromagnetic energy and sound are examples of radiation.

[physics] An instrument that measures the intensity of radiation in a particular band of wavelengths in the electromagnetic spectrum, such as infrared or microwave.

[remote sensing] Procedures that correct or calibrate aberrations in data values due to specific distortions from such things as atmosphere effects (such as haze) or instrumentation errors (such as striping) … Read more

[physics] The sensitivity of a sensor to incoming reflectance. Radiometric resolution refers to the number of divisions of bit depth (for example, 255 for 8-bit, 65,536 for 16-bit, and so … Read more

[Euclidean geometry] The distance from the center to a point on the outer edge of a circle, circular curve, or sphere.

[spatial statistics use for geostatistics] In a spatial model, variation in the value of a variable that cannot be described by a mathematical function and is not spatially correlated: it … Read more

A parameter of a variogram or semivariogram model that represents a distance beyond which there is little or no autocorrelation among variables.

[data structures] A type of attribute domain that defines the range of permissible values for a numeric attribute. For example, the permissible range of values for a pipe diameter could … Read more

[accuracy] A method of assigning an accuracy value to feature classes to avoid having vertices from a feature class collected with a high level of accuracy being snapped to vertices … Read more

1 [data models] A spatial data model that defines space as an array of equally sized cells arranged in rows and columns, and composed of single or multiple bands. Each … Read more

[ESRI software] An ArcGIS Spatial Analyst tool for performing mathematical calculations with operators and functions, setting up selection queries, or typing Map Algebra syntax. Inputs to the Raster Calculator can … Read more

[ESRI software] A collection of raster datasets defined in a table of any format, in which the records define the individual raster datasets that are included in the catalog. Raster … Read more

[ESRI software] The process of drawing, filling, and erasing raster cells using ArcScan Raster Cleanup and Raster Painting tools.

[data models] A representation of the world as a surface divided into a regular grid of cells. Raster models are useful for storing data that varies continuously, as in an … Read more

[data models] In ArcGIS, a raster spatial data model that is stored on disk or in a geodatabase. Raster datasets can be stored in many formats, including TIFF, JPEG 2000, … Read more

[remote sensing] One layer in a raster dataset that represents data values for a specific range in the electromagnetic spectrum (such as ultraviolet, blue, green, red, and infrared), or radar, … Read more

[data models] Three or more lines in a raster that meet at a common point.

[ESRI software] In ArcGIS, a layer that references a raster as its data source and a raster renderer that defines how the raster data should be rendered and any additional … Read more

[data conversion] In ArcScan, the automatic correction of vector feature results immediately after batch vectorization is completed. Postprocessing involves generalizing lines, straightening angles, and smoothing lines.

[data conversion] Simple raster editing that prepares images for viewing and analysis. Preprocessing includes georeferencing, clipping, positioning, resizing, enhancing, and mosaicking.

[ESRI software] In ArcGIS Image Server, an XML file that contains properties of the raster dataset, including metadata, as well as the definition of processes to be applied to one … Read more

[ESRI software] Statistics that are calculated from the cell values of each band in a raster. The statistics that are calculated include the minimum, maximum, mean, and standard deviation cell … Read more

[data conversion] An interactive vectorization process that involves drawing along the boundary of contiguous raster cells to create vector features.

[data models] In ArcGIS, identifies metadata, such as georeferencing, acquisition date, and sensor type, along with a raster format.

[data conversion] The conversion of points, lines, and polygons into cell data.

[ESRI software] A feature layer in ArcGlobe that exists as points, lines and polygons but is rendered as cell data. When layers are added to ArcGlobe, they may automatically be … Read more

[data structures] Data classified relative to a fixed zero point on a linear scale. Mathematical operations can be used on these values with predictable and meaningful results. Examples of ratio … Read more

In digital image processing, enhancing the contrast between features in an image by dividing the values of pixels in one image by the values of corresponding pixels in a second … Read more

[3D GIS] A technique that traces imaginary rays of light from a viewer’s eye to the objects in a three-dimensional scene to determine which parts of the scene should be … Read more