raster
See Also: lattice, vector
[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.
Raster Analysis I
Discussion:
Raster analysis is similar in many ways to vector analysis. However, there are some key differences.
RASTER DATA FORMATS
Raster data models incorporate the use of a grid-cell data structure where the geographic area is divided into cells identified by row and column. This data structure is commonly called raster.
Raster data processing in GRASS GIS
Raster maps in general
The geographic boundaries of the raster file are described by the north, south, east, and west fields. These values describe the lines which bound the map at its edges.
Rasterization or Rasterisation is the task of taking an image described in a vector graphics format (shapes) and converting it into a raster image (pixels or dots) for output on a video display or printer, ...
Raster graphics
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Raster GIS Procedures in ArcMap
Classifying Satellite Images with MultiSpec
Designing for Visibility ...
Raster to Vector
A contour or topographic map first is scanned, and the image is saved in a raster image file format such as TIFF or JPEG.
Raster Elevation Data
To start off, download the sample raster elevation data here. This data is a small square clip of raster elevation data which has been saved in the GeoTiff format. Save the file in a well known location, and extract the data.
Raster Cleanup
ArcScan for ArcGIS also supports tools for performing simple edits on raster images. You can draw, fill, and erase raster cells, all within an edit session.
Raster GIS
A raster GIS models space by tessellating it into regular, discrete locations and assigning attributes to each location. The most common tessellation employed by raster GIS software is the square.
raster model divides the entire study area into a regular grid of cells in specific sequence ...
Support for Popular Wide-format Plotters and Industry-standard Raster Formats
Overview ...
Raster Data
Raster data is characterized by pixel values. Basically, a raster file is a giant table, where each pixel is assigned a specific value from 0 to 255.
Raster Versus Vector Systems
Early GISs were either raster or vector systems. Table 1 lists various advantages and disadvantages of vector and raster data systems (Burrough 1986, Aronoff 1989).
Raster Overlay In raster overlay, the pixel or grid cell values in each map are combined using arithmetic and Boolean operators to produce a new value in the composite map.
Raster : Representation as a regular grid of cells
relate : An operation that establishes a temporary connection between corresponding records in two tables using an item common to both.
Raster and Vector Format
GIS allows map or other visual data to be stored in either a raster or vector data structure: ...
Raster
A method of storing image data which consists of cells (pixels) which make up rows and columns. Each cell represents a feature.
Record ...
Raster-to-Raster & Vector-to-Vector
There are many types of vector formats used in GIS, and even more raster formats.
Raster - Common GIS data model made up of a grid of cells or pixels. Each pixel contains a single value (TWS).
Rectification - Making an image conform to a map projection system (TWS).
Raster - 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 cell contains an attribute value and location coordinates.
Raster - "1. An element of a space that has been subdivided into regular tiles by tessellation. 2. Commonly, a data set, as for an image or DEM, composed of rasters. 3. Often used as a synonym for grid" (Bonham-Carter, 1994, p. 373).
Raster displays and databases build all geographic features from grid cells in a matrix. A raster display builds an image from pixels, pels, or elements of coarse or fine resolution.
raster object - one or more images and/or grids, each grid or image representing a layer, such that corresponding grid cells and/or pixels between layers are congruent and registered.
raster data
One of the three types of spatial data in a GIS (the others being image and vector data). Raster data represents geographic space as a matrix of cells; map features are defined by numeric values assigned to the cells.
Raster
A cellular data structure composed of rows and columns. Groups of cells represent features. The value of each cell represents the value of the feature. Image data is stored using this structure.
RDBMS ...
raster Data displayed as discrete picture elements (pixels).
relate An operation that establishes a temporary connection between corresponding records in two tables using an item common to both.
Raster Data Machine-readable data that represents values usually stored for maps or images and organized sequentially by rows and columns. Each "cell" must be rectangular but not necessarily square, as with grid data.
Raster: Raster data takes an evenly spaced grid (like a piece of graph paper) and places a value in each square, or cell.
Raster Data Types
Raster data represent features as a matrix of cells within rows and columns in continuous space. These cells are formed by pixels of a specific dimension size, and can be described as either "cell-based" or "image-based" data.
Raster
A raster data type is, in essence, any type of digital image. Anyone who is familiar with digital photography will recognize the pixel as the smallest individual unit of an image.
The raster model
models continuous features
a collection of grid cells
Both the vector and raster models for storing geographic data have unique advantages and disadvantages and modern GISs are able to handle both types.
Input Rasters
Working with raster data is a snap, particularly with direct access without data conversion, enabling rapid application or web service development.
Raster Data - raster (or grid cell type) data can be used for analyzing, overlaying, and modelling area features such as soil types or forested areas. Raster data are generally typically scanned in from maps.
Raster Based USGS Topographical Maps
The USGS topographical map archive is the map database most familiar to most people. Outdoorsmen are used to purchasing these paper maps from their nearest camping supply store for a few dollars.
Raster data capture: Capturing of attributes, etc without physical contact. This is usually done with the help of satellite imaging techniques, Ariel photography.
Raster means of managing and manipulating the data are to be preferred for handling continuous information such as altitude (see Digital Elevation Models, below), vegetation, etc.
Raster versus vector datasets
Gridded data
Surfaces
Interpolation and contouring
Hillshading
Integrating and interconverting raster and vector data
TIGER files ...
Raster data files can be manipulated quickly by the computer, but they are often less detailed and may appear less visually appealing than vector data files, which can approximate the appearance of more traditional hand-drafted maps.
Raster data such as the DOQs, rather than vector data, may be more effectively used for some applications. Much like the symbology on a topographic map, vector data tend to be more generalized (i.e.
Raster grids, on the other hand, contain a robust range of values and organizational structure amenable to map analysis and modeling. As depicted on the left side of figure 3.
Raster Map
A digital base map in which geographic objects are depicted using a grid of pixels, with the color of each pixel individually defined. Examples of raster maps include aerial imagery or scanned paper maps.
Real Time ...
Raster Image Processing; Raster Image Processor; Road Inventory Program
RIPS
Remote Image Processing System; Remote Information Processing System ...
Raster - A data structure that is based on the use of grid cells. See also Tessellation and Vector.
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Raster Data: One method of storing, representing or displaying spatial data in digital form.
In the raster approach, we manually overlay or scan onto the map a grid array of cells, having some specific size. As shown in the right panel (grid format, above), an irregular polygon then includes a number of cells, completely contained therein.
Vector and Raster Models: Geographic information systems work with two fundamentally different types of geographic models--the "vector" model and the "raster" model.
The vector and raster data types are called as feature and coverage respectively. The geometry of the spatial data is defined for the 'Well-Known-Types' (WKT). Their instances are called 'Well-Known-Structures'.
An overlay of a raster map and vector features showing the urban area and buildings of Iqaluit in 1995
Shaded relief map of Iqaluit and surrounding area
larger image
[JPEG, 131.0 kb, 610 X 553, notice] ...
Increase the cell size and resample data in a raster format GIS. Generating Globe The conceptual globe from which map projections can be devloped. Geographic Data The composite locations and descriptions of geographic entities.
For raster imagery, a layer can represent one sensor in a multispectral array. In some cases, a layer may contain a coverage, hence provide an attribute value at all locations.
Image data from a satellite that has been interpreted by a computer to produce a land use map can be "read into" the GIS in raster format. Raster data files consist of rows of uniform cells coded according to data values.
The data structure of scanned maps is raster. schema A structured framework. A metadata schema specifies the order and types and labels of information elements describing a geodata set. SCOTS Standards based commercial off-the-shelf software.
An image is stored as a raster data set of binary or integer values that represent the intensity of reflected light, heat, or other range of values on the electromagnetic spectrum.
A pixel is the basic unit of measurement in computer screen resolution and is also, the smallest unit constituting a bitmap (raster) image.
Satellite images, for example, usually app ear as raster data, a gridded matrix in which the position of each data point is indicated by its row and column numbers.
A typical feature with respect to co-ordinate transformations is the possibility in ILWIS to match vector and raster data by an on-the-fly transformation of the vector data.
Scanners sometimes can replace digitizing by automatically converting hard-copy maps to a digital raster file. Once in a GIS, the raster image can be converted to a vector format through a "raster-to-vector" conversion.
Currently, two varieties of raster image formats are widely supported on the World Wide Web: CompuServe's popular Graphic Interchange Format (GIF) and the Joint Photographic Experts Group (JPEG) based format JFIF.
 See also: Information, GIS, Map, Image, Model
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