**raster data model**

See Also: vector data model

[data models] A representation of the world as a surface divided into a regular grid of cells.

The **Raster Data Model**

The **Raster data model** is the simpler of the two and is based on the division of reality into a regular grid of identically shaped cells. Each cell is assigned a single value which represents the attribute for the area of that cell.

4.1 **Raster Data Model**s

Learning Objective

The objective of this section is to understand how **raster data model**s are implemented in GIS applications.

**Raster data model**:

Continuous numeric values, such as elevation, and continuous categories, such as vegetation types, are represented using the raster model. The **raster data model** represents features as a matrix/lattice of cells in continuous space.

**raster data model**

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 aerial photograph, a satellite image, a surface of chemical concentrations, or an elevation surface.

raster dataset ...

The **raster data model** has become the primary spatial data source for analytical modeling with GIS. The **raster data model** is well suited to the quantitative analysis of numerous data layers.

vector and **raster data model**s

field and object data models

representations for fields - pointgrids, contours, TIN data models

even data structures such as GBF/DIME and chaincodes have been called data models (Peuquet 1990) ...

Both vector and **raster data model**s use LIDAR data. Many GIS programs have automated routines that convert the x, y, and z (elevation or altitude) points first into vector point files, ...

In this section the implications of vector and **raster data model**s on encoding, storage, and analysis are discussed. The inherent statistical characterizations of mapped data and their implications in map analysis are described.

A DEM held as a regular matrix suffers the same disadvantages due to size as does the **raster data model**.

Grid layers are graphical representations of the ArcGIS and ArcInfo implementation of the **raster data model**. Grid layers are stored with a numeric value for each cell. The numeric cell values are either integer or floating-point.

While it is recommended that software incorporate both vector and **raster data model**s, priority should be given to vector data model capabilities.

I would suggest you explore the Object-relational database, the ESRI website, the vector and **raster data model**, geostatistics or spatial statistics, topology or geospatial topology, and the open-geospatial consortium (OGC) website.

For example, the vector data model represents geography as collections of points, lines, and polygons; the **raster data model** represents geography as cell matrixes that store numeric values; and the TIN data model represents geography as sets of contiguous, nonoverlapping triangles.

The **raster data model** is composed of a grid and each cell within the grid holds data. Another way to explain it is that the polygon has a grid laid over it and the polygon would fill those cells with data, each cell in the grid being assigned a value.

Each point feature is represented as a single coordinate pair, while line and polygon features are represented as ordered lists of vertices. Attributes are associated with each vector feature, as opposed to a **raster data model**, which associates attributes with grid cells.

With the **raster data model**, spatial data is not continuous but divided into discrete units.

Rubber Sheeting: A procedure to adjust the coordinates of all the data points in a data set to allow a more accurate match between known locations and a few data points within the data set.

See also: Data Model, Raster Data, Raster, Model, GIS

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