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Raster Data

Georeference, analyze and transform gridded data

Raster data, also known as data grids, stores map data as matrices. Regular data grids require a referencing object, vector, or matrix that describes the sampling and location of the data points. Geolocated data grids explicitly identify the latitude and longitude coordinates of all rows and columns.

Functions

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Reference Objects and Latitude-Longitude Grids

georefcellsReference raster cells to geographic coordinates
georefpostingsReference raster postings to geographic coordinates
refmatToGeoRasterReferenceReferencing matrix to geographic raster reference object
refvecToGeoRasterReferenceReferencing vector to geographic raster reference object
geoloc2gridConvert geolocated data array to regular data grid
meshgratConstruct map graticule for surface object display

Analyze and Manipulate Data

georesizeResize geographic raster
geocropCrop geographic raster
geointerpGeographic raster interpolation
geopeaksGenerate synthetic data set on sphere
imbedmEncode data points into regular data grid
filtermFilter latitudes and longitudes based on underlying data grid
findmLatitudes and longitudes of nonzero data grid elements
changemSubstitute values in data array
encodemFill in regular data grid from seed values and locations

Reference Objects

maprefcellsReference raster cells to map coordinates
maprefpostingsReference raster postings to map coordinates
refmatToMapRasterReferenceReferencing matrix to map raster reference object

Analyze and Manipulate Data

mapresizeResize projected raster
mapcropCrop projected map raster
mapinterpMap raster interpolation
pixcentersCompute pixel centers for georeferenced image or data grid
mapoutlineCompute outline of georeferenced image or data grid
changemSubstitute values in data array
encodemFill in regular data grid from seed values and locations
georasterrefConstruct geographic raster reference object
maprasterrefConstruct map raster reference object
refmatToWorldFileMatrixConvert referencing matrix to world file matrix

Objects

GeographicCellsReferenceReference raster cells to geographic coordinates
GeographicPostingsReferenceReference raster postings to geographic coordinates
MapCellsReference Reference raster cells to map coordinates
MapPostingsReference Reference raster postings to map coordinates

Topics

Introduction to Geodata in Raster Format

Raster Geodata

Raster geodata represents map data in matrix format.

Georeferenced Raster Data

Each element of georeferenced raster data corresponds to a defined quadrangle of territory on a planet.

Types of Data Grids and Raster Display Functions

You can display regular and geolocated data grids in many ways, such as a 2-D indexed image where color represents the data value, or as a 3-D surface with light shading.

Regular Data Grids

Construct a Global Data Grid

This example shows how to store a matrix in a geographic referencing object. Display the matrix on a map, and specify display properties such as the projection, axes labels, and color map.

Precompute the Size of a Data Grid

This example shows how to compute the expected size of a large data grid, before creating the grid, to confirm that the grid will be manageable and will fit in memory.

Compute Gradient, Slope, and Aspect from Regular Data Grid

This example shows how to compute relationships between neighboring cells in a regular data grid.

Geolocated Data Grids

Geolocated Data Grids

A geolocated data grid is defined by three matrices giving latitude and longitude coordinates and indices associated with the mapped region.

Geographic Interpretations of Geolocated Grids

The dimensions of a map matrix and associated latitude and longitude matrices determines the interpretation of the geographic map data.

Applications of Gridded Geodata

Creating a Half-Resolution Georeferenced Image

This example shows how to create a half-resolution version of a georeferenced TIFF image, using spatial referencing objects (requires Image Processing Toolbox™).

Compute Elevation Profile Along Straight Line

This example shows how to compute an elevation profile along a straight line by defining waypoints.

Display Shaded Relief Map Using Raster Data

This example shows how to generate a shaded relief map using geographic data in an array. You can change the displayed projection of the map without modifying the raster data.

Data Grids as Logical Variables

You can perform logic tests on data grid variables to create a binary logical grid.

Featured Examples