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.