Read a GeoTIFF image of Boston as an array and a map cells reference object. The array is of size 2881-by-4481-by-3 and specifies the red, green, and blue components of the image. Display the image using the mapshow function.

[A,R] = readgeoraster('boston.tif');
mapshow(A,R)

The data used in this example includes material copyrighted by GeoEye, all rights reserved.

Read and display a land cover classification of Oahu, Hawaii.

First, read the land cover data as an array, a map cells reference object, and a colormap. The elements of A index into the colormap. Each row of the colormap specifies the red, green, and blue components of a single color. Then, display the land cover data.

[A,R,cmap] = readgeoraster('oahu_landcover.img');
mapshow(A,cmap,R)

The data used in this example is courtesy of the National Oceanic and Atmospheric Administration (NOAA).

Read and display elevation data for an area around South Boulder Peak in Colorado.

First, read the elevation data as an array and a geographic postings reference object. To display the data as a surface, the geoshow function requires data of type double or single. In this case, preserve precision by specifying the output type as 'double'.

[A,R] = readgeoraster('n39_w106_3arc_v2.dt1','OutputType','double');

Create a map. First, create map axes by specifying the latitude and longitude limits of the data. Then, display the data as a surface using the geoshow function. Apply a colormap appropriate for elevation data using the demcmap function.

latlim = R.LatitudeLimits;
lonlim = R.LongitudeLimits;
usamap(latlim,lonlim)
geoshow(A,R,'DisplayType','surface')
demcmap(A)

The elevation data used in this example is courtesy of the US Geological Survey.

Raster data sets sometimes indicate missing data values using a large negative number. Import raster data, find the missing data indicator, and then replace missing data with NaN values.

Import raster data and a reference object using the readgeoraster function. Find the missing data indicator using the georasterinfo function.

[A,R] = readgeoraster('MtWashington-ft.grd');
info = georasterinfo('MtWashington-ft.grd');
m = info.MissingDataIndicator

m = -32766

Verify the raster data contains missing data using the ismember function. The ismember function returns logical 1 (true) if the raster contains the missing data indicator.

ismember(m,A)

ans = logical
   1

Replace the missing data with NaN values using the standardizeMissing function.

A = standardizeMissing(A,m);