This example shows how to generate a shaded relief map using raster data, also known as a data grid. Note that the content, symbolization, and the projection of the map are completely independent. The structure and content of the
topo data grid are the same no matter how you display it, although how it is projected and symbolized can affect its interpretation.
topo data grid from the
topo MAT-file and examine the variables returned to the workspace. The data grid
topo contains raster elevation data.
load topo whos
Name Size Bytes Class Attributes topo 180x360 518400 double topolatlim 1x2 16 double topolegend 1x3 24 double topolonlim 1x2 16 double topomap1 64x3 1536 double topomap2 128x3 3072 double
Create a raster referencing object to georeference the
topo data grid.
topoR = georefcells(topolatlim,topolonlim,size(topo))
topoR = GeographicCellsReference with properties: LatitudeLimits: [-90 90] LongitudeLimits: [0 360] RasterSize: [180 360] RasterInterpretation: 'cells' ColumnsStartFrom: 'south' RowsStartFrom: 'west' CellExtentInLatitude: 1 CellExtentInLongitude: 1 RasterExtentInLatitude: 180 RasterExtentInLongitude: 360 XIntrinsicLimits: [0.5 360.5] YIntrinsicLimits: [0.5 180.5] CoordinateSystemType: 'geographic' AngleUnit: 'degree'
Create an equal-area map projection to view the topographic data.
axesm creates a figure window with map axes set to display a sinusoidal projection. Then generate a shaded relief map. One way to do this is to use
geoshow and apply a topographic colormap using
geoshow displays the geodata in geographic (unprojected) coordinates.
axesm sinusoid; geoshow(topo,topoR,'DisplayType','texturemap') demcmap(topo)
Create a new figure using a Hammer projection (which, like the sinusoidal, is also equal-area), and display the
topo data grid using
meshlsrm, which enables control of lighting effects. This renders a colored relief map of the
topo data set, illuminated from the east, in the second figure window.
figure; axesm hammer meshlsrm(topo,topoR)