geoshow - Display map latitude and longitude data

Syntax

Description

geoshow(lat,lon) projects and displays the latitude and longitude vectors lat and lon using the projection stored in the axes. If there is no projection, lat and lon are projected using a default Plate Carrée projection. The default behavior for geoshow is to display lat and lon as lines.

geoshow(s) displays the vector geographic features stored in s as points, multipoints, lines, or polygons according to the Geometry field of s. If s includes lat and lon fields, then the coordinate values are projected to map coordinates. If s includes X and Y fields, then the coordinate values are plotted as preprojected map coordinates, and a warning is issued.

geoshow(lat,lon,Z) projects and displays a geolocated data grid.

geoshow(Z,R) projects and displays a regular data grid, Z.

geoshow(lat,lon,image) or geoshow(lat,lon,A,cmap) projects and displays a geolocated image as a texturemap on a zero-elevation surface. lat, lon, and the image array must match in size. Examples of geolocated images include a color composite from a satellite swath or an image originally referenced to a different coordinate system.

geoshow(image,R) or geoshow(A,cmap,R) projects and displays an image georeferenced to latitude-longitude through the referencing matrix R. The image is shown as a texturemap on a zero-elevation surface.

geoshow(ax,...) and geoshow('Parent',ax,...) set the parent axes to ax.

geoshow(filename) projects and displays data from the file specified according to the type of file format.

geoshow(...,Name,Value) specifies parameters and corresponding values that modify the type of display or set MATLAB graphics properties. Parameter names can be abbreviated, and case does not matter.

h = geoshow(...) returns a handle to a MATLAB graphics object.

Tips

• When calling shaperead to read files that contain coordinates in latitude and longitude, be sure to specify the shaperead argument pair 'UseGeoCoords',true. If you do not include this argument, shaperead will create a mapstruct, with coordinate fields labelled X and Y instead of Lon and Lat. In such cases, geoshow assumes that the geostruct is in fact a mapstruct containing projected coordinates, warns, and calls mapshow to display the geostruct data without projecting it.

• If you do not want geoshow to draw on top of an existing map, create a new figure or subplot before calling it.

• When you display vector data in a map axes using geoshow, you should not subsequently change the map projection using setm. You can, however, change the projection with setm for raster data. For more information, see Changing Map Projections when Using geoshow.

• If you display a polygon, do not set 'EdgeColor' to either 'flat' or 'interp'. This combination may result in a warning.

• When projecting data onto a map axes, geoshow uses the projection stored with the map axes. When displaying on a regular axes, it constructs a default Plate Carrée projection with a scale factor of 180/pi, enabling direct readout of coordinates in degrees.

• geoshow can generally be substituted for displaym. However, there are limitations where display of specific objects is concerned. See the remarks under updategeostruct for further information.

• You can access geoshow through the Plot Selector workspace tool, which is represented by this icon . In your workspace, select the data you want to display. The Plot Selector icon changes to look like this: . Scroll down to geoshow(s): Plot a geostruct array.

Input Arguments

[cells/degree northern_latitude_limit western_longitude_limit]

[lon lat] = [row col 1] * R

Name-Value Pair Arguments

Output Arguments

Class Support

Examples

Display world land areas using a default Plate Carree projection:

figure
geoshow('landareas.shp', 'FaceColor', [0.5 1.0 0.5]);

Override the symbolspec default rule:

% Create a worldmap of North America.
figure
worldmap('na');

% Read the USA high resolution data.
states = shaperead('usastatehi', 'UseGeoCoords', true);

% Create a symbolspec to make Alaska and Hawaii polygons red.
symspec = makesymbolspec('Polygon', ...
   {'Name', 'Alaska', 'FaceColor', 'red'}, ...
   {'Name', 'Hawaii', 'FaceColor', 'red'});

% Display all the other states in blue.
geoshow(states, 'SymbolSpec', symspec, ...
   'DefaultFaceColor', 'blue', ...
   'DefaultEdgeColor', 'black');

Create a worldmap of Korea and display the korea data grid as a texture map:

load korea
figure;
worldmap(map, refvec)

% Display the Korean data grid as a texture map. 
geoshow(gca,map,refvec,'DisplayType','texturemap');
demcmap(map)

% Display the land area boundary as black lines.
S = shaperead('landareas','UseGeoCoords',true);
geoshow([S.Lat], [S.Lon],'Color','black');

Display the EGM96 geoid heights, masking out land areas:

load geoid
% Create a figure with an Eckert projection.
figure
axesm eckert4; 
framem; gridm;
axis off

% Display the geoid as a texture map. 
geoshow(geoid, geoidrefvec, 'DisplayType', 'texturemap');

% Create a colorbar and title.
hcb = colorbar('southoutside');
set(get(hcb,'Xlabel'),'String','EGM96 Geoid Heights in Meters.')

% Mask out all the land.
geoshow('landareas.shp', 'FaceColor', 'black');

Display the EGM96 geoid heights as a 3-D surface using the Eckert IV projection:

load geoid

% Create the figure with an Eckert projection.
figure
axesm eckert4; 
axis off

% Display the geoid as a surface. 
h = geoshow(geoid, geoidrefvec, 'DisplayType','surface');

% Add light and material.
light; material(0.6*[ 1 1 1]);

% View as a 3-D surface.
view(3)
axis normal
tightmap

Display the moon albedo image projected using Plate Carree and in an orthographic projection:

load moonalb

% Projection not specified. Uses Plate Carree.
figure
geoshow(moonalb,moonalbrefvec) 

% Orthographic projection
figure
axesm ortho 
geoshow(moonalb, moonalbrefvec, 'DisplayType', 'texturemap')
colormap(gray(256))
axis off

Read and display the San Francisco South 24K DEM data:

filenames = gunzip('sanfranciscos.dem.gz', tempdir); 
demFilename = filenames{1}; 

% Read every point of the 1:24,000 DEM file. 
[lat, lon,Z] = usgs24kdem(demFilename,2); 

% Delete the temporary gunzipped file. 
delete(demFilename); 

% Move all points at sea level to -1 to color them blue. 
Z(Z==0) = -1;

% Compute the latitude and longitude limits for the DEM. 
latlim = [min(lat(:)) max(lat(:))];
lonlim = [min(lon(:)) max(lon(:))];

% Display the DEM values as a texture map. 
figure
usamap(latlim, lonlim)
geoshow(lat, lon, Z, 'DisplayType','texturemap')
demcmap(Z)
daspectm('m',1)

% Overlay black contour lines onto the texturemap.
geoshow(lat, lon, Z, 'DisplayType', 'contour', ...
  'LineColor', 'black');

% View the DEM values in 3-D.
figure
usamap(latlim, lonlim)
geoshow(lat, lon, Z, 'DisplayType', 'surface')
demcmap(Z)
daspectm('m',1)
view(3)

See Also

axesm | makesymbolspec | mapshow | mapview | updategeostruct

How To

• Displaying Vector Data with Mapping Toolbox Functions
• Understanding Raster Geodata

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