wmline

Display geographic line on web map

Syntax

wmline(lat,lon)

wmline(P)

wmline(wm,___)

wmline(___,Name,Value)

h = wmline(___)

Description

wmline(lat,lon) displays a line overlay defined by the vertices in lat,lon on the current web map. If there is no current web map, wmline creates one. wmline centers the map so that all vector overlays displayed on the web map are visible.

wmline(P) displays a line overlay based on the content of the geopoint or geoshape vector P.

wmline(wm,___) displays the line overlay on the web map specified by the web map handle, wm.

wmline(___,Name,Value) specifies name-value pairs that set additional display properties.

h = wmline(___) returns a handle to line overlay.

Examples

Display Line on Web Map

Find the coordinates of London and Paris.

cities = shaperead('worldcities.shp', 'UseGeoCoords', true, ... 
    'Selector', ... 
    {@(v)(ismember(v, {'London', 'Paris'})), 'Name'}); 
lat = [cities.Lat]; 
lon = [cities.Lon];

Display a line on the web map from London to Paris.

wmline(lat,lon)

Display Reduced Line on Web Map

Large data sets can sometimes be slow to display, making the web map browser appear to hang. To work around this issue, reduce the size of the data set using the reducem function before calling wmline.

Load vector data representing the coordinates of coastlines.

load coastlines

Reduce the number of points in the latitude and longitude vectors using the reducem function.

[lat,lon] = reducem(coastlat,coastlon);

Create a web map that does not wrap because the data is of global extent.

webmap('ocean basemap','WrapAround',false) 

Display the coastlines on the web map. The figure shows the description balloon that appears when you click on the line. Name the feature using the 'FeatureName' name-value pair.

wmline(lat,lon,'LineWidth',3,'FeatureName','coastline') 
wmzoom(2) 

Display Circles on Web Map

Define the latitude and longitude of the feature. This example shows how to display lines on a web map that represent range data for an airport approach pattern.

lat0 = 51.50487; 
lon0 = 0.05235; 

Create a web map and specify a base layer.

webmap('OpenStreetMap')

Compute a small circle with a 1000 meter radius. Setting the az parameter to an empty matrix causes scircle1 to compute a complete circle.

radius = 1000; 
az = []; 
e = wgs84Ellipsoid; 
[lat,lon] = scircle1(lat0,lon0,radius,az,e); 

Display a red circle with 1000 meter radius, using the latitude and longitude values returned by scircle1 in the previous step.

wmline(lat,lon,'Color','red','OverlayName','1000 Meters')

Compute another small circle, this time with a 2000 meter radius.

radius = 2000; 
[lat,lon] = scircle1(lat0,lon0,radius,az,e);

Draw the 2000 meter radius circle on the web map, setting the color to black.

wmline(lat,lon,'Color','k','OverlayName','2000 Meters')

Input Arguments

lat — Latitudes of vertices

matrix

Latitudes of vertices, specified as a matrix.

Data Types: single | double

lon — Longitudes of vertices

matrix

Longitudes of vertices, specified as a matrix.

Data Types: single | double

P — Geographic features

geopoint vector | geoshape vector

Geographic features, specified as a geopoint or geoshape vector.

• If P is a geopoint vector, the overlay contains a single line connecting its vertices.

• If P is a geoshape vector, the overlay contains one line feature for each element of P.

wm — Web map

web map handle

Web map, specified as a web map handle.

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: wmline(lat,lon,'OverlayName','Shortest Route');

'Autofit' — Overlay visibility

true (default) | false

Overlay visibility, specified as the comma-separated pair consisting of 'Autofit' and the scalar logical or numeric value true (1) or false (0).

• If true, wmline adjusts the spatial extent of the map to ensure that all the vector overlays on the map are visible.

• If false, wmline does not adjust the spatial extent when this vector layer is added to the map.

Data Types: double | logical

'Description' — Description of feature

empty character vector ('') (default) | character vector | cell array of character vectors | scalar structure

Description of feature, specified as the comma-separated pair consisting of 'Description' and a character vector, cell array of character vectors, or a scalar structure. The description defines the content of the description balloon displayed when you click the feature in a web map. Description elements can be either plain text or HTML markup. When an attribute spec is provided, the display in the balloon for the attribute fields of P are modified according to the specification.

• If you specify a scalar cell array, wmline applies the value to all line features.

• If you specify a nonscalar cell array, the cell array must contain a value for each feature, that is, the cell array must be the same length as P.

• If the value is a structure, wmline applies the attribute specification to each line.

Data Types: char | struct | cell

'OverlayName' — Name of overlay layer

'Line Overlay N', (default) | character vector

Name of overlay layer, specified as the comma-separated pair consisting of 'OverlayName' and a character vector. wmline inserts the name in the Layer Manager under the "Overlays" item. The Layer Manager is the tool that appears on the right side of the web map browser. The default name is 'Line Overlay N' where N is the number assigned to this overlay.

Data Types: char

'FeatureName' — Name of feature

'OverlayName: Line K' (default) | character vector | cell array of character vectors

Name of feature, specified as the comma-separated pair consisting of 'FeatureName' and character vector or cell array of character vectors. The name appears in the balloon that displays when you click the feature in the web map. The default value is 'OverlayName : Line K', where OverlayName is the name of the overlay and K is the number assigned to the particular line.

• If the value is a character vector, it applies to all features.

• If the value is a cell array of character vectors, it must be either a scalar or the same length as P.

Data Types: char | cell

'Color' — Line color

'black' (default) | ColorSpec | cell array of character vectors | M-by-3 double array

Line color, specified as the comma-separated pair consisting of 'Color' and a MATLAB^® Color Specification (ColorSpec), a cell array of color names, or a numeric array.

• If you specify a scalar cell array, wmline applies the value to all line features.

• If you specify a nonscalar cell array, the cell array must contain a value for each line feature, that is, the cell array must be the same length as P.

• If the value is a numeric array, it must be M-by-3, where M is either 1 or the length of P.

Data Types: double | char | cell

'LineWidth' — Width of line in pixels

1 (default) | positive numeric scalar or vector

Width of line in pixels, specified as the comma-separated pair consisting of LineWidth and a positive numeric scalar or vector. If you specify a vector, it must include a value for each line, that is, the vector must be the same length as P.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

'Alpha' — Transparency of line

1 (default) | numeric scalar or vector

Transparency of line, specified as the comma-separated pair consisting of 'Alpha' and a numeric scalar or vector. If you specify a vector, it must include a value for each line, that is, the vector must be the same length as P. The default value, 1, means that the line is fully opaque.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Output Arguments

h — Overlay layer

handle to line overlay

Overlay layer, returned as a handle to a line overlay.

Tips

• Under certain conditions, when you zoom in on a line overlay in a web map, parts of the line may become invisible. This can occur if the data is one long line segment that is composed of many parts. To workaround this issue, break the long line into a series of line segments by inserting NaNs in the line data.