camroll

Set or query roll angle of camera for geographic globe

Since R2020b

Syntax

camroll(g,roll)

camroll(g,'auto')

camroll(g,'manual')

outRoll = camroll(g)

outRoll = camroll(___)

Description

Set Roll and Mode

camroll(g,roll) sets the roll angle of the camera for the specified geographic globe. Setting the roll angle rotates the camera around its lens. For more information about how camera rotations affect your view of the globe, see How Camera Orientation Affects Globe View.

camroll(g,'auto') sets the camera roll to automatic mode, enabling the geographic globe to determine the roll angle based on plotted data. The mode defaults to automatic when you create a geographic globe. If you interact with the globe using your mouse, then the mode switches to automatic.

camroll(g,'manual') sets a manual mode, specifying that the geographic globe preserve the roll angle when the plotted data changes. If you change the roll angle using the camroll function, then the mode switches to manual.

Query Roll

outRoll = camroll(g) returns the roll angle of the camera.

outRoll = camroll(___) sets the roll angle or mode and then returns the roll angle of the camera. You can return the roll angle using any combination of input arguments from the previous syntaxes.

Examples

Change Roll Angle of Camera

Create a geographic globe. Position the camera near Mount Kilimanjaro by specifying a latitude, longitude, and ellipsoidal height. Set the pitch angle to 0 degrees, so that the camera points across the summit.

uif = uifigure;
g = geoglobe(uif);
campos(g,-3.1519,37.3561,5500)
campitch(g,0)

By default, the roll angle is 0 degrees. Rotate the mountain in a counterclockwise direction by increasing the roll angle to 30 degrees.

camroll(g,30)

Animate Changes to Roll Angle

Create a geographic globe. Position the camera near Mount Washington by specifying a latitude, longitude, and ellipsoidal height. Change the heading and pitch angles so that the camera faces the mountain.

uif = uifigure;
g = geoglobe(uif);

campos(g,44.2668,-71.3849,1757)
camheading(g,90)
campitch(g,0)

Animate the view by incrementally changing the roll angle. As the roll angle increases, the mountain rotates in a counterclockwise direction.

for roll = 0:5:180
    camroll(g,roll)
    drawnow
end

Get Information About Camera View

Get the position and the heading, pitch, and roll angles of the camera. Use this information to control the view of a different geographic globe or to automate navigation.

Create a geographic globe. Navigate to an area of interest using your mouse or gestures. For this example, navigate to an area around Hawaii.

uif = uifigure;
g = geoglobe(uif);

Query the latitude, longitude, and ellipsoidal height of the camera, and assign each to a variable.

[camlat,camlon,camh] = campos(g)

camlat =

   18.3172


camlon =

 -155.5891


camh =

   6.2692e+04

Query the heading, pitch, and roll angles of the camera, and assign each to a variable.

heading = camheading(g)
pitch = campitch(g)
roll = camroll(g)

heading =

    3.7590


pitch =

  -29.9880


roll =

  359.9993

Use these values to control the view of a different geographic globe. For example, create a new geographic globe and programmatically set the view.

uif2 = uifigure;
g2 = geoglobe(uif2);
campos(g2,camlat,camlon,camh)
camheading(g2,heading)
campitch(g2,pitch)
camroll(g2,roll)

Preserve Camera View

Preserve the position and the heading, pitch, and roll angles of the camera by setting the camera modes to manual. If you do not set the camera modes to manual, then the camera view resets when you plot new data.

Import a sample route along roads in Massachusetts using the gpxread function. Create a geographic globe with a road map and no terrain data. Preserve the basemap and terrain settings by using the hold function. Then, navigate to an area near Eastern Massachusetts using your mouse.

track = gpxread("sample_tracks.gpx","Index",2);
lat = track.Latitude;
lon = track.Longitude;
height = track.Elevation;

uif = uifigure;
g = geoglobe(uif,"Basemap","streets","Terrain","none");
hold(g,"on")

Set the camera modes to manual and plot the data. Note that the camera position does not change.

campos(g,"manual")
camheight(g,"manual")
camheading(g,"manual")
campitch(g,"manual")
camroll(g,"manual")
geoplot3(g,lat,lon,height,"LineWidth",3)

Input Arguments

g — Geographic globe

GeographicGlobe object

Geographic globe, specified as a GeographicGlobe object.¹

roll — Roll angle of camera

0 (default) | scalar

Roll angle of the camera, specified as a scalar value in the range [–360, 360] degrees.

More About

How Camera Orientation Affects Globe View

The values of the camera heading, pitch, and roll angles affect your view of a geographic globe. Mapping Toolbox™ references these values to the globe using a north-east-down (NED) coordinate system. As a result, when the heading, pitch, and roll angles of the camera are zero, the camera sits on a plane that is parallel to the tangent plane of the globe at the current latitude and longitude. For more information about NED coordinate systems, see Comparison of 3-D Coordinate Systems.

Change your view of a geographic globe by changing the heading, pitch, and roll angles of the camera:

• Heading — Rotate the camera about its z-axis, which shifts the view left or right. Move the view to the right by increasing the heading angle.

• Pitch — Rotate the camera about its y-axis, which tilts the view up or down. Tilt the view up by increasing the pitch angle.

• Roll — Rotate the camera about its x-axis, which spins the camera around its lens. Spin the view counterclockwise by increasing the roll angle.

Tips

• When the pitch angle is near –90 (the default) or 90 degrees, the camera loses one rotational degree of freedom. As a result, when you change the roll angle, the heading angle may change instead. This phenomenon is called gimbal lock. To avoid the effects of gimbal lock, call the camheading function instead of the camroll function.

Version History

Introduced in R2020b