readCartesian

Read laser scan ranges in Cartesian coordinates

Syntax

cart = readCartesian(scan)
cart = readCartesian(___,Name,Value)
[angles,cart] = readCartesian(___)

Description

example

cart = readCartesian(scan) converts the polar measurements of the laser scan object, scan, into Cartesian coordinates, cart. This function uses the metadata in the message, such as angular resolution and opening angle of the laser scanner, to perform the conversion. Invalid range readings, usually represented as NaN, are ignored in this conversion.

example

cart = readCartesian(___,Name,Value) provides additional options specified by one or more Name,Value pair arguments. Name must appear inside single quotes (''). You can specify several name-value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

[angles,cart] = readCartesian(___) returns the scan angles, angles that are associated with each Cartesian coordinate. Angles are measured counter-clockwise around the positive z-axis, with the zero angle along the x-axis. angles is returned in radians and wrapped to the [ –pi, pi] interval.

Examples

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Connect to ROS network. Subscribe to a laser scan topic, and receive a message.

rosinit('192.168.154.131')
sub = rossubscriber('/scan');
scan = receive(sub);
Initializing global node /matlab_global_node_60179 with NodeURI http://192.168.154.1:60889/

Read the Cartesian points from the laser scan. Plot the laser scan.

cart = readCartesian(scan);
plot(cart(:,1),cart(:,2))

Shutdown ROS network.

rosshutdown
Shutting down global node /matlab_global_node_60179 with NodeURI http://192.168.154.1:60889/

Connect to ROS network. Subscribe to a laser scan topic, and receive a message.

rosinit('192.168.154.131')
sub = rossubscriber('/scan');
scan = receive(sub);
Initializing global node /matlab_global_node_98143 with NodeURI http://192.168.154.1:60989/

Read the Cartesian points from the laser scan with specified range limits. Plot the laser scan.

cart = readCartesian(scan,'RangeLimit',[0.5 6]);
plot(cart(:,1),cart(:,2))

Shutdown ROS network.

rosshutdown
Shutting down global node /matlab_global_node_98143 with NodeURI http://192.168.154.1:60989/

Input Arguments

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'sensor_msgs/LaserScan' ROS message, specified as a LaserScan object 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: 'RangeLimits',[-2 2]

Minimum and maximum range for scan in meters, specified as a 2-element [min max] vector. All ranges smaller than min or larger than max are ignored during the conversion to Cartesian coordinates.

Output Arguments

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Cartesian coordinates of laser scan, returned as an n-by-2 matrix in meters.

Scan angles for laser scan data, returned as an n-by-1 matrix in radians. Angles are measured counter-clockwise around the positive z-axis, with the zero angle along the x-axis. angles is returned in radians and wrapped to the [ –pi, pi] interval.

Introduced in R2015a