plot

Display laser or lidar scan readings

Since R2019b

Syntax

plot(scanMsg)

plot(scanObj)

plot(___,Name,Value)

linehandle = plot(___)

Description

plot(scanMsg) plots the laser scan readings specified in the input LaserScan object message. Axes are automatically scaled to the maximum range that the laser scanner supports.

Note

plot will be removed. Use rosPlot instead. For more information, see ROS Message Structure Functions

plot(scanObj) plots the lidar scan readings specified in scanObj.

plot(___,Name,Value) provides additional options specified by one or more Name,Value pair arguments.

linehandle = plot(___) returns a column vector of line series handles, using any of the arguments from previous syntaxes. Use linehandle to modify properties of the line series after it is created.

When plotting ROS laser scan messages, MATLAB^® follows the standard ROS convention for axis orientation. This convention states that positive x is forward, positive y is left, and positive z is up. For more information, see Axis Orientation on the ROS Wiki.

Examples

Plot Laser Scan Message

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

rosinit('192.168.17.129')

Initializing global node /matlab_global_node_90279 with NodeURI http://192.168.17.1:50889/

sub = rossubscriber('/scan');
scan = receive(sub);

Plot the laser scan.

plot(scan)

Shutdown ROS network.

rosshutdown

Shutting down global node /matlab_global_node_90279 with NodeURI http://192.168.17.1:50889/

Plot Laser Scan Message With Maximum Range

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

rosinit('192.168.17.129')

Initializing global node /matlab_global_node_31712 with NodeURI http://192.168.17.1:51463/

sub = rossubscriber('/scan');
scan = receive(sub);

Plot the laser scan specifying the maximum range.

plot(scan,'MaximumRange',6)

Shutdown ROS network.

rosshutdown

Shutting down global node /matlab_global_node_31712 with NodeURI http://192.168.17.1:51463/

Plot Lidar Scan and Remove Invalid Points

Specify lidar data as vectors of ranges and angles. These values include readings outside of the sensor range.

x = linspace(-2,2);
ranges = abs((1.5).*x.^2 + 5);
ranges(45:55) = 3.5;
angles = linspace(-pi/2,pi/2,numel(ranges));

Create a lidar scan by specifying the ranges and angles. Plot all points of the lidar scan.

scan = lidarScan(ranges,angles);
plot(scan)

Remove invalid points based on a specified minimum and maximum range.

minRange = 0.1;
maxRange = 7;
scan2 = removeInvalidData(scan,'RangeLimits',[minRange maxRange]);
hold on
plot(scan2)
legend('All Points','Valid Points')

Input Arguments

scanMsg — Laser scan message

LaserScan object handle

sensor_msgs/LaserScan ROS message, specified as a LaserScan object handle.

scanObj — Lidar scan readings

lidarScan object

Lidar scan readings, specified as a lidarScan (Navigation Toolbox) object.

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: "MaximumRange",5

Parent — Parent of axes

axes object

Parent of axes, specified as the comma-separated pair consisting of "Parent" and an axes object in which the laser scan is drawn. By default, the laser scan is plotted in the currently active axes.

MaximumRange — Range of laser scan

scan.RangeMax (default) | scalar

Range of laser scan, specified as the comma-separated pair consisting of "MaximumRange" and a scalar. When you specify this name-value pair argument, the minimum and maximum x-axis and the maximum y-axis limits are set based on a specified value. The minimum y-axis limit is automatically determined by the opening angle of the laser scanner.

This name-value pair works only when you input scanMsg as the laser scan.

Outputs

linehandle — One or more chart line objects

scalar | vector

One or more chart line objects, returned as a scalar or a vector. These are unique identifiers, which you can use to query and modify properties of a specific chart line.

Version History

Introduced in R2019b

R2021a: ROS Message Structure Functions

You can now create messages as structures with fields matching the message object properties. Using structures typically improves performance of creating, updating, and using ROS messages, but message fields are no longer validated when set. Message types and corresponding field values from the structures are validated when sent across the network.

To support message structures as inputs, new functions that operate on specialized ROS messages have been provided. These new functions are based on the existing object functions of message objects, but support ROS and ROS 2 message structures as inputs instead of message objects.

The object functions will be removed in a future release.

Message Types	Object Function Name	New Function Name
Image CompressedImage	readImage writeImage	rosReadImage rosWriteImage
LaserScan	readCartesian readScanAngles lidarScan plot	rosReadCartesian rosReadScanAngles rosReadLidarScan rosPlot
PointCloud2	apply readXYZ readRGB readAllFieldNames readField scatter3	rosApplyTransform rosReadXYZ rosReadRGB rosReadAllFieldNames rosReadField rosPlot
Quaternion	readQuaternion	rosReadQuaternion
OccupancyGrid	readBinaryOccupanyGrid readOccupancyGrid writeBinaryOccupanyGrid writeOccupanyGrid	rosReadOccupancyGrid rosReadBinaryOccupancyGrid rosReadOccupancyGrid rosWriteBinaryOccupancyGrid rosWriteOccupancyGrid
Octomap	readOccupancyMap3D	rosReadOccupancyMap3D
PointStamped PoseStamped QuaternionStamped Vector3Stamped TransformStamped	apply	rosApplyTransform
All messages	showdetails	rosShowDetails