LaserScan

(To be removed) Create laser scan message

LaserScan object will be removed in a future release. Use message structure format when you create ROS messages using the rosmessage function, by specifying the Dataformat name-value argument as "struct". You can use rosReadLidarScan, rosReadCartesian, and rosReadScanAngles functions to read laser scan data from ROS messages. For more information, see ROS Message Structure Functions.

Description

The LaserScan object is an implementation of the sensor_msgs/LaserScan message type in ROS. The object contains meta-information about the message and the laser scan data. You can extract the ranges and angles using the Ranges property and the readScanAngles function. To access points in Cartesian coordinates, use readCartesian.

You can also convert this object to a lidarScan (Navigation Toolbox) object to use with other robotics algorithms such as matchScans (Navigation Toolbox), controllerVFH (Navigation Toolbox), or monteCarloLocalization (Navigation Toolbox).

Creation

Syntax

scan = rosmessage('sensor_msgs/LaserScan')

Description

scan = rosmessage('sensor_msgs/LaserScan') creates an empty LaserScan object. You can specify scan info and data using the properties, or you can get these messages off a ROS network using rossubscriber.

Properties

MessageType — Message type of ROS message

Read-only: character vector

This property is read-only.

Message type of ROS message, returned as a character vector.

Data Types: char

Header — ROS Header message

Read-only: Header object

This property is read-only.

ROS Header message, returned as a Header object. This header message contains the MessageType, sequence (Seq), timestamp (Stamp), and FrameId. Timestamp relates to the acquisition time of the first ray in the scan.

AngleMin — Minimum angle of range data

scalar

Minimum angle of range data, specified as a scalar in radians. Positive angles are measured from the forward direction of the robot.

AngleMax — Maximum angle of range data

scalar

Maximum angle of range data, specified as a scalar in radians. Positive angles are measured from the forward direction of the robot.

AngleIncrement — Angle increment of range data

scalar

Angle increment of range data, specified as a scalar in radians.

TimeIncrement — Time between individual range data points in seconds

scalar

Time between individual range data points in seconds, specified as a scalar.

ScanTime — Time to complete a full scan in seconds

scalar

Time to complete a full scan in seconds, specified as a scalar.

RangeMin — Minimum valid range value

scalar

Minimum valid range value, specified as a scalar.

RangeMax — Maximum valid range value

scalar

Maximum valid range value, specified as a scalar.

Ranges — Range readings from laser scan

vector

Range readings from laser scan, specified as a vector. To get the corresponding angles, use readScanAngles.

Intensities — Intensity values from range readings

vector

Intensity values from range readings, specified as a vector. If no valid intensity readings are found, this property is empty.

Object Functions

lidarScan (Navigation Toolbox)	Create object for storing 2-D lidar scan
plot	Display laser or lidar scan readings
readCartesian	(To be removed) Read laser scan ranges in Cartesian coordinates
readScanAngles	(To be removed) Return scan angles for laser scan range readings

Examples

Inspect Sample Laser Scan Message

Load, inspect, and display a sample laser scan message.

Create sample messages and inspect the laser scan message data.The scan object is a sample ROS LaserScan message object.

exampleHelperROSLoadMessages
scan

scan = 
  ROS LaserScan message with properties:

       MessageType: 'sensor_msgs/LaserScan'
            Header: [1×1 Header]
          AngleMin: -0.5467
          AngleMax: 0.5467
    AngleIncrement: 0.0017
     TimeIncrement: 0
          ScanTime: 0.0330
          RangeMin: 0.4500
          RangeMax: 10
            Ranges: [640×1 single]
       Intensities: [0×1 single]

  Use showdetails to show the contents of the message

Get ranges and angles from the object properties. Check that the ranges and angles are the same size.

ranges = scan.Ranges;
angles = scan.readScanAngles;
size(ranges)

ans = 1×2

   640     1

size(angles)

ans = 1×2

   640     1

plot(scan)

Create Empty LaserScan Message

scan = rosmessage('sensor_msgs/LaserScan')

scan = 
  ROS LaserScan message with properties:

       MessageType: 'sensor_msgs/LaserScan'
            Header: [1×1 Header]
          AngleMin: 0
          AngleMax: 0
    AngleIncrement: 0
     TimeIncrement: 0
          ScanTime: 0
          RangeMin: 0
          RangeMax: 0
            Ranges: [0×1 single]
       Intensities: [0×1 single]

  Use showdetails to show the contents of the message

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