PointCloud2

(To be removed) Access point cloud messages

PointCloud2 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 rosReadXYZ, rosWriteXYZ, rosReadRGB, and rosWriteRGB functions to work with point cloud messages. For more information, see ROS Message Structure Functions.

Description

The PointCloud2 object is an implementation of the sensor_msgs/PointCloud2 message type in ROS. The object contains meta-information about the message and the point cloud data. To access the actual data, use readXYZ to get the point coordinates and readRGB to get the color information, if available.

Creation

Syntax

ptcloud = rosmessage('sensor_msgs/PointCloud2')

Description

ptcloud = rosmessage('sensor_msgs/PointCloud2') creates an empty PointCloud2 object. To specify point cloud data, use the ptcloud.Data property. You can also get point cloud data messages off the ROS network using rossubscriber.

Properties

PreserveStructureOnRead — Preserve the shape of point cloud matrix

Read-only: false (default) | true

This property is read-only.

Preserve the shape of point cloud matrix, specified as false or true. When the property is true, the output data from readXYZ and readRGB are returned as matrices instead of vectors.

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.

Height — Point cloud height in pixels

integer

Point cloud height in pixels, specified as an integer.

Width — Point cloud width in pixels

integer

Point cloud width in pixels, specified as an integer.

IsBigendian — Image byte sequence

true | false

Image byte sequence, specified as true or false.

• true —Big endian sequence. Stores the most significant byte in the smallest address.

• false —Little endian sequence. Stores the least significant byte in the smallest address.

PointStep — Length of a point in bytes

integer

Length of a point in bytes, specified as an integer.

RowStep — Full row length in bytes

integer

Full row length in bytes, specified as an integer. The row length equals the PointStep property multiplied by the Width property.

Data — Point cloud data

uint8 array

Point cloud data, specified as a uint8 array. To access the data, use the Object Functions.

Object Functions

readAllFieldNames	(To be removed) Get all available field names from ROS point cloud
readField	(To be removed) Read point cloud data based on field name
readRGB	(To be removed) Extract RGB values from point cloud data
readXYZ	(To be removed) Extract XYZ coordinates from point cloud data
scatter3	Display point cloud in scatter plot
showdetails	(To be removed) Display all ROS message contents

Examples

Inspect Point Cloud Image

Access and visualize the data inside a point cloud message.

Create sample ROS messages and inspect a point cloud image. ptcloud is a sample ROS PointCloud2 message object.

exampleHelperROSLoadMessages
ptcloud

ptcloud = 
  ROS PointCloud2 message with properties:

    PreserveStructureOnRead: 0
                MessageType: 'sensor_msgs/PointCloud2'
                     Header: [1×1 Header]
                     Fields: [4×1 PointField]
                     Height: 480
                      Width: 640
                IsBigendian: 0
                  PointStep: 32
                    RowStep: 20480
                       Data: [9830400×1 uint8]
                    IsDense: 0

  Use showdetails to show the contents of the message

Get RGB info and xyz-coordinates from the point cloud using readXYZ and readRGB.

xyz = readXYZ(ptcloud);
rgb = readRGB(ptcloud);

Display the point cloud in a figure using scatter3.

scatter3(ptcloud)

Create pointCloud Object Using Point Cloud Message

Convert a ROS Toolbox™ point cloud message into a Computer Vision System Toolbox™ pointCloud object.

Load sample messages.

exampleHelperROSLoadMessages

Convert a ptcloud message to the pointCloud object.

pcobj = pointCloud(readXYZ(ptcloud),'Color',uint8(255*readRGB(ptcloud)))

pcobj = 
  pointCloud with properties:

     Location: [307200×3 single]
        Count: 307200
      XLimits: [-1.8147 1.1945]
      YLimits: [-1.3714 0.8812]
      ZLimits: [1.4190 3.3410]
        Color: [307200×3 uint8]
       Normal: []
    Intensity: []

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