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Pointcloud from Xtion in Matlab with ROS IO package

asked 2015-02-18 07:56:59 -0500

dd_diode gravatar image

Hey there,

I'm trying to get a Pointcloud from ROS to MATLAB via ROS IO. Getting the Data works so far with


function pointCloudMessage( message )
    pclmsg.width = message.getWidth();
    pclmsg.height = message.getHeight();
    pclmsg.offset = message.getData().arrayOffset();
    pclmsg.pointStep = message.getPointStep();
    pclmsg.rowStep = message.getRowStep();
    pclmsg.isDense = message.getIsDense();
    pclmsg.isBigendian = message.getIsBigendian();
    pclmsg.data = uint8(message.getData().array());

    numberOfPoints = pclmsg.width*pclmsg.height;

    pcl = pclmsg.data(pclmsg.offset+1 : numberOfPoints * pclmsg.pointStep+pclmsg.offset);
    pcl = reshape(pcl, pclmsg.pointStep, numberOfPoints );
end

as file, and


>> roscore.RosMasterUri='http://localhost:11311';
>> node = rosmatlab.node('MATLAB', roscore.RosMasterUri);
>> ir_subscriber = rosmatlab.subscriber('/camera/depth_registered/points','sensor_msgs/PointCloud2',1,node);
>> ir_subscriber.setOnNewMessageListeners({@pointCloudMessage});

in the console. This code generates a 32x307200 matrix with uint8 data.

Now I'm stuck at interpreting the resulting data. Is is float (4 byte) data? Is the reshaping of the data correct? What is included in the data? RGBD as floats would be 6*4= 24 byte.

Thanks for the help.

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answered 2015-02-21 12:08:41 -0500

paulbovbel gravatar image

It depends on the number of fields, and the size of the fields. These are defined in the message ( http://docs.ros.org/api/sensor_msgs/h... ) fields[] array ( http://docs.ros.org/api/sensor_msgs/h... ).

If you're doing something quick and dirty and you know the shape of your incoming data, you can always hardcode the sizes, however the more robust approach would be to process based on the fields[] data.

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Asked: 2015-02-18 07:56:59 -0500

Seen: 315 times

Last updated: Feb 21 '15