how to save pcap file after extracting groud plane

Hello,

I extracted ground data using 'segmentGroundFromLidarData(ptCloud)' form 3D lidar (Velodyne) data. How to save ground segmented data as a pcap file to use for the further process?

I tried to save using as below but it is not working out.

  save('pointCloudTest.mat','ptCloud') 
  save GroudData.pcap groundPtsIdx 

Please find the code:

  veloReader = velodyneFileReader('lidar.pcap','VLP16');
  for i = 1 : 597 
         % Read current frame.
         ptCloud = veloReader.readFrame(i); 
         
         % Create label array.
         colorLabels = zeros(size(ptCloud.Location,1),size(ptCloud.Location,2)); 
 
         % Find the ground points.
         groundPtsIdx = segmentGroundFromLidarData(ptCloud);
 
         % Map color ground points to green.
         colorLabels(groundPtsIdx (:)) = greenIdx;
         
         % Map color nonground points to red.
         colorLabels(~groundPtsIdx (:)) = redIdx;
         %save('pointCloudTest.mat','ptCloud') 
         %save GroudData.pcap groundPtsIdx 
         view(player,ptCloud.Location,colorLabels)
     end 

Answer 1

[Harsh Sharma]

Hi Pavan,

PCAP is a file format used to store network packet data captured over a network. In MATLAB only the following packet types can be written to a PCAP file using the “pcapWriter” function:

• Generated and recovered WLAN protocol packets
• Generated and recovered 5G NR protocol packets (requires 5G Toolbox™)
• Generated and recovered Bluetooth low energy (LE) link layer (LL) packets (requires Bluetooth® Toolbox)

You may refer to the following documentation for “pcapWriter” function - https://www.mathworks.com/help/wlan/ref/pcapwriter.html

The output from the “segmentGroundFromLidarData” function is a logical matrix which cannot be written to a PCAP file in MATLAB. You can save the “groundPtsIndex” matrix to another format using the “writematrix” function. Please refer to the following documentation to understand more about the “writematrix” function- https://www.mathworks.com/help/matlab/ref/writematrix.html