segment point cloud data into clusters | The input point cloud must be organized (M-by-N-by-3)

Hello All,

I am trying to segment 3D point cloud into clusters using pcap file. When I give pcdenoised cloud as a Input it throwing "The input point cloud must be organized (M-by-N-by-3)" . How to fix this problem?

veloReader = velodyneFileReader('data.pcap','VLP16');
 xlimits = [-35 118];
 ylimits = [-55 75];
 zlimits = [-10 10];
 player = pcplayer(xlimits,ylimits,zlimits);

 for i = 1 : 600
     ptCloud = veloReader.readFrame(i);
     ptCloudIn = removeInvalidPoints(ptCloud);
     ptcloudFil = pcdenoise(ptCloudIn);
    
     groundPtsIdx = segmentGroundFromLidarData(ptCloudFil);
     ptCloudWithoutGround = select(ptCloudFil,~groundPtsIdx,'OutputSize','full');

     distThreshold =500;
     [labels,numClusters] = segmentLidarData(ptCloudWithoutGround,distThreshold);

     numClusters = numClusters+1;
     labels(groundPtsIdx) = numClusters;

     labelColorIndex = labels+1;
     %colormap([hsv(numClusters);[0 0 0]]);
     view(player,ptCloudFil.Location,labelColorIndex);
 end

Answer 1

[Sulaymon Eshkabilov]

Probably, you'd need to generate meshes using meshgrid()

[Pavan Kumar B N]

Hi @Sulaymon Eshkabilov thank you very much for your quick response. I tried to create meshgrid() as per your sugesstion as below.

[x,y,z] = meshgrid(ptCloudFil.Location(:,1), ptCloudFil.Location(:,2), ptCloudFil.Location(:,3));
Error using repmat
Requested 11688x11688x11688 (5948.1GB) array exceeds maximum array size preference (7.7GB). This might cause MATLAB to become unresponsive.

But I am getting this error. Any suggestions to fix this issue?

[Pavan Kumar B N]

Hi @Sulaymon Eshkabilov using meshgrid() can we create (M-by-N-by-3) matrix?

[Stephen23]

"using meshgrid() can we create (M-by-N-by-3) matrix?"

m = 5;
n = 2;
[x,y,z] = meshgrid(1:n,1:m,1:3);
size(x)

ans = 1×3

5 2 3

[x,y,z] = ndgrid(1:m,1:n,1:3);
size(x)

ans = 1×3

5 2 3

[Pavan Kumar B N]

@Stephen Cobeldick Thank you very much for your response. I will try it in this way.

[Pavan Kumar B N]

@Stephen Cobeldick Still I am facing the same problem. I am able to create the grid. When I assign 11776 x 3 values to to X,Y, Z. It is giving error. Please guide me to fix this issue.

Please correct me.

   t =  ptCloudFil.Location(:,1);
     y =  ptCloudFil.Location(:,2);
     u =  ptCloudFil.Location(:,3);
     [X,Y,Z] = ndgrid(t,y,u);

ptCloud = 

  pointCloud with properties:

     Location: [16×1810×3 single]
        Count: 28960
      XLimits: [-35.7891 117.1103]
      YLimits: [-65.8583 70.7026]
      ZLimits: [-7.6524 7.0585]
        Color: []
       Normal: []
    Intensity: [16×1810 uint8]

>> ptCloudFil

ptCloudFil = 

  pointCloud with properties:

     Location: [11776×3 single]
        Count: 11776
      XLimits: [-34.8347 115.3167]
      YLimits: [-58.5607 62.0888]
      ZLimits: [-7.6524 7.0585]
        Color: []
       Normal: []
    Intensity: [11776×1 uint8]