pointcloud data to mat data

Question

I have to convert ply data to mat data. For this i have used plyreader of pcl and convert in into point cloud and now my next step is to convert it into mat data from point cloud. I guess the point cloud which i obtained from plyreader is unorganised. I have been trying to extract the xyz values of point cloud and then copying it in at data.

pcl::PointCloud::Ptr cloud (new pcl::PointCloud); // create a new point cloud (POINTXYZ)

pcl::PLYReader reader;               
reader.read(filename,*cloud);         // read the ply file

cv::Mat output;
//...
output = cv::Mat(1,cloud->points.size(),CV_32FC3);
for(size_t i=0; i<cloud->points.size();++i)
{
    int m = cloud->points[i].x;
    int n = cloud->points[i].y;
    int l = cloud->points[i].z;

    float x0;
    float x1;
    float x2;

    output.at<cv::Vec3f>(x0,x1,x2)= cv::Vec3f(m,n,l);

}

I know it is wrong. I found one post about this but that is for organised cloud Link is here -->

Visit [pointcloud to mat]

Coversion from PointCloud to Mat

I am new to this field. If anyone know or could help!!!

Thanks in advance

score 0 · Answer 1 · answered Apr 04 '15 at 17:36

0

It should be:

output.at<cv::Vec3f>(1,i)[0] = cloud->points[i].x; //(1,i) is (row,col)
output.at<cv::Vec3f>(1,i)[1] = cloud->points[i].y; // [1] is y float
output.at<cv::Vec3f>(1,i)[2] = cloud->points[i].z;

answered Apr 04 '15 at 17:36

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Yes.. I have done the same thing yesterday. But will try and build it tomorrow. Thanks for the help. Will update whatever the result will be. :) – Akash Apr 06 '15 at 12:21
: It is creating an Exception while after the loop has been initialized at this statement ' output.at(1,i)[0] = cloud->points[i].x; ' – Akash Apr 13 '15 at 09:55

score 0 · Accepted Answer · answered Apr 14 '15 at 10:31

cv::Size sz;
sz= cv::Size(cloud->width,cloud->height);


cv::Mat output(sz,CV_32FC3);
cvWaitKey(50);



for (int j=0; j<output.rows;++j)
{
     for(int i= 0; i<output.cols;++i)
      {
    output.at<cv::Vec3f>(1,i)[0] = cloud->points[i].x;
    output.at<cv::Vec3f>(1,i)[1] = cloud->points[i].y;
    output.at<cv::Vec3f>(1,i)[2] = cloud->points[i].z;

      }}

There is no error in the code and runs properly but still at the cv:: Mat output, the values are not copying and giving some absurd result. Does anyone know the mistake or how to get values at output as cvmat data only.

Solved....Just need to add zeroes while defining the cvmat so that it can overwrite the values. cv::Mat output; output = cv::Mat::zeros(1,cloud->points.size(),CV_32FC3); — Akash, Apr 23 '15 at 07:16

pointcloud data to mat data

2 Answers2