c++ - memcpy vtkPoints using GetVoidPointer method -

i have opencv 3-channel mat each pixel contains 3d point. want copy mat (points) vtk points , polydata visualize it. there example here showing want copy cv::mat vtkpoints directly using memcpy.

i did:

// create colored point clodu in opencv format cv::mat cld_cv = cv::mat::zeros(1, 3, cv_32fc3); int num_points = cld_cv.cols * cld_cv.rows;  // fill cld_cv code here // .....  vtksmartpointer<vtkpoints> points =         vtksmartpointer<vtkpoints>::new(); points->setnumberofpoints(num_points); ::memcpy(points->getvoidpointer(0), cld_cv.data, sizeof(float) * num_points * 3);  vtksmartpointer<vtkpolydata> pointspolydata =         vtksmartpointer<vtkpolydata>::new();  pointspolydata->setpoints(points);  // normal vtk pipeline shown in example 

however can see 1 point seems @ origin. please point out have done wrong.

what version of opencv using? don't see cv::mat::data in currents docs.

also, there no guarantee vtkpoints or cv::mat stored in contiguous block of memory. looking @ vtk 6.2 source, data inside vtkpoints stored floatarray default, has contiguous storage, should ok there. opencv provides method check. try

if (cld_cv.iscontinuous())     ::memcpy(points->getvoidpointer(0), cld_cv.ptr<float>(), sizeof(float) * num_points * 3); else  {     std::cerr << "cv mat not contiguous" << std::endl;      // other, perhaps not fast, method of copy } 

see opencv docs iscontinous details.