View multiple Point Clouds in same window using PC

Question

I have two point cloud, which I want to visualise in the same window.

#include <pcl/io/io.h>
#include <pcl/io/pcd_io.h>
#include <pcl/visualization/cloud_viewer.h>

int main ()
{
    pcl::visualization::CloudViewer viewer("Cloud Viewer");

    pcl::PointCloud<pcl::PointXYZRGBA>::Ptr body (new pcl::PointCloud<pcl::PointXYZRGBA>);
    pcl::io::loadPCDFile ("body.pcd", *body);

    pcl::PointCloud<pcl::PointXYZRGBA>::Ptr head (new pcl::PointCloud<pcl::PointXYZRGBA>);
    pcl::io::loadPCDFile ("head.pcd", *head);

    viewer.showCloud (body);
    viewer.showCloud (head);
    while (!viewer.wasStopped ())
    {
    }
    return 0;
}

I can see only the last PCD file.

Please note that I don't want to use pcd_viewer tool since I need to do some other processing on this data.

Answer 1

As per the pcl documentation, you can provide a name for the display point cloud.
If you provide the same name it overwrites the existing cloud.

This basically means changing the following calls:

viewer.showCloud (body);
viewer.showCloud (head);

With:

viewer.showCloud (body, "body");
viewer.showCloud (head, "head");

of course you can use whatever names you want.

Answer 2

  pclPointCloud<pcl::PointXYZ>::Ptr head (new pcl::PointCloud<pcl::PointXYZ>);
  pcl::PointCloud<pcl::PointXYZ>::Ptr body (new pcl::PointCloud<pcl::PointXYZ>);

 //initialize the point cloud viewer
  pcl::visualization::PCLVisualizer viewer ("");

 //visualize head
  pcl::visualization::PointCloudColorHandlerCustom<pcl::PointXYZ>  source_cloud_color_handler (head, 230, 20, 20);
  viewer.addPointCloud (head, source_cloud_color_handler, "head");

  //visualize body
  pcl::visualization::PointCloudColorHandlerCustom<pcl::PointXYZ> transformed_cloud_color_handler (body, 255, 255, 255); // Whiite
  viewer.addPointCloud (body, transformed_cloud_color_handler, "body");

  viewer.addCoordinateSystem (1.0, "body", 0);
  viewer.setBackgroundColor(0.05, 0.05, 0.05, 0); // Setting background to a dark grey
  viewer.setPointCloudRenderingProperties (pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 2, "head");

Answer 3

Regarding the comment

"Okay. I will check it soon. Can you tell me to set camera parameters and background color using cloud_viewer API?"

I am not 100% sure if you can do this using pcl::visualization::CloudViewer. However, if you move your code to pcl::visualization::PCLVisualizer you can do viewer.setBackgroundColor(double red,double green,double blue) (where the values range 0..1. To set a camera). For the camera, you can use pcl::visualization::PCLVisualizer::setCameraPosition. Moving your code from CloudViewer to PCLVisualizer is preatty easy.

#include <pcl/io/io.h>
#include <pcl/io/pcd_io.h>
#include <pcl/visualization/pcl_visualizer.h>

int main ()
{
    pcl::visualization::PCLVisualizer viewer("Cloud Viewer");

    pcl::PointCloud<pcl::PointXYZRGBA>::Ptr body (new pcl::PointCloud<pcl::PointXYZRGBA>);
    pcl::io::loadPCDFile ("body.pcd", *body);

    pcl::PointCloud<pcl::PointXYZRGBA>::Ptr head (new pcl::PointCloud<pcl::PointXYZRGBA>);
    pcl::io::loadPCDFile ("head.pcd", *head);

    viewer.addPointCloud (body,"body");// note that before it was showCloud
    viewer.addPointCloud (head,"head");// note that before it was showCloud
    viewer.spin();
    return 0;
}

EDIT Ther is acutally a way to do this. By looking into here, you can see that you can run any of the function of the pcl::visualization::PCLVisualizer using the pcl::visualization::CloudViewer::runOnVisualizationThreadOnce or pcl::visualization::CloudViewer::runOnVisualizationThread functions. For this, you will need to create a function that does all the part that uses pcl::visualization::PCLVisualizerand pass it to the CloudViewer::runOnVisualizationThreadOnce or CloudViewer::runOnVisualizationThread.

For example

#include <pcl/io/io.h>
#include <pcl/io/pcd_io.h>
#include <pcl/visualization/cloud_viewer.h>

void 
setBackground (pcl::visualization::PCLVisualizer& viewer)
{
    viewer.setBackgroundColor (1.0, 0.5, 1.0);    
}

int main ()
{
    pcl::visualization::PCLVisualizer viewer("Cloud Viewer");

    pcl::PointCloud<pcl::PointXYZRGBA>::Ptr body (new pcl::PointCloud<pcl::PointXYZRGBA>);
    pcl::io::loadPCDFile ("body.pcd", *body);

    pcl::PointCloud<pcl::PointXYZRGBA>::Ptr head (new pcl::PointCloud<pcl::PointXYZRGBA>);
    pcl::io::loadPCDFile ("head.pcd", *head);

    viewer.showCloud (body,"body");
    viewer.showCloud (head,"head");

    viewer.runOnVisualizationThreadOnce(setBackground);

    while (!viewer.wasStopped ())
    {
    }
    return 0;
}

The only issue is that I do not see how you could potentially pass arguments to the pcl::visualization::PCLVisualizer function that you want to use in the function we crated (in the previous example pcl::visualization::PCLVisualizer::setBackgroundColorin setBackground. For this, I think using directly pcl::visualization::PCLVisualizer is much better.