ROS中订阅两个消息，发布一个数据。

今天测试转换出来的点云数据，利用Rviz显示不出来结果。提示错误如下：

no message received in Rviz

Status:Error.

Points Showing [0] points from [0] messages.

Topic No messages received.

Transform For frame[]: Frame[] does not exist.

在网上Google了一下，就把网友的例子和回答，在博客里面备份一下吧！

代码如下：通过订阅两个消息，发布一个数据。

typedef pcl::PointCloud<pcl::PointCloud<int> > PointCloud;
typedef pcl::PointXYZ PointType;

ros::Publisher pub;

pcl::PointCloud<int> keypoint_indices;

pcl::PointCloud<pcl::PointXYZ>::Ptr keypoints_ptr (new pcl::PointCloud<pcl::PointXYZ>);
pcl::PointCloud<pcl::PointXYZ>& keypoints = *keypoints_ptr;


float angular_resolution_;
float support_size_ =0.2f;//-0.1f

image_geometry::PinholeCameraModel model_;

void cameraModelCallback(const sensor_msgs::CameraInfoConstPtr &info_msg)
{
    model_.fromCameraInfo(info_msg);
}

void depthimage_cb(const sensor_msgs::ImageConstPtr &depth_msg)
{
    const uint16_t* depthImage = reinterpret_cast<const uint16_t*>(&depth_msg->data[0]);

    pcl::RangeImagePlanar range_image_;
    pcl::RangeImageBorderExtractor range_image_border_extractor_;

    // convert the depth-image to a pcl::rangeImage
    angular_resolution_ = 0.5f(float)(-1);
    /*range_image_.setDepthImage(depthImage,depth_msg->width, depth_msg->height, (depth_msg->width)/2, (depth_msg->height)/2, 600.0, 600.0, angular_resolution_);*/
    range_image_.setDepthImage(depthImage,depth_msg->width, depth_msg->height, model_.cx(), model_.cy(),model_.fx(), model_.fy(), angular_resolution_);

    range_image_.setUnseenToMaxRange();
    pcl::NarfKeypoint keypoint_det;

    // extract the indices of the NARF-Keypoints
    keypoint_det.getParameters ().support_size =  support_size_;
    keypoint_det.setRangeImageBorderExtractor (&range_image_border_extractor_);
    keypoint_det.setRangeImage (&range_image_);
    keypoint_det.compute (keypoint_indices);

    keypoints.points.resize (keypoint_indices.points.size ());
    for (size_t i=0; i<keypoint_indices.points.size (); ++i)
    keypoints.points[i].getVector3fMap () = range_image_.points[keypoint_indices.points[i]].getVector3fMap ();
    pub.publish (keypoints);
} 



int
main (int argc, char** argv)
{
  // Initialize ROS
  ros::init (argc, argv, "keypointsplanar");
  ros::NodeHandle nh1;

  // Create a ROS subscriber for the input point cloud
  ros::Subscriber sub1 = nh1.subscribe ("/camera/depth/image", 1, depthimage_cb);   
  ros::Subscriber sub2 = nh1.subscribe ("/camera/depth/camera_info", 1, cameraModelCallback);   

  // Create a ROS publisher for the output point cloud
  pub = nh1.advertise<pcl::PointCloud<pcl::PointXYZ> > ("keypoints", 1);

  // Spin
  ros::spin ();
}

解决方法： 参考   参考2   参考3

所发布数据，需要给定frame_id和stamp标签。因为Rviz显示数据，需要知道数据的frame_id和时间戳。

keypoints.header.frame_id = depth_msg->header.frame_id;
keypoints.header.stamp = depth_msg->header.stamp;