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here and Here are the description how to install the driver and its ros-wrapper and how to run them. Then listen to one of the .../points topics as described in 10. or 11. here.
The driver publishes:
* /camera/depth/camera_info : Camera parameters for the IR (depth) camera
* /camera/depth/image : single channel floating point (float32) depth image, containing the depth in meters.
* /camera/depth/points : point cloud without color information
* /camera/rgb/camera_info : Camera parameters for the RGB camera
* /camera/rgb/image_color : RGB image
* /camera/rgb/image_mono : Grayscale image
* /camera/rgb/points : point cloud containing RGB value for each point
A good start how to use ROS can be found here. When you reach step 11 then you learn how to publish and subscribe in ROS. For point clouds using the Kinect camera, then you need to setup you subscriber to retrieve point clouds, which is found under the sensor_msgs documentation. Down below you can find the simple schematic for a class that reads the point cloud data from the kinect.
#include <ros/ros.h>
#include <pcl_ros/point_cloud.h>
#include <sensor_msgs/PointCloud2.h>
using namespace ros;
using namespace sensor_msgs;
class processPoint {
NodeHandle nh;
Subscriber sub;
public:
processPoint() {
sub = nh.subscribe<sensor_msgs::PointCloud2>("/camera/rgb/points", 1, &processPoint::processCloud, this);
}
~processPoint() {
}
void processCloud( const sensor_msgs::PointCloud2ConstPtr& cloud );
};
#include "processPoint.hpp"
void processPoint::processCloud( const sensor_msgs::PointCloud2ConstPtr& cloud ) {
}
int main(int argc, char **argv) {
init(argc, argv, "processPoint");
processPoint processPoint;
Rate spin_rate(1);
while( ok() ) {
spinOnce();
spin_rate.sleep();
}
}
I have been working on the depth pointer( the pointer that stores the depth data for the Kinect). If you are using the Openkinect driver and not using the ROS and writing the code yourself, the function you should be looking for is
void depth_cb(freenect_device *dev, void *v_depth, uint32_t timestamp)
and the data is stored in the v_depth pointer. You can take the data from the v_depth pointer. Hope this is useful for those start out finding the depth data.Thanks to those who helped, appreciate their help.
hi... thanks.... i have done that... now how to get the data...is it using /camera/depth/image to get the depth data?? am i right?how to publish the /camera/depth/image? or how to get the depth data from the kinect driver?
let me explain more in detail. After the post by aslund, i did go thru the tutorials. i reached step 8. My supervisor stopped me and wanted me to use openkinect to get the point cloud data. He told me to do the tutorials later. not at the current moment.i need the data for further processing and i using cppview to get the data. I wanted me to urgently to get the point cloud data.so was looking at ways to get it. taught of using this code to get the point cloud data into distance. float gamma[2048];
for (size_t i=0; i<2048; i++) { const float k1 = 1.1863; const float k2 = 2842.5; const float k3 = 0.1236; gamma[i] = k3 * tan(i/k2 + k1); }
Now you have a lookup table for all possible depth values. The second step is to reproject the depth data into Euclidean space.
uint16_t depth_data[640480]; // depth data from Kinect in a 1-D array float x[480640]; // point cloud x values float y[480640]; // point cloud y values float z[480640]; // point cloud z values...you may want to put these into a vector or something // camera intrinsic parameters, representative values, see http://nicolas.burrus.name/index.php/Research/KinectCalibration for more info float cx = 320.0; // center of projection float cy = 240.0; // center of projection float fx = 600.0; // focal length in pixels float fy = 600.0; // focal length in pixels for (size_t v=0, n=0 ; v<480 ; v++) { for (size_t u=0 ; u<640 ; u++, n++) { // note that values will be in meters, with the camera at the origin, and the Kinect has a minimum range of ~0.5 meters x[n] = (u - cx) * gamma[depth_data[n]] / fx; y[n] = (v - cy) * gamma[depth_data[n]] / fy; z[n] = gamma[depth_data[n]]; } would you suggest me to use this code??
Hi friend, have u used OpenKinect instead of Openni( or the one u suggested)? Will the code u suggested be different? does this code apply to all drivers?
Asked: 2011-05-23 18:12:55 -0600
Seen: 16,007 times
Last updated: Jun 19 '11
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