Calibrate Camer using OpenCV in ROS [closed]

asked 2017-04-22 16:25:57 -0500

andyXu gravatar image

Hi all. I am writing code to subscribe raw video frame and calibrate them as well as publish. I was using OpenCV to generate .xml file for camera calibration as expected. I also calibrate the video in OpenCV succesfully by reading "cameraMatrix" and "distCoeffs", getting the image using "videocapture" and watching the image in "imshow" . The OpenCV function I used is "undistort(old_frame, new_frame, cameraMatrix, distCoeffs)".

All things works excellently but when I change it into ROS, I can only get a heavily distorted image and don't know why.

Here is my code

#include "CalibratedVideo.h"
#include <cv_bridge/cv_bridge.h>

using namespace cv;
using namespace std;

CalibratedVideo::CalibratedVideo(ros::NodeHandle n){
image_transport::ImageTransport it(n);
img_sub = it.subscribe("/usb_cam/image_raw", 1, &CalibratedVideo::send_video, this);
img_pub = it.advertise("/CalibratedVideo/image_fine",1);

//read the calibrating parameters.
string path = ros::package::getPath("irb120_cam_cali");
const string inputSettingsFile = path + "/src/out_camera_data.xml";
ROS_INFO("%s\n", inputSettingsFile.c_str());
FileStorage fs(inputSettingsFile, FileStorage::READ); // Read the settings
if (!fs.isOpened())
    ROS_INFO("Could not open the configuration file");
fs["Camera_Matrix"] >> cameraMatrix;
fs["Distortion_Coefficients"] >> distCoeffs;


void CalibratedVideo::send_video(const sensor_msgs::ImageConstPtr& img){
Mat newFrame;
cv_bridge::CvImagePtr inMsgPtr;
inMsgPtr = cv_bridge::toCvCopy(img, sensor_msgs::image_encodings::BGR8);
undistort(inMsgPtr->image, newFrame, cameraMatrix, distCoeffs);
sensor_msgs::ImagePtr msg = cv_bridge::CvImage(std_msgs::Header(), "bgr8", newFrame).toImageMsg();
ROS_INFO("sent frame width=%d height=%d", newFrame.cols, newFrame.rows);

int main (int argc, char* argv[]){
ros::init(argc, argv, "cali");
ros::NodeHandle nh;
CalibratedVideo cali(nh);

return 0;}
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Closed for the following reason the question is answered, right answer was accepted by andyXu
close date 2017-04-23 11:15:55.268864


Oh, OK. The OpenCV calibration part ( ) is closely related to the resolution of the camera but they didn't mention that. I change their resolution to be consistent with the calibration video and fix the problem

andyXu gravatar image andyXu  ( 2017-04-23 11:15:35 -0500 )edit