Henschel.X's profile - activity

Hi! Everyone!

I'm a beginner of ROS, and now I've been focusing on imaging processing on ROS, My robot is Turtlebot, and I use the kinect as the camera, so basically what I need to do is to find the changes in the same background, so I followed the tutorials and started to use Gazebo now, and I tested the kinect all is fine. So my question is, I am pretty lost since there is no example or demo for image processing on wiki, I am wondering what is my first step? and what should I do after that.

If there is any good website for image processing on ROS to follow, that would be perfect! Thank you so much!

Should I follow the Indigo version tutorials on wiki? or fuerte version?

Yeah, but I don't know if I need to install sth about MoveIt bcz of the error comments. Have you work with sth similar before? Plz guide me. Thank you so much!!

My ros version is Hydro, and I cannot find any tutorials for Hydro so I followed groove version on wiki, but when I get to the catkin make part, the terminal comes with these error, Can any one guide me how to fix it plz.

CMake Error at /opt/ros/hydro/share/catkin/cmake/catkin_package.cmake:159 (message):
  catkin_package() DEPENDS on 'moveit_core' which must be find_package()-ed
  before.  If it is a catkin package it can be declared as CATKIN_DEPENDS
  instead without find_package()-ing it.
Call Stack (most recent call first):
  /opt/ros/hydro/share/catkin/cmake/catkin_package.cmake:98 (_catkin_package)
  turtlebot_arm/turtlebot_arm_block_manipulation/CMakeLists.txt:23 (catkin_package)


-- Configuring incomplete, errors occurred!
Invoking "cmake" failed

I found out that when I run git clone https://github.com/corot/turtlebot_arm it was copied from github 'indigo' branch, I don't know. Plz some one help me.

I followed the answer to copy code from amcl_demo.launch and set false to true, but when I roslaunch my new launch file, it just gives me warnning, "waiting transform from......". Have you met this situation?

I followed the answer to copy code from amcl_demo.launch and set false to true, but when I roslaunch my new launch file, it just gives me warnning, "waiting transform from......". Have you met this situation?

yes, but because those numbers from 1 to 7 are all int. so when I see it on Matlab it lacks detail.

I try to use the code below to save one frame of depth iamge from topic /camera/depth/image_raw, but the problem is I could only get a image looks black. When I read it in Matlab, the matrix elements are basically from number 1 to 7, I guess that's why it looks black. But when I rosrun the image_view (camera/depth/image_raw), it looks just fine. I guess probably it's the problem of encoding, can someone guide me what to do to save image just like the image_view showed to me. plz, thank you!

from __future__ import print_function
import sys
import rospy
import cv2
import cv
from std_msgs.msg import String
from sensor_msgs.msg import Image
from cv_bridge import CvBridge, CvBridgeError

class TakePhoto:
    def __init__(self):

        self.bridge = CvBridge()
        self.image_received = False

        # Connect image topic
        img_topic = "/camera/depth/image_raw"
        self.image_sub = rospy.Subscriber(img_topic, Image, self.callback)

        # Allow up to one second to connection
        rospy.sleep(1)

    def callback(self, data):

        # Convert image to OpenCV format
        try:
            cv_image = self.bridge.imgmsg_to_cv2(data,'16UC1')
        except CvBridgeError as e:
            print(e)

        self.image_received = True
        self.image = cv_image

    def take_picture(self, img_title):
        if self.image_received:
            # Save an image
            cv2.imwrite(img_title, self.image)
            return True
        else:
            return False

if __name__ == '__main__':

    # Initialize
    rospy.init_node('take_photo', anonymous=False)
    camera = TakePhoto()

    # Take a photo

    # Use '_image_title' parameter from command line
    # Default value is 'photo.jpg'
    img_title = rospy.get_param('~image_title', 'photo16U.jpg')

    if camera.take_picture(img_title):
        rospy.loginfo("Saved image " + img_title)
    else:
        rospy.loginfo("No images received")

    # Sleep to give the last log messages time to be sent
    rospy.sleep(1)

My project is kind of similar with yours, but the time I see it, it is 2016 lol. I met the same problem just as you do.

The code is like this

#include <opencv/cv.h>
#include <opencv/highgui.h>
#include <opencv2/core/core.hpp> 
#include <opencv2/highgui/highgui.hpp> 
#include <ros/ros.h>
#include <tf/transform_listener.h>
#include <geometry_msgs/Twist.h>
#include <geometry_msgs/Pose.h>
#include <geometry_msgs/PoseWithCovarianceStamped.h>
//#include <move_base_msgs/MoveBaseActionGoal.h>
using namespace cv;
using namespace std;

void PoseCallback(const geometry_msgs::PoseWithCovarianceStamped& msg)
{
     ROS_INFO("hi");
     tf::Vector3 position;
     tf::Quaternion q;
     position = tf::Vector3(msg.pose.pose.position.x,msg.pose.pose.position.y,msg.pose.pose.position.z);
     ROS_INFO("hi");
     q=tf::Quaternion(msg.pose.pose.orientation.x,msg.pose.pose.orientation.y,
                      msg.pose.pose.orientation.z,msg.pose.pose.orientation.w);
}

int main(int argc, char** argv)
{
        ros::init(argc, argv, "frame");
        ros::NodeHandle n;
        ros::Subscriber sub = n.subscribe("/acml_pose", 1, PoseCallback);
        ros::spin();
        //the rest is computation
    float x1 = -1;
    float y1 = -1;
    float x2 = -1;
    float y2 = 0;
    float x_1 = 0;
    float y_1 = 0;
    float x_2 = sin(CV_PI / 6);
    float y_2 = cos(CV_PI / 6);
    Mat t2 = Mat::zeros(2, 1, CV_32F);
    t2.at<float>(0, 0) = x_1 - x_2;
    t2.at<float>(1, 0) = y_1 - y_2;
    Mat t1 = Mat::zeros(2, 2, CV_32F);
    t1.at<float>(0, 0) = x1 - x2;
    t1.at<float>(0, 1) = y2 - y1;
    t1.at<float>(1, 0) = y1 - y2;
    t1.at<float>(1, 1) = x1 - x2;
    Mat theta = Mat::zeros(2, 1, CV_32F);
    theta = t1.inv()*t2;
    Mat theta_v = Mat::zeros(2, 1, CV_32F);
    theta_v.at<float>(0, 0) = theta.at<float>(1, 0);
    theta_v.at<float>(1, 0) = theta.at<float>(0, 0);
    Mat f1 = Mat::zeros(2, 1, CV_32F);
    f1.at<float>(0, 0) = x_1;
    f1.at<float>(1, 0) = y_1;
    Mat f2 = Mat::zeros(2, 2, CV_32F);
    f2.at<float>(0, 0) = y1;
    f2.at<float>(0, 1) = -x1;
    f2.at<float>(1, 0) = -x1;
    f2.at<float>(1, 1) = -y1;
    Mat trans = Mat::zeros(2, 1, CV_32F);
    trans = f1 + f2*theta_v;
    Mat transformation = Mat::zeros(4, 4, CV_32F);
    transformation.at<float>(0, 0) = theta.at<float>(0, 0);
    transformation.at<float>(0, 1) = -theta.at<float>(1, 0);
    transformation.at<float>(0, 2) = 0;
    transformation.at<float>(0, 3) = trans.at<float>(0, 0);
    transformation.at<float>(1, 0) = theta.at<float>(1, 0);
    transformation.at<float>(1, 1) = theta.at<float>(0, 0);
    transformation.at<float>(1, 2) = 0;
    transformation.at<float>(1, 3) = trans.at<float>(1, 0);
    transformation.at<float>(2, 0) = 0;
    transformation.at<float>(2, 1) = 0;
    transformation.at<float>(2, 2) = 1;
    transformation.at<float>(2, 3) = 0;
    transformation.at<float>(3, 0) = 0;
    transformation.at<float>(3, 1) = 0;
    transformation.at<float>(3, 2) = 0;
    transformation.at<float>(3, 3) = 1;
    return 0;
}

I run this node, and nothing gives back, no ROS_INFO "hi". And according to the rostopic echo /amcl_pose, it says no subscriber. Can someone plz tell me where goes wrong plz. I just need to get the position and Quaternion of my turtlebot. Thanks

Hi! I met the same problem just like you, I changed "odom" with "map", instead, I got this error "map" passed to lookupTransform argument target_frame does not exist. Can you tell me what should I do ? I don't even know what odom means. CuzI just started to learn ROS ;(,Thx anyway

I'm following this tutorials: [ http://learn.turtlebot.com/2015/02/03... ] ,and I can get the position and ERY of my turtlebot based on the map frame, but I want to get those number from one moment t=t0 (position[xo,y0,z0],ERY[a0,b0,c0]) in my node written by C++. I know what I should do is subscribe tf. And according to wiki tutorials, tranformListener can automatically subscribe all the information from tf, like this tf::TransformListener listener; but aftrer that I just don't know what to do. All I need is the position and ERY of the current location of my turtlebot. Thank you guys!

Thank you so much !

I know I can transform my quaternion to ERY, and it seems easier to transform between ERYs because it's more direct. For example, I have a vector X (x,y,z) and its ERY is (0,0,a), and I have another vector Y(x',y',z') and ERY is (0,0,b), if I want to get Y by doing RX+T, can I get the rotation matrix R and transformation matrix T by using TF's function? Or if its not possible, how can I compute this? Thx a lot!

For example, I have a vector X (x,y,z) and its ERY is (0,0,a), and I have another vector Y(x',y',z') and ERY is (0,0,b), if I want to get Y by doing RX+T, can I get the rotation matrix R and transformation matrix T by using TF's function? Or if its not possible, how can I compute this? Thx a lot!

oh OK, I didn't know that.... Thanks a lot!

I encountered some problem with image registration on ROS, I have already realized the function on matlab, and I know it's possible to include mex.h in C++ to use matlab functions, so can I do the same when I write the node using C++ on ROS? Like the same for Opencv? Thank you guys a lot!

I have to use the old function cvCvtColor to convert RGB image to gray scale image, but Mat won't work for this, but I figure it out the problem, I have to replace my file name with the path, otherwise it cannot find the image.

I don't know. I just guess it may need that. I plan to do as you said too, get image from ROS, convert it to Opencv Image, do the processing and change it back, I just don't know what else should I do.

I used several ROS_INFO, and it came with this error, I don't know what it means.

OpenCV Error: Assertion failed (scn == 3 || scn == 4) in cvtColor, file /tmp/buildd/ros-hydro-opencv2-2.4.9-2precise-20141231-1923/modules/imgproc/src/color.cpp, line 3737 terminate called after throwing an instance of 'cv::Exception' what(): /tmp/buildd/ros-hydro-opencv2-2.4.9-2precise-20141231-1923/modules/imgproc/src/color.cpp:3737: error: (-215) scn == 3 || scn == 4 in function cvtColor

Hi, everyone ! I'm doing image processing using turtlebot right now, and I have completed programming on VS Windows, it is going perfect, but when I transformed it to ROS, it just went wrong. I am new in this area so I don't know what to do it right, I followed the tutorials and some simple example, and I successfully generated the exe file, but when I rosrun my node, the terminal says 'segmentation fault '.

Here is my program, it's pretty simple even though it looks long:

#include <opencv/cv.h>
#include <opencv/highgui.h>
#include <opencv2/core/core.hpp> 
#include <opencv2/highgui/highgui.hpp> 
#include <opencv2/imgproc/imgproc.hpp> 
#include <ros/ros.h>
#include <image_transport/image_transport.h>
#include <cv_bridge/cv_bridge.h>
#include <sensor_msgs/image_encodings.h>

using namespace cv;
using namespace std;

int main(int argc, char** argv)
{
        ros::init(argc, argv, "environment_changes");
        ros::NodeHandle ench;
    //ParametersSetting
    unsigned char t = 50;                                           //difference threashold
    int w = 50;                                             //window for checking
    int output = 0;                                         //output for whether there are changes
    double  threashold = (2 * w - 1)*(2 * w - 1)*0.92;      //threashold for whether there are changes
    double  r = 0.05;                                       //rate of elimated size
    double  X = 0;                                          //x of the centre
    double  Y = 0;                                          //y of the centre
    int p = 0;                                              //number of the changed space
    int i;                                                  //rows
    int j;                                                  //cols

    //LoadImage
    IplImage * image_ref;
    IplImage * image_trans;
    image_ref = cvLoadImage("test1.jpg");
    image_trans = cvLoadImage("test2.jpg");

    //ChangeToGray
    IplImage * image_ref_gray;
    IplImage * image_trans_gray;
    image_ref_gray = cvCreateImage(cvGetSize(image_ref), image_ref ->depth ,1);
    image_trans_gray = cvCreateImage(cvGetSize(image_trans), image_trans -> depth ,1);
    cvCvtColor(image_ref, image_ref_gray, CV_RGB2GRAY);
    cvCvtColor(image_trans, image_trans_gray, CV_RGB2GRAY);

    //ShowImage
    cvNamedWindow("test1", 1);
    cvNamedWindow("test2", 1);
    cvShowImage("test1", image_ref_gray);
    cvShowImage("test2", image_trans_gray);
    waitKey(0);

    //ComputeTheImage
    IplImage * image_sub;
    image_sub = cvCreateImage(cvGetSize(image_ref_gray), image_ref_gray->depth, 1);
    Mat ref;
    Mat trans;
    Mat sub;
    ref = Mat(image_ref_gray);
    trans = Mat(image_trans_gray);
    sub = Mat(image_sub);
    absdiff(trans, ref, sub);
        i = sub.rows;
    j = sub.cols;
    int m;
    int n;
    for (m = round(i*r); m <= round(i*(1 - r)); m++){
        for (n = round(j*r); n <= round(j*(1 - r)); n++){
            if (sub.at<uchar>(m, n) >= t){
                sub.at<uchar>(m, n) = 255;
                X = X + m;
                Y = Y + n;
                p = p + 1;
            }
        }
    }
    X = X / p;
    Y = Y / p;
    cout << X << " " << Y << endl;
    * image_sub = IplImage(sub);
    cvNamedWindow("test3", 1);
    cvShowImage("test3", image_sub);
    waitKey(0);

    //ReleaseTheSpace
    cvDestroyWindow("test3");
    cvDestroyWindow("test2");
    cvDestroyWindow("test1");
    cvReleaseImage(&image_sub);
    cvReleaseImage(&image_trans_gray);
    cvReleaseImage(&image_ref_gray);
    cvReleaseImage(&image_trans);
    cvReleaseImage(&image_ref);

    return 0;
}

right now I simply just do the image load and processing and then show it without dealing with Turtlebot. Can somebody tell me what to do plz!! Thank you guys sooooo much!