Depth image/disparity

Python
1

Hi, i need a small help with some matter that i cant wrap my head arround.
Im trying to publish a disparity map of a stereo camera, i wrote this node here and i keep getting this error when after starting the node :
could not convert image from '16SC1' to 'rgb8' ([16SC1] is not a color format. but [rgb8] is. The conversion does not make sense)
this is my node :

import rospy
import cv2 as cv
import numpy as np
from cv_bridge import CvBridge, CvBridgeError
from sensor_msgs.msg import Image
import message_filters

def read_cameras():
    imageL = message_filters.Subscriber("/camera_left/image_raw", Image)
    imageR = message_filters.Subscriber("/camera_Right/image_raw", Image)
    

    # Synchronize images
    ts = message_filters.ApproximateTimeSynchronizer([imageL, imageR], queue_size=10, slop=0.5)
    ts.registerCallback(image_callback)
    rospy.spin()

def image_callback(imageL, imageR):
    br = CvBridge()
    rospy.loginfo("receiving Image")

    imageLeft = br.imgmsg_to_cv2(imageL, "rgb8")
    imageRight = br.imgmsg_to_cv2(imageR, "rgb8")

    imageL_new=cv.cvtColor(imageLeft, cv.COLOR_BGR2GRAY)

    imageR_new=cv.cvtColor(imageRight, cv.COLOR_BGR2GRAY)

   

    stereo = cv.StereoBM_create(numDisparities=16, blockSize=15)
    disparity = stereo.compute(imageR_new,imageL_new)






    rospy.loginfo("showing depth image")
    # Process images...

    pub = rospy.Publisher('/left_camera', Image, queue_size=1)
    cv.imshow('disparity', disparity)
    msg = br.cv2_to_imgmsg(disparity, encoding='16SC1')
    pub2 = rospy.Publisher('/Right_camera', Image, queue_size=1)
    msg2 = br.cv2_to_imgmsg(disparity, encoding='16SC1')

    
    pub.publish(msg)
    pub2.publish(msg2)
     

    

if __name__ == '__main__':
    rospy.init_node('my_node')
    try:
        read_cameras()
        
    except rospy.ROSInterruptException:
        pass

is this an encoding Problem ? can someone tell me what im doing wrong exactly? i tried multiple approaches as to change the encodings but that didnt change.
Anyhelp would be appreciated. thanks

2

ROS+numpy issue.

your array has dtype == np.int16 (which is CV_16SC1)

3

the color mode of the image that is being read from the camera is "rgb8" and basically converting it to GRAY imageL_new=cv.cvtColor(imageLeft, cv.COLOR_BGR2GRAY) and inputting into stereo.compute(). i Dont understand what to change here exactly.
Thank you for your response.

4

irrelevant.

and what you get out of that has a dtype of np.int16. do you see?

5

What do i need to change in my code for the conversion ?

6

again, we don’t support cv_bridge. that’s not part of OpenCV. you need to talk to ROS people about this.

cv2_to_imgmsg() appears to support a “passthrough” encoding argument. maybe try that and see if it works.