Questions tagged [opencv]
OpenCV (Open Source Computer Vision) is a cross-platform library of programming functions for real time computer vision.
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Segmentation fault in cv::findContours call
I am struggling to debug a segmentation fault. Any help is appreciated! The node just crashes whenever I launch it and following is the seg fault I am getting when running through gdb:
...
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13
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multiple video streaming
I'm currently experimenting with video stream opencv. But,I think I can only stream one video at a time.Is it possible to stream multiple videos at the same time?If there are other packages that would ...
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2
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Detecting door blockage using computer vision
I want to detect door blockage on a camera. Basically if the exit door is blocked by an object, it detects it as an anomaly. How can we do it? Is it possible to do it using OpenCV?
Remember, it doesn’...
- 111
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Making sense of disparity values after applying `StereoSGBM` from OpenCV
I just started with Kitty Stereo Dataset (2015). The first thing I did was compute the disparity using the stereoSGBM class. And here is the rectified input images ...
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WEBOTS - Connect a external Tkinter Script to main controller?
I have a WEBOTS Simulation with an automobile. Now while WEBOTS provides a camera overlay, I want to display the result of image processing along with sensor data in a comprehensive manner.
For this I ...
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Marker pose flickering one axis from -4 to +18 when camera is not moving
I'm taking a sequence of frames from intel real sense and detecting april tags, I noticed the axis is flickering even camera is not moving. euler angle y axis is changing(visually and numerically) ...
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36
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How can I change the dicitonary of aruco markers in aruco_ros package to the newer DICT_4x4 dictionary?
The arcuo_ros package by pal_electronics uses old dictionaries of aruco markers, the markers of these dictionaries are coded in uint64_t integer in the code file of the dictionaries dictionary.cpp (...
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Outlier rejection of fisheye stereo feature, how to do it?
OpenCV provides a nice outlier rejection feature with findFundamentalMat function. But that's for the pinhole projection model.
How do we detect the outliers around the edge of the image circle where ...
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Convert CameraInfo K & D to OpenCV format convenience functions?
Are there existing functions to convert from camera info arrays of K and D to intrinsic and distortion cv::Mats that can be passed into opencv functions like ...
- 3,099
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OpenCV: What does it mean when the number of inliers returned by recoverPose() function is 0?
I've been working on a pose estimation project and one of the steps is finding the pose using the recoverPose function of OpenCV.
...
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Configuring ROS2 for OpenCV and C++
How to properly setup the ROS2 workspace (i.e., cmakelists and package.xml, etc.) for using OpenCV and C++ ?
I could not find proper examples for that.
Thanks in advance.
Originally posted by ...
Werewolf_86
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105
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Vision programming with OpenCV
I am currently working on a project on NiryoOne which requires facial detection of a person through NiryoOne camera (ELP SONY IMX).
The code that I am using works on my laptop running Ubuntu. However, ...
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How to enable GPU-Features of Rtabmap
OS: Ubuntu 20.04
CUDA 11.6, CuDNN 8.4 (GPU is Nvidia Quadro T 1000)
OpenCV 4.5.5 with GPU support also for CUDA and also the opencv_contribs
currently using Rtabmap standalone, but I intend to use the ...
TurBot
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1
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2
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CMake detects intended OpenCV+CUDA, but runtime does not use intended OpenCV version
CMakeLists.txt contains
...
MrOCW
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Catkin_make failed to build opencv
Hello guys,
I want to compile a package (https://github.com/mjshiggins/ros-examples) with the catkin_make command from the catkin_ws folder, but it seems that the OpenCV header file is depreceated or ...
Petros ADLATUS
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Why would we solve AX=XB instead of just using the Kabsch algorithm?
I have a high precision stereo camera and a robot which are independent units (the camera is not mounted to the robot). I wish to compute a transformation from the camera frame to the robot base frame....
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ROS2: How to publish cv Mat image?
I'm having trouble understanding how to publish a cv::Mat image in C++, and I can find very little documentation about this.
Here's my publish code. I based it on this tutorial: https://docs.ros.org/...
zjeffer
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2
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4
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upgrade opencv version in melodic
Hello,
i want to upgrade opencv version to over 3.4 in Melodic.
Melodic installs opencv 3.2 originally,
so I tried to uninstall opencv 3.2, and re-install opencv 3.4
But some packages which are ...
danekim
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1
answer
322
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Error when compiling cv_bridge in Raspberry Pi 4B with Raspbian buster and ROS Noetic
Im using Raspberry Pi 4B, with Raspbian Buster and ROS Noetic. When I tried to compile my catkin ws with a cv_bridge package I got the following error:
CMake Error at vision_opencv/cv_bridge/...
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5
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Noetic python raw Image publisher (from video)
Hi everyone,
I have spent nearly 2 full days with this problem now and have some extensive research, but just can't figure it out.
My apologies for being a burden, I ussually hesitate to waste anyones ...
USAotearoa
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1
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3
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Image Subscriber Lags (despite queue_size=1 and buff_size=2**30)
Hi,
I have been working on a Python class that will allow me to spawn an object in gazebo, take an image of the object, and then delete that object, for a given number of objects that I provide. I am ...
jdastoor3
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1
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10
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ModuleNotFoundError: No module named 'cv_bridge' IN windows10 running foxy
I was following this tutorial https://automaticaddison.com/getting-started-with-opencv-in-ros-2-foxy-fitzroy-python/ to implement a simple ros2 image publisher and subscriber. everything was built but ...
aniketwagh
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1
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270
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Does a stable library exist for docking robots using images?
I built a mobile base from scratch, and now I am focused on getting the robot to charge.
The robot is using an on-board webcam (and PC) to detect a QR barcode on the charger unit. Using OpenCV I find ...
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1
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857
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Implementing PID on a line following bot using turtlebot
I am using ROS melodic,turtlebot 2 on Ubuntu 18.04.
The idea is to create an environment consisting of lines as a path (slightly curved), and to program the turtlebot to follow the lines. Basically, a ...
- 131
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What is the exact format and size of Image() object?
I cannot figure out what is the exact format of the sensor_msg Image() file. When I issue the command:
rostopic echo /camera/image_raw
I get a massive output ...
Tejas Rao
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2
answers
102
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Reflective surface
Have you encountered the problem of reflective surfaces for realsense camera (d435 or t265) and lidar (A1 or A2). I would like to know what are the ways to solve problems with reflective surfaces for ...
- 11
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2
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OpenCV and ROS2
I've checked all the related questions here and I still wasn't able to get this example to run. I apologize in advance if the solution was right in front of me and if that offended anyone.
Problem ...
mintybim
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1
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7
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Compress Image topic with h264 streaming for low bandwidth connection?
Hello,
I faced the problem that sending the video with big resolution (1920x1080) is very difficult even with image transport. The raw or compressed images are too bit for sending over the network (...
Yehor
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3
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Find intrisic camera matrix from gazebo model
Hello,
I made a my camera model in gazebo and I want to extract the intrinsic matrix to use Opencv matrix.
Here is my model:
...
xavier12358
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293
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Path planning for robot car on grid
I am currently doing a project as my hobby. I am trying to simulate a robot car in a grid arena. Below is the image of the arena:
The start point of the car is the bottom-right corner(dark green ...
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1
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158
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Eliminate grey space around the saved map
I have mapped my Gazebo environment using the slam_gmapping node. On running ...
- 314
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1
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377
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Need help in loading occupancy_grid map to OpenCV window
I have generated a map named map_1.pgm using map_server package. I want to display it in an ...
- 314
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45
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Trouble aligning/calibrating camera with laser scanner
I have a robot which has 2 multi-spectral cameras and 1 laser scanner attached. In the end I would like to have the images from the cameras aligned with the scanner so that I can have spectral ...
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Finding OpenCV Paths in ROS Builds
Short version: How do I find the path to haarcascade_frontalface_alt.xml provided by opencv?
Long version:
I'm working on getting the ...
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openCV transform datatypes to ROS msg tf/goal
Hi,
Iam looking for the best practice to make a openCV transform (getAffineTransform() ) into a pathplanner goal message (angle, translation). I dont really understand all the different datatypes used....
Dragonslayer
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2
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publish and subscribe to numpy.ndarray topic in ROS2
Hello!
My question is quite simple is it possible to create publishers/subscriber of a numpy.ndarray topic and how?
I searched on the internet and I found these two links :
https://answers.ros.org/...
Kreace
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1
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3
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Best OpenCV version for ROS Noetic
I ran this command to find out if my OpenCV version was 4:
kg-config --modversion opencv4
The outcome was:
4.2.0
I also tried ...
ajpaezm
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1
answer
1
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cv_bridge and OpenCV both define Exception class
I am trying to use cv_bridge in my project on Windows 10 using Visual Studio 2017. When I try to compile my code, I get the following errors:
...
sterlingm
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2
answers
693
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Triangulation: Ceres solver minimizes only the last residual block
I have been attempting to estimate a bunch of 3d coordinates viewed via a multi-view setup with known poses, I have the code running, but the output of ceres seems baffling.
There are 7 image frames/...
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How can I convert the KITTI dataset into a bag file?
Hi, I want to convert the monocular KITTI image dataset and poses into a bag file to test computer vision algorithms. I have done some research, however, I have not found any reliable solution.
...
EDU4RDO-SH
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Problems building melodic compressed_depth_image_transport on 18.04
Following these instructions to do a source build of melodic desktop full (I want to build it with thread sanitizer because of something I'm debugging): http://wiki.ros.org/melodic/Installation/Source
...
tyler-picknik
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2
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280
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OpenCV4.2 and Ubuntu16.04 with python2.7?
Summary:
I'm using new vision of opencv, opencv 4.2 with ubuntu 16.04 and python 2.7
After built cv_bridge, the output is:
...
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352
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How to find visual odometry by video from cellphone camera mounted on robot?
I am writing codes in python for visual odometry from single camera. I used cell phone camera for testing. I took video of 35 sec with camera moving. I used code below to read first image
...
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3
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How to get OpenCV 4 working with ROS Melodic?
I'm trying to run ROS Melodic with Opencv 4.2.0 on windows
What is wrong with my CMAKELISTS?
I have added opencv to my system path, but Catkin_make always gives this error:
...
wgengland
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6
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1
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catkin_make opencv version conflict
Hello everyone ;
When I write catkin_make it gives such a warning.
...
jahim44229
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1
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3
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rtabmap: g2o, GTSAM
why do I need them?
I have installed rtabmap-ros as ROS package. Have I already running g2o and GTSAM?
Originally posted by june2473 on ROS Answers with karma: 83 on 2020-02-03
Post score: 0
june2473
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Is there a way to publish a video file so it can be displayed with a camera display in RViz? (solved)
I have recorded videos I want to display in RViz with a camera display so that I can overlay them with my other plugins.
Is there a way to do that?
I tried with the video_stream_opencv plugin already ...
Fetzle
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85
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Interpreting results from Camera Calibration?
I used OpenCV's findChessboardCorners on a few checkerboard images (40~) and about 27 seemed to find the corners accurately. How does one proceed from here? Do I calculate the reprojection error over ...
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99
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Visual-Positioning Method
I'm working on mobile manipulator and trying to do visual-positioning of the end-effector.
My camera will located around 1-2 meters from the robot.
I'm sure i cant use color tracking method because ...
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