Questions tagged [computer-vision]

The goal of computer vision is an automatic extraction of information out of images. It includes methods for acquiring, processing, analyzing, and understanding images and high-dimensional data from the real world in order to produce numerical or symbolic information, e.g., in the forms of decisions. The image data can take many forms, such as video sequences, views from multiple cameras, or multi-dimensional data from a medical scanner.

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How to perform time-offset calibration use GTSAM in Camera-IMU system?

Assume we have camera poses data and IMU data(which include gyr and acc data) with different timestamps, now I want to estimate this value, I known that this can be done in many ways(EKF,MSCKF), but I ...
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Camera Calibration Matrix accuracy

When we do camera calibration, we have to find calibration matrix $M$, which is found by first finding extrinsic matrix and then intrinsic matrix. To validate the accuracy of calibration matrix, we ...
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What type and how many cameras are needed for SLAM?

I would like to know what are the sensors needed to effectively do real-time SLAM with a robot. I have seen 2 fish eye cameras being used with good results, but there is also solutions for real-time ...
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6D pose estimation of a known 3D CAD object [closed]

I'm looking for a codebase for 6DOF pose estimation of a known 3D CAD object with RGB or RGBD. It must be: -Usable commercially (licensed under BSD, MIT, BOOST, etc.), not GPL. -Easy to setup and use (...
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Adding/ Subtracting vertex and edge constraints using g2o dataset in a monocular odometry project

I have come across a relatively new rotation averaging solver with full python implementation and helpful examples https://github.com/dellaert/ShonanAveraging However, I am having a hard time ...
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Screen Coordinates [ x, y ] to Pan and Tilt angles

So I have a pan-tilt system with an airbrush on top, the pressure is quite strong so that I can place the robot at a distance of at least 1.5 meters. I currently have normalized coordinates XY that I ...
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How to find the camera matrix and distortion matrix from the given data

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Essential Matrix constraint violated, computed using numerical libraries only

Lets say that I have eight pairs of correspondance points taken from two images (left and right). Also, I know the intrinsic matrix (K) of both cameras (is the same). I'm trying to find the Essential ...
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Monocular SLAM position estimation

I have been reading about mono SLAM and I have a couple questions which are not so clear: When doing pose estimation, I have seen people both reference homography transformation and also reference 5\...
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How is loop closure mechanism incoporrated in particle filter based SLAM algorithm?

Could any one please explain, how is loop clousre mechanism introduced in filtering based SLAM techniques like FAST Slam ?
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How to program a custom microcontroller to USE CUES FROM A PC to change the position of a servo motor? (Without using Arduino/Raspberry Pi)

I want to program a custom microcontroller that ideally connects to a camera and performs some sort of image analysis and do something(like change the position of a servo motor). The initial idea is ...
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How to find fundamental matrix based on other fundamental matrix and camera movement?

I am trying to speed up some multi-camera system that relies on calculation of fundamental matrices between each camera pair. Please notice the following is pseudocode. ...
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Center line steering with differential drive

I’ve got 2 motors that drives my unit and I can easily steer it manually by simply adding more speed to one wheel vs the other. Now I’m automating the rover using image processing to follow a driveway....
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How does baseline work with forward motion in Monocular Visual Odometry

In my computer vision class we are studying visual odometry. In this we calculate the Fundamental matrix using 2 frames from forward motion using the concept of stereo-vision. But in stereo vision the ...
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roslaunch exit code 2 error

I am implementing a simple roslaunch file but I am getting an exit code 2 status I have pasted the exact log below any idea what would cause this and how I can rectify it. ...
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Mobile robotic arm camera position

I'm working on my graduation project which is a mobile robotic arm that performs pick and place tasks. I wanted to know the possible ways to mount the camera where i can reach the desired destination ...
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Explanation of the epipolar constraint in stereo imaging

I am watching this video, in which the epipolar constraint is defined as $x_l \cdot (x_l \times t)=0$ It means that the vector $x_l$ that passes through the observed point and the left camera origin ...
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What is the usual output format for 3D BBox detection?

I have read several papers dealing with 3D BBox detection. However the wording is quite convoluted and I don't see the results obviously. I am trying to download the KITTI benchmark data to check it ...
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What are the usual results for pedestrian posture detection?

When talking about lane detection in a road, usually robotic computer vision system give lines in an image. For detecting obstacles, those system give Bounding Boxes. My question is, for pedestrian (...
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Unstable principal point estimation in zoom camera calibration

I have a camera with a 1/2.9" image sensor from FLIR and a 12-50mm motorized zoom lens from Theia. Because the lens is a motorized zoom lens, I tried to calibrate the camera for different zoom ...
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Number of pixels required to identify something

When using an RGB camera, what is the minimum number of pixels of an object that you need to identify something (theoretical or rule of thumb)? The image would be taken out in the wild with a complex ...
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Can you plug a CMOS camera (like the iPhone 8 back camera) into an mPCIe in a laptop?

I read that 12 megapixel iPhone cameras don’t record video in 12 megapixels because the processors are not able to keep up. It seems though, that if I could plug the CMOS sensor to the CPU of a laptop,...
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Cheap global shutter cameras with external synchronization

Please recommend cameras for multi-camera setup satisfying the following conditions: Relatively cheap (up to 100$ per camera). Global shutter. No filters on lenses or pixels. Resolution of 1 MP or ...
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Autonomous harvesting robots. What are model possible components and interactions for the entire system? [closed]

I found a video which talk about best autonomous robots that use IA technology to harvest crops. The video is very interesting because, the “ecosystem” of each robot varies a lot from company to ...
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Depth camera pixel values to 3D coordinates

I have a robotic arm 6-DOF and an Intel RealSense depth camera. I want to go from pixel values to 3D world coordinates, is it possible with eye-in-hand calibration? If yes can you guide me on how to ...
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ROS Webcam Stream Really Slow

I am trying to stream the images from my camera to a VM via ROS. Here is my setup: Raspberry Pi 3B+ with Picamera v2. It is running ROS Noetic with cv_camera_node ...
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Visual Odometry terminology: Scale, Relative scale, absolute scale

I'm watching a MOOC about Machine Vision for Robotics, but I really do not know the meaning of some vocabulary of this domain. For example, What does the professor mean when he says this: However, we ...
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Is two cameras equivalent to Stereo camera setup?

I have two webcams, which are mounted close together. I plan to use them to find out the true depth of certain pixels of images. Suppose I use a standard multi camera calibration setup and find out ...
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Is there any RAPID instruction to save image as variable in YuMi integrated vision without using RobotStudio?

I want to perceive the images from the cameras embedded in YuMi IRB 14000 arms and store them as videos, in Ubuntu without using ABB RobotStudio. is there any way to do that? if yes how can I do that ...
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What are the purpose of pre-trained weights for YOLO object detector?

Dear Research Community, I am new to object detection research and currently working on a project which will detect people using YOLO from a top-down camera image. While looking through tutorials for ...
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Is easier to detect a large or a small marker? (Aruco / Apriltags)

I need to detect Aruco/Apriltags markers and perform pose estimation, but I've no particular constraint on their physical size. I'm not talking about the number of square (e.g. 4x4, 6x6, etc.), but of ...
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Choosing cameras for stereo vision system?

I'm in the process of building a stereo vision system with YOLO detection. The system have to detect airplanes in far distance and also measure the depth from the airplane to the camera. I think ...
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How well does object detection transfer from simulation to reality? [closed]

I'm looking to learn more about this sim-to-real gap. I'm new to the concept and am trying to understand what to look for. Most notably i'm curious about how well an object detection algorithm trained ...
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Trajectory planning in unstructured environments

How is trajectory planning normally carried out in off-road/unstructured environments? In particular I'm interested in how stereo vision can be used to plot trajectories over obstacles - for example, ...
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Size of smallest feature from pixel depth resolution

How do I get the size in mm of the smallest feature a depth camera can detect? Known variables are: distance from the target (for instance 1 meter), depth resolution in pixels (for instance 1280 x 720)...
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How can I calibrate 3 cameras without knowing global pose of the object & camera locations? How can I find the pose of each camera wrt the first one?

I have camera feed (in the form of RGB images) from 3 cameras with partially overlapping Field-of-view i.e. for the time stamp 0 to 100, I have total 300 frames or say synchronized 100 RGB frames for ...
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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 is the depth estimation done in DTAM / LSD-SLAM (direct VSLAM)?

I know that DTAM and LSD-SLAM both employ the photometric error between two keyframes to estimate the image depth. But I don't know what the photometric error describes precisely. In the DTAM paper, I ...
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Computing Essential Matrix from Fundamental Matrix

I have calibrated my cameras using OpenCV. I used cv.stereoCalibrate to get the E, and F matrices. I wanted to do a sanity check to see if the E matrix obtained is ...
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Automatic License Plate Recognition System in Highway

We are working on a computer vision project where an automated robotic system will be deployed on a 3-lane highway. We are using a bosch IP camera (I don't remember the model exactly, but it cost ...
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2 votes
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Sensors to detect targets in low visibility environment

I want to know what type of sensor hardware I need to allow detection of moving targets (20mm - 200mm size range) in heavily murky water, where visibility range of typical camera can be limited to 0.5 ...
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Guidance on SBC for Visual-Based SLAM [closed]

Intro: I am a student that just started a project regarding prototyping a mobile robot that involve Indoor SLAM implementation. I am very new to the field of computer vision, SLAM and SBC (single ...
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How does inverse compositional Lucas–Kanade algorithm work?

I am trying to understand the Lucas–Kanade algorithm since I am reading a paper in which is applied the inverse compositional Lucas–Kanade algorithm, but in order to understand the latter I have to ...
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Dual constraint non-linear optimization for SLAM

I am trying to achieve a nonlinear optimization for SLAM on a function that contains two different constraints, like this : $$ T_{opt} = \underset{T}{\arg\min} \sum_i(\left\lVert T.X_i - x_i \right\...
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Good Software Projects for Aspiring Engineers [closed]

With the pandemic going on, our school has decided to officially shutdown all sponsored club meetings. Now that we are all digital, our robotics club was looking for projects that students can do at ...
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Intel Realsense Cameras for Object Avoidance and SLAM to go to destination

My goal is to make a UAV which can search an area while avoiding obstacles. I figured I would navigate using the SLAM and Intel Realsense D435i (a stereoscopic camera with an IMU built in), but all of ...
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Intel RealSense Depth Camera D435i Wide Imager questions?

I have just ordered my d435i and while it was not intended to do NDVI I read the data sheet and noticed it had seperate image sensors, it is possible to read the IR image from either left, right or ...
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Single Camera + Laser Projector Triangulation

I want to combine a laser line projector (projects a laser plane) and a single web camera to determine the X, Y, Z position of the laser point. I am slightly confused as to how to use the fact that we ...
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Tracking 3D motion using a stereo camera

Assuming you have a fixed stereo camera, looking at a rigid object, what are the techniques used to track the object? My google searches lead me to optical flow and similar algorithms, but I believe ...
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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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