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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17 views

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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24 views

How can I calibrate 3 cameras and track the object using only synchronized cameras feeds from all the cameras?

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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18 views

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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98 views

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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2answers
49 views

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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Drone based CV via base station - power requirments

Currently computer vision based inference is impractical on a drone given the significant power draw. Is connecting a drone to a base station which does CV a viable solution to this issue? Has it been ...
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1answer
54 views

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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37 views

ModuleNotFoundError: No module named 'second.core.non_max_suppression.nms'

I am using Anaconda base environment for second.pytorch of ubuntu 16.04 after executing the following: nvidia-docker run -it --rm -v /media/yy/960evo/datasets/:/root/data -v $HOME/pretrained_models:/...
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Are there some papers or books that compactly elaborate the essential part of the multiple view geometry?

I am a novice to visual SLAM and computer vision. Recently I've read a paper "A micro Lie theory for state estimation in robotics" dedicated to introducing the essential part that necessary to ...
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21 views

get position of objects using ir

I originally wanted to make a shoddy vr system with two IMU's in two seperate right and left controllers, which their values could be sent over wifi to the game service unity so I can plot their ...
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25 views

Serial communication of IMU and Encoder arduino code

Pls, I need people to help me look at where I am getting it wrong. I test this code on Arduino ide and got the result I wanted but sending it to Matlab through serial communication, I obtained a ...
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1answer
41 views

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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1answer
36 views

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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Bundle Adjustment for Monocular SLAM

I am confused with how monocular BA works in visual-based SLAM. Is there any tutorials I can do in openCV to provide me some visualization aid? Thank You.
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22 views

How is a point triangulated with SVD with 2 correspondences?

According to these slides, if you have 2 correspondences for one 3D point, is is possible to build a system of linear equations (slide 27): AX = 0 And solve for <...
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1answer
39 views

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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60 views

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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32 views

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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1answer
43 views

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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1answer
34 views

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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What is the jacobian of an image lookup function?

I'm trying to solve a computer vision problem whereby I wish to use Levenberg-marquardt non-linear optimization to solve the following equation: Whereby xi is the x,y coordinates in the image, I ...
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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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1answer
25 views

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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43 views

Rescaling a local Map in VSLAM (orb slam)

I am trying to inject metric scale into a vslam algorithm, namely the popular ORB-SLAM2. I have read several papers(1,2) whereby people have successfully calculated scale factor from the actual height ...
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57 views

Use Camera Calibration Matrix without Toolbox

I am doing this little project where try to calibrate a Raspberry Pi Camera. I use Matlab and I do not want to use the Calibration Toolbox (!). The algorithm I use is the direct linear transformarion ...
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31 views

Which is the recommended depth estimation method for under vehicle scanning?

There are many ways to estimate depth e.g. Structural light based solutions Time-of-flight (ToF) cameras LiDAR Stereo cameras Computer Vision image based methods Monocular models such as monodepth2 ...
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29 views

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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1answer
2k views

AprilTag vs Aruco markers [closed]

AprilTag and Aruco are both popular methods for vision-based fiducial marker pose estimation. What are the pros and cons of each fiducial marker pose estimation systems?
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How to handle landmarks in Bundle Adjustment?

At the moment I try to understand Bundle Adjustment on a level to be able to implement it on my own. The major point I'm still confused at is the management of the landmarks. So, let's think of a few ...
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1answer
39 views

Camera mounted on robotic arm - XYZ mapping

I have a 5 axis robotic arm that has a depth camera mounted near the toolhead on the left side. I have object detection software running on the camera and can find the XYZ of any object in mm that ...
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0answers
21 views

Disparity error in active light stereo systems?

Based on this relationship, if we have to estimate the 'disparity error' of a stereo system which uses active light on the scene - can we estimate the disparity error to be very small? According to ...
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1answer
28 views

Active Light Stereopsis: 1 Camera + Projector Vs. 2 Camera + Projector

What is the difference between using 1 Camera and a Projector and using 2 Cameras and a Projector for creating structure from motion? Is it that if we use only 1 camera and a projector then we will ...
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1answer
32 views

Facial Detection combined with Path Planning using Kinect Sensor

I am planning to use a Kinect Sensor on a mobile robot for path planning based on facial detection. Assuming I am able to detect the faces of 5 individuals in a room (both the environment and the ...
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1answer
85 views

Fusing Multiple Lidars Into 1 Point Cloud

I have a car with 8 lidars, each with a field of view of 60 degrees. My car looks like this How can I merge all the lidar readings into 1 point cloud?
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27 views

How to perform Image alignment using pyramid levels

To gain some confidence, I want to implement the camera tracking (optimization problem) discussed in Semi Dense Visual Odometry for a monocular cameraJ Engel, J Strum, D Cremers $$E(\xi) = \underset{...
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17 views

Detecting pieces of a Version 1 QR code and processing the assembled version

I am building an aerial robot that needs to be able to detect pieces of a QR code (examples below) and combine them to process the information contained in the fully assembled QR code. I don't have ...
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1answer
21 views

Depth images with undetectable outlines

I'm trying to capture depth images with a RGBD camera, but all of the images have undetectable outlines around objects: Is this expected from RGBD cameras or is mine a dud? It's an Astra Pro.
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25 views

How to make x variable change each time and read its value from txt file

I am working on my undergraduate project and this is my first time in using use python to control parrot bebop 2 drone and use BCI or BMI technology. I have x variable (int) and I want to read its ...
2
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1answer
110 views

ORB-SLAM pose estimation

I've been reading about ORB-SLAM and ORB-SLAM2, but I can't quite figure out how pose estimation is done. I see that it uses a bag-of-word method for loop detection, but how are current features ...
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1answer
92 views

what is ultrasonic based slam

i am confused about SLAM implementation, and i need your advise to organize my mind. Fist let me say that i have to generate 2D map, what is in this case the SLAM input? is it like (x1,y1),(x2,y2)...(...
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1answer
78 views

Efficient sphere surface area search

As shown in the figure, there are objects of arbitrary shapes placed on the surface of the sphere at arbitrary locations. The problem is to search the surface to locate these objects in most efficient ...
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2answers
314 views

How does structured light improve accuracy in stereo vision?

In my understanding, in order to improve accuracy for the estimation of depth with a stereo vision camera, patterns of light are projected into the scene, because the resulting texture makes it easier ...
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1answer
271 views

What is the relation between FOV, Focal Length and Sensor size in a Pin hole Camera Model?

I aim to recreate the camera parameters of my camera in the Unity rendering system, which has the following variables: 1) I tweaked the focal length and saw that the Field of View is changing (...
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Is it possible to calculate a homography matrix for any 2 views?

I've been experimenting with opencv to estimate the homography matrix between 2 images captured with my computer's webcam. I have noticed that when the 2 views are not very far apart (that's when I ...
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Undo pitching effect of camera when pose (y-axis) is near 90 degrees?

I am using KITTI odometry dataset whereby the camera's axis is pointing X (east), Y (down) and Z (north). It also contain the frame to frame poses of the camera (first pose is fixed as the map frame). ...
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1answer
100 views

vision guided robotic arm always required 6d pose of object? [closed]

I have an object like attached in image. It is hanging vertical (its position may change but static object) and I want to grasp it using 6DOF Robotic arm. I am Using camera to detect object. I am ...

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