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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83 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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41 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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41 views

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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45 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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137 views

robot Hand Eye Calibration problem

I am trying to understand the implementations and the relative performance of various classical and new Hand-eye calibration approaches. Note: The following discussion assumes implementations are in ...
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55 views

Tracking object in realtime using depth image stream from a RGBD camera

I have an Intel RealSense camera which can stream RGB and depth image. Using those information I want to track an object moving on a table top. More specifically, I want to know position $(x,y)$ and ...
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97 views

How to update a new pose in iterative pose optimization problem?

There are multiple ways to update new pose in iterative pose optimization problem. The easiest one we often find in papers in robotics is as SO3 + translation Update on right \begin{equation} \...
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89 views

Algorithm for orientation (pan/tilt) towards a moving point

Main Question: note: The code in this question is pseudo-code, I'm using Python, but my pseudo-code is a mix of Python and C++. I have a camera on the top of my robot's "head" which has pan and tilt ...
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1answer
416 views

Pictures coordinates to robot coordinates

I have a picture on my C# software and the corresponding object in real world on 2d plane of motorized XY axis table. What I want is when I select a pixel on my picture, the motorized table should be ...
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172 views

Which Kinect to use for robotic arm pick and place application with object detection?

I am building a robotic arm for pick and place application. The robot is going to recognize several objects using the RGB feed from Kinect (will use a model such as YOLOv2 for object detection, ...
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288 views

Maintaining scale factor for essential matrix

I want to recover the trajectory of a vehicle using a monocular camera via the computation of the essential matrix between t-1 and ...
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0answers
77 views

Cloth (non-rigid body) manipulation with computer vision? [closed]

I am currently working on a prototype device to automate cloth ironing task. So basically the mechanical design involves 4 manipulators and a separate manipulator arm with a hot pad (iron) to ...
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131 views

Starting out, dissertation project using computer controlled drone [closed]

For my final year in Computer Science university I will be doing a dissertation that includes controlling a drone through computer and communication with an onboard camera for computer vision. The ...
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24 views

Is the distortion introduced by a lens protector significant in practice?

I have a computer-vision application I made to localize a robot in a room; the software has been in use for a while and is working fine. When I calibrated the camera and got the intrinsics and lens ...
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55 views

Depth of view for a hypercatadioptric camera

I am trying to determine the depth of view for a hypercatadioptric camera (camera lens system and a hyperbolic mirror) based on 1. The following illustration seems pretty clear. For an image point $...
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198 views

How to change the orientation of an object w.r.t a scene?

I am trying to localize an object in a point cloud using ROS, PCL. For that I capture the scene and model using Asus xtion pro sensor. I use RGBDSLAMv2 for capturing the model. Then I use ICP (...
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2answers
173 views

TU Munich Monocular Visual Odometry Dataset has NaN values in the ground truth data.

I am trying to use the motion sequences in the dataset to create trajectories for VR systems. A major portion of the ground truth data in almost all sequences has NaN values. Is there any other source ...
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2answers
49 views

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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2answers
68 views

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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1answer
104 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
93 views

Any reference for “3D feature matching + ICP”?

One of the simple tricks in getting high performance for a global 3D point cloud registration is combining "3D feature matching + ICP". For example FPFH matching + RANSAC for initial pose estimation ...
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3answers
39 views

Sensing an actuator using vision [closed]

I am looking forward for a method to sense in real time, using computer vision for a control application. For this I am unsure of which is the right platform . I am well versed with MATLAB, but I am ...
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4answers
868 views

What is the cheapest way to detect and identify vehicles entering a gate in real time?

I want to detect and identify each of the vehicles passing through a gate. I have the live video feed of the gate which I initially thought to process and detect the number plates with the help of ...
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2answers
639 views

how to plot a line between two centroids in matlab

I am able to locate centroids of each blocks, but i am unable to join two blocks with a line segment by avoiding the obstacle as shown in the figure. Please need help how do i achieve this using ...
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2answers
291 views

How do we make our robot work?

As a holiday project we are building a surveillance robot that is capable of transmitting live images using a webcam and is also capable of lifting small objects. It uses a CC2500 module for ...
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1answer
28 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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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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1answer
130 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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1answer
40 views

Obstacle width measurement

On non-lidar equipped rovers, how is the width of an obstacle detected such that it can be avoided? If the ultrasonic sensors are used for obstacle detection, these sensors usually don't give data ...
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1answer
67 views

Transformation matrix between a 2D and a 3D coordinate system

I have 2 sensors : one has 2D coordinate system and the other has a 3D coordinate system (not same origin). Knowing the positions of some corresponding target points (used as fixed reference) in both ...
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1answer
39 views

Combining multiple constraints in optimization

Let's say we have two equations for a pose $\textbf{R},\textbf{t}$ optimization problem. For ICP constraint $$\textbf{e}{_{I}}=\textbf{n}^\top(\textbf{p}_d-(\textbf{R}\textbf{p}_s+\textbf{t}))$$ For ...
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1answer
228 views

How can I compute the covariance of a camera-based relative pose measurement?

I am trying to compute the relative pose between two cameras using their captured images through the usual way of feature correspondences. I use these feature matches to compute the essential matrix, ...
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1answer
194 views

How can I estimate depth of a feature point / object using single camera?

I am trying to estimate depth of a feature point that i find in my image. I read this paper that estimates the depth using a motionless camera and an object of known height to calculate horizon line. ...
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1answer
610 views

Relative scale in SfM

I'm using monocular visual odometry. As in this case absolute scale can't be recovered, we rather compute relative scale for subsequent transformations as in this tutorial To do this, triple matches ...
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1answer
100 views

Best way to detect a range of key points in the image of a given cloth article

I am designing a robot which irons and folds clothes autonomously. For this purpose, I need the robot to detect a certain number of key points in a given cloth in order to execute a certain folding or ...
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1answer
4k views

normalized point coordinates in undistortPoints function

In undistortPoints function from OpenCV, the documentations says that http://docs.opencv.org/2.4/modules/imgproc/doc/geometric_transformations.html#undistortpoints where undistort() is an ...
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1answer
341 views

setup requirement of stereo camera

In the stereo camera system, two cameras are needed and should be mounted side by side. I see someone just glues two cameras to a wooden board. However one mobile phone manufacture claimed that the ...
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1answer
183 views

Google's 'Tango' - How it works and what's special about the hardware?

I'm looking for a good breakdown and explanation of Google's 'Tango' AR platform. Specifically how the hardware works together to generate depth maps and the SDK's use of it. I know the hardware ...
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1answer
55 views

Calculate Transformation between two point sets - but with constrained Degrees of Freedom

How can I calculate the rigid-body transformation [R|t] between two 3d triangles, but restricted to a given N degrees of freedom (for N = 1..6) ? I know for N=6 I can get a least-squares solution via ...
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1answer
444 views

detect post-it from an image of a visual management Board [closed]

'm trying to detect all the post-it in an image and get them into an arrayList. I tried many alternatives (removing backgroud -> detecting contours, haar Cascade classifier, detecting rectangular ...
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1answer
123 views

Pick and place using only vision information and forward kinematics [closed]

Is it possible to do pick and place tasks using only forward kinematics and object detection information from a camera? I want to avoid having to do inverse kinematic calculations for my robot. Is ...
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2answers
153 views

On-site waste-sorting robot feasibility and availability [closed]

I am thinking about a project at my university for doing on-site waste sorting. The problem with having one waste bin for recyclables, compost and landfill and doing the sorting at a facility, is that ...
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1answer
100 views

How do I get started in Computer Vision? [closed]

I want to know how to write and run the correct code. I understand that I need to download OpenCV (which I have), but when I try to compile sample code - for example, Blob Detection - it doesn't ...
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0answers
28 views

Number of pixels on an object [closed]

I want to find out how many pixels will cover a specific object in an image at a set distance. My plan is to use the known objects height and distance to calculate the angle it subtends from the ...
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0answers
14 views

3D real-world coordinates detection of an object using Multi camera set up

I have multiple cameras that are stationary and provide a view of a certain area, and I have an object that has some markers on it and I am able to detect it, I want to gather the data from the ...
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0answers
37 views

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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0answers
41 views

ROS2 Stereo View Fails And Stereo Image Proc Doesn't Show Anything

I have set up 2 Monocular Cameras as a stereo camera in ROS2. I successfully published the 2 rectified and calibrated images through the following formats: ...
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18 views

Semantic Segmentation vs Optical Flow Object Detection

Can anybody compare semantic segmentation against optical flow for pixel-level clustering and object detection?
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30 views

RGBD Camera Compatibility with ROS

I am looking for a good RGBD Camera that I want to use with ROS. Is there a way to know if a camera will work with ROS? Or is it that every camera is compatible with the usb_cam node? I want to send ...
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0answers
13 views

Understanding how the Kinect v1 works with Structured Light to compute disparity

I am reading this description here concerning calibration of the Kinect v1. I am trying to get an understanding of how it all works. From what I understand, the kinect has an near-infrared projector ...