6
votes
Which is the best visual fiducial marker (2D barcode)?
AprilTag is the state-of-the-art solution for pose estimation. The library itself already has pre-built functions to compute the marker position, given its size. The pose is estimated by homography ...
- 161
4
votes
Accepted
Determine the relative camera pose given two RGB camera frames in openCV-python
If you understand how relative pose estimation works in theory, it should be quite trivial to translate it into OpenCV code. First, you can pick any feature detection/description approach you like (...
- 1,086
4
votes
Accepted
Robotic Hand Grasp Planning - How do I find the initial contact point for each finger when grasping an object?
This is an excellent question that is currently being explored directly by field experts. Here are some of the latest publications that consider the problem you are encountering:
Robotic Grasping of ...
- 483
4
votes
Accepted
Visual-Positioning Method
So it sounds like you have an external camera system to track the end effector position and orientation?
In that case I would use QR codes or april tags. Stick a couple of these on your end effector, ...
- 1,721
4
votes
Accepted
Does a stable library exist for docking robots using images?
There's a lot of solutions out there already for this. I'll start by suggesting AR tags not QR tags. They're better optimized for localizing.
The Alvar library is commonly used for tracking AR tags.
...
- 1,767
3
votes
what's confidence level? and how can we use it for vehicle detection using OpenCV?
Statistical confidence is most often defined in terms of a score that is the number of standard deviations away from the mean.
Now let's say you have a set of states (a state vector) used to define ...
- 1,377
3
votes
Accepted
Algorithm for centering an object that is changing speed
It seems that your algorithm that controls the speed of your telescope does not make use of any integral part, thus you've been observing drifts while tracking.
Let $e_x$ be the error in the image ...
- 3,985
3
votes
Stereo Camera calibration with different camera types
It looks like what I saw when a colleague of mine was working with fisheye lenses; I found this post after doing an image search for "rectify fisheye image" and following the link from this picture.
...
- 15.8k
3
votes
Accepted
Real-time object classification for an indoor autonomous quad-rotor
tl;dr - SLAM is good enough for your task.
The ceiling is the area where your robot will be traveling in. Few things to notice -
Ceiling is fixed and not changing.
Things on the ceiling are fixed as ...
- 421
2
votes
Accepted
Stereo Vision Using Compute Module: Pi camera synchronization
You need real camera synchronization which means using cameras that both have external trigger capability (it is like the "remote shutter" on consumer/DSLRs). What you do is feed a common trigger ...
- 633
2
votes
How to check lane departure in OpenCV?
One of the best ways is to use a combination of hough-transform (what you have achieved is nice) and inverse perspective transform (as in http://www.vision.caltech.edu/malaa/publications/aly08realtime....
2
votes
Image registration with ground plane for surround view
I don't know what the proper way to do this is but I can give you ideas to make it better:
define an exact transformation for each camera. You could calibrate each camera using a grid pattern and by ...
- 571
2
votes
Converting Image Coordinates to (x, y) Position for Robotic Arm
A quite simple math is involved in this task, but you need to be aware of the pinhole camera model as well as of the homographic projection.
The pinhole camera model gives you the 3D position $(x,y,z)...
- 3,985
2
votes
Accepted
OpenCV get topdown view of planar pattern by using intrinsic and extrinsic from cameraCalibrate
Added
OK, guys, simple mistake. I previously used warpPerspective to warp images instead of restoring. Since it works that way, I didn't read the doc thoroughly. It turns out that if it is for ...
- 51
2
votes
Trigger two usb cameras at the same time
As you say, you can't trigger them at the exact same time without hardware capable of doing so. Some IMU's supply an external trigger pin, and I see no reason why you couldn't buy cameras that have a ...
- 151
2
votes
Reflective surface
Reducing reflection on an image is hard, really hard, because you only have the pixels, and they are most likely white.
So changing the environment to get good images is the desired solution.
Robotiq ...
- 21
1
vote
Make robot drive as far from obstacles as possible
Some hints:
Use Minskowski sums to "grow" the obstacles taking into account the shape/orientation of the robot.
Not easy to understand and implement, BUT already implemented in geometrical algorithm ...
- 311
1
vote
Algorithm for centering an object that is changing speed
The description of the problem fits great to a technique which is called model predictive control. It can solve the problem of tracking an object with a telescope on a mathematical satisfying way. The ...
- 794
1
vote
Algorithm for centering an object that is changing speed
Thanks for the replies. I figured out to make it work. I divided the image into different regions using horizontal lines. Then, I have a timer in C# that every x milliseconds figures out which region ...
- 23
1
vote
Image data fusion
What do you mean by data fusion
Here's some definitions I can think of:
Determine from the features in the scene the positions of the camera
Determine from the positions of the camera the geometry ...
- 5,292
1
vote
Fixing robot orientation using AR
I recommend using april tags. They are similar to qr codes but were specifically designed with robotics in mind. There is a library on the april tag website. The library can be used to solve for the ...
- 1,833
1
vote
Accepted
How to tringulate many projections of a point to optimal postion?
I will assume, similar to OpenCV, that each camera is a pinhole camera, so you already corrected for things like lens distortion. In this case each visible point in 3D space $(x,y,z)$ gets projected ...
- 941
1
vote
Pictures coordinates to robot coordinates
First note that for px =250 (picture x) you get two different table values tx=0 and tx=2098, then for a difference of 1 unit in px you get a difference of around 2000 in tx (table x). From that it ...
- 1,402
1
vote
Scan an Auditorium, Count People, and Display Open Seats
A Near-IR or IR camera which can rotate and tilt, that is installed over the stage would probably be an acceptable and fairly well performing solution.
Installation would be simple: screw on, and ...
- 411
1
vote
normalized point coordinates in undistortPoints function
http://docs.opencv.org/2.4/modules/calib3d/doc/camera_calibration_and_3d_reconstruction.html, this link maybe helpful. Here is my answer based on that.
1.What does normalized point coordinates means?
...
- 111
1
vote
Scale problem with monocular visual odometry
processing 1st vs 10th image and 9th vs 10th image - will the fist give 10x relative scale than the second?
It depends. In the simplest perspective, 'relative' means what the transformation is from ...
- 1,086
1
vote
Accepted
Google's 'Tango' - How it works and what's special about the hardware?
I suspect, but don't know, that the Tango uses a variant of volumetric reconstruction using a Truncated Signed Distance Function (Good intro at http://www.cs.nyu.edu/courses/fall12/CSCI-GA.2945-001/dl/...
- 26
1
vote
detect post-it from an image of a visual management Board
As HighVoltage already suggested this should be an easy task using the HSV spectrum.
Your code could look something like this:
...
- 37
1
vote
Stereo Camera calibration with different camera types
Maybe you should rectify the wide-angle camera images with cv::fisheye::stereoRectify, which outputs a pair of undistort images with aligned epipolar lines.
- 11
1
vote
Save Depth Map Video
If you search a bit you'll find others have all done variations on this approach.
- 4,335
Only top scored, non community-wiki answers of a minimum length are eligible