All Questions
Tagged with computer-vision camera-calibration
37
questions
2
votes
2
answers
168
views
Camera sensor artifacts next to edges in calibration images; what is causing these?
I am trying to image some ChArUco targets using a monochrome machine vision camera with a CMOS sensor and the attached images show the artifact I am observing:
2-pixel-wide bright vertical streaks ...
- 41
1
vote
1
answer
74
views
Projection Matrix -- where does it come from?
I've started with these series to teach myself image processing and I am wondering when the camera's projection matrix (i.e. intrinsic and extrinsic matrices) is calculated?
Is camera calibration a ...
- 113
1
vote
0
answers
130
views
calibrating camera using 3d objects such as rubik's cube?
Hello all hope everyone is doing fine.
I have a vision related problem where I want to calibrate my camera using a 3d object such as rubik's cube with known dimensions. I have a cube with 60mm length, ...
- 11
0
votes
2
answers
55
views
Fixing distortion in photographic reproductions
I am currently building a photographic setup which I intend to use to make reproductions of a large amount of transparencies(positive and negative film strips). As I will be using a fairly small (1&...
- 103
1
vote
0
answers
70
views
How is focal length estimated?
There are a number of approaches to calibrate cameras. In this process you estimate the intrinsic parameters using a checkerboard of known size.
I'm confused on how the focal lengths are found. The ...
- 854
3
votes
0
answers
892
views
Reprojecting an image to another viewpoint using planar homography
I have an image rendered by a simulated camera in Unity. Using this image and the known (virtual) camera pose it corresponds to, I would like to render a new image from another viewpoint. Having read ...
- 429
-1
votes
1
answer
41
views
Best targets to calibrate camera with long focusing distance
I am currently using a number of cameras with long focusing distance, i.e. >3m, and I want to calibrate them to find the intrinsic matrix.
My problem is that if I want to cover all or most of the ...
- 111
2
votes
1
answer
1k
views
How to apply rotation to extrinsic and intrinsic camera parameters post-calibration?
I currently have a set of intrinsic / extrinsic camera parameters, and am using them to project 3D world coordinates to the 2D image, using projection matrix $P = K[R | t]$.
My problem is that this ...
- 31
0
votes
0
answers
47
views
Equation of line in the Homogeneous coordinate system
Given two points P and Q we can convert them to the homogeneous coordinate system, compute their cross product and thus get the ...
- 167
0
votes
1
answer
108
views
How to calculate the plane at infinity? either in Matlab or Python
I tried to implement this function to compute the plane at infinity $n_\Pi$ from the equation:
where $w^{-1}$ is the image of the absolute conic IAC, $M_j$ is the Projection Matrix of image $j$,
but ...
- 167
0
votes
1
answer
169
views
Understanding legacy code: Algorithm to remove radial lens distortion
The method below to remove lens distortion from a camera was written more than ten years ago and I am trying to understand how the approximation works.
...
0
votes
1
answer
38
views
How can I infer the cost function from Kruppa's simplified equations
The following equations are Kruppa's simplified equations used in camera autocalibration. My objective here is to infer the cost function(Error Function) from this equations, So I can minimize the ...
- 167
0
votes
1
answer
518
views
Camera Pose Estimation from Vanishing Points
I want to estimate the pose of camera (Location and Orientation). Can I use Vanishing Points to get the location and orientation of the camera?
There is object in the image which I also know his size,...
- 3
2
votes
1
answer
507
views
What are the parameters of a calibrated spherical camera?
I'm aware if we have a pinhole camera model several parameters describe the specific camera (such as aspect-ratio, focal length, principal point, distortion parameters etc).
There're standard ...
- 425
1
vote
2
answers
8k
views
Camera calibration and extrinsic parameters for perspective transformation
I'm working in a photogrammetry camera and laser application where I need to measure a displacement in a specific plane, this is a quick diagram of the setup:
In order to get proper measurements I'm ...
- 137
0
votes
1
answer
323
views
Pinhole camera model from houdini parameters
From a simulation with Houdini software I retrieved these parameters:
Camera position: -0.675839, 33.5945, 0.0318854
Camera Rotation: 0.0318854, 92.4693, 0.1
Focal Length: 52.5172 mm
Image size: 1920 ...
3
votes
0
answers
814
views
Correct Fish Eye camera Radial Distortion and blurry effect at the image edges
There are a lot of questions regarding this topic ,but I am trying to get a more clear picture from these questions.
I am trying to calibrate a fish eye camera and I am using OpenCV omnidir class ...
- 131
0
votes
1
answer
124
views
Estimating exterior camera parameters by matching lines using least square estimations (Lowe, 1991)
I'm new to computer vision and graphics. I want to estimate exterior camera parameters using non-linear least square estimation as suggested by "Lowe, David G. "Fitting parameterized three-dimensional ...
- 103
0
votes
2
answers
1k
views
How can we combine 2D image with 3D image for the same sense?
We have 3D point cloud data captured by a laser scanner and need to register it with 2D images to get further information. In our case, the 2D image and 3D points are not overlapping and therefore we ...
- 185
1
vote
0
answers
140
views
Extrinsic Camera Parameters without introducing control points?
I am new to the field of Camera Calibration. We have successfully calibrated our camera through classic method (using checkerboard etc).
I recently realized there is a field of research for Automatic ...
- 1,976
3
votes
1
answer
265
views
How should calibration points be distributed?
I do camera calibration for a single camera with a chessboard pattern in opencv for the first time.
The focus is fixed.
I'm not sure how to do it, there seems to be many questions:
How many images ...
- 252
-1
votes
1
answer
159
views
camera calibration change orientation of axis
I want to solve for the extrinsics by using direct linear transformation on corresponding 3D LIDAR points and 2D camera points. I already have the intrinsics.
Problem is, points behind the camera ...
6
votes
1
answer
3k
views
How are the scaling parameters included (extracted from) an essential matrix?
An essential matrix relates corresponding points between two images assuming that a camera satisfies the pinhole camera model, and can be expressed as:
$$E=K'^TFK$$
where K is the calibration and F ...
user17348
5
votes
1
answer
2k
views
Obtain motion between image features by means of the homography matrix
I have been reading several really good answers about how to obtain camera pose (rotation, translation, etc), such as this one and this one, but I am not sure how this applies to my problem.
My ...
user17348
4
votes
2
answers
8k
views
camera calibration: why chessboards?
Chessboards are very frequently used for camera calibration, this website also talks a bit about why: wiki. One of the reasons is, that chessboards define many natural interest points.
Now my (very ...
- 183
5
votes
2
answers
3k
views
How to estimate radial distortion from lens characteristics?
Is there a way to estimate the radial distortion coefficients without calibration, given the lens characteristics, such as its diameter and its focal length?
Typically for camera calibration a ...
- 5,101
1
vote
2
answers
3k
views
How to find the actual size of an existing object from the pixels of an image?
I am quite new to vision and OpenCV, so forgive me if this is a stupid question but I have got really confused.
My aim is to detect an object in an image and estimate its actual size. Assume for now ...
- 111
3
votes
2
answers
6k
views
Camera calibration using multiple images
I am trying to get the hang of camera calibration. For this purpose, I have mainly watched this lecture on youtube: Lecture 12: Camera Model by UCF CRCV. I believe that I understood the main ideas:
...
- 183
1
vote
2
answers
156
views
Pinhole calibration
This is a conceptual question I am having difficulty to understand due to my limited knowledge of computer vision: If a pinhole calibration or any calibration is a mapping from world coordinates to ...
- 13
9
votes
1
answer
3k
views
Is it possible to hack camera calibration without having access to the camera?
Many times we have a stream of video to process without access to camera. Having access to camera matrix would be beneficial for various processing techniques. Is it possible to hack camera ...
- 170
1
vote
1
answer
381
views
Does accurate translation estimation using a camera matrix mean the orientation estimation will also be accurate?
Pose Estimation of single camera and planar pattern:
If I have an appropriate camera matrix with intrinsic parameters that allows me to calculate translation of the camera relative to a chessboard, ...
- 91
2
votes
3
answers
346
views
Can you average out focal length from different camera calibration sessions?
If I perform a number of camera calibration routines at a fixed resolution, with various sizes of calibration patterns (like checkerboards), at various distances and get various values for focal ...
- 91
1
vote
1
answer
1k
views
How does chessboard configuration affect camera calibration?
When calibrating a camera with a chessboard, are more squares better or worse? When would you use more or less? And how does the size of the blocks effect the calibration results?
- 91
2
votes
4
answers
1k
views
Camera Calibration using Single Input Image
Given a camera, permanently located at the same position, angle and distance from what is being captured, and a single calibration image ( a row of vertical lines [ | | | | ] ), how would one go about ...
- 21
2
votes
1
answer
1k
views
How to warp a pixel patch to another camera
I have two cameras with rotation and translation starting from the world origin and a patch in the first camera's reference coordinate system. I want to warp this patch into the second camera's ...
- 247
1
vote
1
answer
195
views
(Rough) camera calibration of manipulated images
Coming from a photogrammetry background, I am quite familiar with camera calibration, and the common assumptions that are used for crowd-sourced images (i.e. center point in the middle of the image, ...
- 243
1
vote
1
answer
336
views
create a Calibration Board [closed]
How could I know the best size of the board for my camera?
My camera is Canon D-100 It's 18 megapix
I have created a board consist of 14*10 squares
the length of each square is 7*7cm
I need to know ...
- 11