Questions tagged [camera]
Camera is a device that records and stores images.
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Python - CV, contour and measurements
I have small problem with cv in Python and rhombus. I can read frame from the camera and create contours...
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Image resolution vs. dimensions
Doing a machine learning computer vision project, and I am a bit unsure of the difference between image resolution and dimensions is, and how I should refer to them in writing. The images in my ...
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Detecting camera raw image saturation/clipping level
I'm looking for a fast but robust algorithm to detect whether a camera raw image has clipped/saturated highlights and, if so, compute the level at which saturation occurs. This saturation/clipping ...
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Why do my set of IR LEDS yield a purple-ish images on one camera sensor and greyscale on another?
I have a set of IR LEDS, and two different cameras. The resulting image from one of them is purple-ish, the other is grayscale when blocking all visible light with a thick plastic bag. Both cameras ...
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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, ...
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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&...
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Detecting bullet holes using Python with camera or sensors
I am trying to build a system to detect bullet holes in paper. I've read many StackOverflow threads but not a single one satisfied me. Current methods, which I am using, are good but not perfect and ...
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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 ...
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Convert pictures from the same camera with different FOV to pictures with same FOV
I have a camera device that produce two pictures at the time:
depth picture with FOV: 87° × 58°
RGB picture with FOV: 90 × 65°
I expect that they "share" the same objective so their origin ...
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Calibration using Camera Calibration Toolbox for Matlab vs OpenCV
I am currently working to calibrate a camera and I tried using both the Caltech Camera Calibration Toolbox for Matlab and OpenCV. I used the same images for both methods. Even if the error seems to ...
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How to remove dark shadows from camera capturing when combining LED spots and ambient light
I'm getting strange moving shadow strips on my camera capture during a computer vision experiment:
As the gif image above shows, those strips move to bottom slowly. I have also noticed that it ...
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Find camera tilt
If I have a camera that captures tilted images what is the way to find the tilt of the camera? Is there a pattern that I can photograph or something similar. I want to reduce the tilt as precisely as ...
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Is it worth recording 4K resolution from a 1080p camera input?
I work with this as a recording setup: Canon 5D3 into an ATEM MINI recorder into Ecamm Live (primarily for the sake of bypassing the 30 minute limit at present, not for live-streaming), but eventually ...
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Fisheye Lens Calibration for precision
OpenCV library offers a fisheye calibration method. I have looked at the code and looked at some papers and still don't understand how it works completely. The reason why I am interested is following:
...
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Find camera pose by knowing triangle coordinates
I have this concrete problem where I know the 3 coordinates of a triangle $ABC$ in a $xyz$ frame reference and I need to estimate the position $P$ and direction $\vec{n_{p}}$ of a stationary camera ...
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Projecting 3D point to 2D image coordinates
I am trying to replicate the projections of a 3D point to 2D using the pinhole camera model and the formula $x = K * [R|-RC] * X$, where $x = s\begin{bmatrix}
u\\
v\\
1
\end{bmatrix}$, $K$ is the ...
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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.
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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,...
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Why reprojection error is minimized instead of triangulation error for bundle adjustment?
For bundle adjustment optmization why is reprojection error minimized instead of traingulation error or ray-to-3d point error? Disadvantage with reprojection error is: for perspective camera, its ...
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Stereo triangulation similar triangle derivation
I understand that the similar triangles are the red and blue triangles. I'm trying to understand where $T + x_r - x_l$ comes from. I understand we are trying to compute the length of the base of the ...
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Response function for digital camera pixel
To help me with doing some signal processing on an image, I'd like to model how a digital camera works.
The camera has a bunch of pixels. What is the relationship between the value of that pixel in ...
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Virtual camera from panorama
I'm trying to virtualize a camera from a panorama.
That is, suppose I have a really big picture, for example: a soccer field.
Then I want to simulate a camera that focuses on certain regions of the ...
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Camera Calibration - why do you have to move the calibration board?
I understand the mathematical derivation of Zhang's Method for camera calibration but what I don't understand is why we need to move and rotate the calibration board for several frames in order to get ...
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Is it possible to generate depth map from graycode sequence without using printed calibration patterns?
In a camera-projector system, if only the camera's intrinsics are known, is it possible to generate the depthmap fully automatically through a graycode sequence without any manual calibration process (...
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API/ Library for re-orienting 360 degree camera frame efficiently
I am trying to correct the orientation of a 360 degree camera frame using roll, pitch and yaw estimates coming from my C++ Extended Kalman Filter (EKF) code. I am interested in using libraries and ...
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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 ...
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Is camera magnification a constant?
Magnification $M$ is defined as $\frac{-d_i}{d_o}$, where $d_i$ and $d_o$ denote the image distance and object distance, respectively. For a given camera, is the value $M$ typically the same for all ...
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computer vision - How to correctly calibrate my camera with a wide angle lens using openCV?
I am trying to calibrate a camera with a fisheye lens. I therefor used the fisheye lens module, but keep getting strange results no matter what distortion parameters I fix.
This is the input image I ...
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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 ...
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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 ...
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Near Infra-Red Cameras for Eye-Tracking
I am trying to investigate the use of NIR cameras in eye-tracking research e.g. the use of eye-tracking with infra-red glint (Purkinje Image). What I would like to know is what Make and Model of ...
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Why are two cameras mounted in paralle in stereo application?
For stereo cameras on the market, two cameras are always mounted side by side and with a displacement that is perpendicular to the cameras’ optical axes. I take this setup for granted. One idea came ...
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the position of image plane in optical imaging
In the book Learning OpenCV, there is one figure that show the image plane always is focal image.
The description of the figure from the book is as follow.
We begin by looking at the simplest model ...
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camera movement calculation
I'm trying to work out how to estimate camera movement between 2 equirectangular photos (static scenes indoor). Both photos are taken with the same camera (Ricoh Theta S) on the tripod. Height of the ...
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Why is my laser beam intensity profile not Gaussian?
I am kind of new to laser physics and signal processing, I hope I am in the right place to ask this question. I am also sorry for my not-great English.
I have been asked to study the transverse ...
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Hardware advice for machine vision project
I am working in facial feature detection in video images. I was hoping to get some general advice about camera/lens technologies to determine if I can upgrade my camera/lens.
Basically, the problem ...
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Oversampled Binary Image Sensor vs Active Pixel Sensor(CMOS)
I am a beginner in the field of Image processing. I was designing a camera sensor when I came across these two type of sensors:
CMOS (Active Pixel Sensor).
Oversampled Binary Image Sensor.
Now, I ...
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Estimate camera generalized velocity from consecutive frames
Let's suppose I have a camera which can move freely in 3D space and has 6 degrees of freedom. Is it possible to estimate the linear and angular velocity of the camera from 2 or more consecutive frames?...
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Capturing images on fast moving conveyor belt
This may or may not be an image processing problem.
I am developing a simple system that captures images of a part as they are being manufactured and sent out along the conveyor belt.
I've solved ...
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How to get an objects dimensions from video
I want to be able to measure an object using the camera on my phone. How would I go about getting an objects width and height from a video? My first thought was some type of 3D tracking of the video. ...
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Accurate measurement of object's position on a bayer-filtered and grayscaled images
This is an experience-related question about cameras and image processing.
I have a laboratory setup. Under some simplifications it looks like a red ball rolling on a white table (the real setup is ...
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Sampling rate: camera resolution when taking a photo of an LCD
Consider a digital camera that faces an LCD and that is perfectly focused on the LCD. The LCD shows an image of $n \times n$ pixels. What resolution does the camera have to have to perfectly capture ...
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Camera calibration vs. registration
Suppose I have two cameras, c1 and c2 that are securely installed and do not move. What I want is a matrix T, that takes a pixel of an image from camera c1 and calculates the according pixel in an ...
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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 ...
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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:
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Does the Quality of the Pictures Taken by a USB 3.0 Camera Depend on Cable Length?
I've got a JAI GO-5000-USB camera and have tried several cable lengths, ranging from 40cm to 5m.
So far, I haven't observed many differences in the quality of the pictures I've taken. Since I want ...
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Machine Vision - Infinity Focus effect
I am working on a research project that involves machine vision. The camera we are using implements infinite focus - I have been informed that this can affect the accuracy of computer vision ...
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Requirement on processor and memory for image processing
I'm designing a camera system to use a 5MP CMOS image sensor with a micro controller board. In order to select proper components I'm looking for some numbers. It would be very appreciated if you give ...
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How to Linearise an Input Image before applying Color Correction?
I'm doing color correction on Raw images taken from Camera directly. I want to make my Camera reproduce same colors as my Target camera.
Here are the steps I'm following:
Take Target Color values ...
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What are characteristics of shadows in an image given an outdoor setting from an image processing point of view?
I'm wondering what basic characteristics of shadows are. I'm looking from a camera image/video processing point of view. I'm considering the case of an outside scene in direct sunlight.
These are the ...
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