Questions tagged [camera]

Camera is a device that records and stores images.

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1 answer
37 views

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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1 vote
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31 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, ...
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2 answers
40 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&...
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3 votes
2 answers
415 views

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 ...
1 vote
0 answers
34 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 ...
1 vote
0 answers
89 views

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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2 answers
331 views

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 ...
1 vote
1 answer
217 views

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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56 views

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 ...
0 votes
1 answer
147 views

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 ...
1 vote
0 answers
145 views

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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1 answer
146 views

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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1 vote
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177 views

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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1 answer
112 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. ...
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1 answer
252 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,...
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-1 votes
1 answer
214 views

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 ...
2 votes
1 answer
242 views

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 ...
1 vote
1 answer
77 views

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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1 vote
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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 ...
0 votes
3 answers
691 views

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 ...
0 votes
1 answer
320 views

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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1 vote
2 answers
6k 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 ...
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1 vote
1 answer
40 views

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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1 answer
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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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1 answer
248 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
744 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 ...
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1 vote
1 answer
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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 ...
0 votes
1 answer
481 views

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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1 answer
2k views

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 ...
0 votes
1 answer
423 views

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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2 votes
3 answers
648 views

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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1 answer
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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 ...
1 vote
2 answers
531 views

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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1 vote
2 answers
304 views

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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2 answers
2k views

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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1 vote
0 answers
43 views

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. ...
1 vote
1 answer
40 views

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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0 answers
628 views

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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1 vote
1 answer
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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 ...
4 votes
2 answers
2k 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 ...
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2 votes
2 answers
5k 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: ...
7 votes
1 answer
106 views

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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1 answer
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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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1 answer
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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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5 votes
7 answers
15k views

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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3 votes
0 answers
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Horizontal banding (flickering) due to electronic rolling shutters

It is a well-known artifact that in CMOS cameras with electronic rolling shutter, horizontal banding (flickering), i.e. brightness intensity variations, are observed when the image is recorded under ...
1 vote
2 answers
169 views

How does 3D Time-of-Flight (TOF) camera work?

This is my first post in this forum! So Point me if anything is not clear! I want to know how TOF camera works? So I've done Google & read some nice explanation about How Phase difference between ...
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2 votes
3 answers
278 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 ...
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