Questions tagged [camera]

Camera is a device that records and stores images.

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7 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 ...
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1answer
27 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 ...
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Reading specs of a depth camera

This question might sound stupid. I need to know the specs of the following: https://ark.intel.com/content/www/us/en/ark/products/128255/intel-realsense-depth-camera-d435.html More specifically: ...
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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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35 views

Camera obstruction detection

I'd like to detect if camera view is obstructed (fully or partially) by some object (paper, hand, some device, etc). Do you know any good methods for this task? I've already experimented with: RGB ...
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Converting from 2D coordinates in image plane to 3D, use of focal length in gnomonic projection

I'm currently using libgnomonic to perform a gnonominc projection. I cannot find a derivation of the used formulas. But they don't seem to be particularly involved and there's a specific bit I'd like ...
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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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8 views

Efficient way to compute how much light is present in a scene (for camera focusing)

I'm developing somewhat of a camera app and need a way to compute how much light is present in a specific scene to know how to adjust the exposure and iso level so that the focused point will detailed ...
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2answers
92 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 ...
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1answer
155 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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115 views

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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2answers
2k 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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1answer
31 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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1answer
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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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1answer
124 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 ...
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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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1answer
51 views

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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1answer
158 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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1answer
908 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 ...
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1answer
251 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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3answers
348 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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1answer
75 views

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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2answers
336 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 can ...
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2answers
260 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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2answers
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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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28 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. ...
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1answer
38 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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554 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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1answer
590 views

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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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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3k 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: ...
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1answer
60 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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1answer
124 views

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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650 views

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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1answer
200 views

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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7answers
11k 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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7k views

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 ...
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2answers
152 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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3answers
156 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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2answers
58 views

Changing camera and image properties to calibrate a camera

Is it OK to calibrate a camera using effects and filters such as increasing contrast and brightness etc. to improve the detection of corners of a chessboard? Even if the used mode for detecting the ...
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0answers
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Looking to understand line artifacts in “overscanned” image

Essentially I'm looking for an explanation how the second image results from a capture of the original. Possibly you've seen something like this before and you can tell just from looking at the result ...
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1answer
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Image processing and Camera Calibration

I have several related questions about camera resolutions. If I calibrate my camera to a particular resolution say 640x360, can I use it for another resolution like 1024x768? Also, I want to know as ...
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1answer
144 views

How to unify the color and brightness measure of two given camera?

I have two cameras, and I'm up to perform some matching stuff on videos captured by these two cameras since I'm a CV guy. The problem is the two cameras have very different performance in terms of ...
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1answer
1k views

AutoExposure with nonlinear camera: Non linear proportional PID?

Now I', wondering how to best implement a control algorithm for it. I tried using a PID controler but started with a simple P-control first. The problem is, that when using the equation ...
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1answer
525 views

Histogram evaluation for image quality concerning illumination

I'm currently trying to develop an algorithm to control the camera characteristic of a camera (the camera characteristic can be controlled to adopt it to the different lightning situation which can ...
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1answer
131 views

camera motion detection

I am working on camera motion detection.How do I decouple translation and rotation? I have obtained rotation by using sensors. I understand we can do something as simple as X'=RX+T , where R-rotation, ...
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1answer
72 views

Is gamma correction applied in my setup

I am working on a scientific application where I would like to evaluate luminance in an image, however I am unsure if what I receive from my setup is luminance (Y) or luma (Y'). I use a camera with a ...
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1answer
601 views

Are there characteristics of photographic film that would make it an analog medium?

There was an article a few years ago entitled "Analog is Not the Opposite of Digital". Film is not analog, period. I used to shoot film on a Canon AE-1 from the ’70s. Now I have a digital SLR from ...
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11k views

How does resizing an image affect the intrinsic camera matrix?

I have a camera matrix (I know both intrinsic and extrinsic parameters) known for image of size HxW. (I use this matrix for some calculations I need). I want to use a smaller image, say: $\frac{H}{2}\...
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1answer
5k views

FPS to Hertz in a camera

Not sure if this is the proper place to ask this, but I'm sure someone here will know the answer. I have this optical camera (TrackIR 4), which, for what you can see on the table, samples images at a ...