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Questions tagged [camera-calibration]

In Computer Vision, camera-calibration is the process of finding the true parameters of the camera that produced a given photograph or video. Usually, the camera parameters are represented in a 3 × 4 matrix called the camera matrix.

Usually we say a camera is calibrated when we know the Intrinsic Parameters.

Source: Wikipedia

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Computing x,y coordinate (3D) from image point

I have a task to locate an object in 3D coordinate system. Since I have to get almost exact X and Y coordinate, I decided to track one color marker with known Z coordinate that will be placed on the top of the moving object, like the orange ball in…
Banana
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How to verify the correctness of calibration of a webcam?

I am totally new to camera calibration techniques... I am using OpenCV chessboard technique... I am using a webcam from Quantum... Here are my observations and steps.. I have kept each chess square side = 3.5 cm. It is a 7 x 5 chessboard with 6 x 4…
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OpenCV 3.0: Calibration not fitting as expected

I'm getting results I don't expect when I use OpenCV 3.0 calibrateCamera. Here is my algorithm: Load in 30 image points Load in 30 corresponding world points (coplanar in this case) Use points to calibrate the camera, just for…
timbo
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Get 3D coordinates from 2D image pixel if extrinsic and intrinsic parameters are known

I am doing camera calibration from tsai algo. I got intrensic and extrinsic matrix, but how can I reconstruct the 3D coordinates from that inormation? 1) I can use Gaussian Elimination for find X,Y,Z,W and then points will be X/W , Y/W , Z/W as…
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Why does the focal length in the camera intrinsics matrix have two dimensions?

In the pinhole camera model there is only one focal length which is between the principal point and the camera center. However, after calculating the camera's intrinsic parameters, the matrix contains (fx, 0, offsetx, 0, 0, fy, offsety, 0, …
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Python How to detect vertical and horizontal lines in an image with HoughLines with OpenCV?

I m trying to obtain a threshold of the calibration chessboard. I cant detect directly the chessboard corners as there is some dust as i observe a micro chessboard. I try several methods and HoughLinesP seems to be the easiest approach. But the…
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What are the main references to the fish-eye camera model in OpenCV3.0.0dev?

I am wrestling with the Fish-Eye Camera Model used in OpenCV 3.0.0.dev. I have read the documentation in this link several times, especially the "Detailed Description" part and formulas modeling fish-eye distortion. By now I have two concerns:…
masih
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Does a smaller reprojection error always means better calibration?

During camera calibration, the usual advice is to use many images (>10) with variations in pose, depth, etc. However I notice that usually the fewer images I use, the smaller the reprojection error. For example with 27 images, cv::calibrateCamera…
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OpenCV: solvePnP detection problems

I've got problem with precise detection of markers using OpenCV. I've recorded video presenting that issue: http://youtu.be/IeSSW4MdyfU As you see I'm markers that I'm detecting are slightly moved at some camera angles. I've read on the web that…
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How to understand the KITTI camera calibration files?

I am working on the KITTI dataset. I have downloaded the object dataset (left and right) and camera calibration matrices of the object set. I want to use the stereo information. But I don't know how to obtain the Intrinsic Matrix and R|T Matrix of…
Yao Liu
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FindChessboardCorners cannot detect chessboard on very large images by long focal length lens

I can use FindChessboardCorners functions for images that less than 15 Mega pixel such like 2k x 1.5k. however when I use it on the image from DSLR, the resolution at 3700x5300, it doesn't work. I tried to use resize() to reduce the image size…
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Calibrating Webcam using Python and OpenCV Error

Pretty new to all this and I'm trying to do the calibration for a Webcam following this guide and using the code below. I get the following error .. OpenCV Error: Assertion failed (ni > 0 && ni == ni1) in collectCalibrationData, file…
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Python Opencv SolvePnP yields wrong translation vector

I am attempting to calibrate and find the location and rotation of a single virtual camera in Blender 3d using homography. I am using Blender so that I can double check my results before I move on to the real world where that is more difficult. I…
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finding the real world coordinates of an image point

I am searching lots of resources on internet for many days but i couldnt solve the problem. I have a project in which i am supposed to detect the position of a circular object on a plane. Since on a plane, all i need is x and y position (not z) For…
user3417020
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findChessboardCorners fails for calibration image

I am trying to get OpenCV 2.4.5 to recognize a checkerboard pattern from my webcam. I couldn't get that working, so I decided to try to get it working just using a "perfect" image: but it still won't work--patternFound returns false every time.…
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