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I know there is some post talking about this topic but I could not find my answer.

I want to calibrate my android camera without chessboard for 3d reconstruction, so I need my intrinsic and extrinsic parameters.

My first goal is to extract the 3D real system to be able to put some 3d Model on screen.

My step :

  • From a picture of a building I extract 4 points that represent the real 3D system

  • /!\ this step require camera calibration /!\

    Convert them to 3d Point (solvePnP for exemple)

  • Then from my 3D Axis I create a OpenGL projection and modelview matrix

My main problem is that I want to avoid a calibration step, so how can calibrate without chessboard? I have some data from android such as focal length. I can guess that the projection center is the center of my camera picture.

Any idea or advice? or other way to do it ?

kakou
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  • You could improve your question by writing what have you tried, what have you read. – Rui Marques Sep 13 '13 at 08:58
  • I'm working on this but some difficulties to understand http://www.cs.unc.edu/~marc/pubs/PollefeysIJCV04.pdf – kakou Sep 13 '13 at 10:10
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    Yes it is a hard topic but the article you have pointed is the right direction. Look for more resources about Structure from motion. – Rui Marques Sep 13 '13 at 13:11

1 Answers1

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here is nochess calibation of qtcalib.

This scheme is recomended when you need obtain a camera calibration from a image that don't have calibration chessboard. In this case, you can approximate the camera calibration if you know 4 points in the image forming a flat rectangle in real world. Is important to remark that the aproximated calibration depends on the 4 selected points and the values that you will set for the dimensions of the rectangle

plan9assembler
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  • if I calib my an nexus 4 camera and get distorsion, skew factor and focal length, can I assume that all nexus4 camera hve the same value ? – kakou Sep 16 '13 at 09:52
  • No, not you cannot assume that. In general, if you want proper camera calibration you have to use a camera that cannot change the focus. Furthermore, the cameras of such mobile devices are usually not even suitable for static camera calibration, i.e., if you calibrate your Nexus 4 camera it does not guarantee that it is calibrated after using it for a while. – who9vy Oct 09 '13 at 20:48
  • To be honest even though what the QtCalib offers seems to be working this is quite a task with all the parameters that the user has to enter some of which (example: dimensions of the plane) are quite difficult to extract with high enough accuracy (depends on the task at hand of course). – rbaleksandar Oct 25 '14 at 15:02
  • i have question now, i have a line with two point, after calibration by your library, i want to know where is my Line points location now ? how i calculate new point ? because i want two determine size of that line after calibrate, please help me to know whats formula to calculate : (Xnew,Ynew)= Function(Kc,Rc,Tc) – Rashed DIP Jul 28 '18 at 09:30