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I have calibrated stereo cameras and got the extrinsic matrix. I know the Translation Vector 'T' between co-ordinate systems of the first and second camera. 

T: [ -35.831, 36.364,18.837]

How can I calculate the base line distance between the cameras.

Humam Helfawi
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MMH
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2 Answers2

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You can find the norm of the vector T by using Pythagorean theory. The following is an example from GCSE Bitesize:

Example

This cuboid has side lengths of 2cm, 3cm and 6cm.

Cuboid

Work out the length of the diagonal AF.

Solution

First use Pythagoras' theorem in triangle ABC to find length AC.

AC^2 = 6^2 + 2^2
AC = √40

You do not need to find the root as we will need to square it in the following step. Next we use Pythagoras' theorem in triangle ACF to find length AF.

AF^2 = AC^2 + CF^2
AF^2 = 40 + 3^2
AF = √49
AF = 7cm

Chris
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  • Sorry I can not relate your answer with my question. the cameras are in same line ,their optical axis are parallel so how do I form the above cuboid you mentioned? I am getting more confuse now...I am really sorry..but please explain you answer more clearly . Thanks. – MMH May 25 '12 at 08:38
  • I am assuming that camera 1 is located at (0, 0, 0), and that the translation vector you provided is the location of camera 2. Therefore the distance between the cameras is equal to the norm of the vector T, which can be calculated using Pythagoras. In the example given you would equate the point A to camera 1, and point F to camera 2, with your three coordinates of T the length of each side of the cuboid. – Chris May 25 '12 at 08:48
  • Thank you.This is my first time I am using Stereo Camera.So I don't had any idea. – MMH May 25 '12 at 09:00
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baseline is the norm of translation vector. as you told translation from camera1 to camera is T: [ -35.831, 36.364,18.837] then the baseline length is

baseline=sqrt(T(1)*T(1)+T(2)*T(2)+T(3)*T(3))

or briefly

baseline=norm(T)
M. Balcilar
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