Take the 2-minute tour ×
Signal Processing Stack Exchange is a question and answer site for practitioners of the art and science of signal, image and video processing. It's 100% free, no registration required.

this post also contributes to the post at Step by Step Camera Pose Estimation for Visual Tracking and Planar Markers by Jav_Rock (since I cannot add any comment there and I don't know why)

It can be seen that the translation vector 1x3 and rotation matrix 3x3 can be derived from homography matrix. However, the following question is: - where are the camera coordinate system and object coordinate system and how are they attached to the camera (or object)?? - there is the relative transformation between the two but the computation from homography or transformation matrix implies nothing about these coordinate systems' location & direction

Then, how to solve the pose estimation problem??

share|improve this question

1 Answer 1

The coordinate system you choose is completely arbitrary, as no information about real-world coordinates can be inferred. From an image of a table there is no reason to know that one leg is located at any particular $(X, Y, Z)$, or that it is any particular size (you can't tell if it's a doll's table or a giant's table).

Normally you would choose one of your cameras to be located at the origin, looking down the $z$ axis, defined by the matrix:

$$[R|t] = \begin{bmatrix} 1&0&0&0 \\ 0&1&0&0 \\ 0&0&1&0 \end{bmatrix}$$

Then due to the scale ambiguity you would have to choose an arbitrary scale, for example if you are using a stereo camera you could set the distance between the cameras to be one unit distance.

share|improve this answer
    
I would not agree with the idea: from 1 image, pose cannot be derived. According to Zhang's method as I mentioned, the unknown pose & depth problem can be solved. The fact is, in his computation, the camera matrix is included as an additional information –  Son Le Aug 28 '12 at 10:50

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.