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jenny_wui

Member Since 12 Jan 2013
Offline Last Active Jul 01 2014 06:44 PM

Posts I've Made

In Topic: Some clarification about inversing rotation only around particular axes

01 July 2014 - 06:44 PM

Thanks for the suggestion and sorry for my poor knowledge. Actually I again want to write down some observation. As I said I have an opencv matrix. I would like to convert it to OpenGL matrix. As opencv is row-major, in opengl, I need to store in column-major order. I did that.

Next, Opencv y and z axis need to be reversed too. In order to get back the proper-oriented matrix in OpenGL, I multiplied the matrix with the following unit matrix:

|1 0 0 0|
|0 -1 0 0|
|0 0 -1 0|
|0 0 0 1|

I get the matrix with proper orientation ( I assume), but still with y and z axis vectors reversed. I know if I just inverse the sign of y and z-axis vectors, it will give me the desired result.

My question, what is the standard step of converting an opencv matrix to opengl matrix.
If anyone has done similar work, please let me know.

In Topic: Some clarification about inversing rotation only around particular axes

30 June 2014 - 06:38 PM

Thank you. I am trying to rotate an object by multiplying with a rotation matrix, but can't find it get right. That's why I was asking whether there is any difference getting transformation from basis vectors.

Actually I have opencv rotation matrix which I need to use for my OpenGL programming.I swapped the rows for columns to get rotation matrix to be used for OpenGL. Now I find the rotation around x axis is inversed. How can I make it correct? I know it is possible to make it correct by manipulating the basis vectors, but I need to know where I am wrong. Please let me know.

How to get the correct rotation matrix from OpenCV to OpenGL? I have posted this topic before but without any clarification.

Please shed some light if you have answer.

In Topic: Some clarification about inversing rotation only around particular axes

30 June 2014 - 01:05 PM

Hello, I would like to know is it possible to get the transformation matrix from a given x, y and z-axis basis vectors. Thanks

In Topic: Some clarification about inversing rotation only around particular axes

29 June 2014 - 10:04 PM

Thanks for the reply. I understand you are suggesting to decompose the matrix and then negate the corresponding rotation angle and again build the matrix. Is there any way to get that by multiplying the unit reflection matrix?

Thanks again in advance.

In Topic: Some question about transformation

10 April 2014 - 04:22 PM

Thank you very much for the reply Crossbones. I tried with changing the eye position calculated from rotation vector but don't understand why it is not working. I would like to use OpenGL. Could you provide any related examples? Also could be a more elaborate on how to change gluLookAt function?
Thanks again.

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