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cvFindHomography

sarfraaz ahamed
Hi All,

Could you please expali how to use cvFindHomography?
It would be good if you can show me some example where cvFindHomography is used for somethin other than chessboard callibration. I have a object in the image like "L" with five specific markers in it. I need to calculate the translation and rotation matrix with respect to the camera. Could you suggest few ideas please?

I have added a sample image in

http://picasaweb.google.de/sarf123456/SamplePics#

Thanks in advance.

Regards
Sarfraaz

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Re: cvFindHomography

Walter Lucetti
Look at findobject.c example in OpenCV samples folder... it is the best
bay to understand it :)

Walter

sarfraaz ha scritto:

>  
>
> Hi All,
>
> Could you please expali how to use cvFindHomography?
> It would be good if you can show me some example where
> cvFindHomography is used for somethin other than chessboard
> callibration. I have a object in the image like "L" with five specific
> markers in it. I need to calculate the translation and rotation matrix
> with respect to the camera. Could you suggest few ideas please?
>
> I have added a sample image in
>
> http://picasaweb.google.de/sarf123456/SamplePics# 
> <http://picasaweb.google.de/sarf123456/SamplePics#>
>
> Thanks in advance.
>
> Regards
> Sarfraaz
>
>


[Non-text portions of this message have been removed]

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Re: cvFindHomography

sarfraaz ahamed
Hello,

I had a look in find_obj.cpp butin thet example we need to give two image inputs.

In mycase i just have the 2D projection of the image but i need to find the rotational and translational matrix from that. Please help me with this.

Thanks in advance.

Regards
Sarfraaz

--- In [hidden email], Walter Alex Lucetti <w.lucetti@...> wrote:

>
> Look at findobject.c example in OpenCV samples folder... it is the best
> bay to understand it :)
>
> Walter
>
> sarfraaz ha scritto:
> >  
> >
> > Hi All,
> >
> > Could you please expali how to use cvFindHomography?
> > It would be good if you can show me some example where
> > cvFindHomography is used for somethin other than chessboard
> > callibration. I have a object in the image like "L" with five specific
> > markers in it. I need to calculate the translation and rotation matrix
> > with respect to the camera. Could you suggest few ideas please?
> >
> > I have added a sample image in
> >
> > http://picasaweb.google.de/sarf123456/SamplePics# 
> > <http://picasaweb.google.de/sarf123456/SamplePics#>
> >
> > Thanks in advance.
> >
> > Regards
> > Sarfraaz
> >
> >
>
>
> [Non-text portions of this message have been removed]
>


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Re: Re: cvFindHomography

Samuel Audet
sarfraaz wrote:
> Hello,
>
> I had a look in find_obj.cpp butin thet example we need to give two image inputs.
>
> In mycase i just have the 2D projection of the image but i need to find the rotational and translational matrix from that. Please help me with this.

It's not part of OpenCV, but it's possible:
http://citeseer.ist.psu.edu/triggs98autocalibration.html

The paper includes a small snippet of MATLAB code for the difficult bit..

Samuel
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Re: Re: cvFindHomography

sarfraaz ahamed
The method uses more than five views,
but i have just one view.
would it be posssible to find the rotation and translation parameters??

2009/9/28 Samuel Audet <[hidden email]>

>
>
> sarfraaz wrote:
> > Hello,
> >
> > I had a look in find_obj.cpp butin thet example we need to give two image
> inputs.
> >
> > In mycase i just have the 2D projection of the image but i need to find
> the rotational and translational matrix from that. Please help me with this.
>
> It's not part of OpenCV, but it's possible:
> http://citeseer.ist.psu.edu/triggs98autocalibration.html
>
> The paper includes a small snippet of MATLAB code for the difficult bit..
>
> Samuel
>  
>


[Non-text portions of this message have been removed]

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Re: cvFindHomography

sarfraaz ahamed
In reply to this post by Samuel Audet
The method uses more than five views,
but i have just one view.
would it be posssible to find the rotation and translation parameters??


--- In [hidden email], Samuel Audet <samuel.audet@...> wrote:

>
> sarfraaz wrote:
> > Hello,
> >
> > I had a look in find_obj.cpp butin thet example we need to give two image inputs.
> >
> > In mycase i just have the 2D projection of the image but i need to find the rotational and translational matrix from that. Please help me with this.
>
> It's not part of OpenCV, but it's possible:
> http://citeseer.ist.psu.edu/triggs98autocalibration.html
>
> The paper includes a small snippet of MATLAB code for the difficult bit..
>
> Samuel
>


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Re: Re: cvFindHomography

Walter Lucetti
In reply to this post by sarfraaz ahamed
This could help:

http://webdiis.unizar.es/~csagues/publicaciones/05JRS-cp.pdf

sarfraaz ahamed ha scritto:

>  
>
> The method uses more than five views,
> but i have just one view.
> would it be posssible to find the rotation and translation parameters??
>
> 2009/9/28 Samuel Audet <[hidden email]
> <mailto:samuel.audet%40gmail.com>>
>
> >
> >
> > sarfraaz wrote:
> > > Hello,
> > >
> > > I had a look in find_obj.cpp butin thet example we need to give
> two image
> > inputs.
> > >
> > > In mycase i just have the 2D projection of the image but i need to
> find
> > the rotational and translational matrix from that. Please help me
> with this.
> >
> > It's not part of OpenCV, but it's possible:
> > http://citeseer.ist.psu.edu/triggs98autocalibration.html 
> <http://citeseer.ist.psu.edu/triggs98autocalibration.html>
> >
> > The paper includes a small snippet of MATLAB code for the difficult
> bit..
> >
> > Samuel
> >
> >
>
> [Non-text portions of this message have been removed]
>
>


[Non-text portions of this message have been removed]

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Re: Re: cvFindHomography

Samuel Audet
In reply to this post by sarfraaz ahamed
sarfraaz ahamed wrote:
> The method uses more than five views,
> but i have just one view.
> would it be posssible to find the rotation and translation parameters??

Yes, but only if your camera is already calibrated... read the paper!

Samuel

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