## A4 - Problem 3 - eightpoint algorithm

Moderator: Computer Vision

robert.n
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### A4 - Problem 3 - eightpoint algorithm

I have a problem implementing the eightpoint algorithm.

My $$V_A^T$$ has only 8 entries. However, on slide 36 nine entries are referenced when the matrix $$\tilde{F}$$ ("F tilde") is built (l10-twoview-v1.pdf).

tanne
Endlosschleifenbastler
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### Re: A4 - Problem 3 - eightpoint algorithm

sounds like your created equationsystem is wrong, e.g. the matrix you use with svd.

robert.n
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Registriert: 29. Sep 2008 19:17

### Re: A4 - Problem 3 - eightpoint algorithm

I didn't stack the equations (each vector corresponds to one row), instead I used the vectors as columns of my matrix. Apparently I got confused by the wikipedia article. (They use the vectors as columns.)

Fundamental matrix still does not seem to be correct, though.

//EDIT:
I got confused by Matlab's transpose operator, while reading the slides. -.- I noticed that earlier, actually, and fixed my code almost completely. But only a few minutes ago I noticed that I missed something: T and T' are two entirely different matrices, too! Arggghhh... me dumbass... gah

tanne
Endlosschleifenbastler
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Registriert: 30. Sep 2008 16:05

### Re: A4 - Problem 3 - eightpoint algorithm

robert.n hat geschrieben: //EDIT:
I got confused by Matlab's transpose operator, while reading the slides. -.- I noticed that earlier, actually, and fixed my code almost completely. But only a few minutes ago I noticed that I missed something: T and T' are two entirely different matrices, too! Arggghhh... me dumbass... gah
yeah right, i was confused by the notation too. you have one T matrix for each set of points.

qgao
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Registriert: 7. Apr 2009 11:38

### Re: A4 - Problem 3 - eightpoint algorithm

robert.n hat geschrieben:My $$V_A^T$$ has only 8 entries.
$$V_A^T$$ should have 9 entries, because there is one additional constraint |f| = 1.

qgao
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Registriert: 7. Apr 2009 11:38

### Re: A4 - Problem 3 - eightpoint algorithm

robert.n hat geschrieben:T and T' are two entirely different matrices, too! Arggghhh... me dumbass... gah
Right! T' is not the transpose of T, but a different matrix.