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POHow to calculate the fundamental matrix for stereo vision
 

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  1. POHow to calculate the fundamental matrix for stereo vision
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    <p>I'm trying to write some code that will calculate the fundamental matrix to determine the relationship between stereo images. I started with the Hartley and Zisserman book that most people recommend, but it didn't have any practical examples and the sample code for it was in MATLAB which I don't have. I then switched to <a href="http://books.google.com/books?id=tS3RMy2ay3gC&amp;pg=PT69&amp;lpg=PT69" rel="noreferrer">An introduction to 3D Computer Vision Techniques and Algorithms</a> which is more practical and has actual examples in it. I implemented the recommended 8-point algorithm using Python and numpy, but I'm having trouble verifying the validity of it.</p> <p>I'm using the dataset listed on page 48 (use that link above to see a Google Books excerpt) of that book. When I normalize the points, I get the same results as that book. However, when I use numpy's SVD function to calculate the fundamental matrix, I get the following value for F:</p> <pre><code>[[-0.01851684 -0.21631176 -0.67036356] [ 0.2605251 -0.01023853 0.14234079] [ 0.63748775 -0.09404508 -0.00220713]] </code></pre> <p>This matrix satisfies the equation <strong>p_R^ * F * p_L = 0</strong> so it seems correct. However, it is very different from the matrix calculated in the book. I tried to double check the answer using OpenCV's cv.FindFundamentalMat() and I got a third answer:</p> <pre><code>[[ 22.98129082 271.46453857 853.74273682] [-334.1673584 -4.84123087 -175.99523926] [-809.88891602 125.99833679 1. ]] </code></pre> <p>I'm not how those other two matrices are calculated, but I can't find any examples of fundamental matrix calculation on the web to verify my implementation of the 8-point algorithm. The fact that my implementation returns a value that satisfies the equation gives me confidence, but I'm worried that I did something silly which is why I can't match the results in the book or by OpenCV.</p>
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    1. COdid you start with the normalized points from your dataset or with the original points to get at the two fundamental matrices above?
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