Tuesday, September 06, 2005

Loads more work and a good weekend

I really need to post more often!

I now think I understand where the errors come from that I discussed in my last post. From what I have read, I am trying to use SVD as if I am doing a rigid body transformation - which I'm not. The fact that I am using a linear method to try and find errors in a nonlinear system means that I am getting a less exact answer than I would like.

As a result I've spent the last week trying to understand how nonlinear least squares minimisation works. With the help of some great people on the Seattle Robotics Society mailing list I think I am now getting a handle on it. The next step is trying to figure out the practical application of the mathematical theory to my work. This mostly entails trying to decipher how to call the appropriate functions in the GNU Scientific Library.

I also figured out that there should be no error accumulation. That was due to my misunderstanding of how the ego motion is calculated. I was transforming my SIFT feature coordinates to world coordinates one step too early and was accidentally cumulating the error over each subsequent frame.

Hopefully with the fix to the latter problem and the incorporation of a nonlinear method to calculate the ego motion I should be getting much more accurate results.

In other news, I had a great weekend watching NZ win the Tri-nations with an exciting win over Australia. Had a great BBQ at our place on Saturday night. And to top it all off, watched my Hockey team gain a convincing win in their first game of the season (GO RACERS!) ;-)


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