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Posit - 3D estimation - negative angles

PostPosted: Mon May 11, 2015 5:59 am
by fastlater
Hi everyone.
I am trying to get the orientation of a cube and I get good results when I rotate the cube to the left. However, when I rotate the cube to the another side, I got some results that I wont say are wrong but it was not what I was expecting. For example,
orientation result
20 degrees 21 degrees OK
40 degrees 42 degrees OK
-20(or 340) degrees 70 degrees not OK (attached file)
-60(or 300) degrees 30 degrees not OK

Looks like when I rotate counterclockwise, the yaw angle should be 90 degrees - the result. My question is why?
Should I have an assumption to get the result expected, a negative angle or 300 and something?
I am using the sample application from http://www.aforgenet.com/articles/posit/

I hope someone with experience using this application can help me. I just would like to understand the result and see if I can avoid add assumptions to determinate the correct orientation.

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