Using quaternions in Augmented Reality sample code “pARk” from Apple

Question

I'm on an AR app for iOS for showing annotations on a camera view - like we all know from wikitude, junaio etc. I am new to this subject, so sorry for my stupid question :)

I downloaded the "pARk" sample code from apple here to study how to visualize the annotations using another technique than getting in complex calculations with pitch,yaw,roll and the azimuth: http://developer.apple.com/library/ios/#samplecode/pARk/Introduction/Intro.html#//apple_ref/doc/uid/DTS40011083

Apple uses rotation matrices in this sample and I would like to transfer it so it uses quaternions. How can I achieve this? I understand the conversion of the coordinates to ECEF and ENU... must I change this conversion, I think no (right?).

I see problems in representing the projection matrix (the frustum) as quaternion... this is not possible, right?

Maybe someone could give me hints, what and how I have to change this example to get what I want.

Thanks for all answers!

Answer 1

Solved, there is no practical use of quaternions in this sample. I would only need them, if I multiply rotations with rotations.