Re:How Quaternions encode rotations: derivation and sample code
by jblow on Wednesday September 07, 2016 @08:00AM
(#12442569)
It's correct that you can look in any direction with only two planes, but that's not enough; you need to be able to control your orientation around that final axis. You need 3 planes for that (3 "rotational degrees of freedom"). The idea that a quaternion is somehow two complex numbers is wrong.
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Re:How Quaternions encode rotations: derivation and sample code
by uryga on Wednesday September 07, 2016 @08:32AM
(#12442794)
Thanks. I did some research and found out that, indeed, my vague understanding of quaternions was wrong. I remember skimming the Wikipedia article and seeing this: https://en.m.wikipedia.org/wiki/Quaternion#Quaternions_as_pa...
I then assumed that my idea with two rotations is how quaternions work. Here's to actually reading about a concept before I start explaining it next time...
Re:How Quaternions encode rotations: derivation and sample code
by chombier on Wednesday September 07, 2016 @08:36AM
(#12442818)
I think you can do that using two rotation axis only (cf. proper Euler angles).
And quaternions are made of two complex numbers.
edit: typo.
Re:How Quaternions encode rotations: derivation and sample code
by Kristine1975 on Wednesday September 07, 2016 @09:32AM
(#12443204)
>And quaternions are made of two complex numbers.
I don't pretend to grok quaternions (I only use them), but I'm fairly sure a quaternion consists of three imaginary numbers plus a real number.