quaternions

I use slerp to interpolate between two quaternions representing rotations. The resulting rotation is then extracted as Euler angles to be fed into a graphics lib. This kind of works, but I have the following problem; when rotating around two (one works just fine) axes in the direction of the green arrow as shown in the left frame here the rotation soon jumps around to rotate from the opposite site to the opposite visual direction, as indicated by the red arrow in the right frame. This may be logical from a mathematical perspective (although not to me), but it is undesired. How could I achieve

I need to have a game object point north AND I want to combine this with gyro.attitude input. I have tried, unsuccessfully, to do this in one step. That is, I couldn't make any gyro script, which I found on the net, work with the additional requirement of always pointing north. Trust me, I have tried every script I could find on the subject. I deduced that it's impossible and probably was stupid to think it could be done; at least not this way (i.e. all-in-one). I guess you could say I surmised that you can't do two things at once. Then I thought possibly I could get the same effect by

Quaternion can describe not only rotation, but also an orientation, i.e. rotation from initial (zero) position. I was wishing to model smooth rotation from one orientation to another. I calculated start orientation startOrientation and end orientation endOrientation and was wishing to describe intermediate orientations as startOrientation*(1-argument) + endOrientation*argument while argument changes from 0 to 1 . The code for monkey engine update function is follows: @Override public void simpleUpdate(float tpf) { if( endOrientation != null ) { if( !started ) { started = true; } else {

I'm currently implementing a C++ solution to track motion of multiple objects. In that I have tracked points of those objects in a frame sequences such that multiple points in each frame. As a result of that I have x, y, z coordinates of those points of the entire frame sequence. By studying an already generated model I understood it consists of a joints system which move relative to each other. Every joint has a parent and their movements are written relative to its parent in Quaternion format. Therefore, I want to convert my x,y,z coordinates, which are in 3D space relative to same origin,

I've got a longitude and latitude and want to convert this to a quaternion and wondering how I can do this? I want to use this, because I've got an app which projects the earth on a sphere and I want to rotate from one location to another one. Best! There's a way to go about this without using matrices or vectors, similar to this numpy implementation . We can think of longitude/latitude as two quaternion rotations composed together. Let's work with a Z-up right-handed coordinate system. Let's call longitude φ and latitude θ, and the point represented by the two as (φ, θ). For visualization,

So I'm very new to quaternions, but I understand the basics of how to manipulate stuff with them. What I'm currently trying to do is compare a known quaternion to two absolute points in space. I'm hoping what I can do is simply convert the points into a second quaternion, giving me an easy way to compare the two. What I've done so far is to turn the two points into a unit vector. From there I was hoping I could directly plug in the i j k into the imaginary portion of the quaternion with a scalar of zero. From there I could multiply one quaternion by the other's conjugate, resulting in a third