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Axis angle rotations and changing rotation values

  1. Nov 28, 2012 #1
    I have two 3d applications and when an object(a cube for example) is transferred between them, the rotation values of the cube change(the object stay at the same location. translation and scale values stay the same) and I can't find why that occurs and it's driving me crazy.

    app 1 rotation values:


    Axis-angle representation of the above

    -0.7096853 0.4914011 -0.5048483 -42.20802

    app 2 rotation values:


    I've read a few wikipedia articles on rotation and specifically axis-rotation stuff but I haven't really figured out what's really happening.

    Any help is appreciated.
  2. jcsd
  3. Nov 28, 2012 #2

    D H

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    Staff Emeritus
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    You're jumping in a bit to deep, getting to specifics way too early. Before we get to the specifics, there are some key important question that needs to be addressed:
    • Are these your applications or are the someone else's? In other words, did you write the code?
    • If you didn't write the code, did you carefully read the documentation (if it exists) and follow it?
    • If you did write the code, did you carefully test it?
    • How does the code represent composite bodies, sub-bodies, and the connections between them?
    • Is this transfer is an atomic action, or is it essentially a detachment immediately followed by an attachment? If it's the latter, is it the attachment or detachment where things go awry?
  4. Nov 28, 2012 #3
    Sorry about lack of clarity. Both applications are closed sourced and there is no information about how they store the data.

    The transfer file format converts x,y,z angles to Axis-angle representation
  5. Nov 28, 2012 #4


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    Yes, but what do those angles have to do with a rotation? A single axis of rotation can be given by its three direction angles- the angles the axis makes with the three coordinate axes. Also, if this is the case, x, y, and z are not independent. We must have [itex]x^2+ y^2+ z^2= 1[/itex]. Is that what you mean? Where do you give the angle through which you are rotating?
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