Well, a nonunit quaternion is a perfectly valid thing, it just means your
vector will be scaled when transformed. To transform a vector v by a
quaternion you just compute qvq*. If q is a nonunit quaternion, and r
is a unit quaternion such that q = sr, then v' = srvsr* = s^2(rvr*). So you
rotate the vector and scale it by the square of the quaternion's length
(i.e. the dot product of the quaternion with itself).
I don't remember how the 3dsmax polar decomposition works, though,
so I won't say anything about whether it's giving you the right answer or
not, or whether you're forgetting something when putting factors
back together. If you believe that the matrix you're converting to a
quaternion is not supposed to have any scale in it, then there is
definitely some misunderstanding somewhere in the system.
Jonathan.
 Original Message 
From: "y o g i w p" <yogiwp2@...>
To: <gdalgorithmslist@...>
Sent: Thursday, July 31, 2003 5:39 AM
Subject: [Algorithms] Nonunit Quat from Matrix?
> Hi,
>
> Some of our bone local orientation matrices converts to nonunit quats. What's
> this mean? Is there something wrong with the matrices? The orientation matrices
> came from polardecomposed (QS) 3DSMax bone TM.
>
> The problem is, I cannot covert these nonunit quats back to matrices correctly
> (results in completely different orientation matrix).
> Normalization doesn't help, because it also produces different orientation matrix.
>
> I think the bone matrices are fine, as I can use them to skin the character correctly.
>
> Any help will be greatly appreciated. Thanks.
>
>
> Yogi Wahyu Prasidha
>
>
>
> 
> This SF.Net email sponsored by: Free prebuilt ASP.NET sites including
> Data Reports, Ecommerce, Portals, and Forums are available now.
> Download today and enter to win an XBOX or Visual Studio .NET.
> http://aspnet.clickurl.com/go/psa00100003ave/direct;at.aspnet_072303_01/01
> _______________________________________________
> GDAlgorithmslist mailing list
> GDAlgorithmslist@...
> https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist
> Archives:
> http://sourceforge.net/mailarchive/forum.php?forum_id=6188
