In retrospect, perhaps "orthogonalize" would have been a better name.
We'll at least update the documentation for Java 3D 1.3 to make its
function more clear.
--
Kevin Rushforth
Java 3D Team
Sun Microsystems
[EMAIL PROTECTED]
>Date: Tue, 20 Mar 2001 13:55:58 -0800
>From: Paraskevas Orfanides <[EMAIL PROTECTED]>
>Subject: Re: [JAVA3D] Transform.normalize -- what does it do?
>To: [EMAIL PROTECTED]
>
>Hello Kevin,
>Isn't that a bit counter intuitive? Normally, in the world of math, when
>people talk about normalizing a vector, matrix, or other tensor (call it
>T), they mean that they adjust it such that |T|=1, where |T| is a norm,
>usually the L2 (euclidian) norm. In general this is done by setting
>T=T/|T|. Thus, in a trasform3D, I would expect that "normalize" would
>change the determinant to 1. Of course, this can be done even if the
>element of the bottom left corner (the scaling one) is not equal to 1, as
>long as the rotational and translational components are appropriately
>adjusted.
>In any case, the term "normalize" doesn't seem correct for this type of
>error correction that you mention. Am I missing something here?
>Paraskevas
>
>--- Kevin Rushforth <[EMAIL PROTECTED]> wrote:
>> No, the normalize methods ensure that the column vectors are orthogonal
>> to each other. It does not alter the scale. (Earlier versions
>> of Java 3D had a bug that would force the scale to 1.0, but that was
>> never the intent). The main use of these methods is to correct for
>> floating point errors that accumulate over time when concatenating
>> a large number of rotation matrices.
>>
>> --
>> Kevin Rushforth
>> Java 3D Team
>> Sun Microsystems
>>
>> [EMAIL PROTECTED]
>>
>>
>> >Date: Tue, 20 Mar 2001 10:34:57 -0600
>> >From: "Andrew R. Thomas-Cramer" <[EMAIL PROTECTED]>
>> >Subject: [JAVA3D] Transform.normalize -- what does it do?
>> >To: [EMAIL PROTECTED]
>> >
>> >
>> >The class javax.media.j3d.Transform has methods normalize() and
>> normalizeCP() that "normalizes the rotational components (upper 3x3)" of
>> the transform. Pardon my ignorance, but what exactly does that mean? Is
>> that another way of saying that these methods replace the scaling
>> component with uniform scale factor = 1?
>> >
>> >-----------------------------------------------------------------------
>> >Andrew R. Thomas-Cramer
>> >Work: [EMAIL PROTECTED] http://www.prism-cs.com/
>> >Home: [EMAIL PROTECTED] http://www.execpc.com/~artc/
>> >-----------------------------------------------------------------------
>>
>>
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