Re: tangent maps

[André Adam <a_adam(at)49games.de>]

A tangent map describes the direction of a texture projection's u 
coordinate in space relative to the polygons it is bound to. Basically 
think of a texture map with lots of small arrows pointing to the right 
mapped onto an object. The vector in 3d-space they describe once 
textured onto the object's surface is the tangent space, which gets 
stored on a per sample basis.
The tangent space is a reference for bump mapping effects, where the 
original surface normals gets bent towards certain directions. These 
directions have to be relative to some sort of direction fixed right in 
the object - the tangent space. :)

This technique brings along lot's of ways to produce unwanted artifacts, 
which might explain the trouble of getting a decent piece bump mapping 
to work...

Hope that sheds some light, cheers!

   -André


Andi Farhall wrote:
> actually i'm a bit confused as to what a tangency map is. I understood tangency to be where one curve flows cleanly into another, either that or "at 90 degrees to". I'm wrong aren't i....
>
> Subsequently i've no idea how you would use them in the context of displacement or bump mapping... boy do i feel thick
>
>
> regards
>
> Andi
>
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM]On Behalf
> Of Bernard Lebel
> Sent: Wednesday, January 24, 2007 12:08 PM
> To: XSI(at)Softimage.COM
> Subject: Re: tangent maps
>
>
> Bumpmap and displacementmap substitution, we do a lot of em.
>
>
> Cheers
> Bernard
>
>
>
> On 1/24/07, Andi Farhall <andi(at)clearpost.co.uk> wrote:
>   
> > Do have tangent maps have any other uses apart from hair instance
> > orientation? without scripting stuff that is...
> >
> >
> > regards
> >
> > Andi

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