Re: [Algorithms] approximation to pow(n,x)?

[Robin G. <rob...@gm...>]

The difference is in the shape of specular highlights. Where Phong
specular highlights at grazing angles are streched out moon shapes,
the Blinn half-angle highlights retain a more circular shape. Real
world photos of specular surfaces at grazing angles more closely
resemble Blinn shapes than Phong, plus the Blinn model has some good
physical reasoning behind it to do with reflection from distributions
of microfacets.

http://img22.imageshack.us/img22/7/blinn.jpg
http://img526.imageshack.us/img526/758/phong.jpg

- Robin Green.



On Wed, Nov 4, 2009 at 10:14 AM, Jeff Russell <je...@8m...> wrote:
> Not to derail the conversation, but I've never really understood why half
> vectors are preferable to an actual reflection vector, either in terms of
> efficiency or realism. I've always just used reflection, am I missing
> something?