Why don't you set Rendermap to use 'scene camera' instead of perpendicular to surface?
Matt
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM
> [mailto:owner-xsi(at)Softimage.COM] On Behalf Of peter boeykens
> Sent: Tuesday, May 27, 2008 1:07 PM
> To: XSI(at)Softimage.COM
> Subject: Re: rendermap / lightmap SSS shader
>
> Thanks for the link.
>
> I am doing multiple rendermaps with the camera in different
> positions, and recombining them - this gives me a fairly good result.
>
> It's just a lot of work - mostly because of the very slow
> rendering times and instability of rendermap.
> A 2k rendermap is 1.5 hours on average on the stuff I'm
> working on - regular 2k renders are less than 15 minutes. I'm
> scripting overnight renders of several rendermaps which helps
> out a lot - but one night out of two rendermap either
> crashes, freezes or simply disappears.
>
> ...
>
>
> ----- Original Message -----
> From: "Halfdan Ingvarsson" <hingvars(at)Softimage.COM>
> To: <XSI(at)Softimage.COM>
> Sent: Tuesday, May 27, 2008 5:06 PM
> Subject: RE: rendermap / lightmap SSS shader
>
>
> It's not complicated what it does. It's basically a trick
> they used on
> Finding Nemo, described in some Siggraph notes, but using the
> camera's pov,
> rather than the light's pov. (see:
> http://graphics.stanford.edu/facecourse/facecloning05/Presenta
> tions/scat.pdf
> )
>
> The lightmap contains the interleaved illumination of the
> front and back
> surfaces (+depth of back) as seen from the camera, then the
> fast_sss shader
> simply blurs the image samples based on distance, for each
> sample lookup.
> This is why this trick won't work in a wraparound mode. If
> you froze the
> lightmap and then orbited, the SSS effect would look quite
> funky where you
> were viewing perpendicular to what the original camera's
> sampling position
> was.
>
> The only decent way to do it would be something along the
> lines of what Alan
> describes.
>
> - ½
>
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM
> [mailto:owner-xsi(at)Softimage.COM] On Behalf Of
> Alan Jones
> Sent: 27-May-2008 10:55
> To: XSI(at)Softimage.COM
> Subject: Re: rendermap / lightmap SSS shader
>
> On Tue, May 27, 2008 at 3:20 PM, peter boeykens
> <peter_b(at)skynet.be> wrote:
> > For "unsupporting" SSS - this seems lame - as it wouldn't take all
> > that much to get it to work.
> > The downfall is with the lightmap being camera dependent.
> > I dont think that's a limitation of lightmaps - as color sampler
> > lightmap is working with UV space.
>
> The fast SSS shaders don't do anything akin to an ordinary
> lightmap in UV
> space.
> They use lots of strange trickery behind the scenes to do
> their work and Zap
> is very tight lipped on their secret sauce used. Don't forget
> that Halfy is
> an exceptionally intelligent guy, if there was something on
> his end he could
> do to resolve this it would already be done.
>
> There's nothing stopping you from writing/employing someone
> to write your
> own SSS shader which could achieve similar speed using
> lightmaps by doing
> some nice trickery to store to a kdtree/bih instead of a UV
> space texutre
> and then looking that up within the main shader. It'd be nice
> and fast and
> you'd avoid the camera dependency that makes fast SSS so unhappy.
>
> Though if you use SSS a lot grab a copy of 3Delight - their SSS is
> absolutely gorgeous, though I've not look at whether they support
> rendermapping in XSI, though I'm sure Aghiles would be more
> than happy to
> provide customers with something that does this within XSI in
> order to get
> 3Delight into a new facility.
>
> Cheers,
>
> Alan.
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