Sobre los pelos de Aki en FinalFantasy!

nexen · 28 jun 2005

Hola tengo una curiosidad y no encuentro alguna reseña al respecto, sobre que el pelo de aki fue modelado uno a uno y eso tengo bastante interes en saber algo al respecto..

Comentarios? algun link?

Os Agradesco mucho

Leander · 28 jun 2005

Te recomendaría la guía de A:M y verás como PEINAN el pelo.

Fijate en el Wookie.

ftp://ftp.hash.com/pub/updates/windo...2005Manual.pdf

Cesar Saez · 28 jun 2005

La verdad no tengo mucha idea de en que programa fué hecho pero hoy por hoy hay varios sistemas de pelo que te permiten peinar a tu modelo con más livertad, yo uso max y en la version 7.5 incluyeron un sistema basado en shave & haircut bastante bueno donde "peinar" a tu personaje no tiene tanta complicacion como con hairFX (opinion personal aunque tambien se puede hacer como con hairFX y sus splines), tambien hay sistemas como el de ornatrix donde literalmente tienes un peine y tijeras para peinar y cortar el cabello a tu personaje con la mayor libertad posible (en hair and fur de max 7.5 es muy similar).

Salu2

HalfVector · 28 jun 2005

Te pongo un extracto del documento Advanced Renderman Course que se presentó en el Siggraph 2001. Concretamente el extracto pertenece al capítulo 6; Using Maya with RenderMan on Final Fantasy: The Spirits Within, escrito por Kevin Bjorke.

Es bastante técnico ya que está orientado a programadores pero bueno, a lo mejor te aclara algo.

Cita:

6.2.1 Hair

Hair in Final Fantasy was rendered using RiCurves primitives. This in itself is not a new technique, but our implementation was unique. Hair, unfortunately, remains a very brute-force-intensive part of character animation and rendering.

An early design decision was whether to use Maya curves directly, to use a MtoR ribgen appearance (a plugin written in C), or to delay hair generation until render time and use an RenderMan geometry DSO. We opted for using MtoR ribgen appearances, because:

- The hair generation and animation itself occurred within Maya, using proprietary plugins. The data was already resident in memory for use by the MtoR plugin—this data and relationships would need to be duplicated for a RenderMan DSO.
- By using a ribgen appearance, we could control large numbers of hairs through a small number of Maya nodes—a node for each hair in Maya would have been unworkable (and MtoR would have attached one shader per hair!)
- By using a ribgen appearance, we could have more-exacting control over the exact values passed to the RIB stream than if we had used MtoRs built-in curve-to-RiCurves conversion.
- By defining hair in RIB, it could be potentially cached for use with RiReadArchive. On some motion-blurred frames, Akis hair could take up to 30 minutes in RIB-conversion calculation time, so RIB archiving posed a large potential savings in compute time.

Different characters had differing hair needs. Aki had the longest hair in the film, and up to 90 percent of the RIB representation for Aki was contained in the storage of her hairs. A fully-tressed Aki typically had a RIB representation that was about ten times that of Ryan, who had a very short patch of fuzzy hair just at the top of his head. Aki was our worst-case character, with respect to hair — she was about twice as complex as any other character in the film, and almost all of that complexity came from her hair.

Aki was in almost every shot, and her hair made her expensive to render. During the year 2000, almost 30 percent of all render cycles were used rendering just Aki . Considering that upwards of 80 percent of Akis render time could be spent rendering just her hair, this gave us a lot of incentive to render it as efficiently as possible.

Shading rate had little impact. Generally the strands were smaller than the shading rate already, so changing the shading rate from 0.5 to 1 or even to 10 rarely changed the render time by more than 3-5% (and because these strands were so fine, we often had to use very high pixel sampling rates to avoid aliasing — “turn it up to eleven” eventually gave way on some shots to sampling rates of 17 or 25).

The strands were long, thin, and thus were rarely fully obscured by one another or by any single primitive in the head. This means that RenderMan occlusion culling was generally ineffective in reducing the number of strands before they were diced and shaded, so shading efficiency became the single most-important key to getting Aki (in particular) to render more quickly. Since most likely every strand would be shaded, and the shading samples would be small, and worse yet the shading grids would probably be smaller than four samples per grid, it was important to keep shading complexity at a minimum.

One way we made Aki more efficient was to have different versions of her hair, which were chosen based on the demands of each shot. Aki had three versions of her hair: tagged Low, Medium, and High. Most shots used the high-detail version, but it was possible for the lighting artist to use a simpler version while preparing a shot, decreasing the render times for their test renders. The lower-detail versions had fewer (but thicker) hairs.

Animated RIB caches were prepared for some shots — especially if we anticipated a lot of re-rendering. Typically we would use the caches only while doing lighting setup — by avoiding motion-blur we would speed-up the lighting process and halve the size of the required RIB files.
But this meant that the archives were inappropriate for the final, motion-blurred renderings. At the end of the pipeline, those archives would be swapped-out, just before final render, and the last pass would be done without the benefit of the archive files.

Characters with shorter hair could sometimes have their hair entirely replaced with a single, static RIB element. For the male characters like Gray or Neil, only the portion of hair near the nape of the neck actually animated with respect to the character deformations—whenever those areas were hidden, we could just use a locked version of the hair via RiReadArchive and not have to worry about it (this archive could also be used for motion-blurred renders). Similarly, Janes pulled-back hairstyle was essentially rigid everywhere save the ponytail.

An unusual feature of our hair genrib node was that it could generate different versions of the hair for the RGB render and for shadow passes. For shadow passes, we would usually set a shadow simplification value—the number of hairs in shadow passes would be reduced by this factor, while the width of the shadow strands would be likewise increased. This often provided a shadow that was adequate for use in the scene, with fewer high-frequency parts, and that rendered much more quickly than a shadow map containing all of the hairs. Users could control the level of shadow simplification via a single Maya attribute.

In the case of RIB cached hair, this meant that we needed two archive files —one cache for normal hair, and one cache for shadow hair (in some shots, there were even multiple versions of the shadow hair used, with different simplification values). Fortunately, shadow hair tended to consume far less disk space than the regular hair. Furthermore, since it rendered quickly, the lighting artists would often use the shadow archives in place of the highly-detailed archives while they did test renders.

The largest single speedup we could apply to hair was in careful control of shadow parameters when lighting. We often found that shots could be sped up by 30%, 60%, even 300%, simply by altering the shadow settings, or sometimes unlinking shadowed lights and ignoring them or replacing them with shadowless lights — without compromising the look of the shot. Well return to this subject later, when discussing light sources.

6.2.2 Hair Shading

The shader for hair was a simple one. This was an important feature! Shading efficiency was crucial.
The method used was a close relative of the shading method used in the 1992 Siggraph paper “A Simple Method for Extracting the Natural Beauty of Hair,” by Anjyo, Usami, and Kurihara. As noted in that paper, the algorithm performs better on dark hair than on light hair, and our graybearded character, Sid, was particularly difficult to shade well.

Color selection was done through a range of colors that was initially a painted gradient. The texture artists could paint whatever colors they liked into this map, and then randomized parameters in the hair RIBs could be used as indices into this map. Unfortunately, this method proved to be very inefficient. But when the gradient maps were replaced by calls to the shader language color spline() function instead, using the same colors, render times improved by about 30%.

El documento habla sobre más cosas en el desarrollo de Final Fantasy. Por ejemplo Skin, Shaders, Shadows, etc. Pero como digo es un documento más bien orientado a programadores, pero como curiosidad...

Saludos.

nexen · 28 jun 2005

Cita:

Escritos por HalfVector

Te pongo un extracto del documento Advanced Renderman Course que se presentó en el Siggraph 2001. Concretamente el extracto pertenece al capítulo 6; Using Maya with RenderMan on Final Fantasy: The Spirits Within, escrito por Kevin Bjorke.

Es bastante técnico ya que está orientado a programadores pero bueno, a lo mejor te aclara algo.

El documento habla sobre más cosas en el desarrollo de Final Fantasy. Por ejemplo Skin, Shaders, Shadows, etc. Pero como digo es un documento más bien orientado a programadores, pero como curiosidad...

Saludos.

Vaya si muy interesante de verdad gracias

... veo que fue un gra royo aki para ellos y eso del pelo les fue realmente complicado.

28 jun 2005	#1
nexen Senior Member Fecha de Ingreso: noviembre-2002 Ubicación: Inside a Dot. Mensajes: 267	Sobre los pelos de Aki en FinalFantasy! Hola tengo una curiosidad y no encuentro alguna reseña al respecto, sobre que el pelo de aki fue modelado uno a uno y eso tengo bastante interes en saber algo al respecto.. Comentarios? algun link? Os Agradesco mucho __________________ "Siempre sueña y apunta más alto de lo que sabes puedes hacer. No te preocupes por ser mejor que tus contemporáneos o predecesores. Trata de ser mejor que tú" William Faulkner

28 jun 2005	#2
Leander Tresmiltornillero Fecha de Ingreso: octubre-2004 Ubicación: Zaragoza (ESPAÑA) Mensajes: 10,462	Re: Sobre los pelos de Aki en FinalFantasy! Te recomendaría la guía de A:M y verás como PEINAN el pelo. Fijate en el Wookie. ftp://ftp.hash.com/pub/updates/windo...2005Manual.pdf

28 jun 2005	#3
Cesar Saez just another monkey Fecha de Ingreso: marzo-2004 Ubicación: Buenos Aires, Argentina Mensajes: 2,869	Re: Sobre los pelos de Aki en FinalFantasy! La verdad no tengo mucha idea de en que programa fué hecho pero hoy por hoy hay varios sistemas de pelo que te permiten peinar a tu modelo con más livertad, yo uso max y en la version 7.5 incluyeron un sistema basado en shave & haircut bastante bueno donde "peinar" a tu personaje no tiene tanta complicacion como con hairFX (opinion personal aunque tambien se puede hacer como con hairFX y sus splines), tambien hay sistemas como el de ornatrix donde literalmente tienes un peine y tijeras para peinar y cortar el cabello a tu personaje con la mayor libertad posible (en hair and fur de max 7.5 es muy similar). Salu2 __________________ Blog::Demo Reel '07 ____________________ "Debes practicar hasta que lo dificil resulte fácil, luego practica hasta que lo fácil resulte hermoso" Stephen Covey

Temas Similares
Tema	Autor	Foro	Respuestas	Último mensaje
una opinion sobre mi imagen :)	nexen	Trabajos Finalizados	6	29 ene 2004 18:01
en que web podria encontrar terminos sobre animacion.	nadia	Tutoriales, Libros y Manuales.	5	12 nov 2002 07:45

Usuarios activos actualmente viendo este tema: 1 (0 miembros y 1 visitantes)