Special effects of The Lord of the Rings film trilogy
Encyclopedia
The Lord of the Rings film trilogy
used many groundbreaking practical and digital visual effects. The first film has around 540 effects shots, the second 799, and the third 1488 (2730 in total). The total moves up to 3420 with the Extended cuts. 260 visual effects artists worked on the trilogy, and the number would double by The Two Towers. The crew, led by Jim Rygiel and Randy Cook, would work long and hard hours overnight to produce special effects within a short space of time, especially with Jackson's active imagination. For example, they produced several major shots of Helm's Deep within the last six weeks of post-production of The Two Towers, and the same amount of shots for The Two Towers within the last six weeks on The Return of the King. Despite WETA
being the major stylistic force behind the films, a single scene where Arwen confronts the Black Riders in The Fellowship of the Ring was done by Digital Domain
.
on a level never seen before in the film industry. Elijah Wood
is 5 ft 6in (1.68 m) tall in real life, but the character of Frodo Baggins
is 3 ft 6in (1.06 m) in height. Large and small scale doubles were used in certain scenes, while entire duplicates of certain sets (including Bag End in Hobbiton) were built at two different scales, so that the characters would appear to be the appropriate size. At one point in the film, Frodo runs along a corridor in Bag End, followed by Gandalf. Elijah Wood and Sir Ian McKellen were filmed in separate versions of the same corridor, built at two different scales, then these two separate shots are combined to create a shot of both actors appearing to be in the same corridor.
Forced perspective
was also employed, so that it would look as though the short hobbits were interacting with taller Men and Elves. Surprising the makers of the film, the simple use of kneeling down was used to great effect. As well as this, some actors wore over-sized costumes to make average sized actors look small, and there were numerous scale doubles, who are disguised with costumes, and an avoidance of close-ups and numerous back shots, and even latex faces for the Hobbit doubles.
WETA coined the term bigature for the 72 large miniatures
produced for the film, in reference to their extreme size. Such miniatures include the 1:4 scale for Helm's Deep
, which alongside Khazad-dûm and Osgiliath, was one of the first built. Most sets were constructed to allow compositing with the models and matte paintings. Notable examples include the Argonath, Minas Tirith
, the tower and caverns of Isengard
, Barad-dûr
, the trees of Lothlórien and Fangorn Forest and the Black Gate. Alex Funke led the motion control camera
rigs, and John Baster and Mary Maclahlan led the building of the miniatures. The miniatures unit worked more than any other special effects crew, working over 1000 days. Often they held parties to celebrate each landmark, such as day 666. Their final shot was one of the Black Gate for the third film in November 2003.
, the Balrog
, the Ent
s, the fell beasts, the Warg
s, the mûmakil and Shelob
were created entirely within a computer. Creators would spend months of creation and variation as sketches before approved designs were sculpted into five-foot maquettes and scanned into a computer. Animators would then rig skeletons and muscles before animation and final detailed colouring scanned from painted maquettes. Treebeard
had a digital face composited upon the original animatronic, which was scanned for the digital model of his longshots.
As well as creatures, WETA also created highly realistic digital doubles for many miniature longshots, as well as numerous stunts, most notably Legolas. These doubles were scanned from having actors perform movements in a motion-capture suit, and with additional details created using ZBrush
. There are even morphs between the doubles and actors at times. Horses also performed with mo-cap points on them, although deaths are animation.
Weta began animating Gollum in late 1998, using a generic human muscle system, to convince New Line they could achieve it. Andy Serkis
played Gollum by providing his voice and movements on set, as well as performing within the motion capture
suit. His scenes were filmed twice, with and without him. Originally Gollum was set to solely be a CG character, but Jackson was so impressed by Andy Serkis' audition tape that they used him on set as well. A team led by Randy Cook performed the animation using both motion capture data and manual recreation of Serkis' facial reference.
Gollum's CG model was also redesigned during 2001, now using a subdivision surface
model instead of the NURBS model for Fellowship (a similar rebuild was also done for the digital doubles of the lead actors), when Serkis was cast as Sméagol, Gollum's form before he is cursed by the One Ring, so as to give the impression that Andy Serkis as Sméagol transforms into the CG Gollum. The original model can still be glimpsed briefly in the first film. Over Christmas 2001 the crew proceeded to reanimate all the previous shots accordingly within two months. Another problem was that the crew realized that the cast performed better in the versions of the film with Serkis. In the end, the CG Gollum was often animated on top of these scenes and Serkis would be painted out. Due to Gollum not being human, shots such as him crawling down a sheer cliff were shot with no live reference. Serkis also did motion-capture for the character which would drive the body of the model, whilst animators did all fingers and facial animation. Gino Acevedo supervised realistic skin tones, which for the first time used subsurface scattering
shader
, taking four hours per frame
to render. Render time refers to the amount of time it took the computer to process the image into a usable format; it does include the amount of time it took the texture artists to "draw" the frame. The hair dynamics of CG Gollum in The Two Towers were generated using Maya
Cloth. Because of its technical limitations, Weta subsequently moved to the Syflex
system for The Return of the King.
Christoper Hery (ILM), Ken McGaugh and Joe Letteri
(both Weta and previously ILM) received a 2003 Academy Award, Scientific or Technical
for implementing the BSSRDF
technique used for Gollum's skin in a production environment. Henrik Wann Jensen
(Stanford University
), Stephen Robert Marschner (Cornell University
and previously Stanford University), and Pat Hanrahan
(Stanford University) (but not the fourth coauthor Marc Levoy
), who developed BSSRDF, won another the same year.
developed the system in 1996, originally to create crowd scenes in King Kong. The system creates a large number of choices for each software agent
to pick when inside a digital arena. Catherine Thiel provided the movements of each type of soldier, like the unique fighting styles (designed by Tony Wolf) or fleeing. To add to this, digital environments would also be created for the simulations. Massive also features Grunt, a memory-conservative special purpose renderer, which was used for scenes containing as much as 200,000 agents and several million polygons. The Pelennor Fields scene also contains "multi-body agents" in the form of a 5 × 5 grid of Orcs.
Whilst Jackson insisted on generally using miniatures, sometimes shots would get too difficult for that, primarily with the digital characters. Gray Horsfield led the creation of digital versions of Dwarrowdelf, the Chamber of Mazarbul, ruins in Eregion
, Helm's Deep, the Barad-dûr and Black Gate for complicated sequences, such as destruction or having an arena for a digital camera to move around. He himself spent his entire Christmas
2002 break creating the Barad-dûr for The Return of the Kings climax. Sometimes natural elements like cloud, dust, fire (which was used as the electronic data for the Wraithworld scenes and the Balrog) would be composited, and natural environments were composited to create the Pelennor Fields.
To give a "painterly" look to the films, cinematographer Andrew Lesnie
worked on every scene within the computer to strengthen colours and add extra mood and tone to the proceedings. Gold was tinted to Hobbiton, whilst cooler colours were strengthened into Lothlórien, Moria and Helm's Deep. Such a technique took 2–3 weeks to do, and allowed some freedom with the digital source for some extra editing.
The Lord of the Rings: The Return of the King
required the help of the company Next Limit Technologies
and their software RealFlow
to simulate the lava in Mount Doom
.
A technical overview of the special effect is given by Matt Aitken et al. (2004).
The Lord of the Rings film trilogy
The Lord of the Rings is an epic film trilogy consisting of three fantasy adventure films based on the three-volume book of the same name by English author J. R. R. Tolkien. The films are The Fellowship of the Ring , The Two Towers and The Return of the King .The films were directed by Peter...
used many groundbreaking practical and digital visual effects. The first film has around 540 effects shots, the second 799, and the third 1488 (2730 in total). The total moves up to 3420 with the Extended cuts. 260 visual effects artists worked on the trilogy, and the number would double by The Two Towers. The crew, led by Jim Rygiel and Randy Cook, would work long and hard hours overnight to produce special effects within a short space of time, especially with Jackson's active imagination. For example, they produced several major shots of Helm's Deep within the last six weeks of post-production of The Two Towers, and the same amount of shots for The Two Towers within the last six weeks on The Return of the King. Despite WETA
Weta Workshop
Weta Workshop is a special effects and prop company based in Miramar, New Zealand, producing effects for television and film.Founded in 1987 by Richard Taylor and Tania Rodger as RT Effects, Weta Workshop has produced creatures and makeup effects for the TV series Hercules: The Legendary Journeys...
being the major stylistic force behind the films, a single scene where Arwen confronts the Black Riders in The Fellowship of the Ring was done by Digital Domain
Digital Domain
Digital Domain is a visual effects and animation company founded by film director James Cameron, Stan Winston and Scott Ross. It is based in Venice, Los Angeles, California...
.
Scale
Production was complicated by the use of scale doubles and forced perspectiveForced perspective
Forced perspective is a technique that employs optical illusion to make an object appear farther away, closer, larger or smaller than it actually is. It is used primarily in photography, filmmaking and architecture...
on a level never seen before in the film industry. Elijah Wood
Elijah Wood
Elijah Jordan Wood is an American actor. He made his film debut with a minor part in Back to the Future Part II , then landed a succession of larger roles that made him a critically acclaimed child actor by age 9. He is best known for his high-profile role as Frodo Baggins in Peter Jackson's...
is 5 ft 6in (1.68 m) tall in real life, but the character of Frodo Baggins
Frodo Baggins
Frodo Baggins is a fictional character in J. R. R. Tolkien's legendarium.He is the main protagonist of Tolkien's The Lord of the Rings. He was a hobbit of the Shire who inherited Sauron's Ring from Bilbo Baggins and undertook the quest to destroy it in the fires of Mount Doom...
is 3 ft 6in (1.06 m) in height. Large and small scale doubles were used in certain scenes, while entire duplicates of certain sets (including Bag End in Hobbiton) were built at two different scales, so that the characters would appear to be the appropriate size. At one point in the film, Frodo runs along a corridor in Bag End, followed by Gandalf. Elijah Wood and Sir Ian McKellen were filmed in separate versions of the same corridor, built at two different scales, then these two separate shots are combined to create a shot of both actors appearing to be in the same corridor.
Forced perspective
Forced perspective
Forced perspective is a technique that employs optical illusion to make an object appear farther away, closer, larger or smaller than it actually is. It is used primarily in photography, filmmaking and architecture...
was also employed, so that it would look as though the short hobbits were interacting with taller Men and Elves. Surprising the makers of the film, the simple use of kneeling down was used to great effect. As well as this, some actors wore over-sized costumes to make average sized actors look small, and there were numerous scale doubles, who are disguised with costumes, and an avoidance of close-ups and numerous back shots, and even latex faces for the Hobbit doubles.
Size Doubles
In the Middle-earth storyverse, Hobbits are 3 ft 6in tall, Dwarves are taller at about 4 ft 6in, and Men and Elves are normal human height (~5 ft-6 ft). However, the films only use two scale sets instead of three: this is achieved by simply casting taller than average actors to play Dwarves, then combining Dwarves and Hobbits into one size scale. For example, John Rhys-Davies, who played Gimli, is taller than Elijah Wood, who played Frodo. Thus in the ending shot of the Council of Elrond scene when all nine members of the Fellowship of the Ring are standing together, Rhys-Davies and the four hobbit actors were filmed all at once, then the human-sized characters (Gandalf, Aragorn, Boromir, Legolas) were filmed in a second take, then the two shots were composited at different scale to make one image, with the initial dwarf/hobbit character shot made smaller. A practical upshot of not creating a third scale for Dwarves is that in a scene in which only Dwarves and Hobbits interact, no scale doubles are needed. For example, when they are entering Lothlórien for the first time and Gimli claps Frodo on the shoulder and says "stay close, young hobbits", the entire scene employs no size doubles, because Rhys-Davies is naturally the proportionately taller height needed between Dwarves and Hobbits.Miniatures
Scale model
A scale model is a physical model, a representation or copy of an object that is larger or smaller than the actual size of the object, which seeks to maintain the relative proportions of the physical size of the original object. Very often the scale model is used as a guide to making the object in...
produced for the film, in reference to their extreme size. Such miniatures include the 1:4 scale for Helm's Deep
Helm's Deep
In J. R. R. Tolkien's Middle-earth writings, Helm's Deep was a large valley in the north-western Ered Nimrais .The valley was described as being blocked over its entire width by the natural series of hills called Helm's Dike and behind that lay the fortress of Aglarond or the Hornburg, at the...
, which alongside Khazad-dûm and Osgiliath, was one of the first built. Most sets were constructed to allow compositing with the models and matte paintings. Notable examples include the Argonath, Minas Tirith
Minas Tirith
Minas Tirith , originally named Minas Anor, is a fictional city and castle in J. R. R. Tolkien's Middle-earth writings. It became the heavily fortified capital of Gondor in the second half of the Third Age...
, the tower and caverns of Isengard
Isengard
In J. R. R. Tolkien's fictional universe of Middle-earth, Isengard , a translation of the Sindarin Angrenost, was a large fortress. Both names mean "Iron fortress" In J. R. R. Tolkien's fictional universe of Middle-earth, Isengard , a translation of the Sindarin Angrenost, was a large fortress....
, Barad-dûr
Barad-dûr
Barad-dûr is the fortress of Sauron in the heart of the black land of Mordor and close to Mount Doom in the fantasy world of J. R. R. Tolkien's The Lord of the Rings...
, the trees of Lothlórien and Fangorn Forest and the Black Gate. Alex Funke led the motion control camera
Motion control photography
Motion control photography is a technique used in still and motion photography that enables precise control of, and optionally also allows repetition of, camera movements. It can be used to facilitate special effects photography. The process can involve filming several elements using the same...
rigs, and John Baster and Mary Maclahlan led the building of the miniatures. The miniatures unit worked more than any other special effects crew, working over 1000 days. Often they held parties to celebrate each landmark, such as day 666. Their final shot was one of the Black Gate for the third film in November 2003.
Animation
Creatures such as TrollsTroll (Middle-earth)
In J. R. R. Tolkien's legendarium, Trolls are large humanoids of great strength and poor intellect.While in Norse mythology, the Troll was a magical creature with special skills, in Tolkien's writings they are portrayed as evil, stupid, with crude habits, although still intelligent enough to...
, the Balrog
Balrog
Balrogs are fictional demonic beings who appear in J. R. R. Tolkien's Middle-earth legendarium. Such creatures first appeared in print in his novel The Lord of the Rings, though they figured in earlier writings that posthumously appeared in The Silmarillion and other books.Balrogs are described as...
, the Ent
Ent
Ents are a race of beings in J. R. R. Tolkien's fantasy world Middle-earth who closely resemble trees. They are similar to the talking trees in folklore around the world. Their name is derived from the Anglo-Saxon word for giant....
s, the fell beasts, the Warg
Warg
In Norse mythology, a vargr is a wolf and in particular refers to the wolf Fenrir and his sons Sköll and Hati. Based on this, J. R. R. Tolkien in his fiction used the Old English form warg In Norse mythology, a vargr (often anglicised as warg or varg) is a wolf and in particular refers to the...
s, the mûmakil and Shelob
Shelob
Shelob is a fictional character from J. R. R. Tolkien's Middle-earth legendarium. She appears at the end of the fourth book, second volume , of The Lord of the Rings.-Literature:...
were created entirely within a computer. Creators would spend months of creation and variation as sketches before approved designs were sculpted into five-foot maquettes and scanned into a computer. Animators would then rig skeletons and muscles before animation and final detailed colouring scanned from painted maquettes. Treebeard
Treebeard
Treebeard is a fictional character from J. R. R. Tolkien's Middle-earth fantasy writings. The eldest of the species of Ents, he is said to live in the ancient Forest of Fangorn and stands fourteen feet in height and is tree-like in appearance, with leafy hair and a rigid structure. Fangorn Forest...
had a digital face composited upon the original animatronic, which was scanned for the digital model of his longshots.
As well as creatures, WETA also created highly realistic digital doubles for many miniature longshots, as well as numerous stunts, most notably Legolas. These doubles were scanned from having actors perform movements in a motion-capture suit, and with additional details created using ZBrush
ZBrush
ZBrush is a digital sculpting tool that combines 3D/2.5D modeling, texturing and painting. It uses a proprietary "pixol" technology which stores lighting, color, material, and depth information for all objects on the screen...
. There are even morphs between the doubles and actors at times. Horses also performed with mo-cap points on them, although deaths are animation.
Weta began animating Gollum in late 1998, using a generic human muscle system, to convince New Line they could achieve it. Andy Serkis
Andy Serkis
Andrew Clement G. "Andy" Serkis is an English actor, director and author. He is popularly known for playing Gollum in The Lord of the Rings film trilogy, for which he earned several award nominations, including the Saturn Award for Best Supporting Actor for his performance in The Two Towers...
played Gollum by providing his voice and movements on set, as well as performing within the motion capture
Motion capture
Motion capture, motion tracking, or mocap are terms used to describe the process of recording movement and translating that movement on to a digital model. It is used in military, entertainment, sports, and medical applications, and for validation of computer vision and robotics...
suit. His scenes were filmed twice, with and without him. Originally Gollum was set to solely be a CG character, but Jackson was so impressed by Andy Serkis' audition tape that they used him on set as well. A team led by Randy Cook performed the animation using both motion capture data and manual recreation of Serkis' facial reference.
Gollum's CG model was also redesigned during 2001, now using a subdivision surface
Subdivision surface
A subdivision surface, in the field of 3D computer graphics, is a method of representing a smooth surface via the specification of a coarser piecewise linear polygon mesh...
model instead of the NURBS model for Fellowship (a similar rebuild was also done for the digital doubles of the lead actors), when Serkis was cast as Sméagol, Gollum's form before he is cursed by the One Ring, so as to give the impression that Andy Serkis as Sméagol transforms into the CG Gollum. The original model can still be glimpsed briefly in the first film. Over Christmas 2001 the crew proceeded to reanimate all the previous shots accordingly within two months. Another problem was that the crew realized that the cast performed better in the versions of the film with Serkis. In the end, the CG Gollum was often animated on top of these scenes and Serkis would be painted out. Due to Gollum not being human, shots such as him crawling down a sheer cliff were shot with no live reference. Serkis also did motion-capture for the character which would drive the body of the model, whilst animators did all fingers and facial animation. Gino Acevedo supervised realistic skin tones, which for the first time used subsurface scattering
Subsurface scattering
Subsurface scattering is a mechanism of light transport in which light penetrates the surface of a translucent object, is scattered by interacting with the material, and exits the surface at a different point...
shader
Shader
In the field of computer graphics, a shader is a computer program that is used primarily to calculate rendering effects on graphics hardware with a high degree of flexibility...
, taking four hours per frame
Film frame
In filmmaking, video production, animation, and related fields, a film frame or video frame is one of the many still images which compose the complete moving picture...
to render. Render time refers to the amount of time it took the computer to process the image into a usable format; it does include the amount of time it took the texture artists to "draw" the frame. The hair dynamics of CG Gollum in The Two Towers were generated using Maya
Maya (software)
Autodesk Maya , commonly shortened to Maya, is 3D computer graphics software that runs on Microsoft Windows, Mac OS and Linux, originally developed by Alias Systems Corporation and currently owned and developed by Autodesk, Inc. It is used to create interactive 3D applications, including video...
Cloth. Because of its technical limitations, Weta subsequently moved to the Syflex
Syflex
Syflex is one of the fastest and most powerful cloth simulators. It is being used by a wide range of creative companies and individuals, from big-name studios, to smaller special effects houses and independent animators. Syflex is available For Maya, Softimage, Houdini and LightWave....
system for The Return of the King.
Christoper Hery (ILM), Ken McGaugh and Joe Letteri
Joe Letteri
Joe Letteri is a senior visual effects artist, winner of 4 Academy award, 4 BAFTAs and 4 VES. He is the current Director of the Academy Award-winning Weta Digital, having joined the company in 2001. He has been the visual effects supervisor of several movies, his latest work being Avatar...
(both Weta and previously ILM) received a 2003 Academy Award, Scientific or Technical
Academy Award, Scientific or Technical
Since 1931, the Academy of Motion Picture Arts and Sciences has given the Scientific and Technical Award, an Academy Award for scientific or technical achievements, which are presented at "a dinner ceremony separate from the annual telecast."...
for implementing the BSSRDF
Bidirectional scattering distribution function
The definition of the BSDF is not well standardized. The term was probably introduced in 1991 by Paul Heckbert. Most often it is used to name the general mathematical function which describes the way in which the light is scattered by a surface...
technique used for Gollum's skin in a production environment. Henrik Wann Jensen
Henrik Wann Jensen
Henrik Wann Jensen is a Danish computer graphics researcher. He is best known for developing the photon mapping technique as the subject of his PhD thesis, but has also done important research in simulating subsurface scattering and the sky....
(Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...
), Stephen Robert Marschner (Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...
and previously Stanford University), and Pat Hanrahan
Pat Hanrahan
Pat Hanrahan is a computer graphics researcher, the Canon USA Professor of Computer Science and Electrical Engineering in the Computer Graphics Laboratory at Stanford University....
(Stanford University) (but not the fourth coauthor Marc Levoy
Marc Levoy
Marc Levoy is a computer graphics researcher and Professor of Computer Science and Electrical Engineering at Stanford University. He is noted for pioneering work in volume rendering....
), who developed BSSRDF, won another the same year.
Programs
MASSIVE was the name of a computer program developed by WETA to create automatic battle sequences rather than individually animate every soldier. Stephen RegelousStephen Regelous
Stephen Regelous is a pioneering computer graphics software engineer from New Zealand. He is best known as the creator of the Massive simulation system that generated the battle scenes of the Peter Jackson movie trilogy The Lord of the Rings. In 2004, Regelous received an Academy Award for...
developed the system in 1996, originally to create crowd scenes in King Kong. The system creates a large number of choices for each software agent
Software agent
In computer science, a software agent is a piece of software that acts for a user or other program in a relationship of agency, which derives from the Latin agere : an agreement to act on one's behalf...
to pick when inside a digital arena. Catherine Thiel provided the movements of each type of soldier, like the unique fighting styles (designed by Tony Wolf) or fleeing. To add to this, digital environments would also be created for the simulations. Massive also features Grunt, a memory-conservative special purpose renderer, which was used for scenes containing as much as 200,000 agents and several million polygons. The Pelennor Fields scene also contains "multi-body agents" in the form of a 5 × 5 grid of Orcs.
Whilst Jackson insisted on generally using miniatures, sometimes shots would get too difficult for that, primarily with the digital characters. Gray Horsfield led the creation of digital versions of Dwarrowdelf, the Chamber of Mazarbul, ruins in Eregion
Eregion
In the fiction of J. R. R. Tolkien, Eregion or Hollin was a kingdom of the Noldorin Elves in Eriador during the Second Age, located near the West Gate of Moria under the shadow of the Hithaeglir . Its capital was Ost-in-Edhil...
, Helm's Deep, the Barad-dûr and Black Gate for complicated sequences, such as destruction or having an arena for a digital camera to move around. He himself spent his entire Christmas
Christmas
Christmas or Christmas Day is an annual holiday generally celebrated on December 25 by billions of people around the world. It is a Christian feast that commemorates the birth of Jesus Christ, liturgically closing the Advent season and initiating the season of Christmastide, which lasts twelve days...
2002 break creating the Barad-dûr for The Return of the Kings climax. Sometimes natural elements like cloud, dust, fire (which was used as the electronic data for the Wraithworld scenes and the Balrog) would be composited, and natural environments were composited to create the Pelennor Fields.
To give a "painterly" look to the films, cinematographer Andrew Lesnie
Andrew Lesnie
Andrew Lesnie is an Australian cinematographer. Lesnie attended the Australian Film Television and Radio School , graduating in 1979. His first job after graduation was as a cameraman on the Logie Award-winning Australian magazine-style afternoon TV show Simon Townsend's Wonder World...
worked on every scene within the computer to strengthen colours and add extra mood and tone to the proceedings. Gold was tinted to Hobbiton, whilst cooler colours were strengthened into Lothlórien, Moria and Helm's Deep. Such a technique took 2–3 weeks to do, and allowed some freedom with the digital source for some extra editing.
The Lord of the Rings: The Return of the King
The Lord of the Rings: The Return of the King
The Lord of the Rings: The Return of the King is a 2003 epic fantasy-drama film directed by Peter Jackson that is based on the second and third volumes of J. R. R. Tolkien's The Lord of the Rings...
required the help of the company Next Limit Technologies
Next Limit Technologies
Next Limit Technologies is a computer software company based in Madrid, Spain. Founded in 1998 by engineers Victor Gonzalez Sanchez and Ignacio Vargas the firm now creates cross-platform particle simulation and light simulation software for fluid and rigid body modeling, and accurate visual rendering...
and their software RealFlow
RealFlow
RealFlow is a fluid and dynamics simulator for the 3D industry, created by Madrid-based Next Limit Technologies. Currently at version 2012, the stand-alone application can be used to simulate fluids, water surfaces, fluid-solid interactions, rigid bodies, soft bodies and meshes...
to simulate the lava in Mount Doom
Mount Doom
Mount Doom is a volcano in J. R. R. Tolkien's Middle-earth legendarium. It is located in the heart of the black land of Mordor and close to Barad-dûr, it is approximately high. Alternative names, in Tolkien's invented language of Sindarin, include Orodruin and Amon Amarth...
.
A technical overview of the special effect is given by Matt Aitken et al. (2004).