I Learned How To Fake Water Exactly Like Hollywood
Summary
TLDRThis script delves into the complexities of computer-generated imagery (CGI), particularly in simulating realistic water in films. It explores the evolution of CGI water from simple sine wave animations to sophisticated fluid dynamics simulations. Highlighting the challenges faced by VFX artists, the script interviews Chris White, a VFX supervisor involved in 'Avatar' sequels, to understand the principles behind creating photorealistic water. The journey illustrates the balance between technological tools and the artist's intuition in crafting visually compelling and story-driven effects.
Takeaways
- 🌐 The advancement in computer graphics has made it possible to create highly realistic visuals, including complex elements like water in films.
- 🎨 Water is considered a challenging element to simulate in CGI due to its intricate and complex nature.
- 🎬 The film 'Nad' exemplifies the effort required to create computer-generated water that moves and behaves convincingly.
- 💧 Hollywood movies often feature fake water that is virtually indistinguishable from real water, showcasing the high skill of VFX artists.
- 👨💻 Chris White, a VFX supervisor, played a key role in developing a new water pipeline for 'Avatar' sequels and worked on 'Nad', emphasizing the importance of water's role in storytelling.
- 🔍 Understanding the principles of water is crucial for creating realistic simulations, more so than the specific tools used.
- 🛠️ The in-house system 'Loki' was developed for the 'Avatar' sequels but is not available to the public, indicating that advanced tools are often proprietary.
- 📚 The history of fluid dynamics and its application in computer graphics has evolved significantly, with early methods being simple but not physically accurate.
- 🌊 Films like 'Water World' and 'Titanic' used a combination of linear displacement and particle simulations to create the appearance of water.
- 💡 The breakthrough in combining volume-based and particle-based simulations for fluid dynamics was seen in the film 'Antz', allowing for more realistic water movement.
- 🎭 The artist's role in CGI is to use their intuition and creativity to refine simulations, ensuring they serve the story and achieve photorealism.
Q & A
What is the main challenge in creating photorealistic CGI water?
-The main challenge in creating photorealistic CGI water is understanding and replicating the complex physical properties and behaviors of water, such as its reflective and refractive qualities, as well as its interactions with other elements like air and surfaces.
Why was the water in the film 'Nad' created using CGI?
-The water in 'Nad' was created using CGI because the filmmakers wanted to control the direction and movement of the water to help tell the story, which could not be achieved with practical effects within the limitations of a water tank.
What role did Chris White play in the development of CGI water?
-Chris White played a pivotal role in the development of Weta Digital's new water pipeline for the 'Avatar' sequels and also worked on 'Nad', contributing to the advancement of CGI water simulation techniques.
What is an 'in-house system' in the context of CGI water simulation?
-An 'in-house system' refers to a proprietary software or set of tools developed specifically by a company for their own use, in this case, for creating and managing CGI water simulations.
What does the term 'Loki' refer to in the script?
-In the script, 'Loki' refers to the in-house system developed by Weta Digital for simulating water in their CGI projects, which was used in the making of the 'Avatar' sequels.
How did the understanding of fluid dynamics contribute to the early stages of CGI water simulation?
-The understanding of fluid dynamics provided the foundational principles that were translated into mathematical models and algorithms, which were then implemented in early computer graphics to simulate the behavior of water.
What was the significance of the film 'Water World' in the history of CGI water simulation?
-The film 'Water World' was significant because it was one of the first to use actual oceanographic and atmospheric data to emulate the waves of the open ocean, marking a step forward in the realism of CGI water.
What is the difference between particle simulations and volume simulations in CGI water?
-Particle simulations are good at retaining volume but struggle with solving for velocity and pressure, while volume simulations excel at calculating pressure and velocity but have difficulty with retaining volume and capturing splashes or other small-scale water behaviors.
How did the film 'Ants' (1998) contribute to the advancement of CGI water simulation?
-The film 'Ants' contributed by combining the benefits of both particle and volume simulations to create a more realistic and dynamic representation of water, marking a landmark achievement in CGI fluid simulation.
What is the role of the artist in the process of creating photorealistic CGI water?
-The role of the artist is crucial in the process of creating photorealistic CGI water as they use their intuition and artistic vision to make manual tweaks and decisions that enhance the realism and storytelling aspects of the water simulation.
What software was used in the script to attempt creating a photorealistic river?
-Houdini was the software used in the script to attempt creating a photorealistic river, allowing the user to apply their understanding of fluid dynamics and CGI techniques.
Outlines
🎨 The Art of CGI Water in Film
This paragraph delves into the complexities of creating computer-generated imagery (CGI) for water in films. It discusses the challenges faced by visual effects (VFX) artists in replicating the intricacies of water and highlights the impressive work done in films like 'Nad' and 'Avatar'. The speaker expresses intimidation by the task and seeks advice from Chris White, a VFX supervisor who contributed to 'Avatar' and 'Nad', about the tools and techniques used in the industry. The importance of understanding water's behavior is emphasized, and the limitations of in-house systems like Loki are mentioned, suggesting that such tools are not accessible to everyone.
🌊 The Evolution of Water Simulation in CGI
This section traces the history and development of water simulation in computer graphics, starting from the basics of fluid dynamics to the application in films. It explains how early computer graphics struggled with water visualization, often resorting to practical effects. The paragraph discusses the transition from simple sine wave simulations to more complex methods like linear displacement and particle simulations, as seen in films like 'Water World' and 'Titanic'. It also touches on the limitations of particle simulations and the need for a more comprehensive approach to fluid dynamics in CGI.
🚀 Bridging the Gap: Combining Volumes and Particles for Realistic Fluids
The third paragraph focuses on the technical advancements in CGI that allowed for more realistic fluid simulations. It describes the challenges of using volumes and particles separately and how the film 'Ants' (1998) pioneered a method that combined the benefits of both approaches. This breakthrough enabled the creation of CG fluids that could move and interact more naturally. The paragraph also outlines the progress made in fluid simulations over the years, with examples from films like 'The Perfect Storm', 'The Day After Tomorrow', and 'Pirates of the Caribbean: At World's End', showcasing the increasing sophistication and control in CGI water effects.
🖌️ The Artist's Role in Achieving Photorealistic CGI Water
In this paragraph, the speaker shares their personal journey of attempting to create photorealistic water using Houdini, a 3D animation software. They discuss the process of setting up a simulation with a dry ravine and rocks, and the reliance on pre-existing mathematical models to handle the physics of fluid dynamics. The speaker realizes that despite the advancements in technology, the artist's intuition and manual adjustments are crucial for achieving the desired level of realism. They consult with Chris again to understand the current state of water simulation in films like 'Avatar' and the importance of artist involvement in fine-tuning the simulation results.
🎬 The Final Touch: Artistic Intuition in CGI Water Rendering
The final paragraph concludes the speaker's quest to create realistic CGI water. They reflect on the importance of artistic intuition in the rendering process, beyond the mathematical and scientific aspects. The speaker manually tweaks the render to address issues like the lack of wetness on the riverbed, light breakup on the water surface, and the absence of foam and cavitation. The result is a photorealistic water render, which underscores the significance of the artist's role in storytelling through visual effects. The paragraph ends with a philosophical note on the harmony between technology and artistry in creating beautiful and believable imagery for the screen.
Mindmap
Keywords
💡Computer Graphics
💡CGI
💡Water Simulation
💡Photorealism
💡Fluid Dynamics
💡Particle Simulation
💡Volumes
💡Houdini
💡State Machine
💡Artistic Vision
💡Cavitation
Highlights
The complexity of creating CGI water and its importance in films like 'Nad' where all the water was fake yet realistic.
Chris White's role in developing a new water pipeline for 'Avatar' sequels and his work on 'Nad'.
The significance of water movement in storytelling and its enhancement through CGI in 'Nad'.
The limitations of traditional methods like green screen with water and the evolution to computer-generated water.
The development of the in-house system 'Loki' for simulating water in 'Avatar' sequels.
The importance of understanding the principles of water over the tools used for simulation.
The history of fluid dynamics and its application in computer graphics for water simulation.
The challenges of simulating water's interaction with other visual effects like green screen.
The use of oceanographic data in 'Water World' to emulate realistic ocean waves.
The introduction of particle simulations to create effects like bubbles in 'Titanic'.
The limitations of particle simulations in capturing the physics of water.
The breakthrough in combining volume and particle methods in 'Antz' for more realistic fluid simulation.
Advancements in fluid simulations from 'The Perfect Storm' to 'Pirates of the Caribbean'.
The philosophical question of whether it's possible to perfectly simulate water physics.
The role of the artist in shaping the simulation process and the importance of storytelling.
The realization that artistry is crucial in the final touches of CGI water to achieve photorealism.
The final outcome of creating photorealistic water and the appreciation for the artist's role in CGI.
Transcripts
welcome to the wonderful world of
computer Graphics you know this place is
pretty great these days we can make just
about anything in here robots Aliens big
old worms and of course Henry C's upper
lip but I bet you didn't realize how
much CGI was in this scene there you go
oygen please this is a scene from the
film naad and it required just as much
effort to create in the computer as any
of the other examples because all of the
water you are seeing is fake and I don't
think people understand how crazy that
actually is and it's not just this film
most Hollywood movies these days are
filled with fake water that is basically
invisible to the public because it's
just that good as a VX artist I've
always found water to be very
intimidating we've replicated so much of
the intricacy of nature but water is so
complex it's very difficult to recreate
which is why this water looks like crap
but what if I could make it not look
like crap what if I could create a river
entirely in the computer that is 100%
photo well I'd have to figure out what
tools were used on films like niad and
Avatar way of water to accomplish their
incredible CG fluids and what better way
to do that then talk to somebody who
knows the way of water better than
anyone else we are joined by what FX
supervisor Chris White how you doing
Jordan I'm doing very good Chris played
a pivotal role in the development of
what effect's new water pipeline for the
Avatar sequels but he also worked on
niad my first question when I did see
the VFX breakdown of NAD is why why why
why would you do do this with niad it
was really important to the filmmakers
that the current and the direction and a
movement of the water helped tell the
story that she was being guided with the
current and she was working with it or
she was working against it they weren't
able to capture all of that within the
tank so we came in to help sell that
story point and it was important to not
bring the viewer out of the picture
there's scenes that were extreme
close-ups we know that has to look great
for it to be beli for the audience do
you feel that given where technology is
that I would be capable of creating
something at home that is photorealistic
when it comes to water the key to it is
understanding the principles and the
look of it on way of the water we spent
years like we literally took a
whiteboard erased it started with a
single drop and said okay what's
happening with water and did a deep dive
and studied all of those principles we
created our in-house system that we
built which um is called Loki
our inhouse system that we built like in
houses and we're not allowed our inhouse
system that we built it's not available
for like
me I guess that's it huh the tools I
need are behind closed doors for the
elites I'm not
Elite can't even make water just a
peasant begging for scraps from the
king's table in this case the king's a
really nice guy Chris was lovely thank
you Chris all I wanted to make is a
fully simulated 100% photorealistic
River Dean is that too much to ask but
Chris did say something interesting he
said that the tools don't matter as much
as understanding the principles of water
you know Chris is right if I can just
learn all I can about creating simulated
water then I wouldn't need their fancy
tools even a dirty peasant like me would
be capable of creating CG water that
holds up to the real thing
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you know diving into water simulation
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sorry let's get back to
that so I dove real deep into computer
generated water and in its history I
believe lie the tools to simulate my
River it all starts obviously with how
real water flows the study of fluid
dynamics has actually been around for a
few hundred years fluid dynamics allows
us not only to understand the flow of
liquids but also the flow of gases like
how air bends around the wing of a plane
the laws that guide fluid dynamics are
surprisingly straightforward you can
actually write the critical equations on
the palm of your hand look at that I
don't know what it means but it fits and
I got tiny hands now it wasn't long
after the invention of the computer that
this math was brought into the digital
realm but while the laws are somewhat
simple to outline their actual
application is incredibly complex to
simulate and then orders of magnitude
harder to actually visualize because it
would take another 30 years for computer
Graphics to bring the first genuine
fluid simulation to film prior to this
the only way to visualize water in
movies was well with
water whether it was massive water tanks
being dumped onto real sets or smaller
tanks of water used in conjunction with
Miniatures there was only so much that
could be achieved visually and it really
didn't help that water didn't exactly
play nice with other methods of visual
effects of the time namely green screen
see water is very difficult to capture
on a green screen due to the fact that
it both refracts and reflects the green
of the screen and it's not like you can
manipulate real water with stop motion
either so if you couldn't get the water
to do what you wanted on camera well
tough luck because you couldn't get it
any other way but by the 9s computer
Graphics began to dip its little toe in
the water simulation World it started
with characters that had the appearance
of water like the pseudopod from the
abyss or the T1000 from Terminator 2
which we've made separate videos about
but this was essentially using sine
waves to change the height of the points
on the surface surface of the characters
giving the illusion of a liquidy
organism but what if you have a film
that is a literal world of
water 1995's atly named water world was
the first film to use actual
oceanographic and Atmospheric data to
emulate the waves of the open ocean this
allowed the production to replace the
Horizon around their massive ship sets
with photoreal CG water I mean look at
this this looks great looks like an
ocean moves like an ocean I might as
well just use this 30-year-old method to
simulate my river right well similar to
previous effects it's simply a linear
displacement of the ocean's surface now
what the heck does that even mean well
if we look at this we have a grid with a
simple texture on top of it a black to
white map basically what I want to tell
the computer is hey any elements that
are pure white be the highest point and
anything that is pure black be the
lowest point so if we have an animated
map and that map moves like ocean waves
technically we should be able to use the
same approach to create what looks like
ocean waves
T so this is great this gives the
illusion of an ocean surface but in
reality it's just a grid that's being
displaced in the exact same way we saw
previously now what that means for us is
well it's not real physics we can't ever
get any real waves because at the end of
the day these are points that are being
displaced up or down and in that way
we'll never have a wave dynamically
crash over its neighboring points it's
all just trickery at the end of the
day a similar method to this was used to
even greater effect in 1997's Titanic
like water world it's a linear
displacement of the ocean's surface but
there were a few physics-based
simulations used in the CG of Titanic
and to create this River we're going to
need those physics when we see the
propellers of the ship you can see these
tiny bubbles being churned up by this
machine there was actually a version of
this effect achieved in camera with a
miniature but Cameron thought the
bubbles created were too big to achieve
this massive sense of scale of the ship
they needed to be even tinier so the VFX
team used a particle simulation you see
particles had existed since 1983 and
these little guys could actually
simulate gravity as well as collisions
with other objects now in the real world
bubbles are generated through this
entirely complex physical reaction to
the propellers and what the water's
actually made of we don't have to worry
about any of that what if we could just
create particles on the edges of the
blade and shoot them out into 3D space
well we get a really cool looking result
we got lots of little buddies floating
out into the ether these obviously are
not bubbles right these are actually
just tiny little points in 3D space that
we are shooting out not a lot of math
but you do get a very cool result so if
we can simulate particles and we can
affect the forces of how they move then
why not just use particles to simulate
my River but if we just pause this
simulation let's zoom in and take a
little bit of a look around look these
particles are actually phasing through
each other in a particle simulation
particles don't interact with each other
they're like New
Yorkers sorry I didn't mean sorry but
what do I mean by that well I can
actually show you with another
simulation here we have a stream of
particles that are being poured into a
box if you'll notice when the Spheres
make contact with each other well
they're not really making contact at all
they all just fall and collapse through
each other as if their neighbors don't
even exist now these particles can
simulate very quickly when they're only
concerned with themselves like New York
is sorry still funnier in my head I
swear I'll land it but imagine how much
more complex it gets when every single
one of these particles needs to know
where its thousand plus neighbors are
every single frame that's a lot of
additional math and if you add 10 times
the math to a calculation guess what
it's going to take 10 times longer to
calculate and this is not a large number
of particles not even close imagine how
many more you would need to simulate a
body of water let alone a full raging
River and then try doing that on a '90s
PC where the most realistic game you'd
ever played was
doomed and even if you had the patience
to simulate all of those interactions
particles really only work well for
emulating some of the phenomena
generated by water because particle
simulations don't really scale that well
what we need is a better way to track
the Dynamics of a fluid system namely
the pressure which is the areas of least
resistance and the velocity which is the
speed and direction of
motion now there is another framework of
thinking about 3D space which is key to
tracking these Dynamics until now we've
been thinking in terms of individual
points in space you know these little
dudes but what if instead we think about
3D space as a volume of 3D cubes
essentially these cubes are containers
of data that can pass information
between themselves so using those
elegant fluid Dynamic equations we can
Define how pressure and velocity move
data through space so that's it we're
done here let's just use volumes to
simulate this River well not so fast me
you see the issue with volumes is
ironically it's imperfect ability to
track how much volume is in it and what
I mean by that is in a volume simulation
you can't really get a splash of water
separating from the larger body and then
recombining with it because it'll shrink
away into nothingness before it lands
and it's gone so this was the Dilemma in
the late '90s volumes are great at
solving velocity and pressure but bad at
retaining volume and particles are great
at retaining volume but bad at solving
for velocity and pressure but in 1998
one film was bold enough to attempt to
bridge this Gap to use the best of both
methods something not even Titanic the
most expensive film ever made to that
point was bold enough to attempt a
groundbreaking classic that you all
remember dearly I'm talking of course
about 1998's ants you're not serious are
you okay maybe ants isn't the most
memorable movie I have a thing about
drinking from the anus of another
creature but it will forever be
responsible for a truly Landmark
achievement look at that just bask in
the glory Now by today's standards maybe
it doesn't look realistic but heck it's
moving like water the team had to hire a
guy who had just finished his PhD to
even figure out how to do this unlike
Titanic and water world it's not just
the surface there was an undulating mass
that literally flows through space Nick
Foster who developed the simulation
software figured out how to take the
benefits of volumes and the benefits of
particles and combine them to create CG
fluid and over the next decade films
began to radically advance both the
speed and the level of complexity of
these fluid simulations there was 2000s
the perfect storm in which industrial
Light and Magic physically simulated
these enormous waves on top of which
were separate particle simulations to
replicate the foam and spray that would
be generated by the boat slamming into
them 2004 is the day after tomorrow with
an incredible flooding sequence where a
giant swell overtakes New York the film
was able to add precise guidance to the
fluid simulation like suction pumps and
whirl pools to control the flow of the
water and speaking of whirl pools who
could forget 2007's Pirates of the
Caribbean at World's
End look at that whirling dervish of CG
Beauty
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and of course Avatar in 2009 which by
many could be deemed as the start of the
modern era of water simulation CG water
was at the point where it could be
precisely directed to do the things that
we could never capture on camera but
still based in physics so we did it
after Decades of trial and error this
elegant MTH of fluid dynamics can now be
properly visualized by computer Graphics
now it's time to see if I can replicate
this magic on my own computer and what
better tool to use when trying to make
some magic than Houdini so since I've
now learned the ins and outs of fluid
simulations I've built my very own from
the ground up now before I can simulate
anything I have to give my River
something to run through and so I found
a photo scan online of a bone dry Ravine
I added a whole bunch of photo scans of
giant rocks and boulders so that those
liquids had something more Dynamic to
interact with so the reality is once I
have my source of water and my Collision
geometry I don't really need to worry
about too much more because like we've
talked about to this point the math has
been done right people much smarter than
me have crunched the numbers and devised
systems to calculate all of that math on
my behalf so all I need to do now is let
physics do its
thing here it is it's not bad like it
moves like water you get the sense that
it is rushing and gushing you know how
the water is literally getting trapped
and churning and spinning before rolling
back out but a lot of the detail
is missing in those areas for some
reason I mean this is nothing compared
to the insane photo realism you're
seeing in movies nowadays so I'm going
to go check back in with Chris to see
how I can take this render into the
realm of the photo real so Chris you
were a VFX supervisor on the original
Avatar and you were also a VFX
supervisor on way of water what are the
major like significant differences from
13 years ago with Avatar to now in terms
of what we can do with water it's still
the the same mathematical approach but
now we created this setup called the
state machine which does the main
simulation but it entrains the air as
well it creates the underwater bubbles
that will travel up and those become the
foam and then becomes the Mist so it's
all this integrated system so it all
works together it sounds like you've
built this state machine to press
simulate and then you have a result
although the the machine lets you do it
the the artist has control of the input
because after it comes out of the
machine there's there's a lot that goes
into sculpting the surfacing of the
water and making sure the parameters are
appropriate to get the maximum detail
you know do I want to make it choppier
so that I get more white water do I want
to have you know more foam or less foam
so the effects artists is making a lot
of decisions to get the result that they
want is it possible to perfectly
simulate the physics of water I think we
can simulate visually very realistic
water I think that gets into into deeper
philosophical like how like like there's
always some level of of detail that
you're simulating to you're not going
down to the the molecules or anything
like that so you do have to cheat it cuz
as you get into it you're like okay yeah
we've got it down to this little level
and you're like but if you really dig
into it more there may be silk that's
being kicked up there there's all these
complex systems I mean we're still at
the at the end of the day we we're still
making movies and it's about telling the
story that was part of the drive was
like if we can give the artist a good
system that looks good from the
beginning then they can spend more time
being artistic that's actually really
interesting that you say that it's
almost like even if we do reach a point
where on a molecular level we can
perfectly recreate water you would
almost still need the artist in order to
draw it in such a way that it tells the
story that needs to be told exactly it
it always comes down to that and the the
tools are there to help it look
realistic and they help give us control
but all the discussions and decisions
are made to that one point like what is
the story being told in this shot and
how do they affect support and help tell
that story I think I've had it backwards
I've been looking at it is you know more
on the tools than the artist but it
seems like the tools are there to
service the vision of the artist versus
the artist to drive the tool yeah it's
it's a it's that it's that support yeah
well Chris thank you so much for joining
us and lending us a little bit of your
expertise it's great just talking about
all this stuff and and kind of digging
into it you know after talking to Chris
I started to realize that in order to
take this render across the Finish Line
I I need to start using my eye as an
artist more so naturally I looked at
real Rivers right reference and I
started to notice the differences
between my render and the stuff that I
was seeing from actual footage real
Rivers the water actually makes the dirt
that it goes over wet in real Rivers
you're getting a much greater breakup of
the overall light on the surface it's
not so globular and perfect like it is
in this render you're getting
volumetrics from inside the body of the
river itself as it moves over dirt and
churns it up into like a thick Inky
paste and of course we're missing a
crucial aspect of this cavitation right
the foam the bubbles beneath the surface
the spray there's nothing here it's just
perfect glassy texture and for all of
these problems I can't just click a
button and solve them I'm going to have
to use my own intuition as an artist
until I'm happy with the final image
well I made those manual tweaks and this
is the
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result I'm I'm very proud looking at
this final image I achieved what I set
out to do I created photorealistic water
and that's awesome but what I've taken
away is how much the hand of the artist
still drives this process Math and
Science without that spark of humanity
is soulless so knowing just how much of
what we see on the big screen is
thoughtfully crafted just makes it that
much more beautiful
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