Waterfall

To follow the steps of this tutorial, the minimum requirements are Phoenix 5.01.02 Nightly, Build from 5th of December 2022 and V-Ray 6 Official Release for 3ds Max 2018 at least. You can download nightlies from https://nightlies.chaos.com and get the latest official V-Ray from https://download.chaos.com. If you notice a major difference between the results shown here and the behavior of your setup, please reach us using the Support Form.

The instructions on this page guide you through the process of using Phoenix to create a grand magnificent waterfall. If you want to create a small waterfall, you can use the Waterfall quick preset from the Phoenix toolbar as a starting point.

The Download button below provides you with an archive containing the scene file.

Download Project Files

Scale is crucial for the behavior of any simulation. The real-world size of the Simulator in units is important for the simulation dynamics.

Large-scale simulations appear to move slower, while mid-to-small scale simulations have lots of vigorous movements.

When you create your Simulator, check the Grid rollout where the real-world sizes of the Simulator are shown. If the size of the Simulator in the scene cannot be changed, you can trick the solver into working as if the scale is larger or smaller by changing the Scene Scale option in the Grid rollout.

The Phoenix solver is not affected by how you choose to view the Display Unit Scale — it is just a matter of convenience. Setting the units to Meters is a reasonable choice for this setup.

Go to Customize → Units Setup and set Display Unit Scale to Metric Meters. Also, set the System Units so that 1 Unit equals 1 Meter.

Here is the final scene layout. It consists of the following elements:

1. A Phoenix Liquid Simulator.
2. Scene geometry: Cliff_Terrain and Rock01~12.
3. A Phoenix Liquid Source emitting from Plane_Emitter.
4. Three Particle Shaders for the Foam, Splash and Mist particles respectively.
5. PHXTurbulence Force to disturb the Mist particles.
6. A Particle Tuner is used for limiting the affected region of the Plain Force.
7. A Phoenix Plain Force as a wind force pushing the liquid more toward the cliff.
8. Cliff_terrain geometry for the terrain. It is roughly 125 meters in height.
9. A Box_pool geometry with its Phoenix properties set to Initial fill, for the pool at the bottom of the waterfall.
10. A Box_particletuner geometry that is used in the Particle Tuner as Distance to condition.

For the Plane_Emitter, let's add a Shell modifier to it. And set one side of faces to ID = 2. Then we rotate it 160.0 degrees on the X axis, so the emitted fluid stream points toward the terrain.

The final scene consists of the following elements:

1. V-Ray Light Dome for lighting;
2. A V-Ray Physical camera.

Set the Animation Length parameter appearing in the Time Configuration window to 230, so that the Time Slider goes from 0 to 230.

The image here is the final render in this tutorial. The river falls from a 125-meter cliff to form a waterfall. Rocks in the river splash water. At the bottom of the waterfall there is a pool where misty air rises. Gradually more and more splashes and mist accumulate at the bottom.

Let's go through the steps and see how to build these features.

Let's start by creating a Liquid Simulator. Go to Create Panel → Create → Geometry → PhoenixFD → PhoenixFDLiquid.

The exact position of the Simulator in the scene is XYZ: [ 76.0, -14.2, 7.8 ].

From the object color swatch, change the color to turquoise. We give the simulator mesh a turquoise color instead of blue, to make it distinguishable from the splash particles (which are in blue by default).

Open the Grid rollout and set the following values:

Open the Output rollout and make sure you have the Liquid's Particle Velocity, Grid Liquid, and Grid Velocity enabled. Leave everything at its default.

Add a Liquid Source from Helpers → Phoenix FD → Liquid Source.

The Liquid Source is a Phoenix helper node. It determines which objects in the scene the Simulator emits from, how strong the emission is, etc.

Add the Plane_Emitter geometry to the Emitter Nodes list.

Once the emitter is added, set the Outgoing Velocity to 2.5 m.

Set the Emit Mode to Surface Force. This makes the object emit only from its surface area.

Set the Polygon ID to 2.

At this stage, we don't need to simulate the full length of the animation. We only need a sample. Go to the Simulation rollout and set the Stop Frame to 180.

Press the Start button to simulate.

Go to the Preview rollout, and enable Show Mesh. Disable all other Voxel Preview channels, so they don't interfere.

Here is a preview animation of the simulation up to this step.

As you can see, the water is too slow. It has is simulated for 180 frames, but still has not reached the edge of the cliff. Let's increase the Time Scale for some frames, so the water can become waterfall in a shorter time range.

With the Simulator selected, go to the Dynamics rollout and set key frames to the Time Scale.

Go to Graph Editors/Track View > Curve Editor and set key frames to the curve of the Simulator's Time Scale. Setting keyframes to the Time Scale allows the water to run faster until frame 125. Each frame and value is shown in the screenshots. All keyframes are set to Tangents to Stepped.

Run the simulation again.

Here is a preview animation of the simulation so far.

Now we start to see a waterfall as the water flows down the cliff.

From a side view, you can see the waterfall is away from the cliff terrain.

To push the water back toward the cliff, we use a Phoenix Plain Force for the task.

Go to Create Panel > the Helpers tab > Phenix and add a Phoenix Plain Force in the scene.

Here is a preview animation of the simulation.

From the side view, we can see that the water now keeps closer to the cliff.

With the liquid simulator selected, go to the Splash/Mist rollout.

Enable the Splash/Mist option. When asked if you'd like a Phoenix Particle Shader generated for the Splash particles, select Yes. This automatically sets up the link between the Splash particles group, the Particle Shader, and the Liquid Simulator.

Rename the new particle shader to ParticleShader-Splash. 

Run the simulation again.

With the simulator selected, in the Preview rollout, enable Particle Preview.

To easily spot which particles are which, let's change the color swatches for the different particle types.

Disable the Liquid particle preview. Set the Splash, Mist, and Foam to Blue (RGB: 0, 0, 255), Red (RGB: 255, 0, 0), and Green (RGB: 0, 255, 0) color respectively.

Now we start to see splash particles in the simulation. But too much liquid gets converted to splash/mist. We'd like both the Mist particles need to be less, and the Liquid particles to remain more numerous. See the FLIP Particles Life Cycle for more information on how liquid converts into splash and mist particles.

Here is how we know the Mist particles are too much:

With the the simulator selected, under the Simulation rollout you can see the Cache File Content window.

Visible from the data, the Mist particles vastly outnumber the Splashes particles. In a waterfall simulation the Mist is less important than splashes, so we will reduce the mist particles number - they are taking away valuable simulation time now.

With the simulator selected, go to Splash/Mist rollout, decrease the Splash to Mist to 0.1. This way fewer splash particles are converted to mist. Decrease the Mist Amount to 0.05.

In the Properties section, reduce the Affect Liquid to 0.3. This reduces the amount of liquid particles being converted to splash/mist particles.

Run the simulation again.

Here is a preview animation of the simulation up to this step. Now we have considerably less mist particles and retain of more liquid particles. Now the amount of Liquid, Splash, and Mist particles is now in good proportion.

The dynamics of the splash/mist look okay, but they need more drag for a great looking waterfall.

With the simulator selected, go to the Dynamics rollout. Enable the Simulate Air Effects option.

Run the simulation again.

Here is a preview animation of the simulation up to this step. With the Air Effects enabled, now the dynamics of falling splashes and mists look more convincing.

To further enhance the heavy look of splash/mist falling, let's increase their Air Drag. With the simulator selected, in the Splash/Mist rollout - Properties set the Splash Air Drag to 2.0 and Mist Air Drag to 3.0.

With those new settings, run the simulation again.

Here is a preview animation of the simulation up to this step.

To make the distribution of the Splash more distinct, let's increase the Threshold of the Splash/Mist to 20.0. To compensate the decreased number of splashes, increase the Splash Amount to 20.0.

Here is a preview animation of the simulation up to this step. Now the distribution of the splashes looks good.

With the simulator selected, go to the Splash/Mist rollout. Increase the By Free Fly to 0.4.

Here is a preview animation of the simulation up to this step. We have more splashes generated when the liquid is in free fall.

Select the Foam rollout of the Phoenix Liquid Simulator and enable it. A pop out window prompts us to create a Particle Shader for the foam, so select Yes.

Rename the new Particle Shader to ParticleShader-Foam.

With the simulator selected, go to the Foam rollout. Set the Half Life to 3.0. Decrease the Size to 0.075 m.

In the Foam on Hit section of the Splash/Mist rollout, set the Foam on Hit Amount to 1.0. Set Min. Age to 0.1.

Run the simulation again.

Now we start to see foam particles being generated in the scene, but they are shooting upward in an unrealistic way.

Let's focus on the Foam dynamics now.

With the Simulator selected, go to the Foam rollout. In the Dynamics section, reduce the Rising Speed to 1.5m (this means that foam bubbles underwater travel upwards are 1.5 meters per seconds). Decrease the Falling Speed to 12.0m (this means that foam particles flying in the air fall at 12 meters per second).

Here's a preview animation of the simulation. Now the foam movement looks convincing.

With the Simulator selected, go to the Foam rollout. In the Patterns section, set the Formation Speed to 1.5 and Radius to 1.6m.

Here is a preview animation of the simulation up to this step.

Go to Create Panel → Geometry → Standard Primitives → Box . Create a box in the scene. Rename the box to Box_Pool.

Set its Length, Width and Height to 103.0 m, and 294.0m and 6.3m respectively. Segs from all sides to 1.

The exact position of Box_Pool is XYZ: [0.77, -74.7, 8.24 ].

Since the Box_Pool only serves as initial fill liquid source, we don't have to render the geometry out. With the Box_pool selected, right-click → Object Properties. Enable the Display as Box option. Disable the Renderable checkbox.

With the  Box_Pool selected, right-click and select Chaos Phoenix Properties.

Enable Initial Liquid Fill. This option fills the geometry with liquid at the very beginning of the simulation.

Run the simulation again.

Here's a preview animation. Now we can see a pool at the bottom of the waterfall, but the pool water gets pushed toward the cliff by the Plain force. Let's fix it in the next step.

Go to Create Panel →Geometry→Standard Primitives → Box. Create a box in the scene. Rename the box to Box_ParticleTuner.

Set its Length, Width and Height to 87.0 m, 296.0m and 95.0m respectively. Segs for all axes can be set to 1.

The exact position of Box_ParticleTuner is XYZ: [0.0, -82.5, 23.0].

Since the Box_ParticleTuner is only used for the Particle Tuner in a later step, we don't have to render the geometry out. With the Box_ParticleTuner selected, right-click → Object Properties. Enable the Display as Box option. Disable the Renderable checkbox.

With the  Box_ParticleTuner selected, right-click and select Chaos Phoenix Properties.

Disable the Solid checkbox. This option will prevent the interaction of the box geometry with the liquid simulation.

Go to Create Panel → Helpers → PhoenixFD → ParticleTuner. Create a Particle Tuner anywhere in the scene.

With the Particle Tuner selected, click on the Edit Condition button to change the condition.

In the Edit Condition window, click on Age_phx, then the Edit Value Expression window shows up.

Switch the condition from Channel - Age to Distance To. Press the None button and choose the Box_ParticleTuner geometry in the scene.

Click on the Is Greater Than, so the Edit Compare Expression window shows on the right. Change the condition from Is Greater Than to Is Less Than.

Below the Is Less Than, change the value from 1.000 to 0.000. When a particle is inside the box geometry, the distance to the geometry will be a negative number, so this is why we set up the condition to "Is Less Than: 0.000".

Now that we're done with the condition settings, close the Edit Condition window. With the Particle Tuner selected, disable the Then - Viscosity checkbox - we don't want to change any of the channels, we just want to limit the effect of the plain force. Then, set the Buildup Time to 0.0 so the Tuner acts instantly, without delay. In the Affect by Forces, add the PlainForce in the scene.

With those new settings, run the simulation again.

Let's preview the animation.

To create a Phoenix Turbulence, go to the Create Panel →  Helpers→ PhoenixFD and click on PHXTurbulence.

Run the simulation again.

Let's preview the animation at this step.

For the final simulation, let's move the simulator and increase its grid size so it covers a larger region.

The exact new position of the Simulator in the scene is XYZ: [ 0.0, -14.2, 7.8].

Open the Grid rollout and set the following values:

Cell Size: 0.4 m
Size XYZ: [ 731, 556, 323]

Run the final simulation.

Here is a preview animation of the final simulation.

We have a Particle Shader for splashes and foam already. For the Mist particles, we have to create a new Particle Shader manually.

Go to Create Panel→ PhoenixFD and press the PHXFoam button to create a new Particle Shader in the scene. Rename it to ParticleShader-Mist.

Press the Add button and pick the Liquid Simulator, then select the Mist particle group. When doing so, a pop up window prompts you to add PhoenixFDLiquid in the Liquid Simulator slot of the shader, press Yes.

Set the ParticleShader-Mist mode to Fog.

Let's take a look at the water material now.

Create a V-Ray Material and assign it to the PhoenixFDLiquid Simulator. Set the Diffuse color to black.

Reflect and Refract colors are set to white - it produces a completely transparent material if the Index of Refraction is set to 1 (which is the IOR of clear air). But let's set the IOR to 1.333, which is the physically accurate Index of Refraction of water.

Keep the Max depth to its default value of 8 for both Reflection and Refraction.

To slightly blur the specular highlights produced by the sources of illumination in the scene, reduce the Reflection Glossiness to 0.95.

If we render now, we'd notice that the water is completely transparent and looks a bit boring.

Instead, let's switch the Translucency to Volumetric. Set the Fog color to RGB : [233, 236, 239] and set the Depth to 100.0.

Set Scatter color to RGB : [44, 140, 119]. Set SSS amount to 0.5. This produces the type of shading expected in a large body of water containing all sorts of particles that interfere with the light rays.

Run a test rendering. The splashes look too big. Let's fix the issue by adjusting the Particle Shader's settings in the next step.

Let's make some adjustments to the Particle Shaders for Foam, Splash and Mist.

For the ParticleShader-Foam:

For the ParticleShader-Splash:

For the ParticleShader-Mist:

Run a test rendering. Now we see the splashes are in appropriate size. Let's continue to the next step, adjust the Absorption Color of the Mist.

With the ParticleShader_Mist selected, go to Fog rollout. Change the Absorption Color to Blue (RGB: 60, 79, 124).

Run a test rendering. Now we have more interesting color contrast in the rendering. The absorption color gives mist particles subtle yellowish tint.

To further increase realism to the shot, let's tweak the value for Phase Function of the Mist particle shader. With the ParticleShader_Mist selected, set the Scattering mode to Ray-traced. Increase the Phase Function to 0.7.

Run a test rendering. Now you can see more back lighting in the mist rich area.

To further fine-tune the image, in the V-Ray Frame Buffer use the Create Layer icon to add layers for Exposure and Filimic tonemap.

The final image is rendered using the V-Ray Frame Buffer with the color corrections and post effects set to:

Exposure:

Filmic tonemap:

Feel free to use other values for the post effects depending on your preferences.

Alternatively, you can load a layer tree Preset from the Waterfall_VFB.vfbl file that is provided in the sample scene.

And here is the final rendered result (from frame 140 to frame 230).