Cloudscape with Chaos Scatter

This setup requires Phoenix 5.20.00, V-Ray 6 for 3ds Max 2019 and Chaos Scatter 2.5 or newer. You can download official Phoenix and V-Ray builds 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.

This tutorial shows how to create a cloudscape that changes from a sunny day to a stormy night. We'll start by creating various cloud types, such as cumulus, anvil, and stratus. Then we will load them into multiple VRayVolumeGrids, integrated into a single scene. We will manually place a few hero clouds in the shot and then use Chaos Scatter to scatter some generic cloud assets over the region. Once we finish the cloudscape for the daytime scene, we will utilize PFlow to strike lightning from the clouds, for the stormy night scene.

For realistic cloud shading, we will tweak the value of the Phase Function of the simulators.

At the end of the tutorial, we will color-correct the image with the V-Ray Frame Buffer, and we will make the shots more cinematic by using V-Ray Light Mix. This allows us to adjust the key-to-fill light ratio without rendering the image again.

The final video is a mix of the daytime and night-time shots with a transition composite.

The Download button provides an archive of the scene files.

Download Project Files

This is an extensive tutorial, which might be overwhelming at first glance. To make it easier to follow, we have created a workflow diagram that illustrates how the article is structured. The tutorial is divided into three major stages:

1. Asset creation: In this phase, we generate various cloud assets using Phoenix Fire/Smoke Simulators. This includes hero clouds such as Cumulus_A, Cumulus_B, and Anvil_Cloud. We also generate some generic clouds that will be scattered in the scene using Chaos Scatter in the next stage. These cloud assets are saved as *.aur cache files.

2. Scene assembly: Once clouds of all types are ready, we load the *.aur files into one scene (cloudscape_daytime_start.max) using VrayVolumeGrid. First, we position our hero clouds and then fill the background and foreground with the generic clouds using Chaos Scatter. Finally, we create a VrayVolumeGrid for the environmental fog. We then render out the sequence for the daylight cloudscape.
3. Lighting and particle effects: Next, we add some lighting effects using PFlow. We adjust the lighting conditions by adding some Omni lights and tweaking the Light Mix. We then render out the sequence as a stormy night.

Scale is crucial for the behavior of any simulation. Large-scale simulations appear to move slower, while medium and small-scale simulations display lots of vigorous movement. When you create your Simulators, have a look at the Grid rollout where the real-world size of the Simulator is shown. If it cannot be changed, you can cheat 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.

Since the height of a cumulus cloud is approximately 1000 meters, we have set the Scene Scale to Metric Meters.

The final scene contains a total of seven VrayVolumeGrids, each loaded with an *.aur file for a specific type of cloud: Cumulus_A, Cumulus_B, Anvil_cloud, Cloud_for_scatter_near, and Cloud_for_scatter_far. Each VrayVolumeGrid has a different smoke color for easy identification. We have also added an extra VrayVolumeGrid for the environmental fog.

The final assembly scene contains the following elements:

1. VRayCam for rendering. The camera is tilted and animated as if we are on an airplane that is flying up.
2. V-Ray Sun & Sky setup is used for the daytime scene lighting.
3. Omni_Cumulus_A, Omni_Cumulus_B, and Omni_Anvil are for the stormy night scene. All of these Omni lights are animated to mimic a lightning effect.
4. Two Chaos Scatter objects are used: one scatters the high-resolution Cloud_for_scatter_near in the foreground, and the other scatters the lower-resolution Cloud_for_scatter_far in the background.
5. Line_Areas_Near and Line_Distribute_Near splines are used to define the region that Chaos Scatter_Near uses to scatter clouds. Line_Distribute_Far splines are used to define the region that Chaos Scatter_Far uses to scatter clouds.
6. Two Particle Flows are used for the night-time lightning: PF Source 001 is positioned within Anvil_cloud, while PF Source 002 is placed inside Cumulus_A. Both emit particles using Lightning_branch as shape instances.
7. PCloud_Stars is used to create a background of stars.

Here are more details about the PFlow setup. As you can see, the particle system uses Group_Lightning as a Shape Instance. Both have VRayLightMtl applied, so their particles illuminate the scene.

Click on the Time Configuration icon ( ) and set the Animation Length to 90, so that the Time Slider goes from 0 to 90.

In the daytime scene, the middle ground is populated with highly-detailed cumulus and anvil clouds. Additionally, there are foggy clouds scattered in the distance, and some generic clouds scattered in the foreground. The stratus clouds intersect with these various types of clouds. The cloud shading is noteworthy, with beautiful and realistic forward scattering in its volumetric shading.

In the stormy night scene, the environment is foggier than during the daytime. Lights illuminate the large cumulus and anvil clouds. Lightning can be observed discharging from the clouds and flashing across the cloudscape.

Instead of scattering the same type of clouds throughout the sky, we are going to create three different types of clouds. This will enhance the realism of the cloudscape. We will create each of these assets in separate 3ds Max scenes and then assemble them in another dedicated scene.

The types of clouds we are going to create are cumulus, cumulonimbus (also known as anvil clouds), and stratus. Each of them looks different and is generated using a different method.

Let's start creating assets for the scene, beginning with the main cumulus cloud - the Cumulus_A.

Please open the provided Cumulus_A_start.max scene file. To save you some time, we have prepared three planes in the scene, each with the Shell, Edit Poly, and Noise modifiers applied, needed to break up the emitted smoke and make the clouds more diverse and asymmetric.

For example, we applied Shell, Edit Poly and Noise Modifiers to Plane002. While in Edit Poly mode, we select the top face of the geometry (marked in red), and set its face ID to 1. We set the face ID of the rest of the faces to 2.

This table shows the details of the three plane geometries with various modifier settings.

Let's create a simulator now. Go to Create Panel > Create > Geometry > PhoenixFD > FireSmokeSim. Rename the simulator to PhoenixFDFire_Cumulus_A.

The exact position of the Phoenix Simulator in the scene is XYZ: [0.0, 0.0, -40.0].

Open the Grid rollout and set the following values:

Select the Output rollout and enable the output of the Grid Smoke and Grid Velocity channels. We don't need the Temperature channel as we won't render fire.

Any channel used after the simulation is done, needs to be cached to disk. Such as:

Go to Create Panel > Create > Helpers > PhoenixFD > PHXSource. Rename it to PHXSource_Cumulus_A_001.

Press the Add button and select the Plane001 geometry from the viewport or from the Scene Explorer.

Set up the PHXSource_Cumulus_A_001's properties:

Changing the Noise parameters greatly influences the simulated cloud. It is recommended that you experiment with different settings once you've completed this tutorial. If you want to recreate the same result as shown here, follow the instructions exactly.

Keyframes for the FIre/Smoke Source's Outgoing Velocity

Repeat the same procedure for adding two more Phoenix Sources in the scene. Rename them to PHXSource_Cumulus_A_002 and PHXSource_Cumulus_A_003, respectively. Add Plane002 to the emitter nodes in PHXSource_Cumulus_A_002 and add Plane003 to PHXSource_Cumulus_A_003's emitter nodes.

Use the table to adjust the Outgoing Velocity of the Phoenix Sources.

Select the Simulation rollout of the PhoenixFDFire_Cumulus_A Simulator. We only need to simulate 10 frames, so set the Stop Frame to 10. Press the Start button to simulate.

This is a voxel preview of the current animation. The cloud appears too short.

In the Dynamics rollout of the simulator, increase the Steps Per Frame to 10. Run the simulation again. The Source emits fluid with very high velocity, so more Steps Per Frame are needed to capture it better.

This is the voxel preview of the current animation. As you can see, the height of the cloud has increased significantly.

Select the PhoenixFDFire_Cumulus_A Simulator and in the Dynamics rollout change the Fluidity Method to PCG Symmetric, with a Quality of 100. Run the simulation again.

This voxel preview shows the current animation.

To define the shape of the cloud more, let's edit the model of Plane001. First, select Plane001 and go to the Modifier panel. Then, add an Edit Poly Modifier and navigate to the Selection rollout. Click on the Polygon button, and then use the Ribbon's By Random option to randomly delete 30% of the faces.

After deleting, assign a Polygon ID of 1 to the top faces, and set an ID of 2 for the rest of the faces. Finally, run the simulation again to see the updated cloud shape.

This voxel preview shows the current animation. Now we see a more defined shape of a cumulus cloud.

To create a more natural-looking cloud, we can add some noise to the simulation. To achieve this, let's increase the Noise value for the Outgoing Velocity to 3.0 for all three PHXSources in the scene.

Additionally, select PhoenixFDFire_Cumulus_A and navigate to the Dynamics rollout to increase the Randomize Amount to 0.2.

Run the simulation again.

This voxel preview shows the current animation. Now we have a more organic-looking cloud.

To bring more realism to the cloud, let's add some forces to the scene. Go to the Create panel > Helpers > PhoenixFD and click on PHXTurbulence. Create a Phoenix Turbulence in the scene.

Then we add a Phoenix Plain Force, a simple directional force in the scene. Go to Create panel > Helpers > PhoenixFD and add a Phoenix Plain Force in the scene.

Now we are ready for the final simulation. Let's increase the grid resolution of the simulator. Make the following changes:

With the new grid resolution and forces in the scene, click on Start to run the final simulation for Cumulus_A.

This voxel preview shows the final animation.

Run a test render of frame 10 with the default volumetric settings. This helps assess what changes are needed to improve the look of the simulation.

Select the PhoenixFDFire_Cumulus_A Simulator and go to its Volumetric Render Settings.

Increasing the value for Light Cache Speedup speeds up the render, but it also lowers the quality of the Volume Light Cache. If dark cubic grid artifacts start forming on the smoke, the parameter is set too high. For more information, visit the Volumetric Rendering In-Depth page.

In this case set the Volume Light Cache to disabled as it will produce cleaner render result.

Alternatively, you can load up a render preset from the Cloud_render_preset.tpr file, that is provided in the sample scene.

With the new volumetric settings , run a test render of frame 10. This is the asset for Cumulus_A.

There's already one cumulus cloud in the scene. Now we will create another variant for the same type. You can open the scene "Cumulus_B_final.max" and save time, as we have already prepared all the required elements and configured the settings there. It is essentially similar to Cumulus_A.

This table shows the details for all three plane geometries in the scene.

This table shows all the settings for the three PHXSouces in the scene.

Here are the settings for the simulator - PhoenixFDFire_Cumulus_B:

The exact position of the Phoenix Simulator in the scene is XYZ: [308.0, -116.5 -40.0].

Open the Grid rollout and set the following values:

The simulator is loaded along with the Cloud_render_preset.tpr, so the volumetric settings are all set for the final render.

Select the Simulation rollout of the PhoenixFDFire_Cumulus_B Simulator. We only need to simulate 7 frames, so set the Stop Frame to 7. Press the Start button to simulate.

Run a test render of frame 7. This is our asset for the Cumulus_B cloud.

Open the scene "Cloud_for_scatter_far_final.max", where we have already prepared all the necessary elements and configured the settings for you. The setup is essentially the same as the previous two. However, the main difference is that since it is far from the camera, this cloud has a low-resolution grid to optimize performance.

This table shows the details for all three plane geometries in the Cloud_for_scatter_far scene.

This table shows all the settings for the three PHXSouces in the scene.

Here are the settings for the PhoenixFDFire_Scatter_far Simulator:

The exact position of the Phoenix Simulator in the scene is XYZ: [95.0, -327.0 -40.0]

Open the Grid rollout and set the following values:

The simulator is loaded along with the Cloud_render_preset.tpr, so the volumetric is all set for the final render.

Select the Simulation rollout of the PhoenixFDFire_Scatter_far Simulator. We only need to simulate 4 frames, so set the Stop Frame to 4. Press the Start button to simulate.

Run a test render of frame 4. This is our asset for the Cloud_for_scatter_far cloud.

Open the scene "Cloud_for_scatter_near_final.max", where we have already prepared all the necessary elements and configured the settings for you.

This table shows the details for all three plane geometries in the Cloud_for_scatter_near scene.

This table shows all the settings for three PHXSouces in the scene.

Here are the settings for the PhoenixFDFire_Scatter_near Simulator:

The exact position of the Phoenix Simulator in the scene is XYZ: [183.0, -63.0 -42.0].

Open the Grid rollout and set the following values:

The simulator has the Cloud_render_preset.tpr loaded, so the volumetric is all set for the final render.

Select the Simulation rollout of the PhoenixFDFire_Scatter_near Simulator. We only need to simulate 7 frames, so set the Stop Frame to 7. Press the Start button to simulate.

Run a test render of frame 7. This is our asset for the Cloud_for_scatter_near cloud.

We created assets for all the cumulus clouds and can move on to creating another type of cloud.

To get started, open the Anvil_cloud_start.max scene. We have prepared a geometry, a camera, and a VraySun for you to use. An anvil cloud is essentially a cumulus cloud before it reaches the ceiling of the stratosphere, so we can apply the experience we gained from making the cumulus clouds to the anvil cloud. Therefore, we will skip some of the steps and focus more on the formation of the distinctive "anvil" shape of this cloud type.

Rename the box to Box_Voxel_Tuner.

Set its Length, Width and Height to 8160.0m, 900.0m and 940.0m, respectively. Set the Segs for all axes to 1.

The exact position of the Box_Voxel_Tuner is XYZ: [125.0, -223.0, 808.0].

Since the Box_Voxel_Tuner is only used for the Voxel Tuner in a later step, we don't have to render the geometry. In its Object Properties, disable the Renderable checkbox and enable See-Through.

Several modifiers have been applied to the plane geometry, which uses the same settings as the planes for the Cumulus Cloud. To create the desired effect, the Phase of the Noise modifier is animated from a value of 1, at frame 0, up to a value of 4, at frame 15.

In the sample scene, we have set up a simulator for you. The simulator is named PhoenixFDFire_Anvil.

The exact position of the Phoenix Simulator in the scene is XYZ: [0.0, 0.0, -40.0].

Open the Grid rollout and set the following values:

The simulator is loaded along with the Cloud_render_preset.tpr, so the volumetric is all set for the final render.

In the Dynamics rollout of the PhoenixFDFire_Anvil, we have set the Fluidity Method to PCG Symmetric and the Quality to 100. However, we have decided to lower the Steps Per Frame to 5 instead of 10.

Set up the PHXSource_Anvil_Cloud's properties:

Changes to the Noise parameters greatly influence the simulated cloud. It is recommended that you experiment with different settings once you've completed this tutorial. If you want to recreate the same result as shown here, follow the instructions exactly.

Keyframes for the FIre/Smoke Source's Outgoing Velocity

Screenshot of the Outgoing Velocity keyframes

Apply the same PHXTurbulence settings as the ones in the Cumulus_A scene. Here are the details:

Select the Simulation rollout of the PhoenixFDFire_Anvil Simulator. We only need to simulate 11 frames, so set the Stop Frame to 11. Press the Start button to simulate.

This voxel preview shows the current animation. You can see a mushroom-like shape. Additional procedures are needed to achieve the distinctive "anvil" shape of this cloud type.

To replicate the atmospheric conditions of the Stratosphere, we can introduce a Phoenix Plain Force into the scene. To do this, go to Create Panel > Helpers > Phoenix and add a Phoenix Plain Force.

To make the visual effect more interesting, animate the Plain Force. Refer to the screenshot for the appropriate frame numbers and values. Set all tangents to Linear.

Go to Create Panel → Helpers → PhoenixFD → VoxelTuner. Create a Voxel Tuner anywhere in the scene.

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

In the Edit Condition window, click on Temperature. The Edit Value Expression window shows up.

Switch the condition from Channel - Temperature to Distance To. Press the None button and choose the Box_Voxel_Turner geometry from the scene.

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

Click on the value of 800.0, change the Value Expresion to Random Between. Edit the value so you have random value from 0.0 to 10.0

After configuring the condition settings, close the Edit Condition window. Next, change the Then parameter to Velocity Z. Set the value to 0.0 and adjust the Buildup Time (sec) to 0.04.

To add a force to the scene, go to Affect By Forces and click on the Add button. Select the PlainForce.

For the anvil shape, a strong wind force is needed. To increase the effect, adjust the With Multiplier parameter to 20.0.

With those new settings, run the simulation again.

This voxel preview shows the current animation. Now we see the cloud forming an anvil shape.

Run a test render of frame 11. This is our asset for the Anvil_cloud.

To start, let's open the file "Startus_top_start.max" which includes a VRaySun, a VRay Camera, and a Sphere.

The sphere has a diameter of 3244.0 meters and 32 segments. It's been flattened and scaled down to 13% of its original height along the Z-axis.

Since the sphere is used solely as a smoke source, the Renderable checkbox is disabled and Display as Box is enabled in its Object Properties.

Go to Create Panel > Create > Geometry > PhoenixFD and click on FireSmokeSim. Rename the simulator to PhoenixFDFire_Stratus_top.

Go to the Create Panel > Create > Helpers > PhoenixFD and create a PHXSource. Rename it to PHXSource_Stratus_top.

Press the Add button to choose which geometry to emit from and select the Sphere001 in the Scene Explorer.

 PHXSource_Stratus_top settings:

When switching the Emit Mode to Volume Brush, Phoenix prompts you to make the Sphere001 non-solid. Click on Make Non-Solid. Otherwise, it collides with the fluid simulation.

Unlike the cumulus cloud, the stratus cloud doesn't need to have great details, so leave everything in the Dynamics rollout at its default.

Select the Simulation rollout of the PhoenixFDFire_Stratus_top Simulator. We only need to simulate 3 frames, so set the Stop Frame to 3. Press the Start button to simulate.

With the PhoenixFDFire_Stratus_top selected, go to the Rendering rollout. Click on the Render Presets and click on Load from File. Load the Cloud_render_preset.tpr, provided with the sample scene.

Run a test render of frame 3. This is our asset for the Stratus_top cloud.

The Startus_bottom has basically the same setup, so we don't need to repeat the procedure. Open up the final scene "Startus_bottom_final.max". It already has the Phoenix Source and Simulator set up for you. The simulator is renamed to PhoenixFDFire_Startus_bottom.

 Here are the settings for PHXSource_Stratus_bottom:

Select the Simulation rollout of the PhoenixFDFire_Stratus_bottom Simulator. We only need to simulate a single frame, so set the Stop Frame to 1. Press the Start button to simulate.

Run a test render of frame 1. This is our asset for the Stratus_bottom cloud.

With all the volumetric data for the clouds ready, it's time to assemble them into a cloudscape. Open up the provided scene "Cloudscape_daytime_start.max". To help you get started, the scene includes an animated camera, a VRaySun, and some splines that will be used to scatter the VrayVolumeGrid. The scene also includes Omni lights, two PFLows, and one PCloud for the stormy night.

Go to Create panel > V-Ray. Click on the VRayVolumeGrid button and click anywhere in the scene. This prompts a dialog window. Locate the *.aur file for Cumulus_A. Open the file to load the cache into VRayVolumeGrid.

Rename the VRayVolumeGrid to VRayVolumeGrid_Cumulus_A. In the Input rollout, change Time Bend Controls Mode to Cache Index. Set the Direct Cache Index to 10.0.

With the VRayVolumeGrid_Cumulus_A selected, move it to XYZ: [183.0, -88.0, 0.0]. Rotate it to XYZ: [0.0, 0.0, -92.0].

With the VRayVolumeGrid_Cumulus_A selected, go to the Rendering rollout. Click on Render Presets and select Load from File. Load the Cloud_render_preset.tpr that is provided with the sample scene.

Go to the Preview rollout of the VRayVolumeGrid_Cumulus_A, change the color of the lowest smoke grid value to light blue - RGB(88,199,225).

Great, we have successfully set up VRayVolumeGrid_Cumulus_A. However, there are six more cloud assets waiting to be loaded into the scene. Please follow the same procedure for each of the remaining cloud assets.

Now we have loaded all seven cloud assets into the scene with their VRayVolumeGrids. While it might look good, there are still many gaps in the frame that need to be filled. Otherwise, the cloudscape won't be convincing enough.

Before we apply Chaos Scatter to the cloud assets, let's simplify our workspace by hiding the other VRayVolumeGrids. To do this, open the Select by Name window and hide all VRayVolumeGrids, except for VRayVolumeGrid_Cloud_for_scatter_far and VRayVolumeGrid_Cloud_for_scatter_near, which are the ones we'll be working with.

Navigate to the Create panel and select the Geometry tab. From the drop-down menu, select Chaos Scatter and create two Chaos Scatter geometries in the scene. To keep things organized, rename them as Chaos Scatter_Far and Chaos Scatter_Near, to match their respective purposes.

With the Chaos Scatter_Far selected, in the Objects rollout, use the "+" button to add Line_Distribute_Far to the Distribute-on target objects list. Then add the VRayVolumeGrid_Cloud_for_scatter_far to the Instanced model objects list. By doing this, the Cloud_for_scatter_far asset will be scattered within the enclosed region defined by the spline shape of Line_Distribute_Far. 

• In the Scattering rollout, set the Max. limit to 60 and the Random seed to 2.
• In the Rotation section of the Transformations rollout, set the Z Rotation To to 360.0.
• In the Scale[%] section, set X From and To to 150.0 and 250.0, respectively.
• In the Viewport Display rollout, set the Previz type to Box.

With the Chaos Scatter_Near selected, in the Objects rollout, use the "+" button to add Line_Distribute_Near to the Distribute-on target objects list. Then add the VRayVolumeGrid_Cloud_for_scatter_near to the Instanced model objects list. By doing this, the Cloud_for_scatter_near asset will be scattered within the enclosed region defined by the spline shape of Line_Distribute_near. 

• In the Scattering rollout, set the Max. limit to 50 and the Random seed to 3.
• In the Rotation section of the Transformations rollout, set the Z Rotation To to 360.0.
• In the Scale[%] section, set X From and To to 50.0 and 80.0, respectively.
• In the Areas rollout, add Line_Areas_Near to the Spline includes list. Click on the item and set the Near distance to 700.0m and the Far distance to 12159.0m. Finally, set the Scale to 0.67 and the Density to 1.0.
• In the Viewport Display rollout, set the Previz type to Box.

Unhide all VRayVolumeGrids in the scene.

Now we have all the clouds set for a cloudscape, but we still need something for a better aerial perspective - fog.

Go to Create panel > V-Ray. Click on the VRayVolumeGrid button and click anywhere in the scene. This prompts a dialog box for loading cache files. Click on Cancel.

Rename the VrayVolumeGrid we just created to VRayVolumeGrid_Fog. Move it to XYZ: [1452.0, 14455.0, 0.0].

In the Grid rollout, set the following settings:

• Voxel Size: 69.0m
• Size XYZ: [413, 393, 26]

Select VRayVolumeGrid_Fog, and click on Volumetric Options to open the Volumetric Render Settings window.

In the Render Setup > Render Elemets tab, add VRayLightMix. This is necessary for relighting the scene in the VFB.

Open the V-Ray Frame Buffer and use the Create Layer icon ( )to add layers for White Balance, Exposure and Filmic Tonemap.

The image is rendered using the V-Ray Frame Buffer. In the current example, the color corrections and post effects are set as follows:

Filmic Tonemap:

The Filmic Tonemap render element simulates a camera film's response to light, making the scene more realistic.

Exposure:

White Balance:

Lens Effects:

Here we will use LightMix to adjust the ratio between the key light (VRaySun) and the fill-light (VRaySky). We will also decrease the weight of the Environment to make the shot more cinematic.

Set the Source to LightMix.

Alternatively, you can load up a render preset from the Daytime_VFB.vfbl file that is provided in the sample scene.

LightMix is a valuable tool that offers precise control over the intensity of individual lights in a scene. This can be particularly useful during look development. However, this feature requires additional sampling during rendering and will slow the render down, when there is already a lot of volumetric data present. The good news is that we can mitigate this issue by using the To Scene button, which allows us to transfer any changes made in LightMix back to the scene without having to repeat the entire render process.

After performing a test render, navigate to the LightMix section in the VFB and click on the To Scene button. This will apply all changes to the colors and intensities of scene items (except for those that were excluded in the previous step).

This prompts a dialogue window, click Yes to confirm.

After the transfer, you can check the VRaySun and Environment Map. The VRaySun now has a slightly orange tint, and the VRaySky is multiplied by the VRayColor. Both changes are based on the adjustments we made in LightMix.

Since the light adjustment has now been baked into the scene, let's navigate to VRay > Render Elements and turn off the Element Active option. We are now ready to proceed with the final render for the daytime cloudscape.

And here is the final animation for the daytime cloudscape.

Let's transform the current scene into a stormy night. Take the current state of the daytime scene and save the scene as Cloudscape_stormy.max. First, in the VRay Light Lister, turn off VRaySun and enable the three Omni lights in the scene.

To turn off the VRaySky, navigate to Rendering > Environment > Environment and Effects, and uncheck the Use Map option.

In the Scene Explorer, unhide the PF Source 001, PF Source 002 and PCloud_Stars, to show the PFlow and the stars in the scene.

Here's a preview animation of PFlows and PCloud to give you an idea. In the animation, lightning discharges from the position of Cumulus_A and the Anvil_cloud. You can also see stars in the background.

(Please replace this image with Particles_preview.mp4)

Since we want to create a stormy night with high humidity, let's adjust the VRayVolumeGrid_Fog by moving it towards the camera to cover more clouds. Its new position should be XYZ: (1452.0, 11957.0, 0.0).

Next, access the Volumetric Render Settings of the VRayVolumeGrid_Fog. In the Opacity diagram, increase the Y value of the first key point to 0.0003.

Now that we've made the fog thicker, let's optimize render performance by hiding the Chaos_Scatter_Far and VRayVolumeGrid_Cloud_for_scatter_far.

Open the V-Ray Frame Buffer and use the Create Layer icon ( )to add layers for White Balance, Exposure and Filmic Tonemap.

The image is rendered using the V-Ray Frame Buffer. In the current example, the color corrections and post effects are set as follows:

Filmic Tonemap:

The Filmic Tonemap render element simulates a camera film's response to light, making the scene more realistic.

Exposure:

White Balance:

Lens Effects:

Alternatively, you can load up a render preset from the Stormy_Night_VFB.vfbl file, provided in the sample scene.

And here is the final rendered result for the stormy night cloudscape.

We now have sequences of cloudscape scenes for both daytime and nighttime. You can use any compositing software to create an animation that transitions from day to stormy night.

(Please replace this image with Cloudscape_day_and_night.MP4)