For those who don’t know the event: ICE.ART is a webinar-style conference for people who build 3D worlds, with sessions published on YouTube for on-demand catching up.

After the fact

ICE.ART 2026.I has published its full set of presentation and panel recordings for free streaming. If you could not make the live dates on 7 and 8 April 2026, the recrodings now turn the whole event into an on-demand playlist you can dip into between dailies.
The archive covers both conference days, including intros, individual talks, and panel discussions. As always, test any new workflow ideas before you put them into production, even if the speaker makes it sound like it will fix your envrionment pipeline overnight.

The Videos

ICE.ART 2026.I Day I Intro
A quick warm-up that sets the tone before the pixels start doing push-ups.

ICE.ART 2026.I Day I Christian Tanner | Toyota City Hunt Physics: A behind-the-scenes look at the project, with physics as the main character and the first steps into Unreal realtime smoking tires. Strap in!

ICE.ART 2026.I Day I Goran Pavles Art directing Physics Simulations for Hollywood Blockbusters: A talk for anyone who has ever argued with gravity and lost.

ICE.ART 2026.I Day II Andrey Lebrov Gaussian Splat Environment Pipeline for Octane Render: A pipeline-focused session that connects splats, environments, and renderer reality checks.

ICE.ART 2026.I Day II Tobias Hauck Geospatial Gaussian Splats 3D Maps of Large Environments: If you know how much fun can be had in large-scale data and larger-scale scenes, this one is for you.

ICE.ART 2026.I Day II Prof. Dr. André Thomas Planning Physical Studios Business and Creativity: A business and studio-planning angle that still remembers artists need working chairs and working budgets.

https://www.ice.art/

The post ICE.ART 2026.I recordings are now live first appeared on DIGITAL PRODUCTION and was written by Bela Beier.

For those who don’t know the tool: Nature Generator is a procedural asset library add-on that lives inside Blender via the Asset Browser and an N-panel, sold on Superhive Market, so you can kitbash nature without leaving your DCC.

The whole point is staying in your scene

Nature Generator builds natural assets directly inside Blender. Rocks, terrains, plants, water, and other environment bits all come in as editable, generated assets rather than fixed meshes. You drag an asset into the scene, the side panel recognizes it, and the controls you need show up without a detour to another app. The comparison to Quixel Megascans is obvious, being fully procedural and customizable.

The minimum version requirement is Blender 4.1 or higher. Hardware requirements call for a modern GPU from NVIDIA, AMD, or Apple Silicon. There is an optional texture options folder with 1K, 2K, and 4K texture resolutions. By default, the add-on uses low resolution preview textures, and the guidance recommends keeping the texture folder on a fast local SSD because it affects performance.

Installation stays simple. You drag and drop the zip into Blender, click OK, and the library sets up inside the Asset Browser. The Nature Gen panel appears in the side panel and opens with the N key. From there, drag and drop assets into the scene and start tweaking.

Geometry controls that reward restraint

Every asset follows a similar structure: shader settings and geometry settings, with slightly unique controls per asset. Geometry includes a resolution section, and most assets support a low-poly option. Viewport and render resolution can be controlled separately, and resolution can be subdivided or voxelized depending on the asset.

The documentation also includes the most honest feature statement possible: resolution can go infinitely high, and every asset can crash Blender if you push it too far. That makes the control powerful, but it also makes self-control part of the user interface.

Base shapes come from primitive forms you can alter in edit mode. Some assets follow the structure of a mesh and react to topology. Some are planes. Some are driven by curves. Displacement settings include multiple texture and noise displacement controls, with patterns such as noise breakup, stratification lines, and crack patterns. Many categories expose basic settings and an advanced subcategory for deeper tuning.

At around the moment you start dialing prcoedural detail like it is free, that crash warning stops reading like documentation and starts reading like prophecy.

Custom shaping can use a gradient with its own displacement, falloff, location, and scale settings, with viewport gizmos available when the modifier is selected. Alternatively, a custom curve object can influence the terrain, with a radius setting and a distance based falloff where farther from the curve means weaker influence. A secondary custom shape can be added, such as one curve for valleys and another for mountains.

Scatter was rebuilt to be more direct

The latest update changes how the scattering system works. If you have an older version, the update workflow shown is to download the new version from Blender Market and drag and drop it into the scene so it overrides the old version.

The new scatter setup aims to be simpler with fewer settings. The key change is the import flow. You import the specific assets you want to scatter, then assign them into the scatter collection. After importing, you can toggle an exclude option so the collection does not sit visibly in the scene, while still being used by the scattering system.

Core scatter behavior remains familiar. You can adjust density, and you can still use slope based scattering, altitude based scattering, and noise based scattering. Scatter zones remain part of the tool, controlled by empties with viewport gizmos so you can define a local area for scattering.

The update also introduces threshold softness controls across settings. The stated purpose is scaling down scattered assets toward the edges of masks. That creates a smoother falloff where a hard cutoff would look like a stamp.

Draw where the scatter goes

A major addition in the update is a scatter curve or grease pencil option. You can assign a curve or a Grease Pencil object and use it to decide where scattering appears and where it does not.

The workflow shown is straightforward: create a blank Grease Pencil object, draw directly on the surface, then select that drawing as the scatter guide. The same idea works with a curve object. You get controls for draw radius and radius softness, and the falloff scales down scattered assets toward the edges. There is also a noise option to distort the shape and avoid a too clean, too perfect outline.

Remove the draw object, and scattering returns to the default behavior. That makes the feature easy to test and easy to abandon if a shot changes direction.

Viewport survival mode, now with choices

Scatter can get heavy. The update adds a display mode control in the instance settings. You can display instances as originals, as boxes, or as wire box. Instance scale stays, but the update adds a secondary scale and a secondary scale probability. That lets a minority of instances become much larger than the rest, adding variation without requiring a second scatter layer. Rotation controls remain.

There is also a new wind animation option for scattered assets. Wind time is a value you animate, with an example workflow of adding a driver expression using hashtag frame and optionally dividing to slow it down. The update explains why this stays manual: using a scene time node inside node trees made performance drop sharply, including an example of frame rate dropping to around seven. Removing the time node restored smooth playback. With many scattered objects each carrying the scatter system, the update keeps wind time explicit to protect performance.

Terrains, water, and the new step look

Terrain and mountain assets use a separate X and Y resolution, because resolution on those axes influences the shape and form of erosion. Terrain maps include a random seed, and terrain can generate from noise or be influenced by a custom shape.

Noise displacement includes control over influence on X, Y, and Z, plus a noise seed and standard noise settings. Texture displacement adds rock detail. Erosion settings apply erosion from a selected height, with placement, falloff, and an option that can add mountains and inverted valleys. Boundary falloff can flatten edges.

Water effects add a cube with a procedural water shader. Controls include height and depth, and rivers can be created by combining a water effect value with custom curve shaping that pushes terrain down so water appears in selected areas. Water shader settings appear in the shader tab, including animated noise controls to create the illusion of moving water with separate speed controls on X and Y.

The update adds terrain presets, including a forest preset and a canyon preset. The forest preset uses the scattering system, and trees can default to box display for performance on lower-end systems, with the option to switch back to originals. The update also adds a terrain steps feature on some presets, described as a stepping effect. Controls include the number of steps, detail, strength, and blur, with noise-based selection and influence. Terrain steps can be found in erosion settings, in noise settings, and when drawing along a custom curve.

Trees arrive, and snow gets more physical

The update adds tree assets. Tree shaders follow the same structure as flowers, including leaf color controls and translucency. Leaves can be pushed toward an autumn look by changing colors. There is also a setting for a leaf mask, and leaf shapes are generated procedurally, with controls for scale and mask threshold.

Scatter categories shown include plants such as flowers, wheats, grass, ground cover, shrubs, plus rocks, snow, and trees. Scattered rocks are procedurally generated and have their own settings such as resolution, shape distortion, size ratio, and a seed.

Snow scattering gets a notable twist. Importing a snow object can be recognized and turned into a volume style approach for creating snow on objects rather than only shader based snow. Snow settings sit in the geometry tab, including resolution and displacement settings. Particle detail adds small particles with alpha textures, intended to improve realism for close-ups. The tool also notes that foamy snow detail may require higher transparency bounces.

Materials, uniqueness, and the new override option

Materials are shared by default. The tool includes Make Material Unique to create a new copy of a material for the selected object, and Revert to return to defaults. The update also adds a use custom material feature for the new scatter effect. The workflow shown duplicates a material and assigns it as an override for the scattered assets, so you can make unique changes without affecting the original material used elsewhere.

Scatter effects can stack, and the update shows renaming modifier labels to organize multiple scatter effects. This is the part where it starts feeling less like an asset pack and more like a small ecosystem.

Pricing and what is actually specified

Pricing is specified on the product page. A Personal License costs $99. A Commercial License costs $169. A Studio License costs $259.

https://superhivemarket.com/products/the-nature-generator?ref=586

The post Nature Generator update brings procedural nature to Blender first appeared on DIGITAL PRODUCTION and was written by Bela Beier.

KIRI Engine has released Scatter, a free object scattering add on for Blender. The plugin provides three placement modes that cover manual layout, procedural distribution using Geometry Nodes, and physics based scattering driven by Blender’s rigid body system. The developer positions the release as a response to the cost barrier of existing advanced scattering tools. According to KIRI Engine, many established add ons come with significant price tags, so for Blender artists who either lack budget for commercial plugins or are early in their learning curve.

Three modes, three workflows

Scatter provides three distinct placement modes. Each addresses a specific production scenario rather than attempting to unify all behaviours into a single opaque system.

The Click mode is described as a point and shoot workflow. It enables manual placement of individual assets directly in the viewport. This mode targets hero assets and composition critical elements where precise positioning, orientation and visual balance matter more than procedural coverage. For layout artists and lookdev teams, this is effectively a structured alternative to duplicating and transforming objects by hand.

Simple Scatter applies a non destructive Geometry Nodes modifier to a target mesh or curve. The distribution is procedural and remains editable. This is intended for large scale coverage tasks such as scattering vegetation across terrain, debris across floors, or objects along splines. Because it relies on Geometry Nodes, the behaviour integrates with Blender’s native node based instancing system. Geometry Nodes in Blender provide procedural control over point distribution, instancing and attribute driven variation. Scatter builds on that system rather than replacing it.

Physics Scatter uses Blender’s Rigid Body physics engine to drop objects into a scene and allow gravity and collision to determine their resting state. This mode is aimed at natural stacking scenarios such as rock piles, filled containers, cluttered surfaces or loosely arranged props. Instead of manually tuning offsets and rotations, users simulate gravity driven interaction.

Interactive physics control

Within Physics Scatter, an Interactive Mode enables real time direction of falling objects during playback. Users can activate Wind and Vortex force fields and toggle gravity while the simulation runs.

In Blender, force fields such as Wind and Vortex influence rigid body objects during simulation. Wind applies directional force. Vortex applies rotational force around an axis. Gravity toggles affect global downward acceleration. Scatter exposes these controls to allow artists to shape the outcome of object drops during simulation rather than relying solely on preconfigured settings. This provides a degree of art direction over what would otherwise be purely physics driven motion. It remains dependent on Blender’s rigid body solver and its constraints.

Non destructive procedural coverage

The Simple Scatter mode applies a Geometry Nodes modifier to the target object. Geometry Nodes in Blender are non-destructive by design, meaning that the underlying mesh remains unchanged and the node tree can be edited at any time. Scatter leverages this behaviour for environmental coverage. Because the modifier is attached to meshes or curves, distribution can follow surfaces or paths. Typical use cases include grass over terrain, debris on architectural floors or repeated assets along splines.

Manual placement without friction

The Click mode targets precision tasks. It is intended for placing hero assets with full compositional control. This mode likely reduces repetitive transform operations by integrating placement into a structured toolset.

Asset ecosystem integration

At launch, KIRI Engine provides one free KIRI Asset Pack alongside the add on. Additional packs may be developed if there is sufficient user interest. Scatter includes a preview gallery and loader for KIRI Asset Packs. The add on is designed not only as a placement tool but also as an entry point into KIRI’s asset ecosystem. The company frames this as a way to manage asset packs more easily.

Free, but not feature vague

Scatter is explicitly described as free. There is no mention of subscription requirements, feature gating or trial limitations in the provided documentation. The stated motivation for releasing a free tool is to give Blender users access to scattering functionality without additional cost. This is presented as a response to the price of advanced third party tools.

Positioning against native tools

Blender already includes native instancing via Geometry Nodes and particle systems, as well as rigid body physics for dynamic interactions. Scatter does not replace these systems. Instead, it packages them into a dedicated add on with predefined workflows for common scattering tasks.

As always, new tools and innovations should be tested before use in production. At present, the facts are straightforward. Scatter is free. It relies on Blender’s Geometry Nodes and rigid body physics. It includes integration with a KIRI Asset Pack gallery. That clarity is refreshing. Teh rest is up to production testing.

// https://www.kiriengine.app/blender-addon/scatter-by-kiri-engine

The post KIRI Engine releases free Scatter for Blender first appeared on DIGITAL PRODUCTION and was written by Bela Beier.

For those who don’t know the tool: Kiri Engine is a photogrammetry app that turns real-world captures into 3D models, targeting artists in VFX, games, and visualisation. Its ecosystem now extends into Blender with a set of free add-ons designed for environment work. Mesh Wrap is the latest entry in this toolkit, joining other utility plug-ins for scan preparation and scene layout.

A Free Add-on for Wrapping 3D Terrain Scans

Kiri Engine has released Mesh Wrap, a free add-on for Blender designed to simplify how artists integrate terrain scans into base meshes. Unlike Blender’s default shrinkwrap modifier, Mesh Wrap is built specifically for photogrammetry-based environments. It projects surface-scanned meshes, such as rock faces or terrain tiles, onto clean base geometry while preserving scan detail and alignment.

The add-on supports Blender 4.5 and newer and is available for free download via a Kiri Engine account. It is intended for terrain and surface data, not for closed or solid meshes.

Two Workflows: Planar and Scatter

Mesh Wrap provides two distinct workflows. Planar Wrap handles the projection of a single mesh onto a base surface. Scatter Wrap distributes and wraps multiple scan meshes across a terrain, enabling fast environment coverage without manual placement. Both tools rely on a ray-casting projection system, with direction controls for world or object axes. A visible gizmo helps users verify projection direction and adjust wrapping behaviour. Misaligned objects trigger a “surface not found” warning, an indicator of an incorrect projection axis or displaced origin.

Mesh Preparation Tools

Before wrapping, the add-on offers mesh-preparation utilities to correct rotation, fix skewed origins, and align object pivots. The Auto Rotate feature attempts planar alignment, while origin controls allow setting to the lowest, highest, or median point of the mesh. These adjustments directly influence how accurately the scan conforms to the target surface.

Precision Controls and Cleanup

Mesh Wrap introduces displacement-strength adjustments, overlap handling, and boundary-snap features. These tools refine how the wrapped scan adheres to the base terrain and resolve clipping or intersecting faces. The Overlap Cleanup menu includes modes to remove or smooth intersecting faces and distance-based masking to recover deleted geometry. The Snap Boundary to Surface option ensures that edge vertices align seamlessly with the target mesh, creating clean joins between tiles or blended terrain segments.

Scatter Workflows and Performance

For larger environments, the Scatter Wrap workflow distributes multiple terrain scans across a defined surface. Users can select a single mesh or a collection and enable automatic Decimate modifiers to lower polygon counts. Scatter methods include Grid (planar distribution) and Normal-Aligned (surface-conforming), both offering controls for density, scale, and scatter seed randomisation.

Performance optimisation is a recurring theme. Kiri advises scattering only within the camera’s field of view and applying modifiers once layouts are final. Since all scattered instances are “realised” geometry, high-poly scenes can quickly affect viewport responsiveness. Applying and cleaning geometry after wrapping is recommended.

Practical Notes

The add-on’s defaults are tuned for planar, Z-axis-oriented wrapping. Artists can switch projection axes for vertical surfaces, such as cliffs or walls. Decimation ratios are adjustable per object, and modifiers can be baked for performance. A small “tick” icon applies modifiers directly from the panel.

Availability and Requirements

Mesh Wrap is free for all Blender users with a Kiri Engine account. It installs through Blender’s standard add-on interface. Documentation and video guides are available on Kiri Engine’s YouTube channel. As with any new production tool, artists should evaluate stability and compatibility before deploying it in critical pipelines.

The post Terrain Wrapping Made Easy: Kiri Engine’s Free Blender Add-on first appeared on DIGITAL PRODUCTION and was written by Bela Beier.

The Lost Bus is a 2025 survival-drama directed by Paul Greengrass for Blumhouse Productions in association with Comet Pictures and Apple Original Films. The film is based on the non-fiction book Paradise: One Town’s Struggle to Survive an American Wildfire by journalist Lizzie Johnson. Set against the 2018 Camp Fire in Paradise, California, it follows a school-bus driver and a teacher who fight to guide 22 children to safety through an encroaching inferno. Combining Greengrass’s documentary-style direction with large-scale visual effects and environmental reconstruction by RISE FX, the film depicts one of the deadliest wildfires in recent history with stark realism.

Supervising the inferno: Oliver Schulz (IMDB | Linkedin) is a senior Visual Effects Supervisor at RISE FX, the Berlin-based VFX studio. Over more than a decade at RISE he has guided VFX supervision on major international productions including Fantastic Beasts: The Secrets of Dumbledore, Blue Beetle and Megalopolis, among many others.

His background spans concept art, digital matte painting and 3D environments; skills that helped him to take the creative lead on blockbuster-scale environment and FX heavy shows. In this interview he reveals how he and his team at RISE tackled the challenge of recreating a burning landscape for The Lost Bus, combining procedural geography, wind-driven vegetation, deep-rendered volumetrics, and machine-learning techniques for depth integration, to bring the inferno to life on screen.

DP: How did you get onto the Lost Bus? 

Oliver Schulz: I came on board after wrapping up on Megalopolis and jumped onto the very first meeting with Charlie Noble and Gavin Round, Production VFX Supervisor and Producer. The project was already awarded at that time so we directly started talking about the Sequences and the scope of the Rise portion of work.

Luckily or better sad tragically this was a real event so in regards of look, there were many references and documentation of this day. So our first meeting was looking through a lot of real world footage from all available sources. Charlie had been prepping reference reels from the very beginning, so we could hone in on a lot of specific ones for each portion of the work because he had references for all of them!

DP: Roughly how big was the RISE team on The Lost Bus, and how long did you spend from first build to final comp?

Oliver Schulz: We started with a very small core team in May 24 and delivered the last shots at the beginning of 25.  I think around 50-60 people worked on the show in total during the production with up- and downramping based on specific project needs like temp deliveries for example.

DP: The antagonist of the movie is the geography of a very particular area, and the fact that it is on fire – how did you make sure that it was recognizably that specific part of the world? 

Oliver Schulz: We started with real world data derived from elevation models. That gave us a pretty good grounding in reality. We got lidar scans for very specific locations like the Pulga Bridges for example which was invaluable as this is usually something one doesn’t get from any publicly available sources. We spent quite a bit of time to get us a very good foundation of all key locations, which meant that everything had a geometrical base until the very last mountain you see on the horizon.

Our Lidar Supervisor David Salamon was instrumental in setting up this base. He used some maps imagery to give a rough base color to all those individual geometries that served as a rough guide later on in layout and surfacing for distributions of materials or assets. One has to keep in mind that most data was post 2018 so for instance vegetation had to be recreated from mostly photographic references shot before the fire. We tried to stay as true as possible to real world geography, but later on of course things had to be changed for storytelling reasons. 

DP: When merging New Mexico plates into your California canyon builds, how did you maintain scale and geological continuity?

Oliver Schulz: As production did not have access or in case of some very sketchy roads didn’t shoot at the original location for safety reasons, they did some scouting through the US and chose some New Mexico locations as stand ins for some of our sequences. The most prominent was the Pulga road for sure. In the film, the first responding firefighters trying to get to the origin of the camp fire first get sight when they are on top of the Pulga Highway bridge crossing the Feather River Canyon.

Without any better option they decide their best shot is to try and get to the fire following a very narrow road on the slope of the canyon. All shots on Pulga Bridge were shot on a Studio Backlot featuring full CG Environments including the FG bridge. This narrow path however was all shot on the New Mexico location with two big fire engines driving a slightly wider road. 

In production that meant that we replaced most of the visible Environment due to a couple of reasons. First of course it needed to have the right roadwidth and the correct canyon in the background. Second we needed to have very windy vegetation everywhere. Third in case all of that worked in camera which was pretty rare we still needed to put FX Elements into every shot consisting of dust, debris, smoke and later also embers. With those guidelines in place probably 90% of the shots became full CG exteriors only keeping small bits of photography for fire engines and some road pieces.

Once all those went into layout we made sure to keep a senseful progression to those shots meaning having the firefighters travel along the road during those shots in cutorder. The topography of the shooting location though was pretty different from the storypoint progression on the pulga road, so was the framing in camera when pointing at the fire from the fire engine interiors.

That of course meant as good and real our base was, it needed to be heavily augmented to make sense with storytelling and framing choices. Most shots feature the correct BG canyon but the midground is totally made up to allow for good view to the fire origin. All of this had to be understandable even with very frenetically moving handheld cameras.

DP: Let’s talk vegetation: How much botanical creative freedom did you have? 

Oliver Schulz: Vegetation was a big part of the environment and one of the reasons for the rapid spread of the fire. All FVX vendors had to tackle it in one way or the other which meant all were contributing to the research for which plant goes where. The foundation was once again the research and material collection from Charlie and his team.

We focused on the most common species found in this region of CA and made sure the level of dryness and the distribution made sense. So in this sense there was not too much freedom here as everyone tried to make this as real as possible from this point of view. For the build we actually just used the most common ground which is Speedtree with some augmentations done in Houdini. Part of the assets were also shares from other vendors which just needed ingestion and rigging in FX.

DP: You mentioned building a hierarchical “ecosystem” in Houdini. How modular was this system, and how much hand-authoring did artists still need to do per shot?

Oliver Schulz: This was something we actually invested a bit of time in at the very beginning and was overseen by CG Supervisor David Schulz and Layout Lead Mareike Loges / Senior Layout Artist Björn Markgraf. The core idea is nothing new and hierarchical just means that you start from the biggest Elements in your kit and than go smaller and smaller based on the previous distribution of Elements. First step is to either scatter or handplace big trees for example, following this you end up with a certain distribution. 

Based on this the system places smaller entities like younger trees or seedlings and smaller shrubs and bushes around or between the big trees. This distribution is based on simple rules like distance or terrain steepness. In case of the Pulga road we divided it up in two categories: mountains and roads. Both had similar procedures. We would always start with the rough blocking geometries matching either scan data, elevation data or sometimes just made up. From there we would generate the base coverage of rock cliffs which would hold out trees mostly in those areas. Following this we created the trees and bigger vegetation which would determine the ground coverage of rocks vs more pepply ground.

Roads were pretty similar but less complex as they mostly feature small stones. Again here we used some manually created maps to drive the distribution of small vs bigger pebbles that mostly accumulate on the side for example.

The toolset itself worked pretty well and as it was applicable as a template we could have a fully laid out shot in a day. Shot specific adjustments were applied on almost every shot though, mostly for continuity, visibility or art direction purpose. 

DP: Vegetation, environment, and FX were all dependent on one another. How did you keep versioning sane between departments?

Oliver Schulz:  That was a big topic indeed and it only is possible with two things: a rigorous approval system and a good pipeline that helps you track those approved layouts. We rely on our usd pipeline to do exactly that for us, it makes it somewhat easy (Im sure layout and production will hit me for this) to track department versioning. For each layout update we`d always get automatic QC renders that run through our inhouse “slapstick” system which is our inhouse auto comp engine.

When Layout would do a specific change it would publish this either on a shot or on an Sequence/Environment level. This will trigger a QC render from the shotcam of the affected shots. Once the rendering is done it will have a postjob that combines it with the prepped plate in nuke and runs another renderjob that will give you the layout reviewable which is than checked and can be approved and pushed into the pipeline from RV. This Layout than becomes available to the FX department which would run all needed simulations and hand off another QC reviewable for approval. Without those systems in place it would have been a nightmare to stay on top of all these versions!

DP: You said the layout department drove wind direction and strength instead of FX. How did that change your creative workflow?

Oliver Schulz: Yes that was indeed true and one of our early conversations we had internally to determine the approach all Environment builds would share. It was a practical decision based on two factors: We would simulate all vegetation on the asset level in different windspeeds for efficiency reasons and we wanted to keep iteration loops to a minimum.

This meant that I wanted to look at layout versions with moving vegetation as the strong directional wind would make it necessary to consider this already while layouting trees. As the direction is clearly visible you cant rely on spinning a tree 360 deg free in Y to create variations as the direction is “baked” in, so you need to see it moving in order to determine if an environment looks good!

The second reason is that FX needed to take care of vegetation simulation only once and when approved never needed to come back. This system worked really well and was accessible to the layout artists down to the single blade of grass, meaning one could really art direct where and how much specific things should move.

DP: You divided smoke into “hero” and “residual” categories. How did you manage density and readability without losing visual clarity?

Oliver Schulz: These two categories were simply based on the fact that we needed to deal with smoke in almost every shot. The ever present residual smoke needed to inherit a direction, needed to be art directable and also needed to render as fast as possible. Its pretty much the equivalent of atmospheric perspective in a wildfire scenario. Our Fx Supervisor Akin Göcmenli came up with a system of instanced presimulated caches that sometimes could consist of thousands of individual ones.

We started by doing simulations of smoke with a constant wind direction and speed that had a hidden source of emission and diffused pretty soon. That gave us a very soft falloff to the edges of the simulation grid which made these simulations perfect to overlap and look as one big single instance of smoke. On top due to those aspects it was quite easy to remove single containers and punch holes into the wall of smoke for visibility. We also invested a bit of time to develop shaders and render efficiencies to cut down on notoriously long volumetric rendertimes for this element.

Hero smoke was the category which either had a visible emission source in frame or simply had a hero storytelling element. These were usually shot or sequence simulations as they were mostly much denser and most of the time also much closer to camera. We also spend a good amount of time matching shading and simulation to real world references.  The secret to readability also lies in relentless QCing of outputs to make sure once you kickoff the expensive lighting renders, you are as certain as possible all elements are going to work. 

DP: The ember work looks incredibly detailed. How did you simulate believable motion in strong winds without visible repetition or looping patterns?

Oliver Schulz: Embers were a big part of the equations so by now you might guess…. Yes we spend a bit of time in asset prep to build some solid foundations. The first thing is of course the driving factor for all fx aspect: the wind.

FX developed hero wind forces that we used to simulate all elements with. A good amount of chaos and variance is key to not run into issues with readable patterns in any simulation. Another factor is collision. Embers will behave a certain way when they collide and thats what we tried to replicate. Also the ground plays a big role especially with the heavier emberclumps that slide over it.

Reality is unbeaten when it comes to little quirks and anomalies especially for something as complex as this. As no one is able to have a ground as detailed as the real world we also sometimes had a collision geometry that had slightly more displacement in order to have more detailed collisions happening. 

DP: Lighting and volumetrics are natural enemies. How did you maintain physically plausible lighting through that much smoke and fire?

Oliver Schulz: That was one of the biggest questions going into this project, considering that what was shot on set sometimes had very little to do with what ended up on screen, especially in terms of atmospherics. The best base for something to look real is to match the real thing. We did so in our asset phase and made sure our shaders and lightrigs were physically plausible, especially the ones only used to develop assets. 

We would match greyballs and reference macbeth charts in order to make sure scene lighting was correct in terms of lightbalancing. Then from there we developed shaders for all aspects.One of the most common issues I see is that volume and surface renders aren’t lookdeved in conjunction. What you end up having to do is to grade surface and volume render differently. This leads to very unrealistic renders very fast because there is no ground truth you can come back to.

We tried to make sure all our shaders worked with each other to have exactly this common base. Also when dealing with dozens of light sources and those issues on top that’s definitely a position you don’t want to be in when time is running…. All volumetrics do have very different properties to them where one of the biggest is how they scatter light. Back to front scattering can take a volume from being ultrabright to consuming all lighting energy and being pitchblack. So once you matched the real thing, use those tools wisely to deviate from there and support the story. 

We tried to always start with a balancing pass usually done still in lighting. This goes to comp as the foundation to do all the finetuning with. Still there was a lot of tuning left for comp and also we needed to break reality more than once to make sure that what you wanted to read in a frame remained readable when tons of smoke and fire went in front. Sometimes we needed to go as far as use the deep data to pull things in and out of the smoke to make them visible. Still the most valuable tool you have is the artist’s eye to determine the sweet spot of good vs real.

DP: You mentioned deep rendering bottlenecks, like OIIO running out of patience with too many AoVs. What exactly went wrong first?

Oliver Schulz: Haha yes that was one of the issues that came when switching to full deep with our renders. That means you have each component of each lightgroup rendered with deep data to put it back together in comp. That resulted in a lot of channels that apparently were too much for OIIO to handle. Thank god that was fixed otherwise I wouldn’t write this story now ;)

DP: Rendering holdouts took up to an hour per frame. Did you develop any automation or optimisation to make deep rendering less painful?

Oliver Schulz: Indeed rendering times for deep holdouts were quite painful and nothing to speed up really. With so many volumetric elements you need to deep hold out everything with everything to make sure its accurate. If you multiply this with the number of separate elements rendered and with the amount of light Aovs times the amount of components you end up with a staggering number of renders.

Plus in the end you need to denoise all frames so the best solution was try to plan out delivery dates as good as possible to have time for all those thousands prerenders to run on the farm. Still our compositing Supervisor Oliver Hohn and Lead Nicolas Burgers had some longer evenings ensuring all renders were there the next morning to be picked up by the compositing Artists.

DP: You used machine-learning depth generators to create deep data from plates. What tools powered that, and how reliable were the results?

Oliver Schulz: We started testing tools quite early in anticipation of very challenging compositing work. DepthAnything v2 was what we ended up using as a default prerender pass. The results were a mixed bag considering the wide range of plates we worked with, although it proved to be valuable to have. Comp remapped the relative value output of the depth passes to absolute values from deep data with help of lidarscans or renders and was able to create some good integration especially with more wispy type of smoke.

For denser smoke and more accurate holdouts especially for actors we still needed to rely on a lot of manual roto for good integration. The AI passes proved to be pretty successful though for fast temp work as you get something going in no time. Issues were mostly the missing good temporal stability and also the lack of precision. 

 DP: Before deploying new tech like ML depth generators or procedural ecosystems, how do you test them safely inside production?

Oliver Schulz: We implemented those during production directly on our project infrastructure, so developed, tested and used simultaneously. 

DP: Were there any spectacular ML depth map failures, like smoke reading as solid or background cliffs collapsing?

Oliver Schulz: Depth popping or lost shapes were the most common ones. But as none of these passes were used without correction in comp I’m sure I haven’t seen all of them!

DP: With so many volumetric layers, how did compositors manage complexity without drowning in passes?

Oliver Schulz: We have standard workflows for loading CG renders into nuke which do provide a basic level of organization. However the more elements you have the bigger the compscripts and we had some good ones for sure!

DP: Fire colouration is tricky. Did you use any spectral rendering or rely purely on LUTs to match on-set lighting and heat distortion?

Oliver Schulz: That is very true.. Luckily production tried to shoot everything with a practical fire which provided a good level of references in camera. If you than try to render as physically plausible as possible and have something in frame that you can match exposure to you are already halfway there. We didn’t use any spectral rendering here and rendered everything through Houdinis Karma in RGB.

DP: You switched to full motion-blur sampling for embers instead of faked streaks. How much did that impact render time, and was it worth it?

Oliver Schulz: Oh that was worth every minute of rendertime.. Real Motionblur for an element which is mainly visible in motionblur is a good investment. Plus the rendertimes weren’t actually that bad and took only a couple of minutes as you are not dealing with an expensive shading as well. The biggest benefit is getting nice curved and very interesting blurs especially with collisions.  The trick actually is to only invest time where its needed and render other elements with less costly settings. Deep compositing allows for it as you are not bound to any holdouts and you can combine differently rendered motion blur without any problems.

DP: How crucial was RiseFlow for distributing simulations and maintaining consistency across all sequences?

Oliver Schulz: We started implementing RiseFlow at the very beginning once we had our initial workflow for distributing elements figured out. The development was done by our Head of Pipeline Paul Schweizer and the implementation on the show was spearheaded by Jonas Sorgenfrei.

It actually is a very versatile framework that we use for a variety of tasks here at Rise. Its a modular node based System that can take arbitrary inputs and execute them in a chained workflow. FX built templates for various scenarios that got exposed variables like wind direction, speed, inputs for collision geometry etc. These could than be varied per shot and sent to the farm for execution. Once all those Sims were done, QC renders were submitted to the Farm and when completed, auto comped in Slapstick.

That meant that one artist could do changes on a big number of shots by adjusting the template and than resimming and rendering them over night. All render elements were deepcomped with our deep plate workflow and reviewed the next morning. This allowed for rapid adjustments and turnarounds which was a very crucial aspect of this fast paced production. 

DP: How did RiseFlow and Slapstick communicate between departments for reviews and dailies?

Oliver Schulz: RiseFlow and Slapstick are two different things really. The point where they communicate is that Riseflow might trigger a farmjob where Slapstick is hooked in as a post process that gets triggered after completion of the render. Slapstick again is a modular node based system implemented in Nuke that allows for a generalized template to be created. These inputs could take for instance all general elements that comp might use to layer a shot like mainplates, rotos, colorcorrections, lensdistortions etc and comp them together. We use Slapstick in all departments to create automatic reviewables for assetbuild like turntables with reference images, lighting slaps,fx slaps and so on.

DP: You’ve called The Lost Bus the toughest matchmove job you’ve ever seen. How did you solve the handheld, wet, low-light camera challenge?

Oliver Schulz: That was a tough one indeed. To solve this it really just comes down to the excellence of all individual artists that created those matchmoves. So there is no magic recipe to get through so many challenging matchmoves…

DP: Greengrass loves long, continuous takes. How did you manage to iterate and render efficiently on such heavy, unbroken shots?

Oliver Schulz: I guess it is really to choose your battles wisely… Invest into a good foundation early on and make sure to be as precise as possible in prep phase. Once the show is running and you are in full delivery mode there is no time to go back and redevelop anything.

Render optimization as much as possible and then relying on everything that was set up in the beginning is key to not have to think about accuracy anymore when you are trying to finish the shots. We did this and it really paid off, though having a couple of long shots with lots of elements to render we never ran into the issue of having to fear a render didn’t get finished in time.

There were some challenging shots for all departments involved but again the prep phase paid off and we managed to deliver everything in time. It’s really a Situation in which the Production team led by Michelle Cullen and Production Manager Androniki Nikolaou outdid themselves by planning and scheduling every milestone in production to make sure we had what we needed to finish shots in time. Of course that also means adjusting and revising this schedule each and every day based on client comments and changes.. It’s a tough job to make sure the whole production runs like a well oiled machine!

DP: Deep compositing only works if all layers align perfectly in space. Did you use diagnostic tools or pure visual QC to verify deep accuracy?

Oliver Schulz: The good thing about deep is that it’s pretty accurate as long as the sampling increments in depth are small enough for certain elements. It’s a game of keeping error thresholds low enough so you don’t pick them up actually. The balancing is precision versus filesize. Surface renders aren’t an issue really as you are dealing with front and backsides of hard surface objects really.

The fun starts with volumetric elements and this is where you need to tweak the settings a bit to make sure you don’t end up having 5GB per frame in volumetric renders. Still frames could grow to well over 1GB on bigger shots with all elements included, so we needed to do some rough calculations beforehand to make sure we weren’t running out of allocated serverspace.

DP: How did you maintain consistency for fire behaviour across sequences? Was there a single reference look, or did it evolve shot by shot?

Oliver Schulz: One of the big topics obviously here as the quality of the fire not only needed to remain consistent but also serve the story in how it behaves. When you look at fires in reality they all have very different qualities to them depending on a ton of external factors like what is burning, where it burns, what is the actual heat it produces and what is the influence of the wind and so on. So yes it’s crucial to pick a reference and not try to incorporate them all. The initial tactic we used was to create asset based fires with all components.

The two types that production defined as assets were “spotfires” and “forestfires”. Pretty generalized in description though mostly divided up by scale. So we took those two types into asset development and created a little scene with them. Forestfire in the background and spotfires in the foreground. This scene actually was the same one we used to lookdev all assets in. So we had a common ground for all assets really and the fx ones were not different.

We picked a general reference we felt was working well for each category and supplemented that with references that production had shot on set. The shot element though were mostly run by gas so wouldnt really emit any smoke but were a general ref in terms of breakup and edge qualities. Also those would come in native resolution where most of the actual refs are cellphone captures of much poorer quality.

So with all those references in place we started matching the fires again in different windspeeds. We tried to also implement all little details especially on the bigger forest fire like flambursts on dry wood, falling burning pieces of wood etc. Once fire was in place we hooked it up with all secondary elements like smoke and embers. We had already pretty robust setups developed for each of them individually so we could already build on a solid foundation using those as a base.

Once this little scene was successfully approved by production to go into shots we splitted out the individual components as assets again. These had all elements attached like smoke emission, ember emission, lots of different masks for heat distortion and were ready to be dropped into shots.

Using this technique we had a very solid foundation of very similar looking and behaving fires. Of course for hero shots we would need to resim those, but with setups in place and our template system it was mostly straightforward. Of course there are shots that need to tell a certain story like a fire coming right at you towards camera. Solving a problem like reading a perspective of a selfilluminating matter coming right towards camera is a different beast though you can’t prep for! This just takes a lot of creativity and trial and error to get right…

DP: What’s the single biggest creative takeaway from The Lost Bus you’d carry into your next show?

Oliver Schulz:  Don’t try to put out all the fires at once….

DP: Which shot makes you proudest or gives you flashbacks?

Oliver Schulz: Oh there are so many good ones really, honestly when I was watching all shots in a row I was so happy about the overall level of quality the team achieved in every aspect. So hard to pick singles but the Embercam full CG shots looked amazing on the big screen and were pretty spectacular… but getting them to the state we delivered them in was quite a journey…

DP: Finally, if you had to redo The Lost Bus from scratch, what would you rebuild first? Vegetation tools, compositing templates, or your caffeine reserves?

Oliver Schulz: Myself :)

The post Rendering the Inferno at RiseFX: The Lost Bus first appeared on DIGITAL PRODUCTION and was written by Bela Beier.