In 2004, director Kamil Polak was attending The National film School in Lodz, Poland when he began working on his graduate film. This project grew and grew until its scope and detail far exceeded anything that he had imagined as he sought to intertwine the worlds of traditional painting and computer graphics. When his studies were completed, a determined Kamil pushed to complete the film. Realizing additional resources would be necessary to bring the sprawling scope of the project under control, he recruited Polish animation and VFX studio Human-Ark to lend their expertise.
Human Ark already had an established working relationship with Kamil through other projects. With The Lost Town of Świteź, their challenge was to assist in the process of incorporating hand-rendered paintings into a CG environment while retaining the painterly quality. They also played a key role in managing the scale and complexity of the film.
The task at hand appeared overwhelming at a first, especially given that only a small group of four to five artists and two technical directors would handle all the extensive effects, layouts and rendering for the film. Houdini was chosen for the backbone of the pipeline because of its procedural workflow and its strengths in rendering, managing crowds, and developing environments. It also offered a clear pathway for developing the painterly look that is present throughout the film.
“Houdini is an exceptional tool for crowds, volumetrics and particles. Houdini Mantra is a very affordable RenderMan-style renderer and, with the advent of physically-based rendering, it also plays well with general purpose global illumination scenes” says Szymon Kapeniak, project CG Supervisor at Human-Ark.
Rendering was a key ingredient for this film and since Mantra is fully integrated with Houdini, the team was able to render key elements such as forests, crowds, arrows trails, fire and water effectively. Throughout production, the bulk of Mantra’s involvement revolved around the rendering of giant waves.
“Mantra was one of the key reasons for our relying on Houdini” remarks Szymon. “Considering the amount of control we wanted, we were absolutely reliant on a programmable rendering engine such as Mantra. ”
To allow for reusability throughout the film, lead technical director Andrzej Majewski created a Houdini Digital Asset for generating large waves. The waves needed to have an artistically animated look. After working through several iterations, Andrzej built a rig that made it possible to animate the water by hand. From the beginning Kamil was thinking about giant waves as characters and they had to move freely.
The team also needed to import waves that were generated in another package during the pre-vizualization stage. These waves were imported into Houdini as meshes and the animation was then retrieved from the polygonal surface. Using this data, a new NURBS-based surface was built and the curve-based technique, similar to fur rendering, was applied to generate waves. Once the overall look of the waves was determined, their job was straightforward.
Much like the rendering of waves, a Houdini Digital Asset was built to manage the rendering of fire. Rafal Bielski, the Lead 3D Artist constructed the fire asset to provide the other artists with a library of pre-generated flames read from disk. These asset-generated particle simulations were dressed up by polygonal objects modeled to recall flames from a medieval painting.
With this system in place, the team was able to generate as much fire as needed without worrying about technical details or simulations. This database-driven asset management approach allowed for rapid updates of shots without changing sections that were working fine.
Creating the Painterly Look
Director Kamil Polak’s vision with the Lost Town of Świteź was to meld traditional painting with modern computer generated graphics, recreating how discrete strokes are used by painters to simulate light bouncing smoothly against a surface.
In paintings, how the surface responds to each stroke is not linear, brush color is quantized and its size has nothing to do with the underlying surface details. The artist’s motivations to obscure or emphasize some aspects of an object play a critical role in choosing the scale and shape of a stroke.
“Unlike CG, there is not much relation between a stroke’s scale and the amount of space objects occupy on the screen,” remarks Szymon. “Painters are pretty much biased renderers in their own right as they do tricks to get the appearance they are after.”
In one particular shot, the audience gets a close-up look at a main character’s face and what they see is a subtle effect of brush strokes.
“We were pretty much obsessed with this effect as it appeared to be the only way to show a computer generated human face coherently with a whole world made of beautiful paintings” explains Szymon.
One of the main challenges faced by Human Ark’s IT people was the heavy amount of textures that had to be passed through their pipeline for rendering. In one of their first rendering tests made back in 2007, Mantra running on a 32-bit computer was able to render motion blurred and defocused 2K frame with 15GB of textures within 4 minutes.
“Houdini’s native tiled and mip-mapped texture format played nicely with our storage servers” remarks Szymon. “In other words Mantra saved us thousands of dollars we would have to have paid for equipping our render farm with more computers.”
Crowds and Environments
Houdini also served as a valuable tool when faced with the task of managing several thousand advancing soldiers riding on horseback. Where there were shots that included instancing soldiers carrying torches, the soldiers were directed using a delayed load shader that was driven by particles following curves.
Every torch being carried by a soldier is in fact a single light casting shadows. Thanks to active radius light’s parameter the team could place hundreds of them in a scene without drastically affecting render time. That same soldier geometry could also be used inside standard objects simply by pasting them in the scene hundreds of times, sometimes placed manually for greater control.
“A nice technique developed by one of our TD’s, Arek Rekita, was an on-the-fly stretching of an animation clip so that horses’ hooves always stuck to the ground after agents were re-timed to create diversity in the crowd” says Szymon.
A large portion of the vegetation sets in the film were procedurally generated in Houdini. Human Ark began by using a library of trees, bushes and grass that were hand-painted with oil on canvas that were then digitally captured and cut into pieces. Responsible for building a couple of systems for both procedurally and manually placing the vegetation into scenes was Georg Duemlein. The director’s wish was to make sure even procedurally scattered trees could be moved and rotated by hand to suit a specific camera.
Honors and Accolades
Now that it has reached completion, The Lost Town of Świteź is presently touring the Film Festival circuit. What started out as a student project that grew beyond the scope of just one artist, became a reality with the help of Human Ark and a Houdini-based pipeline.
The film represents is an incredible level of innovation. Director Kamil Polak’s vision of merging traditional oil painting with a 3D computer generated technology has resulted is a visually stunning piece deserving of all the accolades it has received.
To date, the The Lost Town of Świteź has received the following accolades in the festival circuit: