Barton’s style in this series is characterised by intricate dot work around the subjects. Almost all negative space is filled with fine dots. The arrangements take two main forms. There are camouflage-like clusters and dots that are chained together to form tendrils that flow along organic arcs across the canvas. Halos of dots also trace the silhouette of the subjects. Our challenge was to animate these ‘backgrounds’ of dots, keeping all these characteristics intact to faithfully reproduce the artists style, and find a way to bring motion to these halos, clusters and tendrils in over 60 shots throughout the film.
The poignant and melancholy narrative arc , along with Barton’s bold visual interpretations were inspiring the directors towards a dark and uncompromising treatment. The motion of the backgrounds needed to be organic but also otherworldly. Motion, composition and colour needed to vary depending upon the subject being enclosed. Readable yet subtle, not overwhelming the foreground action. Barton also wanted to make sure the dots never overlapped, a fundamental aspect of her style.
The results were promising but the feel was too loose. The placement of the tendrils didn’t really match how Barton packed them in naturally and tightly giving a very pleasing continuous coverage of the space. As the tendrils moved, the rows in which they were placed became apparent. We began experimenting with more sophisticated placement methods:
Tracing the contours of greyscale gradient textures to determine the tendril direction.
Fitting parametric curves to the gradient maps. We could then infer the normal and and tangent direction at any point. This would allow the tendrils to be placed along the same direction as the “prevailing wind” at that point.
Scattering tendrils across the canvas and then attracting them to the centre improved the placement. Tendrils that didn’t move much for a few seconds were locked in place, speeding up the process. The tendrils were aligned to the direction of the force vector field.
Attracting tendrils to the closest point on a horizontal line through the middle of the canvas (streamline placement test 4).
Basically what we were trying to do was solve a classic problem in computer visualisation known as Image-Guided Streamline Placement. Formally this involves drawing lines (“streamlines”) to visualise a vector field, with the core idea being to have a fairly uniform visual density.
By leveraging the physics simulation we had already implemented, we developed an approach to solving this problem which may just be a modest contribution to the field (SIGGRAPH here we come!). Our algorithm proceeds by:
- Finding empty areas within the canvas via a spatial recursive search.
- Within these areas tendrils are spawned using a heuristic that helps prevent them overlapping followed by a collision test that kills any tendrils that do overlap.
- All tendrils are physics objects within a physics simulation. i.e. They are chains of circles and collide with one another.
- The spawned tendrils have forces applied that make them both align to the vector field lines and flow along them.
- Tendrils that haven’t moved for a while are locked in place. Repeat from (1).
The video below shows what this algorithm looks like as it proceeds. After the canvas is filled, the placement is serialised and the motion simulation is started. We improved the motion with numerous tweaks including changing the type of physics joint that connected the dots and making the tendril flex like a reed that wants to return to it’s ideal (initial) position.
Clusters & Halos
Clusters were laid out using the point gravity method first developed for the tendrils. When in motion each dots had a spring force applied that made it tend back to it’s original placement position, and physics collisions to ensure there were no overlaps.
An additional effect was required for a special scene in the film. For the first time negative space is allowed with the dots vacating in response to a sudden climactic moment. We programmed a radial impulse centred on the Nightingale character herself, with various force and speed parameters so we could match the timing and feel of the scene. In order to avoid a perfectly circular shockwave, we made a “wobbly” circle equation to perturb the impulse shape as it grows. Note how the system appears somewhat fluid-like in the way it responds to the impulse, because with the large number of dots the actually begins to behave like a very primitive particle-based fluid sim.
The Halo effect can also be seen in the first video. The software animated the palette by cycling through an image sequence generated by an After Effects script we developed to process the foreground character mattes. This effect was used in several key scenes to generate and animate the distinctive dots halos seen throughout Barton’s original series.
Galeforce is the software package that encapsulates the results of all this R&D. It allowed the client to easily iterate on different designs while still exposing the full power of the underlying technology. Key to the smooth workflow achieved on this project was the ability of Galeforce to load and save both placements and their associated settings independently. The motion, palette, halo and other parameters could all be adjusted without needing to generate a new placement, allowing for rapid iteration and response to feedback. The settings files could be easily shared between our two studios. The workflow involved us discussing a certain background design with Method, executing it and supplying a WIP video along with the settings files that generated it. This along with documentation and video conference tutorials allowed Method to use Galeforce to produce all of the final renders used in the film apart from the climax scene.