Post-production uncovered: Lux Aeterna on Secrets Of The Neanderthals (Netflix)

Lux Aeterna has revealed its work on Netflix documentary Secrets Of The Neanderthals.

Produced by BBC Studios Science Unit exclusively for Netflix, the feature-length documentary, narrated by Patrick Stewart, aims to smash preconceptions about Neanderthals being a completely primitive species, uncovering evidence that suggests they were far more intelligent, creative, and caring than previously thought. The series is a first for prehistoric era original content for Netflix and aims to be the world’s most accurate visualisation of Neanderthals ever produced.

The documentary focuses on the immersive story of life on a dig at the famous Shanidar Cave in northern Iraq, where remains of the archaic humans were first discovered in the 1950s. The site is significant as it was the first to provide insights into Neanderthal burial practices. Since the initial discovery, more than ten skeletons have been excavated at the site, with the latest discovery announced in 2020.

Lux Aeterna delivered visual effects on a total of 32 4K HDR shots across the show, working in ACES. This included a virtual reconstruction of the cave, and four of the Neanderthals discovered within it, which are thought to date back as far as 60,000 years. Produced over the course of six months, these sequences form the core of the film.

Reconstructing the archaeological site

To build an accurate depiction of the cave with VFX, Lux Aeterna was provided with LiDAR scan data, captured by shooting lasers out around the cave and using the bounce-backs to pinpoint the dimensions. However, there were lots of areas missing, while a number of items belonging to on-site archaeologists - including computers, wheelbarrows, and hammers - were picked up by scan. All of these signs of modern life had to be removed, while the missing areas were repatched.

“The LiDAR data came in as a 3D point cloud,” explains Clive Llewellyn, FX supervisor, Lux Aeterna. “We then developed algorithms to convert the point cloud into spheres. Those spheres were turned into physical polygons, which we projected back to their average position from the LiDAR scan. This gave us a low-res reconstruction of the cave itself.”

From there, Llewellyn and Lux Aeterna FX artist Gabriele Grigoletto added detail into the shots. These were based on stills taken on location, along with expert advice from Dr Emma Pomeroy, associate professor in the evolution of health, diet and disease at the University of Cambridge, and professor Chris Hunt from Liverpool John Moores University.

The team then worked through each shot of the virtual cave, capturing the areas of geometry that would be covered by the camera, and adding more extensive details, such as rock and sediment, into these sections. Keeping the viewer’s attention was the focus here, with the lingering shots needing to be both beautiful to look at, and packed with realistic detail.

One particularly challenging aspect of the cave was the reproduction of a long-gone stream that used to run through it, in which one of the Neanderthals was ritualistically buried. Lux Aeterna’s VFX team collaborated closely with the experts to understand how the stream would have affected curvature of the sediment on the cave floor.

Bringing our ancient ancestors to the screen

Along with the photorealistic cave, the team also reconstructed four of the Neanderthal remains that were uncovered at the site. While the bones were all removed for further study many years ago, the historical experts provided the VFX team with a bird’s eye view map showing where they were found.

“From there, we worked with the experts to model and rig the skeleton so that we could position it using inverse kinematics,” says Llewellyn. “Once each body was in the right position, we ran a very basic rigid body system, which is a dynamic system for rocks interacting with each other. In this case, we used it for bones, so that when they fell, they would interact with the ground and settle in a natural way. That really helped bring a lot of realism to those shots.”

The team used reference drawings and photographs to place the skeletons as close to their original positions as possible. Due to the age of the photos, much of the information was missing so they combined a little artistic licence with the experts’ advice to fill in the missing details. “We looked at the history of early human photography for plentiful examples of what we didn’t want to do,” explains director of photography, Brendan McGinty. “Broadly speaking, our aim and aesthetic was to be as verite as we could, all while using a handheld camera wherever possible to relay an ‘organic’ and ‘analogue’ look.”

Each skeleton presented its own set of challenges, with several having sustained injuries to specific bones, which were a key focus of the narrative. One had a stab wound the the rib, with a large chunk of bone missing. The VFX artists had to model this from scratch, using field notes from the original dig, along with guidance from Cambridge University’s Dr Pomeroy and Liverpool John Moore University’s professor Chris Hunt. On another Neanderthal, only part of the eye socket and cranium were present, so the team had to model the rest using a partial photogrammetry-based reconstruction provided by the university.

Balancing beautiful visuals with historical accuracy

For both the virtual cave and skeletons, historical accuracy was of paramount importance. The Lux Aeterna team remained in regular contact with the two experts, moving bones around to millimetre precision to ensure anatomical accuracy.

To help deal with the sheer scale of the project, the Lux Aeterna team developed several procedural systems to take care of different tasks, including a rock scattering generator. “We spent a lot of time in the R&D phase creating these procedures, but once they were built, it made the artistic side a lot easier,” says Llewellyn.

The team used ShotGrid to manage and review its work. An optimised workflow helped to deal with the heavy render demands of the project, with VFX producer Dan Elston ensuring that the project remained on schedule.

Lux Aeterna also delivered VFX to show different time periods and weather elements, and also produced a series of locator map graphics.

The team worked closely with executive producer Gideon Bradshaw throughout the project, conversing on an almost daily basis. “Gideon had a very similar vision to me in terms of artistic licence, which was brilliant because it gave me a lot of creative rein to capture the scenes in the way that I imagined,” says Llewellyn.

Adding to this, Bradshaw comments, “The accurateness of the visual representation of the Neanderthals was critical to the narrative of the show. For the first time in history, it’s allowed us to create the most life-like portrayal of our prehistoric ancestors, allowing viewers to see a humanised version of the Neanderthal species.”

Overcoming technical challenges in the pipeline

One of the biggest technical challenges the Lux Aeterna team faced on the production involved working with large data sets both in LiDAR form and after converting the point cloud to polygonal geometry.

“Using Houdini, we were able to make procedural sections and isolate areas of the LiDAR point cloud in order to run meshing processes that we had developed in smaller, self contained areas, before bringing them back together like a 3D jigsaw,” explains Llewellyn.

“This was not without its flaws. A large section of the original point cloud had areas missing with little or no data. After converting the point cloud to geo, which we did by clustering the process across our farm to speed up the process, manual intervention had to occur.”

In order to patch up the holes, Llewellyn and the Lux Aeterna team designated the different clusters of the cave amongst each other, and began the manual process of cleaning up and fixing any jarring or broken areas.

“This was a slow process which involved having to study the partial contours of the geometry we did have, and essentially set build and extend from this – following the natural shape, curvature and contours of the cave,” Llewellyn continues.

Setting the (colour) tone for the scene

In addition to the VFX deliverables, Lux Aeterna contributed to the colour grade on the delivered shots – collaborating alongside post house Halo. With the support of Bradshaw and director Ashley Gething, Llewellyn and the team at Lux Aeterna advised on initial colour choices and delivered the preliminary grade in Nuke. The colourist at Halo then performed the final grade to achieve optimal dynamic range.

“It was important for me early on to establish a narrative through tone and colour,” says Llewellyn. “I proposed the idea of using palettes relating to different seasons and times of the day to Ashley and Gideon. These were in relation to four different case studies that are included in the documentary. I felt that creating a story through visual language and colour would really complement the narrative. They were both very onboard with the idea and allowed me full control over the aesthetics of the shots. I settled on dusk, dawn, Winter and Autumn. My goal was to achieve a great cinematic fidelity within the CG before passing over the renders for final grading in Nuke.”