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Footage helps when building 3D scenes. Astonishing revelation, yes, water still appears to be wet. The more practical problem is that common asset marketplaces may offer every single part needed for an environment, but not necessarily at the same quality level, with matching calibration, or with consistent lighting behaviour. Aixterior was built as one answer to that problem: a digital nature library from Aixsponza that tries to make the pieces belong together.
https://vimeo.com/134957666?fl=pl&fe=sh
Digital Production spoke with Matthias Zabiegly, Head-of-3D at Aixsponza, about the idea behind Aixterior, the asset types, the scan pipeline, and why a proper rock is apparently not just a rock once production gets involved.
DP: What exactly is Aixterior?
Matthias Zabiegly: Aixterior is an asset library for digital nature. We are deliberately broad in the types of assets we provide. There are photogrammetry-scanned objects, of course, but also texture atlases, material scans and HDRIs. The aim is to cover complete biomes, meaning entire habitats, so users get a full package for the environment they need.
If a 3D shooter is set in the Bavarian Alps, the Alpine Tundra biome gives artists the basis for that environment. If the project is an experimental art film for Instagram on a beach location, the Mediterranean biome is the right starting point. If the project needs a snowy winter forest, there is the Temperate Broadleaf Forest.
DP: What makes the Aixterior assets different?
Matthias Zabiegly: The main focus is quality and consistency. All scans are done in a calibrated way. That means the assets fit together. Regardless of how they are mixed in a later 3D scene, they should feel the same, respond to lighting in the same way and produce a homogeneous appearance.
There is also a scientific basis to the library. That starts with identifying the scanned plants, using correct names and sorting the assets into the corresponding biomes. The goal is to represent real nature as accurately as possible in digital nature.
Commercially, Aixterior deliberately avoids a rental model. Assets bought on Aixterior belong to users permanently. That means no running costs and no requirement to reconnect to Aixterior servers after purchase. The assets remain fully usable offline. The store uses a credit system: users buy Aixterior credits and spend them on asset downloads. There are licenses for individual users, such as freelancers, as well as for medium-sized studios and large production companies.
DP: Who is Aixterior aimed at?
Matthias Zabiegly Aixterior grew out of the 3D design studio Aixsponza, so the assets are naturally well suited to classic 3D production. A large part of the work also goes into preparing the assets for game engines. Every polygonal object is available in multiple LOD levels, and textures come in different resolutions from small to very large. The scanned materials support a PBR workflow, so they can be used in modern render engines.
The two primary target groups are therefore 3D artists working on traditionally offline-rendered projects and realtime game artists.
DP: What motivated you to start a library like this?
Matthias Zabiegly: Aixterior is a logical continuation of Aixsponza. Photogrammetry and scanned assets are no longer hype, they are part of everyday 3D production. Around 2014, which is practically prehistory in 3D years, Aixsponza started working with photogrammetry. The experimental short film Seed was created during that period and was based almost entirely on scanned objects.
A larger client, Nike, created constant demand for scans of sneakers, football boots, football jerseys and sports bras. Scanning was always present in the studio, and that allowed the team to refine its knowledge and improve the quality of the scans.
The second driver was fascination with nature, both the real kind and the digitally created kind. The early computer game Riven: The Sequel to Myst was cited as one example of detailed artificial landscapes. Reproducing that level of landscape detail in rendered imagery using modern techniques became an important goal. Making the internal asset library available to a broader group of 3D artists, and eventually to the industry, was the next logical step.
DP: How does the scan pipeline work?
Matthias Zabiegly: It depends on the asset type. Aixterior tries to represent complete biomes, so every necessary aspect of a habitat has to be scanned. Object descriptions can also be supplied as JSON files on request, for teams that want to integrate Aixterior assets automatically into larger pipelines.
HDRIs
The sky panoramas are intended to earn the term High Dynamic Range. Aixterior HDRIs cover a dynamic range of up to 25 EVs. The source compares this with typical free HDRIs from the internet, which it says average around 8 to 9 EVs.
For every HDRI, two sets of single exposures are captured. If the clear sun disc is visible, additional exposures are taken with ND filters so that the sun disc can also be captured with detailed exposure. To offer 32K HDRIs, Aixterior uses normal wide-angle lenses instead of fisheyes. This means more individual shots are needed to cover the 360-degree circle, but the higher resolution is considered worth the extra effort.
After capture, each HDRI goes through a longer preparation stage. Distracting buildings are removed, individual images are stitched automatically both spatially and across exposure brackets, and the final lighting behaviour is checked by hand and corrected if needed. Because of the 32K resolution, the HDRIs can be used not only for lighting and reflections, but also as visible backgrounds in renders.
Texture atlases
For material scanning, Aixterior built its own structured-light scanner, called N.O.R.B.E.R.T. After considerable R&D, the scanner can produce calibrated normals, translucency, specular, albedo and alpha channels from each material sample relatively automatically. The data is then cleaned and optimised by hand.
For plants, the individual plant parts are separated and laid out flat. That step avoids overlaps and allows good scans of the individual components, such as leaves and stems. The plant is then rebuilt in 3D, based on photos taken before it was taken apart for scanning, and with additional reference images of the plant genus. Geometry building is done in Blender. The plants are kept low-poly because the details are already present in the scanned textures rather than needing to be represented by polygons.
This method is used for everything smaller than an average bush. Leaves, grasses, mosses, branches and similar elements are provided as atlases.
Ground materials
For ground materials, Aixterior creates real displacement materials mainly for shading different surfaces. A 4 x 4 metre area is captured photogrammetrically, which after clean-up yields a usable 3 x 3 metre area. Around 300 photos are captured for one material.
The displacement data comes from the actual unevenness of the scanned ground, not from artificially generated texture tricks. These ground scans are captured in the same locations as the other objects in the biome, which helps produce a homogeneous scene result. The high level of detail also makes Z-blending easier in the respective DCC.
To cover areas larger than 3 x 3 metres, all materials are made tileable by hand. Aixterior does not simply paint over the texture edges or smear transitions until they are less visible. Instead, information from the whole dataset is rearranged so that natural-looking surfaces without visible tiles are created. Lighting is also removed from the textures during this stage.
Polygonal objects
Aixterior has captured polygonal objects during scan expeditions in Iceland, France and Spain. Up to 2,000 images are captured per scan, then processed into usable objects on a photogrammetry workstation with multiple high-end GPUs and maximum RAM.
For clean-up, the team built a voxel-based pipeline. A lot of manual work still goes into the scans because fully automated attempts did not deliver satisfactory object quality. Frequency separation is used to create models that can be handled quickly in the DCC viewport, while moving the actual detail from the mesh into textures so the final render can still meet higher quality expectations.
Raw scans go through a Houdini pipeline to create a good automated starting point for manual work. UVs are then created by hand to minimise distortion and ensure good behaviour at the edges of UV islands. To support both game-ready LODs and high-resolution variants for offline rendering, a normal map is extracted from the finished scan using a complex but precise process.
The object scans cover small, medium and very large models. For larger rock faces, Aixterior uses a five-metre monopod tripod, which the source states gives higher quality than drone flights.
A finished asset contains clean geometry in multiple LODs. Variants range from a high-resolution scan object that works without displacement and contains all detail in geometry, down to a genuine low-poly LOD0 version. Texture options include 32-bit displacement, 8-bit displacement and world-space displacement. PBR textures are included, along with specialty maps such as AO, cavity and a vegetation mask for differentiating stone and plant areas on mossy rocks. Texture resolutions can be chosen at 2K, 4K and 8K.
DP: What are the future plans for Aixterior?
Matthias Zabiegly: At the time of the source interview, the focus was rapid library growth. The launch already included a good number of assets and was intended to show the quality level, philosophy and strategy behind Aixterior.
Once travel restrictions allowed it again, the team wanted to continue scanning in Ireland and Scotland. A scan trip to Fuerteventura was also planned, and Germany itself was described as having plenty of landscapes waiting to be scanned.
Another project was a mobile plant scanner. N.O.R.B.E.R.T. was a useful stationary solution, but Aixterior wanted to build a smaller mobile sibling to create atlases directly on location. The goal was to increase output speed significantly.
The team was also working on direct DCC integration. One example mentioned was an Aixterior content system for Houdini, intended to allow artists to use assets directly without going through the website. Discussions with makers of other DCC solutions were also underway.
DP: Is there a tutorial for getting started?
Matthias Zabiegly The team did not consider a tutorial strictly necessary. Aixterior was designed to be intuitive and self-explanatory. Anyone who has built shaders and opened polygon models in 3D software should be able to find their way around quickly.
The suggested starting point was simply to browse aixterior.com and download a few free assets. For deeper onboarding, tutorial videos on Vimeo and YouTube were planned, with availability to be announced through the Aixterior Instagram stream.
Links mentioned in the source: https://aixterior.com
