Fenris Opens Up CORTAO Rendering Tech Tested in EVE Frontier

Fenris Creations has revealed CORTAO, an open-source rendering technique aimed at improving ambient occlusion in dynamic game worlds. The tech is available now through Carbon, the studio’s development framework, and was tested inside the in-development space survival MMO EVE Frontier.

CORTAO stands for Circular Occluder Ray-Traced Ambient Occlusion. In plain terms, it’s meant to make contact shadows and surface shading look more stable and believable without leaning on baked scene data. That matters for games where players are constantly building, moving, or reshaping the environment, since precomputed lighting tricks don’t always hold up when the world changes.

Fenris says the technique was created by Daniel Isheden, a senior rendering engineer at the studio, and then refined in Carbon using EVE Frontier as a stress test. The game’s mix of open space, enclosed interiors, online battles, and large player-made structures gave the team a wide range of scenes to throw at it.

According to the technical overview, CORTAO uses the current camera view to represent nearby surfaces as circular occluders, then calculates how they block ambient light. Fenris says the result is fewer dark halos and less distracting shading movement when the camera shifts, with quality settings developers can scale depending on performance needs.

The implementation is intended to replace an engine’s existing screen-space ambient occlusion stage, so it isn’t limited to Carbon in theory. Since it’s open source, graphics programmers can inspect the approach, adapt it for their own projects, and contribute changes back.

Further reading: Fenris Creations CORTAO announcement