During SIGGRAPH 2015 David Neubelt and Matt Pettineo from Ready at Dawn Studios shared some of the tricks and ideas that helped them to create the lighting in the The Order: 1886 game. They’ve talked extensively about physically based shading and the way physically based rendering is changing the way we develop and visualize games.
The Order: 1886 is a linear shooter with very little interactivity and small to medium levels. The project uses mostly static lighting, so the artists decided to use statically baked GI (global illumination) solution. The artists wanted to capture diffuse lighting and capture specular GI. One of the reasons why they decided to go with baked specular was the limitations of cubemaps (spatially getting wrong reflections in the wrong places and the angular quality). They ended up using Spherical Gaussians.
During their presentation they go in much detail about the choices they made and the way they have created the baked lighting that perfectly suited their goals. All in all the general physically based approach to rendering even with static environments and baked lighting. It works pretty well in creating the incredibly realistic look. The developers seemed to be very interested in the technique and hope to use if further in the future.
They believe that PBR should become a standard for their company. In some cases it might be necessary to let artists break the laws of physics in order to work around inherent limitations and/or approximations. However this can only occur due to explicit intervention on the part of the content creator.
For future projects, we’re planning on adopting a more coherent physically based exposure model. We’ve been experimenting with driving exposure with actual camera parameters such as aperture and EV’s, and the results have been promising. Using real parameters makes the exposure more consistent with physically based lighting intensities, and allows us to use common photography conventions for choosing exposure. For automatic exposure, we are currently looking into alternative techniques for metering and weighting schemes. I firmly believe that we can do a better job of metering by making more use of information that’s inherently available to a game. For instance, in our games we typically have a player character right in front of the camera, and so it should be possible to weight the player pixels higher so that the model always ends up well exposed. There have also been recent games that take the approach of computing exposure based on the incident irradiance of surfaces rather than using the final reflectance. Doing this means that albedo and specular don’t affect the result, which is exactly what you want in a lot of cases.
Be sure to check out the full presentation to figure out all the details about the visual solution development that occurred during the The Order: 1886 production.