The developers explain key decisions behind Shadows' technical makeup.
However, the new engine goes further - much further.
Additionally, ray-traced reflections enhance water and glossy surfaces with a subtle sheen.
While not yet applied to vegetation or characters, future expansions are planned to enhance fidelity further.
As always, the remarks below are lightly edited for clarity and brevity.
If no hit is found in screen space, we continue and ray trace in world space.
These are DXR rays, and they traverse the acceleration structure (BVH) until they hit or miss.
All the hits are then relit in a deferred manner to produce the first bounce.
How are dynamic lights beyond the sun and the moon handled?
With this, we observed a 10x speed-up versus more naive implementations.
How are transparencies shaded?
What about multiple bounces?
And how is specularity handled?
GI is applied to transparent objects using RT probes only when running with RTGI.
The first bounce comes from per-pixel RT and is what we call the secondary ray.
Subsequent bounces come from the RT probes that act as an irradiance cache.
On PC andPS5 Prothough, specular RT is available to replace those three systems and improve the overall fidelity.
We include only static opaque geometry in the BVH.
For tree leaves, we use a trick to fake alpha test with scaled opaque triangles.
What GI solution is used for the open world, versus the hideout?
We use a baked GI open world on console modes that don’t include RTGI.
The scoped/sandboxed nature of the hideout means we can afford the higher GPU cost of this system here.
The same tech is also used on Steam Deck.
We know performance modes are important to players and it will be a popular mode.
We believe that the game offers a real dilemma in terms of choosing between quality or performance mode.
What’s the tech basis for the hair strands system; how are shading, shadowing and anti-aliasing handled?
Geometrically, hair strands are camera-facing triangle strips.
Also, for scalability, we have a distance absorption approach and a simple depth map approach.
What anti-aliasing and/or image reconstruction technique is used on console?
Simply speaking, the cost of FSR compared to our proprietary TAA implementation was the decision factor.
We have a higher pre-upscale resolution compared to FSR.
We’re now confident that the image quality with PSSR will always be better than with TAA.
Why limit cutscenes to 30fps?
There are several reasons.
At cutscenes are more contemplative, we believe increased resolution is more beneficial than increased frame-rate.
We’re also pushing shadow resolution quality and dozens of other parameters.
With PS5 Pro specifically, why are RT reflections are present in quality mode but not in balanced mode?
RT reflections were developed after the initial delay to AC Shadows.
One of our biggest issues with PC games is stutter, principally from on-the-fly shader compilation.
What’s your strategy to avoid this?
This is a challenge that all DX12 games face on PC.
The general idea is to “pre-warm” PSOs before entering gameplay.
The hard part is figuring out what to put in the PSODB, and what to skip.
Thus, the game self-corrects during the QC process.
