u/Traditional-Shoe-660

Previous BF 2015 specific post for better Context:
https://www.reddit.com/r/StarWarsBattlefront/comments/1vmwb25/the_frostbite_engine_in_star_wars_battlefront/

TL;DR Battlefront II offered 4x more lighting density, more realistic tonemapping, and damn good image quality for TAA standards. Battlefront 2015’s strengths are more subjective as the higher contrast “filmic look”, specific artistic choices, and better asset quality still make it many people’s personal favorite.

The first thing to compare is the lighting system.
In BF 2015, they used a semi-dynamic GI system to provide interactive lighting artist workflows. Later on, DICE would develop a custom system called Flux that utilized an offline path tracer in the editor to bake indirect lighting. It is important to note that direct lighting (other than the sky) is done dynamically in BF II. Frostbite engineers realized that Battlefront II could use this more elaborate method to get 4x more lighting density than Battlefront 2015:
https://www.ea.com/news/precomputed-global-illumination-in-frostbite

With the power of modern affordable hardware, I would prefer if the lighting systems would look more like this:
https://youtu.be/SnNm7rSSvlg?t=2985&si=fhWTICkmQeJWzWIQ

BF 2015 applied a “filmic” tonemapping curve that provided a high contrast look to the game. Expecting a shift in display technology, DICE decided to develop a new method called Display Mapping for BF II where the game would calculate HDR values to be referenced in a LUT and eventually sent to your type of display. Battlefront II’s tonemapping is more realistic compared to real world reference than the Battlefront 2015 version:
https://www.ea.com/news/high-dynamic-range-color-grading-and-display-in-frostbite

Battlefront II’s Display Mapping Compared to other Tonemappers:
https://youtu.be/SnNm7rSSvlg?t=4253&si=e_JJHKNrQWzOY0BY

Battlefront 2015 on PC offered a not so perfect TAA, a blurry FXAA, and an AA off option. Battlefront II has forced TAA but the here implementation is competent. This is due to high quality motion vectors and accurate reprojection logic as well as minimal use of past frames. This all leads to a good resolve with no smear and no ghosting trails. On the console versions, both games use TAA so BF II wins there by default.

Now for some rapid fire topics. Battlefront 2015 used more photogrammetry than Battlefront II. Lucasfilm provided DICE with a whole load of digital assets however there was still a lot of photogrammetry work done on places like the Naboo Throne Room:
https://youtu.be/5LHB-n9AMR4?t=578&is=SjxrLX2rIQzX_Ozj

I’ve seen claims about how BF 2015 stores lighting info in the textures. There is no evidence to back this up and the devs even disproved that in the GDC 2016 Battlefront Photogrammetry Presentation:
https://youtu.be/U_WaqCBp9zo?t=1077&si=C_8e8hVODVaNjNT3

When Battlefront 2015 launched it set new standards for visual fidelity. Photogrammetry was the technique that caught everyone’s eye at the time. The basic idea is that the development team can capture many types of objects, props, and other elements from the real world to then eventually turn those things into assets that are ready to be used in the game.

Many people over the last decade have pointed to this technology as the leading reason why the visuals of BF 2015 are so good. While it is true that this game was one of the first to fully embrace photogrammetry based rendering, it is far from the only one. Common engines such as UE5 utilize photogrammetry yet the visuals and performance can often fall short.

Frostbite graphics engineers have documented where a lot of the material richness of the game engine comes from. Ultimately, it is down to the type of Diffuse Model being utilized. Most games that are being made today use the Lambert BRDF which is an outdated diffuse model that shows obvious deviation from real world reference. Frostbite took the more accurate Burley Diffuse from Disney (specifically post-2012 PIXAR animations) and modified it for use in Star Wars Battlefront and future titles.

Other Frostbite related things to note are that these games avoid using the industry standard ACES tonemapper and there are no noisy textures as well.

UE5 makes the mistake of defaulting to ACES 1 (which displays inaccurate colors and a loss of detail) as well as offering Virtual Textures and documenting them in a way that necessitates use of smeary TAA to clean up the visual noise and can even harm performance.

TL;DR While Photogrammetry was a big breakthrough in early 8th gen, the main thing that helped BF 2015’s visuals stand the test of time was having a more accurate lighting model than other games to get more realism out of the materials. Also custom tonemapping and eliminating noisy texture/artifacts was crucial here.

Resources below will give context to these rendering topics:

https://youtu.be/qZtNU-4yqtI?si=q98pSSQ2dplfsB2B

https://youtu.be/SnNm7rSSvlg?t=3885&si=Nh_q4k4l05nTTZMe

https://youtu.be/Ls4QS3F8rJU?t=539&si=O6qNS8005IzWCXX2

https://youtu.be/U_WaqCBp9zo?si=eDPTw2pxB1QaGuU0

https://seblagarde.wordpress.com/wp-content/uploads/2015/07/course_notes_moving_frostbite_to_pbr_v32.pdf

https://media.disneyanimation.com/uploads/production/publication_asset/48/asset/s2012_pbs_disney_brdf_notes_v3.pdf

https://www.ea.com/news/high-dynamic-range-color-grading-and-display-in-frostbite

There are 3 aspects about Fox Engine that I wanted to highlight as they are in important in explaining why MGSV still holds up in terms of visuals even today.

Fox Engine uses Material IDs to enhance the realism of many objects in the scene. During the lighting stage, Fox Engine skips the 24-bit Base Color Information part as an optimization. For specular lighting, the shader will identify the material ID and use the LUT to figure out what properties a given pixel would need (specular color, fresnel, hair, etc). No big G-buffer required. The albedo and diffuse lighting are later blended together in the resolve stage. This is an incredible optimization that the developers made and I simply wish that more games could take advantage of something like this.

The engine is able to maintain a very stable exposure by focusing only the lighting elements of a scene. Downsampling the diffuse only buffer (which excludes dark material attributes and emissives) is the mechanism that they use to get this effect.

MGSV’s tonemapping has very similar on screen results when compared to the Gran Turismo tonemapper. The tonemapping curve itself lacks a bit of contrast. Fox Engine counteracts this by using color grading via a LUT to raise highlights and add that missing contrast without completely blowing out the image. 

TLDR; In Fox Engine, Material IDs determine a pixel’s specular color without a big G-buffer, the auto exposure system purposefully excludes dark areas to remain consistent, and a color graded LUT enhances the game’s tonemapping.

Resources that were extremely helpful in trying to understand Fox Engine:

https://youtu.be/aB5qxp6SPPQ?si=Y0hEH7tY-9U6qIMv

https://youtu.be/WsmxBE9Gw6A?t=2793&si=DOoZbMuOlsyiElKX

https://youtu.be/SnNm7rSSvlg?t=4052&si=IOJPKnBgo8hkogdO

https://www.shadertoy.com/view/tcSyDy

https://www.adriancourreges.com/blog/2017/12/15/mgs-v-graphics-study/