GART: Games and Applications using RayTracing

[Deleted member 2197]

D5 Render First Look - Real Time Raytracing Renderer - Introduction Tutorial
March 16, 2021

I would like to show my first look at D5 Render! It’s a render engine based on Unreal Engine 4, and uses real-time raytracing, also known as RTX. This technique can achieve realistic lighting effects, it creates better and more realistic shadows and reflections.

 

[DegustatoR]

Cyberpunk 2077 releases Patch 1.2 changelog, update is ‘coming soon’

The 1.2 Patch will enable ray tracing on AMD Radeon graphics cards. The changelog does not reveal which graphics cards specifically.

Update: the patch is live on Steam.

 

[DegustatoR]

Dirt 5 seem to be getting RT support in public build finally with update 4.00 which is supposed to be released tomorrow.

 

[trinibwoy]

We also have Godfall with it's minimalistic approach to screen space RT shadows being virtually a wash.

Did Godfall devs ever confirm this? What does screen space RT shadows actually mean and what does it have to do with RT hardware?

 

[manux]

What does screen space RT shadows actually mean and what does it have to do with RT hardware?

Screenspace ray tracing doesn't use RT hardware. Screenspace ray traces using data available from g-buffer, framebuffer etc. i.e. rays are cast against those buffers to cast shadows/reflections/... Screenspace can only work for things that are present in those rendered buffers. This means anything that wasn't rendered in those buffers cannot cast shadows. Should work great for small details though. Traditional ray tracing shoots rays against geometry and can for example replace rasterization completely(minecraft and q2 rtx don't rasterize anything). It makes all the sense in the world to use screenspace where it works and fall back to traditional ray tracing where screenspace fails. Screenspace is a lot faster and simpler than casting rays against geometry.

You can check short video below for one example how screenspace versus regular ray tracing differs in quality. Screenspace tends to produce artifacts as anything outside rendered buffer cannot contribute to produced image. Missing reflections is not the only artifact screen space solution tends to produce. The first part of video shows screenspace and then latter part is same scene with tradition ray tracing. Traditional ray tracing is very heavy. Traditional ray tracing suffers from noise unless very high ray counts are used. Big part of the processing is noise removal.

Many "rtx" games like cp2077 have hybrid solution. Screenspace is used to complement traditional ray tracing. Hybrid solutions use screenspace ray tracing only where it is applicable without artifacts.

 

[OlegSH]

Traditional ray tracing suffers from noise unless very high ray counts are used.

Any stochastic technic suffers from noise, it doesn't matter whether it's tracing against geometry or pixels in screen space. Stochastic sampling is used to approximate lighting and other stuff coming from many directions. Rather than calculating an integral of infinity number of samples coming from all possible directions, it's way cheaper to use Monte Carlo method and cast a few rays in random directions, then hopefully temporal accumulation and spatial denoising will do the rest.
Though, nobody forces devs to calculate sampling in a physically correct manner, stochastic sampling is obviously the only way to do this stuff correctly and consistently, but one can simply ignore roughness of PBR materials and treat all materials as prefect mirrors, then blur those samples to achieve the required look without any noise altogether.

 

[JoeJ]

Interestingly, Metro Exodus shows the least difference between NVIDIA and AMD, I am curious whether that will remain the case once the new updated Metro Exodus with it's multiple RT effects gets released. We also have Godfall with it's minimalistic approach to screen space RT shadows being virtually a wash.

My guess: Metro uses incoherent GI rays, so random memory access may become more dominant, limiting NVs HW traversal advantage. Maybe infinity cache helps here on the other side.

Comment about Godfall is indeed confusing. What RT effect(s) do they support? (ah - guess it's reflections but you would have expected shadows too.)

Edit: Seeing all those games in a row is quite interesting. Too bad they missed Quake2 RTX. I realize i somehow like that clear geometry more than impressive realism of modern games. Too much high frequency noise.

 

[DavidGraham]

Comment about Godfall is indeed confusing. What RT effect(s) do they support? (ah - guess it's reflections but you would have expected shadows too.)

Godfall supports only RT shadows on characters and foliages.

They are screen space as they exhibit the same problems as screen space shadows, occluded shadows disappear, rotating the camera also makes these shadows disappear.

See the video below. Start at the 8 minute mark.

 

[JoeJ]

Um... wait, so those screenspace shadows require and run with DXR? I mean it was marketed as (true) RT feature, AFAIK.
It would make sense it it's confused by being: 'Only RX 6000 is fast enough to enable this screenspace effect', but... no, doesn't make sense.

So i have to conclude it's indeed using RT HW, and if character occludes the bush it breaks because it's not really shadows but more kind of AO, i guess?

What a waste to use BVH for that. Kind of bullshit, to be honest. Hellblade did not any worse.

 

[PSman1700]

Godfall is an amazing looking game nonetheless, i havent played with ray tracing yet (2080Ti) but it runs very well maxed out.

 

[OlegSH]

They are screen space as they exhibit the same problems as screen space shadows, occluded shadows disappear

Have not played the game yet, but i don't think RT shadows there are screen space. Most likely they have simply removed dynamic foliage such as grass from BVH to save a lot on processing time. Also, from youtube vids, it looks like a lot of larger objects such as trees are also removed from BVH, this makes a perfect sense to make shadows as cheap as possible since not only BVH building can slow down the process, but the "any hit" shaders are super expensive too since they do dependent texture fetch to check alpha transparency texture for foliage. Also they might simply process all objects near the camera and cull far away objects from BVH. Anyway, this game has super mediocre RT shadows (only hard shadows with missing objects, etc, etc), even software RT shadows in World of Tanks look more impressive. Hopefully AMD will improve their shadows by a lot, because right now there are plenty of rasterization technics which can provide better results at lower cost than their implementation.

 

[manux]

My guess: Metro uses incoherent GI rays, so random memory access may become more dominant, limiting NVs HW traversal advantage. Maybe infinity cache helps here on the other side.

It's going to be interesting to see how metro exodus enhanced edition looks and performs. It goes all in to ray tracing. They will release version for pc requiring dxr as baseline. Attached picture shows dxr features on PC and Consoles for enhanced edition.

Is this first big title requiring dxr to work? Going all in to ray tracing should allow for all kinds of neat optimizations + removing all raster based shadow, light etc. support.



https://www.metrothegame.com/news/t...ails-on-our-ambitious-gen-9-console-upgrades/

 

[DegustatoR]

Going all in to ray tracing should allow for all kinds of neat optimizations + removing all raster based shadow, light etc. support.

They will remove old voxel based GI solution and that's about it.
Reflections will remain SSR on consoles and thus likely be a similar option on PC.
Shadows will remain shadow mapped mostly too probably.
It will require DXR to run the GI but it won't be a fully ray traced game.

 

[manux]

They will remove old voxel based GI solution and that's about it.
Reflections will remain SSR on consoles and thus likely be a similar option on PC.
Shadows will remain shadow mapped mostly too probably.
It will require DXR to run the GI but it won't be a fully ray traced game.

I wasn't claiming it's fully ray traced game. I was asking if it's first big game to require dxr to start? Minecraft and quake2 rtx came before but I don't count quake2 as being big and minecraft binary still supports raster also. Quote below from the link in my previous post to clarify what I was claiming. Removing support for the traditional mechanisms should allow the engine to be optimized fully for ray tracing without having to have fallback path for compute/raster and make compromise due to potentially conflicting requirements to data structures and other engine internal things.

This upgrade is so extensive, it will require a Ray Tracing capable GPU as the minimum spec, and we will need to deliver this version as a separate product – it is not a simple ‘patch’ to the base game – instead it will be offered as an extra entitlement to all existing Metro Exodus PC players.

 

[DegustatoR]

I wasn't claiming it's fully ray traced game. I was claiming it's first big game to require dxr to start. Minecraft and quake2 rtx are others but I don't count quake2 as being big and minecraft binary still supports raster also. From the link in my previous post.

The old version of Exodus won't go anywhere. So technically the game won't require DXR to start, in exactly the same manner as Minecraft.

 

[manux]

The old version of Exodus won't go anywhere. So technically the game won't require DXR to start, in exactly the same manner as Minecraft.

I'm only claiming they now have engine that requires dxr and that is interesting. Being able to do it this way opens up all kinds of optimization possibilities developers can explore and implement. It's then anybody's guess would their next game also require dxr as baseline or would they potentially keep developing 2 separate engines.

I'm not claiming anything about the old version of game, old engine etc. This probably is the first really big game engine that has gone this fully into ray tracing. Delivering it as enhanced edition using old game as base is a good move. This made me buy metro exodus from steam sale in anticipation of enhanced edition.

 

[JoeJ]

Have not played the game yet, but i don't think RT shadows there are screen space.

If you watch the video, you'll see it looks a lot like SS!
Whoever demystifies what they do first, deserves a price.
My bet: Bug in GFX menu. Activating 'RT shadows' in fact activates SS contact hardening or something. Happened to me too. Changed string in GUI, but forgot to change elsewhere. Never fixed the bug

 

[OlegSH]

If you watch the video, you'll see it looks a lot like SS!

Because they heavily use screen space shadows for foliage with RT. Pretty sure RT and screen space shadows are used together here, but screen space shadows obviously can't work for static out of camera shadows, which are visible in many videos in this game with RT On.
There can also be some issues with denoising due to tracing the minimal amounts of rays, probably the denoiser simply can't accumulate enough samples in disoccluded regions and this translates into SSR like artifacts.

 

[JoeJ]

Ah... so you say if enabling RT shadows, they exclude foliage which was handled by SM before, and thus need to add SS hackery to compensate. Yeah, makes sense now, thanks!

Quite curious to see we get an unexpected visual net loss. Hard to predict all such cases ahead - can't blame them, so sorry for the 'bullshit'.

 

[trinibwoy]

That makes a lot more sense. Are there any games out now doing RT shadows on foliage? Nvidia had a video a while back on RT foliage in UE4.