The raytracing discussion

[twistking]

Hello,
in a recent podcast Matt Wagner confirmed that raytracing would come to DCS in the wake of the vulkan API retooling.
On the one hand it was only a question of time until raytracing would come to DCS, as it's now safe to say, that this is where the industry as a whole is going in regards to rendering tech. On the other hand i was a bit surprised about the "announcment" because i feel that the biggest issues of DCS (on the rendering side) will not be alleviated by raytracing. Or put more precisely: It's not obvious how raytracing would help with: Performance, night lighting - especially visibility of sprite based lights (carrier ball, aircraft nav lights etc.), volumetrics (fog)...

Wags mentioned raytraced shadows specifically, which seemed odd to me, since screen space shadows were just recently introduced, which work quite well for a flight simulator (would probably struggle more in a typical action game).

So what can we expect from raytracing? I'm mostly excited about raytracing in combination with the new clouds, but i'm unsure if those are even comaptible with raytracing. Afaik volumetrics like fog cannot be effectively raytraced currently.

Normally i'm a huge fan of realtime GI, but i don't think that it would add a lot to a flightsimulator. Maybe light pollution over cities could be done with RT GI, but i doubt that RT GI would be able to handle atmospherics.
I also wonder, if RT could actually help performance on modern cards - for example by freeing up frametime from the multiple legacy shadow calculation.
Is it reasonable to expect raytracing in VR? I think that RT shadows and RT GI could be done in a single pass for both eyes. Reflections not so much. Are there games that successfully do RT in VR?

What do think could and should be done with RT and what do you expect actually will be done with RT in DCS?

Please don't start a flame war against RT. It was clear that, it would eventually come to DCS. If you for some weird reason dislike that, please make a seperate thread. Also remember: Raytracing is NOT proprietarily Nvidia.

Edited January 11, 2024 by twistking

[speed-of-heat]

From memory, shadows specifically have a high CPU impact, as do mirrors for example using ray tracing would enable those functions ( abd others) to be offset to the GPU, which would  improve performance on those GPU's capable of ray tracing...

[twistking]

24 minutes ago, speed-of-heat said:

From memory, shadows specifically have a high CPU impact, as do mirrors for example using ray tracing would enable those functions ( abd others) to be offset to the GPU, which would  improve performance on those GPU's capable of ray tracing...

Shadows generally have a big CPU impact indeed, but raytracing comes with CPU overhead too. Maybe it will still be a net positive on CPU limited systems. Obviously RT shadows will look nicer, than everything that we have now. I'd assume that RT shadows could also be viable in VR, since it should be safe to calculate them only once for both eyes.

I did not think of RT reflections for mirrors. Interesting point. It will surely be more expensive than the simple render-to-texture, but would allow "realistic" (perspective correct) mirror reflections (maybe even depth in VR).

[speed-of-heat]

As vr user, moving more workload to the GPU is a good thing, it's not that their isn't a cpu impact, but anything that reduces cpu load is a good thing. 

Also cloud effects, and reflections in water and clouds, cockpit lighting effects etc...

[twistking]

35 minutes ago, speed-of-heat said:

As vr user, moving more workload to the GPU is a good thing, it's not that their isn't a cpu impact, but anything that reduces cpu load is a good thing. 

Also cloud effects, and reflections in water and clouds, cockpit lighting effects etc...

I'm generally optimistic about RT, but i doubt that it will give better performance, honestly.

I'm really interested in how the clouds will work with RT. I think they currently already use a type of software ray marching trickery, which might not even be compatible with RT. Hardware raytracing can -generally- not do proper volumetrics afaik. It would be super cool though, to have realistic super soft shadows under overcast conditions which would sharpen up as you climb through the clouds towards the sun.

[Germane]

I m hoping for a good lighting with RT at last. At the moment it is completely oversaturated and requires reshade or constant adjustment of the gamma value.

So I have really high hopes for RT.

Edited January 12, 2024 by Germane

[Nightdare]

Every benchmark I see, RT is a performance hit without really noticing a significant image improvement

(often having to decrease overall quality settings to keep it playable)

So I for one, am not cheering on the race to catch the rainbow

[Eugel]

13 hours ago, Nightdare said:

Every benchmark I see, RT is a performance hit without really noticing a significant image improvement

(often having to decrease overall quality settings to keep it playable)

So I for one, am not cheering on the race to catch the rainbow

Well, benchmarks are designed to test the performance, not necessarily to show off the nice eye-candy.

The posterboy for raytracing certainly is still Cyberpunkt 2077, and while there is a performance hit, it looks absolutely amazing with raytracing.
Also, there are some things to consider: 

RT in DCS will probably not be done at the same level as it is in Cyberpunk. For example, no one cares about reflections in the wheelcaps of random cars, etc.
But I think especially shadows and lighting can be significantly improved.

Then we will get Vulcan before raytracing in DCS and most likely at least one new generation of graphics cards, so the performance hit then might not be as big as it would be today.

[Nightdare]

On 1/22/2024 at 3:10 PM, Eugel said:

Well, benchmarks are designed to test the performance, not necessarily to show off the nice eye-candy.

The posterboy for raytracing certainly is still Cyberpunkt 2077, and while there is a performance hit, it looks absolutely amazing with raytracing.
Also, there are some things to consider: 

RT in DCS will probably not be done at the same level as it is in Cyberpunk. For example, no one cares about reflections in the wheelcaps of random cars, etc.
But I think especially shadows and lighting can be significantly improved.

Then we will get Vulcan before raytracing in DCS and most likely at least one new generation of graphics cards, so the performance hit then might not be as big as it would be today.

 

Benchmarks that look like a.. won't sell any cards, or even promote the channel showing them

Thing is that current raytracing is hardly even utilized to the fullest, and already a big hit even for the better GPU's

 

[twistking]

i do wonder, if it's realistic to expect raytracing in combination with VR. doing some napkin math, i think that modern GPUs should be able to handle a modest amount of raytracing effects. my concern would be CPU overhead though.