Biggest weakness in RT games today..

[Deleted member 13]

RT is pretty amazing but depends what you are using it for.
UC4 does pretty good Gi without RT.... RT came so late, we really catched up with raster

Yea, the famous bounced light camera feature. But RT is so much more. You can even RT the normal lighting loop to get good shadows without worrying about shadow map resolution issues. It's also the only way to implement volume rendering correctly.

 

[yewles1]

RT is pretty amazing but depends what you are using it for.
UC4 does pretty good Gi without RT.... RT came so late, we really catched up with raster

Isn't that Voxel Cone Tracing, which was originally used for The Tomorrow Children?

 

[brainchild]

Yes, the visual latency is noticeable with the temporal accumulation technique. There are similar latency issues with Lumen. I prefer NVIDIA's RTXGI (DDGI) solution which is faster even if the precision is limited. Of course, with probe-based techniques, scene authoring for each grid is going to be super important to get right, but it's definitely worth the extra prep time in order to have nice gi without that visual latency:

Faucher does a great job here showing how to implement RTXGI. DDGI resampling can improve the quality even more.

 

[BloodMod]

This latency issue is probably a symptom of making RT lighting process asynchronous with respect to other aspects of the rendering engine. Deferred rendering makes sense, especially for this kind of problem.
It's either that, or deal with horrendous framerates.

Once hardware can handle it faster, the problem will go away.

Or perhaps the real issue is how much of a brute force technique ray tracing is.

 

[Killer_Sakoman]

Hey guys,

I thought about putting this in the Metro thread but this actually extends to all other RT games so I decided to make it's own thread.

There is a very annoying side effect of full on RT games using Global Illumination (although it is also seen in the UE5 demo with Lumen).

Latency.

If you pay attention enough to the objects/camera moving dynamically in a RT game, you will see a blur mimicking motion blur on the object or a delay in the lighting once the camera is still. It is absolutely annoying. I found this in Metro: EE and the Marbles demo. It's also seen in other games that mimic GI like Lumen in the UE5 demo when the ceiling in that cave broke apart and the GI bounces poured in the cavern.

This will more than likely be a thing until graphics cards/consoles get a LOT more powerful to remedy the delay. Right now I believe the RTX3090 is about the fastest in resolving the ray bounces.

FYI folks. RT doesn't come without some caveats.

I think current hardware is still not good enough for RT. Most developers will likely drop RT from their upcoming games.

 

[mansoor1980]

the only problem is that it tanks performance , imo

 

[Deleted member 13]

the only problem is that it tanks performance , imo

Yup. It does. It's not an opinion at all.

 

[yewles1]

the only problem is that it tanks performance , imo

The hardware acceleration tech is new still, manufacturers need more R&D to advance it further, and that takes time.

 

[Deleted member 13]

The hardware acceleration tech is new still, manufacturers need more R&D to advance it further, and that takes time.

Yup. First few iterations won't have enough bandwidth to move the needle to realtime path-traced games. That's a long way away.