Ghost shadow on the water

[efis007 827]

Gentlemen, can you check if you have this strange reflex?

I was flying over Lake Geneva, no addons on my XP12 b7, all scenarios strictly default, updated video drivers, aircraft Cessna default.
The anomaly only occurs over the reflection of the mountains, so if you want to replicate it you have to fly into a lake and move the camera to put the plane over the reflection of the mountains.

Is it a new bug? 🤔

 

 

[C2615 298]

not new, it's the limitation when use screen space ray tracing, the algorithm can only see what you can see, in this case, you can't see the mountain behind the aircraft either.

[mjrhealth 740]

Known issue.

[efis007 827]

I didn't know him, when was it discussed?

[tonywob 4,509]

It's a known issue. It was being discussed the other week in the developer group, so they're aware of it

[efis007 827]

Ah ok, so it's a relatively recent bug.

[efis007 827]

13 hours ago, C2615 said:

it's the limitation when use screen space ray tracing, the algorithm can only see what you can see, in this case, you can't see the mountain behind the aircraft either.

Forgive me but XP12 does not use Ray Tracing. 
Also your explanation of the algorithm that "calculates only what the eye can see" seems a bit strange to me. 
The reflections (on the water) of the mountains must be calculated and rendered regardless of whether there is an object (the aircraft) flying in front of the mountains and partially hiding them from view.
XP11 doesn't have that problem, it correctly generates reflections of the mountains on the lake even if there is an airplane in front.

[Bjoern 1,061]

1 hour ago, efis007 said:

Forgive me but XP12 does not use Ray Tracing. 

Technically correct, but the clouds are rendered using ray marching, which is what @C2615 must have referred to.

[blingthinger 598]

55 minutes ago, efis007 said:

XP12 does not use Ray Tracing

Every video game out there uses at least coarse-resolution ray tracing to some degree. All of them. It's more than just a technique to fill in colors and shadows for pixels. 

Look up screen-space rendering like C2615 mentions. This is new in XP12. It speeds up rendering significantly but is also prone to artifacts such as this derpy, bugged reflection. 3D spatial info outside of the camera view is lost in the process.

Also, volumetric 3D clouds are indeed fully ray-traced to the extent you're accustomed to thinking about when hearing about RT. Probably more like 'path traced', actually, given there's more than just a bounce or two.

[blingthinger 598]

1 hour ago, efis007 said:

"calculates only what the eye can see"

https://lettier.github.io/3d-game-shaders-for-beginners/screen-space-reflection.html

Here's a really good explanation of screen space reflections.

[efis007 827]

7 hours ago, blingthinger said:

It speeds up rendering significantly but is also prone to artifacts such as this derpy, bugged reflection. 3D spatial info outside of the camera view is lost in the process.

Let's hope they fix the problem, these graphical bugs aren't nice to see (especially knowing that his "brother XP11" currently has better reflexes) 🙄

[blingthinger 598]

2 hours ago, efis007 said:

Let's hope they fix the problem, these graphical bugs aren't nice to see (especially knowing that his "brother XP11" currently has better reflexes) 🙄

Not for me at least. I'm afraid of sharks so I fly over land 110% of the time (including streams).

Pretty sure all screen-space renderers have this problem. Doesn't simzilla suffer from this derp as well?

[C2615 298]

Yeah, I use the "Ray Tracing" in a broad meaning, not just RTX from Nvdia which have access to the game geometry data rather than screen space.

Not sure if it can be fixed without using (much more performance heavy) RTX or similar tech that have full access to all 3D geometry, maybe use some sort of AI to fill the gap?

[Murmur 3,885]

On 8/31/2023 at 1:53 AM, efis007 said:

Is it a new bug?

Rather than a bug, it's unfortunately a limitation of the technique used (screen space reflection). Infact, even The Other Sim has the exact same bug. So I don't know if it can be corrected.

[efis007 827]

Sorry but I don't understand what the problem is.
Are you saying that without RTX it will be impossible to have artifact-free reflections?
There are "old" simulators that worked without Nvidia RTX, and the reflections of objects on the water were generated perfect and without artifacts.
These simulators didn't take advantage of the power of recent Nvidia cards with Raytracing, and therefore these older simulators confirm my thesis that reflections can be generated perfectly without using futuristic RTX technologies.

XP11

XP10 (I captured this image on August 21, 2015)

In both photos the geometry of the mountain reflected on the water is not altered in the slightest by the object/plane passing in front of it.
How is it possible that simulators older than XP12 (at that time I was using an old GTX-960 card with no raytracing processing) can do better reflections than XP12? 
If XP 10 and 11 did it, then XP12 must do it too. 

Here below XP12 is not making a "new effect" never seen before!
It's doing an "old effect", a normal reflection on water, exactly the same as how XP10 and 11 did it.
So this bug is not excusable in the year 2023, they need to fix it. 😒