Dynamic shadows artifacts

[jonimake]

https://youtu.be/A0BfZoFZyBs?t=30m38s it is said that there is auto biasing. Guess its another WIP/coming sometime soon feature.

But is that for the actual engine or just an experiment for the "human race" tech demo?

[overfuze]

But is that for the actual engine or just an experiment for the "human race" tech demo?

I got no idea, hopefully for the actual engine, kinda seems pointless to showcase a feature like that at GDC and not have it included in the engine one day.

[aWinter]

seems pointless to showcase a feature like that at GDC and not have it included in the engine one day.

You mean like... uh... for example Real time GI?

[Maximum-Dev]

You mean like... uh... for example Real time GI?

Don't you dare unloading trucks of salt on my wounds! :P

[jonimake]

Master branch seems to have some PCSS tech in it, it's not complete and there are artifacts with the shadows, but it does help with the acne quite a bit. The shadows are more costly though.

[Chosker]

Master branch seems to have some PCSS tech in it, it's not complete and there are artifacts with the shadows, but it does help with the acne quite a bit. The shadows are more costly though.

oh gosh, just what I feared

[Zeblote]

Master branch seems to have some PCSS tech in it, it's not complete and there are artifacts with the shadows, but it does help with the acne quite a bit. The shadows are more costly though.

Hiding the artifacts by reducing shadow quality is not a solution.

[Chosker]

Hiding the artifacts by reducing shadow quality is not a solution.

it's more like hiding the artifacts with a high-end -only feature

[jonimake]

You can try it yourself if you compile the engine and then ues the r.shadow.filteringmethod 1 console command.

[Kalle_H]

For Mobile I fixed shadow acne by calculating depth slope bias when applying dynamic shadows.

half slopeBias = 0.25; // smaller value is more bias
Settings.TransitionScale = MobileDirectionalLight.DirectionalLightShadowTransition * lerp(slopeBias, 1.0, NoL);

[Chosker]

Just put a texture on the object and it's barely noticeable (unless you put a really plain texture on it).

it isn't barely noticeable. asphalt or landscape textures in general, the issue cannot be unseen.

As for people saying "XXXX engine does YYYYY that ZZZZZ still can't do!!!" it's pointless to compare engines like that because they all spend their resources in different ways. Some engines might prioritize material accuracy, some might prioritize shadow accuracy, some might even prioritize physics. It depends on what they want to focus on. Those that keep bringing up the cryengine, who knows what kind of hacks they had to use to pull it off or what other sector they had to rob resources from.

might be pointless for really really specific features. but shadow mapping? that's as basic as shading or texture mapping. something as basic as that cannot be so sub-par.

If it's a problem, then don't use them or if you really must, nothing is stopping you from overhauling the lighting/shadowing engine.

actually yes. time, experience and final outcome performance are all stopping me from doing it. I'm trying to make a game here, not develop an engine. And so I'm using a third-party engine -and paying 5% of all income- for a reason, this isn't free software.
And it's not like we're asking for rocket science. Simplifying Maximum-Dev's analogy, we're not pimping our perfectly functional car - we just want the wheels to turn properly.

EDIT: As for the issues with going from 3 to 4 cascades causing a problem, that has more to do with how it splits up the cascades within the frustum. Play around with the exponent and see if you can spread it out or pull it in more. You can also turn on the view setting that shows the various CSM boundaries.

playing around with the exponent just moves the issues to a different place / zoom level. doesn't make it any more acceptable.

[jonimake]

I wonder if there is any way we could attract an Epic employee to respond at least something.

[StrangerGwenn]

I mentioned it to Chance a few weeks ago, no idea if it went anywhere.

[Zeblote]

We already know what the cause is. Unreal doesn't use slope bias, which is a standard feature in every other engine, even the ones people make as their hobby. If you read this topic you'd know that.

[IronicParadox]

We already know what the cause is. Unreal doesn't use slope bias, which is a standard feature in every other engine, even the ones people make as their hobby. If you read this topic you'd know that.

Yes, I'm fully aware of it being a biasing issue, but there are ways you can get around it by playing with the number of cascades(at three, it's almost non-existent), exponent and max distance. Even though UE isn't using slope biasing, it is still using some kind of biasing/filtering.

After doing some research on CSMs, I see PCF and VSM coming up a lot, but nothing about them using slope biasing; with CSMs. I think slope biasing is only used for regular shadow mapping. It might boil down to a CPU vs GPU computing issue or it might be a forward vs deferred issue.

Regular shadow mapping mentions slope scale depth biasing:
https://msdn.microsoft.com/en-us/lib...(v=vs.85).aspx

On that same page(the first link), there is a link to another article about CSMing says nothing about SSDB and only mentions PCF/VSM: https://msdn.microsoft.com/en-us/lib...(v=vs.85).aspx

Also, this brings up some of the issues with trying to use slope biasing in screen space: https://mynameismjp.wordpress.com/20...0/shadow-maps/

I'll keep doing more research on it all, but I'm pretty sure that the Unreal devs know all the tricks and standards for something like shadow mapping.