black stripes on texture when shadow enabled on mobile devices

[riematrix]

Shadows not working as expected on andriod/ios browsers.
on Android there are black stripes when zoom in;
on ios the shadow is not displaying correctly.

Sandcastle example: 3D Tiles Photogrammetry.html

var viewer = new Cesium.Viewer('cesiumContainer', {
terrainProvider: Cesium.createWorldTerrain(),
shadows:true
});

var tileset = new Cesium.Cesium3DTileset({
url: Cesium.IonResource.fromAssetId(6074)
});

viewer.scene.primitives.add(tileset);
viewer.zoomTo(tileset);

Browser: safari ios

Operating System: ios

[hpinkos]

@riematrix can you paste a screenshot of what you're seeing please?

[riematrix]

here is a screenshot of one android device:

on ios the result of shadow can not be recorgnized.

[hpinkos]

Thanks @riematrix! @lilleyse any ideas?

[lilleyse]

We've noticed some aliasing in iOS, likely due to less depth buffer precision #4752. Some Android devices might be having the same problem.

There's also a separate issue for poor shadows on photogrammetry, or really any models that don't have normals. #5723 has some details. But on desktop it still looks a lot better than that screenshot.

@riematrix could you also see if aliasing is a problem in this shadows demo:

https://cesiumjs.org/Cesium/Build/Apps/Sandcastle/gallery/Shadows

[lilleyse]

Also brought up in #7178.

[riematrix]

@lilleyse I tried the official demo which using the single plane model. The shadow looks ok during rotation on ios. Maybe it's a problem of shadow on 3d tilesets?

[lilleyse]

@riematrix thanks for checking that out. Then it is likely #5723 that is responsible for a lot of the aliasing.

[riematrix]

@lilleyse Thank you for the issue reference. I recalculated vertices normal for each tile and it looks correct on ios.
The black stripes still exist on both ios and android when zoom close.

[a0026]

Hello， my issue(#7178) has been closed， I wonder when it can be fixed, 3ks.

[riematrix]

@lilleyse Hi, it seems that I've found something new about the black stripes. The attachment screen shot is a small object of a house that definitely has vertices normal. The black stripes looks much wider and you will notice something when looking very carefully at the phone's screen shot. I think those stripes may be more related with scale rather than buffer precision.
Hope you can give some instructions on how to debug or even fix this. Thank you!

PC:

[hellorayza]

Is it the same question?
https://groups.google.com/forum/#!topic/cesium-dev/8wqgbJuIv1M

[lilleyse]

#9064 fixes this for all the Android devices we've tried so far but I still see lots of artifacts in the original sandcastle on an iPad Pro and iPad 4