Shadow jitter problem in large scenes

[wddl]

The 3D model is placed in a large world where the shadows shake at a Specific camera height. And this phenomenon does not occur in a small scene. How should this problem be solved? The platform is android. Thanks

Originally posted by @wddl in #7188

[wddl]

I have tested version 1.43.1, but the problem still exists. It's strange that the shadow effect is fine when the camera is at a far distance, not in the middle, and in close range the effect is fine. stable is useful, but it has a limited effect, and a slightly larger scene is not. I put the model on the scale of the earth. Recorded a video and sent it out. There was a serious problem at a specific camera height.

[romainguy]

@pixelflinger was working exactly on this problem. Do you have a repro case though?

[pixelflinger]

For very large scenes with the light behind the camera, you have to disable lispsm and use cascades instead.

This is because lispsm optimizes the resolution closer to the camera. In your picture, the light is almost behind the camera and the shadows are far from the camera.

If you want to keep lispsm you have to adjust the near plane hint in Shadow options.

Lispsm works great when the light is above and the direction perpendicular to the view direction.

[wddl]

@romainguy @pixelflinger Thanks to reply
I will test the method you said @pixelflinger , but there are some incomprehensions, the light is sun type and not point light source, it only has one direction and no position. My key code is as follows, the shadow under this code is incorrect, you can refer to it. Hope to fix the bug ,thanks.

// Load Light
m_sunLight = utils::EntityManager::get().create();
LightManager::ShadowOptions shadowOptions;
LightManager::Builder(LightManager::Type::SUN)
.color(Color::toLinear({ 0.98f, 0.92f, 0.89f }))
.intensity(100000)
.direction(normalize(float3( 0.023456405464645523, -0.99952104730682578, -0.020185961293538123 ))) // light direction
.sunAngularRadius(1.9f)
.castShadows(true)
.sunHaloSize(10.0)
.sunHaloFalloff(80.0)
.shadowOptions(shadowOptions)
.build(*m_pFEngine, m_sunLight);

// model entity, Model matrix
auto& tcm = pEngine->getTransformManager();
auto ti = tcm.getInstance(pAsset->getRoot());	
mat4 yMat;	
yMat[0] = { 1.0 , 0.0 , 0.0 , 0.0 };
yMat[1] = { 0.0 , 0.0 , 1.0 , 0.0 };
yMat[2] = { 0.0 , -1.0 , 0.0 , 0.0 };
yMat[3] = { 0.0 , 0.0 , 0.0 , 1.0 };	
mat4 localMat;
localMat[0] = { -0.89529299190596490, -0.44547778692552764, 0.0000000000000000, 0.0000000000000000 };
localMat[1] = { 0.28597298768987378, -0.57473036651310361, 0.76674927852554309, 0.0000000000000000  };
localMat[2] = { -0.34156977172430397, 0.68646525561287353, 0.64194668305129443, 0.0000000000000000 };
localMat[3] = { -2181624.2500000000, 4384490.0000000000, 4072700.0000000000, 1.0000000000000000 };
tcm.setTransform(ti,    localMat * yMat * mat4::scaling(double3{ 0.03, 0.03, 0.03 }) );

//look at
FTransformManager& transformManager = EngineImp::instance()->m_pFEngine->getTransformManager();
double3 feye(-2181820.2299841726  4385344.2504294114  4072977.9097391055);
double3 fcenter(-2181819.888050911    4385343.5628314875    4072977.2691996922);
double3 fup(0.28532232175636818   -0.57348227651259764  0.76792529013796906);
transformManager.setTransform(transformManager.getInstance(m_pFcamera->getEntity()) , mat4::lookAt(feye, fcenter, fup));

[wddl]

@pixelflinger This is the model data.
modern_city_block.zip

[pixelflinger]

Yes, I didn't choose the best words. I meant the distance from the eye to the shadowed point. I'm this case there is no shadow close to the camera, all shadows are far, and lipsm works against you in that case.

[wddl]

Yes, I didn't choose the best words. I meant the distance from the eye to the shadowed point. I'm this case there is no shadow close to the camera, all shadows are far, and lipsm works against you in that case.
@pixelflinger thanks！
I see, but in my case, the effect is good when the camera is far away from the shadow, but the effect is worse when the camera is closer, which is a bit confusing. Shadow effects get better when the camera is very close to the shadow. Shadows work well when the camera is at long distances and very close distances, but shadows don't work well at middle distances.

For the three picture above, the first picture is the shadow effect when the camera is at a far distance, the second picture is the camera at a middle distance, and the third picture is the camera at a closer distance

[pixelflinger]

Yes, it's because lispsm is able revert to an Ortho projection when it figures out that it's not working well. But that logic doesn't work all the time.

Far away it reverts to Ortho, so it looks okay, up close or does what is supposed to, so it works. In the middle, it struggles.

Just disable lispsm, or adjust the znear hint.

[wddl]

Hi
Disabling lispsm is useful. I will continue my research and get back to you if I have any other questions. Thank you very much!

[wddl]

Yes, it's because lispsm is able revert to an Ortho projection when it figures out that it's not working well. But that logic doesn't work all the time.

Far away it reverts to Ortho, so it looks okay, up close or does what is supposed to, so it works. In the middle, it struggles.

Just disable lispsm, or adjust the znear hint.

thanks！I'll try the method you mentioned

[wddl]

This method is useful to disable lispsm, but, whether the performance is affected.I will keep research.Thanks