There is a ghosting in Lumen when i move a bright thing above a dark enviornment

Development Rendering
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1

You can reconstuct the scene by follows:

  1. create a drak material and a bright material, and assign them to the background and the moving object
  2. create a light source in scene, reduce its brigtness to about 200 or 300, you can adjust it appropriately
  3. open the Lumen in rpoject setting.
  4. Move the bright object, you will see the ghosting

If you thinking this problem is caused by TSR, you can turn the aliasing method to FXAA, you will see the ghosting agin.

I have tried many method to find the reason, finally i find it is because the lumen used the previous Frame SceneColor Texture. I have tried some method as follows:

  1. clean the history every frame.(r.Lumen.ScreenProbeGather.Temporal.ClearHistoryEveryFrame 1), this method will close the ghosting problem, but the lighting will be noise.
  2. Try reducing number of accumulate frames used for filtring(r.Lumen.ScreenProbeGather.Temporal.MaxFramesAccumulated 2). This can reduce the ghosting beacause indirect lighting sample data from few previous frames;
  3. Change the threshold of HZB(r.Lumen.ScreenProbeGather.ScreenTraces.HZBTraversal.RelativeDepthThickness 0.0001),This will reduce the indirect lighting around the moving object.So the ghosting will be very faint. This is also a problem of lumen, if you close the direct light , you will find the indriect light will be influence by move object(skeletmesh), the indirect lighting is more bright around the move object. Anyone know the reason? Please call me the reason ,thanks!
2

that’s lumen’s temporal stabilty resolve. it doesn’t bode well with emissives anyway. that’s kinda normal. no need to reproduce that nor hammer lumen with jerky movements. i think we all know it’s not that “flawless”.