Enabling focus blur on a cinecamera using a tracking focus method causes objects in foreground and background to have noisy and grainy visual artifacts. This can be seen inside the vehicle configurator I am working on which uses TSR anti-aliasing; the configurator uses a camera system which utilizes UE5’s cinecameras to zoom, pitch, and yaw around a vehicle. When looking at objects that are not perfectly in focus, static noise is visible which breaks immersion.
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Steps to Reproduce
To reproduce this issue, create a mini car visualizer by placing a car shaped model inside the scene. Enable Use hardware ray tracing when available, high quality translucency reflections, Detail Tracing, and TSR anti-aliasing in the project settings. Disable auto exposure in project settings. Create an unbounded post processing volume, and enable metering mode for exposure, with 2.0 exposure compensation. Add a sky to add visibility. Create a cinecamera script that allows the user to zoom, pitch, and yaw using the vehicle as the pivot point, or use a camera arm. Inside the cinecamera details panel, change the focus method to tracking and select the vehicle in the “actor to track” drop down. Set the focal length for the cinecamera to 28 and set the aperture anywhere between 0.75 and 2.5. Inside the scene, create a ground mesh that stretches out far enough to create a foreground, middle ground, and background. Apply a PBR material to the ground mesh, in my case I’m using asphalt. Place assets in the background about 30-50 feet away from the vehicle, these can be foliage, barriers, cones, glass windows, etc. When hitting play, the focus blur in the cinecamera causes the ground in the foreground and background to flicker like dancing ants, in addition to some objects in the background. Anything that is not in perfect focus is prone to having these visual artifacts. To see an exact representation please see the video attached or visit the Chevrolet website @ New 2027 Corvette Grand Sport | Performance Car | Chevrolet to see the bug inside the Corvette Configurator.
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We were able to isolate the flickering issue to DoF.
DoF Off x AA Off - No Flickering
DoF Off x AA On - No Flickering
DoF On x AA Off - Flickering
DoF On x AA On - Flickering
We’re reviewing the project to look into a solution and will share the feedback as soon as possible.
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We’re still investigating but we have some suggestions that will help:
Gives these a shot and let us know if it helps with the flickering on your end.
Aunmar
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Hi Aunmar,
I’ve integrated the changes you suggested and although modifying all my decals to use regular textures instead of VT did not reduce the flickering, your comment on density gave me a lead to believe the normals on meshes and decals stacked onto one another might be causing normals to be too complex.
I simplified normal complexity by reducing normals on the asphalt road, ground plane, and decals, in addition to increasing normals on the gravel ground meshes above the ground plane. This has reduced the flickering on the overall ground significantly, but not completely as there are still some tiny patches that flicker.
The objects in the near distance like the guard rails and the tire stacks do not seem to have improved after reducing normals, and all objects in far distance still seem to flicker, but this does not break immersion as much as the ground flicker does.
Based on the documentation link you sent above, increasing the thickness of the guard rails might reduce flickering as well.
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Awesome, glad you were able to make progress, keep us posted on how things progress from here!
Aunmar
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