Issue with Reflection Captures + HDRI backdrop lighting


I’m practicing getting to grips with UE4 for automotive rendering purposes, and there is one particular issue I’ve been having lately which I need some help with, please.

The scene is as simple as can be - a car, set as a Movable actor, placed in the center of the scene. An HDRI Backdrop actor, using the default HDRI (although I’ve tried others, with no change). No other lights in the scene. Raytracing is on, Max. Reflection Roughness threshold set to 0.3 in the PPV settings. The alloys material roughness is 0.5.

The problem is that some objects which aren’t getting ray-traced, namely the alloys/brakes, look way too bright, even when I place SphereReflectionCapture actors in those areas, as shown in the “Photoreal Automotive Rendering in Unreal Engine” webinar on UE’s youtube channel (around the 41:00 mark).

Essentially, the ReflectionCapture actors seem to have no effect whatsoever, no matter how many times I rebuild the reflections. There’s one overall ReflCapture with a 3000 influence radius, above the car, and another two, one for each wheel, with a radius of 40. The SkyDistThreshold for the Skylight is set to 5000.

Bumping the Max. Roughness for the ray-traced reflections to 1.0 makes everything look way better, but of course this is not a performance-friendly solution.

So, the question is, what can I do to make the ReflectionCapture actors work properly? Is there any reason why they wouldn’t have any effect whatsoever? Alternatively, is there any other way to darken such areas, as the wheel-well in this case, to get a more natural look?

I’m sure I’m missing something basic here, as I’m coming over from 3DSMax/Vray/Corona rendering, and I have minimal experience with UE4’s non-raytraced rendering solutions.

Using a 2080Ti, by the way.

Please let me know if there’s any info I should include.

Thank you for reading this, and for any tips or advice you might have.