Shadow/Reflection differences M1 Mac/PC

Hiya guys, started to run UE5 (5.1.1) on my M1 Max 32GB Running Ventura 13.1 and the 1st thing I noticed are the shadow/reflection differences from Mac > PC. Any ideas why this is?

M1 Mac


There is a problem with bounced light just not happening. I don’t know if it’s all Macs, or just some. And I don’t know the answer.

Be interested if someone comes along with more info…

You -might- get some joy by tinkering with the skylight, lower hemisphere color. Make it slightly less than black. But that’s not the same as global illumination.

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Interesting, no GI you think eh? I compared both render settings on the respective machines and they’re identically out of the box. A note is I’m running UE5 through Rosetta, so it’s intel based for sure.

I definitely reckon :slight_smile: ( well, that’s exactly what it looks like )

I’m assuming it’s a bug / ‘feature’ of running on a Mac, at the moment.

Gotcha! It’s not a make or break situation currently as I have my PC box close by, but yeah would love to see if they’re additional insights on this for sure…

Thx for the early suggestions.

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Just an FYI, I set the GI to Screen Space(Beta) and got this look. Will hold me to 5.2 haha


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This is pretty old. SSGI is available since UE4.27 or earlier (don’t know the exact Version anymore) and is inferior to Lumen in almost every aspect. You had to activate it via CVAR.

5.2 broke Lumen for non-M1 macs. Running an Intel iMac Pro (2017). They hope to fix it in 5.3. I USED to build Unreal, but I get no advantage (ATM) doing so.

I feel like for macOS it’s one step forward, two steps back.