Brightly colored glow in front of car

I noticed when driving the LEGO Mini Cooper in driver view in LEGO Valley, there is a purple or red glow in front of the car at night which lingers about, especially visible where the road is wet. It’s annoying. This is on the Xbox One X.

Some background: The game uses Screen Space Reflections – SSR – for reflections on the ground. SSR recycles what’s already been drawn on screen, and uses the existing depth and geometry buffers to establish the direction of what’s reflected, as well as if something is in the way.

There are several limitations to this. One is that anything that’s off-screen cannot be reflected, so the reflections get cut off. Another is that objects in the foreground may end up being reflected in distant scenery, or block the reflections altogether.

Forza Horizon 4 works around this by reflecting cube maps of the surrounding scenery wherever SSR fails. They’re also used for reflections in windows, and so on. Those cube maps update a few times a minute and are drawn from a grid of fixed positions.

The LEGO Mini Cooper’s cockpit eats into the screen a lot. This blocks out the SSR more than in many other cars, and the scenery instead reflects more of the cube map. So, inevitably it will cause the ground to reflect objects from the wrong perspective. Fair enough, but unsightly.

But – the phenomenon I’ve seen here is far worse. The glow seems to be from the festival lights. And it sticks around for a long time after I drive out of the festival area. It’s as if the cube map won’t update.

I have a suspicion that it might also be related to the temporal anti-aliasing getting confused and causing content from previous frames to stick. It could be a combination of a lot of things.

I’ll investigate this further and send in a bug report, but if anyone else here who’s into graphics could help out investigating this, it would be very helpful.

The only reflections I see are the reflection in the windscreen of my lego avatar who is wearing a white-ish shirt so there is a white-ish reflection. The only glow I see on the road is an occasional red glow from the red plastic of the car so maybe you changed the colour of your car or shirt somehow or maybe you are driving on a blue tinted surface? I am on PC.

Unfortunately it’s not the cause. This looks like a problem with the implemtation of SSR in the game.

Doing some more testing I’ve noticed that wherever the road is wet, you can see that where the interior of the car has blocked the path tracing of the SSR (which it should, the car shouldn’t be reflected in the road ahead), there’s an afterimage of past frames. For instance, if you park by a puddle and a car drives by, its reflection causes a streak that won’t disappear until something else fills it in. For instance, a red car leaving a red streak until a yellow car drives by and leaves a yellow streak.

The problem with it is that it causes an afterimage even while driving. That purple glow I saw was from the festival arches, the red glow from a passing car. But they stayed on screen, reflecting in the road until something else managed to overdraw them.

It’s probably something that was implemented to reduce flicker, but without taking into account what would happen when there is a high amount of occlusion and/or close geometry as in the LEGO Mini Cooper. It hasn’t bothered me until now though, and I’ve played through the whole expansion. Maybe they broke something in the last update or it’s more visible is in winter since the roads are more reflective from the black ice.

Update:
I’ve tested some other cars and it seems they broke the SSR. It’s not just the LEGO Mini Cooper, it’s all messed up.

I already mentioned in another thread that the colours had gone dark to black which seems to have something to do with reflections. I made a grey van yesterday, and now it’s black. I was making it for someone, I have put it on hold until the colours get sorted out. The sky turned black as well at night, and the sunlight doesn’t seem to be working properly. Actually I can post a photo of what has happened in a minute.

You see the tab on the bottom left is bright, but the truck is dark, and that doesn’t usually happen. I parked the van in the bright light, but it was still dark…

Tried messing with HDR on the XBox One it fixed it for a moment, and then it went even worse after I reloaded the game. I think it’s the HDR Palette that’s broken.

That’s pretty severe discolouration. It must be an Xbox problem, I’m not getting anything like that on PC.

Tried my cars indoors at the Horizon Garage, and they are still dark indoors.

The car ending up the wrong color is a different issue from the SSR one.

It seems with the car that the game doesn’t apply the custom color but goes with a default dark grey/black, as if there’s no particular color given.

I’ll see if the same thing happens to me.

Anyway, two fresh bugs with lighting and shading. annoyed grunt

That car was just an example, all of my cars have turned dark. It’s something to do with HDR, I’ve turned it off on my TV, and things look a bit better. So the game has messed up HDR palette. Houses are bright white, cars are dark… strange.