Limitations to large open world scenes

Hey all

I've been messing with HDRP for a few days. Mostly indirectly, I'm coding the logic of my prototype while tinkering with HDRP settings. I think I got the hang of the basics but I have questions.

So in my current project I want a large world. In the standard rendering pipeline you can avoid large number problems by organizing the scene into layers of different scales. Stacking cameras to create the illusion of moving from orbit, to surface, to inside a keyhole etc. But camera stacking doesn't seem supported in HDRP. Is it safe to assume this kind of project isn't meant for this pipeline? It does sound like a more artist oriented pipeline, to make beautiful self contained scenes. I was hoping I could still use it because it looks nice and shader programming is my nemesis.

 

I think the more important problems is the lack dynamic lighting in large open worlds (Realtime GI), low performence without a DOTS approach (which is in preview) and no floating origin.
But it depends if your world just goes until 10km from the origin, if it has dynamic day-and-night cycles and many point lights and you need a photorealistic look.

For the graphics, you could of course go a more stylized way, more easy when no indirect lighting change is required. But if you want to bake the complete world, I'm not sure if the Unity lightmapper can do it, since they eating a lot of ressources, so you propably would need a render farm depending on the size and quality.

The last time I checked having more than two camera in HDRP is a huge performence issue.
So if already have a scene with one main camera and a lot of nice effects and shaders, then it will cut the framerate into half.

So, I would not touch that open world thing until DOTS is production ready and the new realtime GI comes. Depending on your team size and skills, it would be a lot of pain.

 

It depends on type of the map and Game, space games with really large space? Or RPG like Witcher 3? Witcher 3 has a Mapsize of 136km2.
A square map with 12x12km map size with max 6000 units walkable from the origin. you have am map with 144km2.

I read somewhere in the forum, the in Unity the best max size of good result its about 4000 units from origin, but with HDRP with Camera center rendering i think you can make a total map with 20x20km including not walkable buffer area.

 

Appreciate the input, but I'm not sure I'm explaining myself well.

Large open worlds to me is planetary scale. That's why I mentioned camera stacking. Without the ability to simultaneously render scenes at different scales this is not feasible. I ask because maybe they have a different workflow in mind with the new rendering pipelines, or maybe this super large world is considered an edge case best suited for custom RP or legacy.

 

KSP uses camera stacking and origin shifting. I don't know any other solutions.
URP Camera stacking coming with 7.2.0, and HDRP have some new stuff. i found this: https://forum.unity.com/threads/hdrp-camera-stacking-now-supported.717599/

 

Yeah, I read that and found some other topics too. It seems very convoluted in the URP and unsupported in HDRP.

I guess it's Legacy RP for now. Maybe we'll have some cool new user-made SRPs in the future that support camera stacking with some of the neat features we are missing out on legacy.