Black sky/no sun horrible performance in VR

Im pretty new to Unreal Engine. Im trying to learn it to do Arch visualizations. I have been doing visualizations in 3ds Max/Vray. I bring my models in from 3ds max as either an import or a live link (have tried both). The problem that I seem to be having is that if I leave “Forward Shading” OFF, I have my blue sky and it all looks great, but when I go into this with my headset it basically wont run…just locks up so bad you cant do anything but exit out. If I have “Forward Shading” ON I have black sky and cant see the sun, but I can get into file with my headset and move around with no problems. I dont get this program well enough (yet) to understand what it is doing. The info that I have (Youtube etc.) says that “Forward Shading” should be OFF. I also have Ray tracing on as well as static lighting disabled. Not sure what other settings people would need me to put in here to help. If someone has some insight, or good links as to how things should be set-up for arch visualization that would be much appretiated if you could share it with me. Thank you in advance. My main goal with using UE for visualizations is to put these buildings into VR. I can do straight renders out of Max/vray. But being able to do full walkthroughs is more practical if I can use a program like unreal to do it. Thanks in advanced.

There are a multitude of things you can look into. Lighting will hit the performance the most. There are some introductions to lighting. I like this one:

Lighting in Unreal Engine 5 for Beginners (youtube.com)

You didn’t say what engine you are using. I would use Unreal 5 with Nanite and Lumen. Nanite lets you render millions of polygons and Lumen gives you dynamic ambient lighting.

VR needs 90 frames per second to have a comfortable experience. Your head set can run off your video card. That will be a lot faster than any build in video card, like the Quest 2 has.

Forward shading is comparable to ray tracing and will be the slowest performance wise.
Lumen and Nanite if set up correctly will be fast.

Check the Unreal documentation from Epic. They have good introduction to most topics. There are good videos on YouTube, but there are also not so good ones. Be mindful of that and take them with a grain of salt.

Hope that helps.

Thanks for the reply. I am using Unreal version 5.3.2. I downloaded a few videos from"Gediminas" off of youtube. His videos deal specifically with doing arch vis with unreal. He is bringing them in from rhino and mine are coming in from 3ds max, so that’s basically the only difference. He seems to be knowledgeable. His videos are horribly long. I went through them building custom bookmarks etc in the video files so I can easily go back into them. I have Nanites enabled on all objects except for the glass objects (because his video says you shouldnt have nanites enabled on glass objects). I have ray tracing enabled and as far as I can tell using Lumen. I dont know if my headset is running off my video card or not but will check. I do some VR gaming with it and it works awesome for that. I dont quite understand what forward shading does and not sure if that causes problems if I have ray tracing AND forward shading on or not. I will go to Epics website and look for documentation thats a good idea. Im no rookie when it comes to modeling, textures, lighting etc. I have been doing renderings etc for a long time. Just new with unreal. But trying to do full animated walk throughs of buildings in max/vray just isnt practical. Vray now has vantage, but I need a more expensive video card to run it (one with far more vram). You are correct, there are plenty of people doing vids on youtube that probably shouldnt, and plenty that have super good ones too. Thanks again. :grinning: :grinning:

Yes. :slight_smile:

As a beginner you should consider raytracing and VR as incompatible. If you want to give yourself a good understanding of developing for VR, you should also turn off Lumen and make sure your scene works as-is. UE5’s Lumen, Nanite, and Datasmith make it “easy” to bring in insanely detailed worlds and realistically light them. But keep in mind that Lumen + Nanite are being developed and tested for a 60 FPS use case on current gen gaming consoles, for games being developed by developers that really understand optimization.

VR creates a situation where you want to render this complex world at a much higher resolution (sometimes 4k per eye), and you’re rendering the world twice (once per eye). And to give the best experience to the user you’re aiming for 90 FPS, although 45 is good enough these days.

Also, you have not told us what your graphics card is.

I would recommend watching this talk from Unreal Fest this year. This is literally the highest fidelity real time VR archviz experience there is right now, developed by some of the best UE devs. They baked ALL lighting, but ultimately they turned on Raytracing for high quality reflections, which isn’t really recommended. They are rendering the whole experience at a much lower resolution than native, and added in NVIDIA DLSS to further reduce the amount of pixels drawn. And after months of content optimization they were able to achieve 45 FPS on a RTX 4090 with raytraced reflections but absolutely no dynamic lighting.

I would recommend starting over from the VR template, but most people do want Deferred Rendering instead of Forward for ArchViz. Static lighting is classically the best way to get amazing quality and completely free lighting (dynamic shadows are evil incarnate for VR), but I understand the appeal of effortless Lumen. There are some marketplace templates out there for gameplay, but you’ll need to catch up on the fundamentals of performance optimization in UE.