Hello guys. I am just starting a project for VR and have stumbled across severe technical difficulties as I have literally just started to learn UE 5.
There are two parts to my problem. My first problem is upon creating a project with VR Template, I ran the VR Preview, the HMD (Pimax 8kX) goes to the blank SteamVR Grid screen and displays nothing after that and I have no idea how to make anything display. The 3DOF of the headset works with the game window open, it’s just that the screen is not displaying the actual content.
My second problem is if I create a blank project (scalable quality preset), then the VR preview works. BUT, upon EXITING the preview, everything starts to lag and become unresponsive. If I change the blank project to (maximum quality preset) then UE 5 just crashes immediately after exiting the VR preview with the error (requested texture2d x size too large: 21152, Max: 16384). And I also have noticed every time after exiting VR Preview (with a blank project, not VR template) my GPU (RTX 3080) is at 100% usage even with SteamVR closed (this is causing the lag and crashes I’m guessing?), with just the editor open.
If anyone can tell me what I’m doing wrong then that is greatly appreciated.
Two years on from the OP here and I’m seeing this on 5.1. I’m noticing that the rendering pipe isn’t actually clearing correctly and the headset is just reprojecting the last frame from before the preview was closed, and when observing the task manager afterwards, I see spikes in usage whenever I do anything that prompts the UI to redraw (essentially every action). I also see sporadic warnings for VRAM capacity limits being reached. My running theory is that this afflicts either pimax users specifically or steamvr users broadly and if I can make the preview disconnect correctly from the headset I can fix the issue.
(Translate by DeepSeek)
Hello, everyone!
I’m very excited to introduce to you how I solved the problem of extreme lag after the VR preview.
This problem seems to be caused by that, after VR Preview renders the image, for some reason, when exiting the VR preview mode, the last rendered frame will be used as a texture map of a material in the scene. The resolution of this material is quite large. On my computer, the default monocular resolution is over 4000*4000.
Although rendering such a texture map wouldn’t cause lag under normal circumstances, it DOES in VR scene.
The reason for this problem is a bit strange, and is worth further study later.
So, how can we solve the problem of the excessively large resolution? Where can we adjust this rendering resolution?
In SteamVR → three horizontal lines → Settings → Video → Monocular Resolution
Adjust this value to the lowest. It seems that this value doesn’t affect the clarity during development.
Then, close the UE Editor and restart it. Open the VR preview.
And then you’ll be surprised to find that the lag is gone!
This solution seems to reduce the resolution of the last frame from the previous preview rendered in the scene. This significantly reduces the video memory usage, making the editing process in the UE Editor run smoothly again.
