Active Scene Capture causes static mesh 'Low Latency Update' lag (4.25.3)

Development Platform & Builds XR Development
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1

This is an update for UE-80534 found here: Unreal Engine Issues and Bug Tracker (UE-80534) After testing with 4.25.3, this appears to still be an issue under SteamVR (tested with a HTC Vive). This issue now impacts 4.22, 4.23, 4.24, and 4.25.

Here is a summary of the issue (that I submitted with the original ticket):

It appears that a static mesh’s late
update capabilities are broken when a
scene capture component exists and is
active on a map.

When a scene capture component is not active on a map, a static mesh
correctly performs its late update and
appears to be solidly fixed to its
parent motion controller. You can see
the behavior with a fresh Virtual
Reality template project. When a scene
capture component is actively
capturing and drawing to its render
target, a static mesh that is attached
to a motion controller does not
correctly late update and appears to
lag behind its parent motion
controller.

Skeletal meshes do not appear to be affected by this bug.

PLEASE NOTE: These tests were performed with an original Vive and
SteamVR. This issue may not show up
while using a Rift.

If anyone wishes to test this out on their own, an updated version of my test 4.25.3 project may be found here: VRTemplate_4_25.zip - Google Drive This test is a slightly modified VRTemplate project. Use the Vive’s app menu button (above the touch pad) to toggle the scene capture on and off. Pick up one of the blue cubes and wave your hand around to see the cube lag behind the hand while the scene capture is active.

2

I’ve had the exact same problem on the Oculus Quest, I cannot complete my project until this is fixed

3

This issue is still present in 4.26P2. I had created a new issue just for 4.26 in the hopes that some focus would be placed on it. Unfortunately, Epic just pushed out my original issue with a 4.27 target fix.

How are people doing sniper rifles in VR? Only using skeletal meshes for all pickups? Is this why Pavlov VR is still on 4.21?

4

My project uses a VR sniper rifle with scope that is rendered using a scene capture in 4.25.

I was able to resolve the lag/juddering issue by “disable low latency update” in the motion controller settings

318706-motioncontrollersettings1.png

318707-motioncontrollersettings2.png

5

Oh sure, that will get you past this issue by not taking advantage of that feature.

But now everything you’re holding will appear to lag behind your actual hand positions, essentially making skeletal meshes also act like static meshes when that feature is on. And trying to line up a scope shot without your weapon locked to your hand isn’t a lot of fun.

6

On the Oculus Quest this fixed the issue completely and did not cause the grabbed objects to lag. I will test on my Vive soon and see if I get the same result.

7

Also just tested on my Vive and had no problems with this setting applied. What headset are you using, and with which Unreal engine version?

8

The issue UE-80534 is for versions 4.22 through 4.26, although this particular AnswerHub post is for 4.25.3. The headset is a Vive, and has been tried on multiple machines.

If you download and run the project linked to at the top of this post, do you not see the cube lagging behind the hand while the scene capture is active?

Here is a video showing the issue. While this video is from 4.26 Preview 1 and not 4.25, it demonstrates the same results.

9

Hi thanks for sharing the video, I tested your project and experienced the same issue. However, after I checked “Disable Low Latency Update” everything looked correct with no lagging on both Quest and Vive in 4.25.3