Distortion Correction Issue

thetrakynia
Explorer

Distortion Correction Issue

Hello,

I am noticing a slight warping of the displayed image as I turn my head in the Vive Focus. It seems as though the distortion correction shader is not entirely cancelling out the distortion from the lenses. The issue can be seen clearly near the edges of the view and is very visible when rotating the headset horizontally. Objects close to the outer edge of the view appear to warp further towards the periphery as the user rotates her head away from that side. There is also a smaller general warping in the middle of the view field that makes the virtual world sway slightly during rotation.

This issue is more pronounced after a session with the original Vive, which has no discernible distortion. Are there plans to refine the correction shader to more fully account for the distortion from the lenses? I think that might provide more comfort for all users and prevent nausea in those most susceptible.

Kavery
Explorer

Re: Distortion Correction Issue

I'm also seeing this. Interior stuff with a lot of close mechanical objects. For me I can't tell if it's the tracking or if there is actual screen space distortion. The scene geometry feels slightly floaty, it's either combining with visual warping, or maybe all of it is tracking only. I'm also used to the integrity of the Vive, maybe it's an inside out limitation.
thetrakynia
Explorer

Re: Distortion Correction Issue

I was also unsure at first whether it was related to the sometimes floaty/jittery positional tracking of the Focus, after some testing I am convinced that is not the case. If you use the Focus in a well-lit room with good features for tracking you can still see warping as you rotate your head. It's easier to see the issue if you move away from virtual objects before looking around. The warping is visible even on distant objects indicating that the positional tracking is not the problem.

Switching back and forth between an original Vive and the Focus makes the issue very obvious. I do think it's worth fixing because the distortion is distracting and presence breaking. I'm curious to know what the team thinks and if a fix would be feasible.

Vive Staff

Re: Distortion Correction Issue

@thetrakynia@Kavery Thanks you two for valuable comments for lense and distortion symptom. I'll help to feedback internally and will get back to you if there is any further plan or parameters to fine tune the symptom.

 

thetrakynia
Explorer

Re: Distortion Correction Issue

Thank you for the response. I created a quick graphic to better show what I think is happening.

The blue arrows indicate the direction of the unwanted warping. The red areas show the location and intensity of the warping. Near the middle of the display the warping is weakest and causes only a slight waver to the image as the headset is rotated. The very red areas are where the warping is most intense. Towards the edge of the view the warping relaxes.

Basically the barrel distortion of the shader does not seem to be fully counteracting the pin-cushion effect of the lenses in certain areas of the image. I hope this is helpful to the team.

 

 

distortion_issue.png

 

Vive Staff

Re: Distortion Correction Issue

@thetrakynia Many thanks for your inputs.

To keep better FOV, less distortion and lense selection are always challenges and trade-off decision.

OlivierJT
Builder

Re: Distortion Correction Issue

I confirm, it's VERY swimmy out there.

Especially easy to see in the UE4 level "sea of cube"

 

Pressing eye closer to the lens (having a thiner foam would help), makes it a little better.

 

This definitely needs to be addressed.

Vive Staff

Re: Distortion Correction Issue

@OlivierJT @thetrakynia @Kavery 

Thanks All for your analysis contribution, and our optical team and SDK software are working together to fine tune better parameters regarding this issue.

Could you help to provide ROM version and S/N from your side via below adb command?

So we can clarify more exactly the detail info. on our side.

Many thanks.

 

ROM info: adb shell getprop ro.build.description

S/N: adb shell getprop ro.serialno

OlivierJT
Builder

Re: Distortion Correction Issue

DM sent!

@Tony PH Lin

Thank you!

Moderator

Re: Distortion Correction Issue

Hi all,

 

I've seen similar "swimming" issues especially when rotating your head slightly from left to right from other developers in person but only at certain locations - can everyone test to make sure that the inside-out tracking is not a factor at all (as well as if possible if it's reproducible across different Focus devices?

 

best,

Dario

 

 

OlivierJT
Builder

Re: Distortion Correction Issue

definitely not a tracking issue in my case:
Home:
Looking at the row of menu icons, putting the settings icon at the corner of the lens (left or right) , move your head to the left or right:
The center in the lens will be stable, the side (in that case the Settings icon) will squish in and out (Like the image previously made up in the post in the red "ring").
Every lens edge are swimmy, the rest (center) is stable.

This is not something you notice if you can fix your eyes dead center on the lens, but we never do that, it's hard not to move your eyes... but as soon as you look no in the center and look naturally around... swim swim...

I don't use glasses. IPD is set correctly to my eyes.
thetrakynia
Explorer

Re: Distortion Correction Issue

@Tony PH Lin

 

Thank you for the progress update, good luck to the team as they iron out the issue. Here is the information for my Vive Focus:

 

ROM info
1.22.1400.2 9.0_g CL1033707 release-keys

S/N
FA83FJJ00698

thetrakynia
Explorer

Re: Distortion Correction Issue

@Dario

I only have a single Vive Focus to test with but I am certain with my unit that the issue is caused by distortion and not tracking problems. The view warping occurs in different physical locations each with adequate lighting and good features for tracking. When the Focus has occasionally had trouble tracking the result is a clear erroneous move of the viewpoint itself before the software latches on to features within the physical space.

That is distinct from the persistent warping that I see generally. The issue is a lack of spatial coherence in the final presented images which makes objects within the virtual world appear to bend and change size as the headset is rotated.

andybak
Pioneer

Re: Distortion Correction Issue

All the VR developers I've shown the Focus to have immediately commented on this and they've mainly suggested that the final image isn't being distorted correctly for the optics. 

 

Likewise - really pressing the headset into one's face mitigates the issue somewhat (and improves the FOV) but becomes uncomfortable over time. Even with this there's still some swimminess with horizontal head motion.

jf@htxlabs.com
Builder

Re: Distortion Correction Issue

Yep I've experienced similar issue on two different VIVE Focus units (1.3 update) some experiences (ie: some distances) make this very visible. Standing on the "home" platform and rotating head right to left feels very "swimmy" and some lens warping like in the reference image is very evident when looking at the hand rails, or in experiences like the Car Garage, and the Snow architecture demo.