Center-of-Projection (COP) handling is wrong in UnrealEngine4 (or RenderManager) with our custom HMD about osvr-rendermanager

[JeroMiya]

There is a fix in the works for the projection code to use the overfill-adjusted projections from RenderManager in OSVR-Unreal. In the meantime, could you set your renderOverfillFactor to 1.0 in your renderManagerConfig and see if that improves your center of projection? It still won't be exactly right (the RM projection and the OSVR-Core projection clipping planes are still slightly different even with renderOverFillFactor of 1.0), but it should be closer.

If it's still off, let us know.

[ccll]

@JeroMiya Thanks for the tip, I've tried your solution but unfortunately it's still off.
OverfillFactor 1.5:

OverfillFactor 1.0:

[russell-taylor]

See https://github.com/OSVR/OSVR-Docs/blob/master/Configuring/projectionAndViewMatrices.md for a description of the OSVR RenderManager transformations. Details of the meanings for center of projection, fields of view, overlap percentage and so forth are in https://github.com/OSVR/OSVR-Docs/blob/master/Configuring/distortion.md and to see how to programmatically set them from a new HMD along with distortion correction, see https://github.com/OSVR/distortionizer/blob/master/angles_to_config/doc/anglesToConfig.md

[russell-taylor]

It is correct that the DK2 has its eyes centered on the halfs of the screen, so has 0.5 as its X COP. The OSVR HDK has slightly offset centers of projection, as reflected in the different offsets.

[ccll]

@russell-taylor Thanks for the guides, I thought I've read these thoroughly and fully understanding what the COP means, I'll read these again to ensure nothing is missed, but for now I still suppose the problem is not on our side, because in UE4 center_proj_x only changed 'the center of the radial distortion', while in Unity3D it changed both 'the center of the radial distortion' and 'the center of the rendered image', and our HMD looks correct in Unity3D.

Meanwhile I've accidentally found out that when our display resolution is set to 1920x1080 as the same as DK2, the views align correctly in UE4, but in full resolution 2560x1440 views do not align and looks far apart just as I reported previously, hope this can give some lead.

[russell-taylor]

Glad to hear that you had already found the docs. As Jeremy said, there is a fix in the works for UE4 that uses the RenderManager projection matrices that should help on that platform.

[JeroMiya]

It should already be merged into master.

[ccll]

@JeroMiya Nice to hear that! I would like to known when will this be included in the pre-compiled binaries.

[ccll]

@russell-taylor @JeroMiya I've updated both OSVR-Runtime and OSVR-Unreal to the latest version, OSVR-Runtime to v0.6-1194-g0c54f5e, OSVR-Unreal to b60d5d, and still no luck.
I suppose the 'projection matrices fix' you mentioned is in commit 0f51e9, unfortunately after this commit the left and right eye looks even further away in HMD.

[russell-taylor]

If things are working for you in the RenderManager example programs and Unity, then it looks like we need to take another look at the Unreal plug-in to see what is going on. If it fails in all three, we'll need to take another look at RenderManager and/or how the configuration files match the HMD.

[ccll]

@russell-taylor Just confirmed, it's PERFECT in both the RenderManager example and Unity, the issue only appears in Unreal.

[russell-taylor]

We're looking into this with a device we have, which reproduces the problem. Testing with a current build of and Unreal demo. Failing that, we'll take a look at the following:

[4:25 PM] Jeremy Bell: here is where the projection is calculated: https://github.com/OSVR/OSVR-Unreal/blob/rel-ue-4.12/OSVRUnreal/Plugins/OSVR/Source/OSVR/Private/OSVRHMDDescription.cpp#L255 which we call from here: https://github.com/OSVR/OSVR-Unreal/blob/rel-ue-4.12/OSVRUnreal/Plugins/OSVR/Source/OSVR/Private/OSVRHMD.cpp#L650
[4:26 PM] Jeremy Bell: And this is where we get the projection clipping planes from render manager: https://github.com/OSVR/OSVR-Unreal/blob/rel-ue-4.12/OSVRUnreal/Plugins/OSVR/Source/OSVR/Private/OSVRCustomPresentD3D11.h#L164

[russell-taylor]

We've gotten this fixed in the latest master of RenderManager, and it has been tested in the latest Unreal. We replaced the projection transforms used by the Unreal plug-in with ones that work in this case.

[JeroMiya]

@russell-taylor have we actually tested with the above configuration from @ccll? Also the OSVR-Unreal branch that uses the new API isn't merged yet. I haven't done regression testing with the QAGAME map and Unreal 4.13 build-from-source yet.

[ccll]

@russell-taylor I've sent you an email ([email protected]) with our HMD config json attached, hope that can help debugging the issue.

@JeroMiya Sorry but I couldn't find your email on Github.

[JeroMiya]

Here is OSVR-Unreal with the updated projection code. This is the "extreme" configuration above used to demo the issue. Also, I'm using a renderOverfillFactor of 1.5 in this screenshot.

[ccll]

@JeroMiya Great! It looks correct in the screenshot, I'm curious how it looks like in the VRGate HMD.

[JeroMiya]

@ccll This is now merged into OSVR-Unreal:

OSVR/OSVR-Unreal#75