Vray5 in UE4.26 problem with VrayCamera zooming in during render in the viewport (and VFB not working)

[BeneZ]

Hello,
I tried today Vray5 for Unreal 4.26 and have some issues, especially with the VrayCamera.

I was using a raytraced UE interior scene.
I have created: VrayLightRect (directional =1) , VrayPhysicalCamera and VraySettingsEnvironment
and deleted the existing PostProcessVolume

When I press the Vray-Button to render, I was prompted to deactivate the native raytracing, which I confirmed.
(Is it relevant during IPR render, if I leave the native ray tracing on?)

- Biggest problem - my camera is cropping in the render in the viewport - like zoomed in by 200%
When I move the camera I get a bright preview and the camera again zooms out (which is the right perspective), and when I leave it I'm getting again zoomed in.
(I guess this is just a preview mode during camera movements, but the preview is right and the zooming in for render is wrong)
It is set to 16:9 DSLR.
Although, when I open the VFB then there is the correct render perspective.
Then I have the correct IPR rendering in the VFB and the strange cropped version in the Viewport (which is for sure wasting ressources with two viewports - ideally I would expect in the VFB the IPR render and in the viewport only a simple preview picture).

- When I try using VFB directly, it does never react.
VFB doesn't allow to save in the history (history panel is greyed out)

- Rect Light
In the beginning I got a dark grainy scene because the rect light was not working.
Then I set later the light to directional below 1 and it worked - seems to be a bug.


Denoiser
First Error Message was: "Failed to setup Optix denoiser" Error Code 7001 - no idea what it means
So I have changed to "vray denoiser" in the vray settings, which worked.
I have two Nvidia 1080ti cards.

I did not bake any textures, I want to render just a raytraced scene.
Some Unreal Materials are not supported and "instead the Vray Fallback Material is used" (which is not important for the scene, but is maybe causing other issues - I deleted later all those objects)

Thanks for help

[Alexander.Atanasov]

Hi BeneZ,

When I press the Vray-Button to render, I was prompted to deactivate the native raytracing, which I confirmed. (Is it relevant during IPR render, if I leave the native ray tracing on?)

If you disable the native UE native ray tracing you will get additional resources that V-Ray will be able to utilize if needed. You can leave it on and it is not require to disable it.

- Biggest problem - my camera is cropping in the render in the viewport - like zoomed in by 200%

This is a bug on our end which we are investigating and will be available in the next release. The reason for this is that you either have a desktop DPI scale of 200% or you increased the Screen percentage in the UE viewport. As a workaround for the moment you have to match what DPI scale you set for the windows desktop and the Screen percentage in UE viewport. For example if you set your desktop DPI to 150% then you must set the Screen percentage to 150% in UE as well. That should solve that issue.

- When I try using VFB directly, it does never react.

Can you elaborate on that?

VFB doesn't allow to save in the history (history panel is greyed out)

In order to use the history you must enable it in the VFB settings: https://docs.chaosgroup.com/display/...ttings-History
We will also improve on this in the future.

First Error Message was: "Failed to setup Optix denoiser" Error Code 7001 - no idea what it means

This is probably caused by an outdated or corrupt GPU driver. Do you have the same problem when using the NVIDIA denoiser in other V-Ray host apps? (e.g 3ds Max) Can you please update the driver or make a clean install of the display driver?

Best regards,
Alexander

[BeneZ]

Hi Alexandar,
thanks for the detailed answer!

- VFB buttons don't work means, that whatever button I press, it does not start to render in the VFB. see here: https://www.dropbox.com/s/1nn9i553yn...nreal.mp4?dl=0
Only when I press the Vray button over the viewport. I have disabled in the Vray render settings "render in Viewport" so I have at least only the VFB rendering.

- Yes I have three monitors with different screen resolution (4k und small, which causes trouble sometimes)

- I have updated the driver (Vray warning "CUDA driver version 5001 is newer than the latest verified") and enabled VFB history.

- Another question about the native raytracing:
When Vray disables raytracing, this means only it disables the Project Setting "Raytracing" and nothing else, or?
Is it maybe enough to work instead only with the command r.raytracing.ForceAllRayTracingEffects 0 ?

- And Vray creates small thumbnails at rendertime, which cause UE to ask, if they should be imported ("new assets detected").
I guess those textures have not to be imported.

Best regards,
Ben

[Alexander.Atanasov]

Hi Ben,

VFB buttons don't work means, that whatever button I press, it does not start to render in the VFB

Yes, this is a known issue and it's logged. Currently a render can be started only by using the V-Ray button in the toolbar. We will try to implement it in the next release.

When Vray disables raytracing, this means only it disables the Project Setting "Raytracing" and nothing else, or?

Yes, this disables the Ray tracing option for the project and if you need to enable it again you have to restart the project in order to make it work. We will consider your suggestion for the console command and let you know.

And Vray creates small thumbnails at rendertime, which cause UE to ask, if they should be imported ("new assets detected").I guess those textures have not to be imported.

Yes, when starting a render for your materials to work properly at render time V-Ray loads textures from the Source File path of the texture (located in the texture Details panel) If the texture is not found at the specified location, V-Ray will automatically export the texture in your project folder > Content > Texture Cache. Later those assets are considered by UE that are not imported. You could skip that warning entirely.

Best regards,
Alexander