Hi. I’m using MovieRenderQueue to render a series of HQ screenshots. This worked fine in UE5.0. However, support for using Decals with the PathTracer was added in 5.1, which is something I need. Therefore I’m in the process of switching to UE5.1. Discovered this with 5.1P1, but P2 has the same issue.
Now, to use the PathTracer in need to use DX12. But with DX12, the MovieRenderQueue seems to behave oddly, even when not using the PathTracer. Sometimes I just get a black image. I’m rather new to Unreal, so before reporting this as a bug, am I doing something wrong?
To rule out weird configs from my project, I started with a fresh project:
- Create new blank Unreal 5.1 Preview 2 project with RayTracing enabled
- Add the MovieRenderQueue plugin to the project.
- Follow official steps to “Enabling the Path Tracer in Your Project”.
- Enable Platforms => Windows => D3D12 Targeted Shader Formats => SM6 (to get rid of the warning…)
- Since we want to render screenshots, set Engine => Rendering => Default Settings => Anti-Aliasing Method => MSAA and MSAA Sample Count to 8x.
- Create a new level using the “Basic” template.
- Add a Cube and a CameraActor so we have something to render:
- Create a single frame LevelSequence for the CameraActor:
- Open the MovieRenderQueue window and add the LevelSequence:
- Keep everything default, which means Deferred Rendering, and hit “Render (Local)”. While it’s rendering it shows you a correct looking preview, but the resulting JPG is just black!
.
Now to the interesting observations…
.
Changing Anti-aliasing - Spatial Sample Count
If I happen to add Anti-aliasing settings to the Render Queue settings and set the Spatial Sample Count to 4:
With that, I get an image…but it’s strangely dark:
Increasing the samples seems to increase the brightness for some reason. From my understanding, it’s that why we do 32 warm-up frames by default so this doesn’t happen? At 32 spatial samples I get this, which is starting to look correct:
PathTracer and Resolution
Switching Deferred Rendering for the Path Tracer, works…but only for some resolutions. I can render these resolutions: 1920x1080, 3840x2160 (4K), 7680x4320 (8K), 1024x1024, 2048x2048, 8192x4096
However, trying these results in a black image: 4096x4096, 4320x4320
This seems pretty random, I don’t get the pattern?
High Resolution / Tiled rendering
Let’s just leave it at this screenshot of a TileCount=2 rendering…something very wrong here 
