Summary
Long, shallow-angle, high-contrast silhouette edges show visible stair steps at 1920×1080. During slow camera or object movement, pixels along these edges visibly crawl and flicker. The issue is noticeable at normal 1:1 viewing scale, not only in enlarged screenshots.
It reproduces in a separate minimal project with two unlit boxes, without our game’s content, code or custom rendering effects.
Static comparisons include TSR, FSR native AA, TAA, FXAA, SMAA and MSAA ×4. None eliminates the visible stepping. Motion was also compared between TSR and SMAA; SMAA showed more noticeable crawling on the dark slab. In our game, the issue is visible with TSR, FSR and XeSS. DLSS has not been tested because our GPU is AMD.
Rendering the same static view at 3840×2160 and downsampling to 1920×1080 produces a visibly smoother edge.
What Type of Bug are you experiencing?
Rendering (Graphics / Niagara)
Steps to Reproduce
- Download and extract the reproduction archive linked below.
- Open EdgeAliasingRepro/EdgeAliasingRepro.uproject in Unreal Engine 5.8. The scene contains two unlit boxes, a camera and a PostProcessVolume with manual exposure. Bloom, vignette, grain and motion blur are disabled.
- Launch the project in standalone game mode at 1920×1080:
UnrealEditor.exe EdgeAliasingRepro.uproject /Game/L_Edge -game -windowed -ResX=1920 -ResY=1080 -ExecCmds="r.AntiAliasingMethod 4,r.ScreenPercentage 100,r.Tonemapper.Sharpen 0"
- Observe the shallow-angle upper edges of both slabs at 1:1 display scale.
- For the motion reproduction, open the project in EdgeAliasingRepro_Motion instead. Its automatically playing level sequence moves the camera slowly. Use the same resolution and rendering settings.
- Optionally compare with TAA (r.AntiAliasingMethod 2), FXAA (1) and SMAA (5). FSR and XeSS require separately installed plugins and are not required to reproduce the issue with TSR.
Expected Result
Stable, antialiased silhouette edges during slow camera movement at native 1080p, with less conspicuous stair stepping and crawling.
The downsampled 4K images are provided as a visual reference, not as an expectation of identical quality or performance.
Observed Result
The shallow-angle edges retain visible stair steps at 1080p. During slow movement, the stepped pixels crawl along the silhouette.
The issue occurs on simple unlit geometry in the minimal project, so our game’s boat materials and custom light-beam composite are not required to reproduce it.
TSR produces the closest static result to the downsampled 4K reference among the tested methods, but the stepping remains visible. SMAA does not visibly improve the static edge and shows more crawling during movement on the dark slab.
Affects Versions
5.8
Platform(s)
Windows
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Additional Notes
Reproduction archive, including the static and moving-camera projects and comparison images:
[https://drive.google.com/file/d/1HlKi-IoPrgvzTM7LuJuue1DVouvtuwRX/view?usp=drive_link]
Relevant tests:
- Tonemapper sharpening disabled.
- Higher Screen Percentage values tested; these did not match the improvement from a full 4K output downsampled to 1080p.
- The issue reproduces without our custom beam composite and on unlit geometry.
- Replacing the TSR history resolve with a simple 2×2 average in an offline comparison did not visibly improve the edge.
Questions:
- Is this degree of stepping and crawling expected for shallow, high-contrast edges at 1080p, or does the reproduction indicate a configuration issue or rendering limitation that can be addressed?
- Is there a recommended way to improve these edges while preserving the player’s choice of temporal upscaler: TSR, FSR, DLSS or XeSS? We are looking for a solution compatible with these methods, rather than replacing them with a different AA method.
System:
UE 5.8.0 Launcher build, CL 55116800
Windows 11 Home 10.0.26200, D3D12 SM6
AMD Radeon RX 6800 XT
Adrenalin 25.10.30.02, driver 32.0.21030.2001
AMD Ryzen 5 5600, 32 GB RAM
1920×1080 monitor at 180 Hz