Does packing AO, Roughness, and Displacement into a single ARD texture reduce perceived surface detail?

[wagwag978]

Hi Unreal wizards,

I’m running into a texture-quality issue when packing Ambient Occlusion, Roughness, and Displacement into a single ARD texture, and I’m trying to understand whether this is an expected limitation or a potential engine issue.

I’m making an old metallic material with many fine scratches, where roughness detail is especially important due to strong reflections.
The textures were authored in Substance Designer, and I tested two setups:

1. Individual textures (AO / Roughness / Displacement sampled separately)

2. Packed ARD texture (AO = R, Roughness = G, Displacement = B)

When using the packed ARD texture, the surface appears noticeably softer / lower-detail, especially on shiny, reflective materials. The difference is subtle in matte materials but very obvious once metallic + low roughness values are involved.

I’m attaching two comparison screenshots showing:

• Individual textures → sharper micro-detail

• Packed ARD → visibly reduced surface definition

Technical details

• Texture resolution: 4K

• Source textures: 16-bit TGA

• Packed ARD texture:

  • sRGB: OFF

  • Compression: Masks (no sRGB)

  • Mipmaps: Disabled

• Same material graph logic and same mesh used in both tests

Is some degree of quality loss expected when packing roughness and displacement into an RGB mask texture, particularly for highly reflective materials?
Or is there something else in Unreal’s texture handling (compression, precision, sampling, or channel packing) that could explain this behavior?

Thanks for taking a look!

[wagwag978]

Here are the screenshots for the comparison.

[wagwag978]

[glitchered]

hmm. you sure mipmaps are disabled? either way packing texture will sample them and compress the channels. what texture format are you using? a single channel image usually packs into 8-bit bc4 compression while the packed texture is compresses into bc3 which is 5-6-5 bit rgb compression or if you choose to do so it’ll pack into 8-bit pattern rgb bc7. both of those formats are a lossy compression. the displacement is the most likely to loose detail when packed with the rest of the data being mixed together.