Why are my Unreal SVT textures blurry on low-VRAM devices?

Streaming Virtual Texture pool ran out of pages and is serving lower mips. Increase the VT pool size in Project Settings, lower max anisotropy, or reduce overall texture count using SVT. Low VRAM devices may need a fallback to standard textures.

How do I increase Streaming VT pool size?

Edit Config/DefaultEngine.ini under [/Script/Engine.RendererSettings] add r.VT.PoolAutoGrow=1 and r.VT.MaxUploadsPerFrame=8. Or set explicit r.VT.PoolSizeMB=512 to give the pool more memory. Restart the editor for changes to apply.

Should I use SVT or regular textures on mobile?

SVT shines for unique high-res textures (terrain, photogrammetry). Mobile devices often lack VRAM for the page table cache. For mobile target, prefer standard textures with mip streaming; reserve SVT for desktop and consoles.

Fix: Unreal Virtual Texture Not Streaming on Low VRAM

Quick answer: The SVT pool is exhausted on low-VRAM devices, so high-res pages cannot stream and you see permanent blur. Raise r.VT.PoolSizeMB, enable auto-grow, or fall back to standard textures on platforms with limited VRAM.

Here is how to fix Unreal Streaming Virtual Texture content that stays blurry on lower-VRAM systems. The page table runs out of slots; high-mip pages cannot be uploaded. Adjusting the pool size or platform-specific feature gating is the right path.

The Symptom

SVT-backed materials show low-mip textures even when the camera is close. stat virtualtexturing shows pages waiting on upload. On 4 GB VRAM cards the issue is acute; 8 GB+ rarely.

What Causes This

Pool too small. Default 64 MB or so. Many active SVT-using surfaces exhaust pages.

Upload bandwidth limited. r.VT.MaxUploadsPerFrame caps how many pages can be loaded each frame.

Anisotropy too high. High max anisotropy multiplies page count requirements.

The Fix

Step 1: Raise pool size.

# Config/DefaultEngine.ini
[/Script/Engine.RendererSettings]
r.VT.PoolSizeMB=512
r.VT.PoolAutoGrow=1
r.VT.MaxUploadsPerFrame=16

512 MB is a good baseline for desktop with rich SVT use; auto-grow lets the pool expand on demand.

Step 2: Lower anisotropy where acceptable.

r.MaxAnisotropy=4   # default 8

Halves anisotropic page demand at slight visual cost on glancing surfaces.

Step 3: Per-platform fallback. In Config/Mobile/Mobile_DeviceProfiles.ini:

r.VT.PoolSizeMB=128
r.VirtualTextures=0   # disable SVT entirely on mobile

Runtime VT off; materials fall back to standard texture sampling. Texture import settings should provide non-VT versions for mobile.

Step 4: Check material pin usage. In a Material, ensure SVT samples connect via VT pins, not standard sample pins. Wrong pin fails to use VT, defeating the optimization.

Step 5: Diagnose with stat. Run stat virtualtexturing in PIE. The overlay shows pool usage, page faults per frame. Sustained high faults = pool too small.

“SVT pool exhaustion is the most common blur cause. Bigger pool, fewer uploads per frame, platform fallback for mobile.”

Related Issues

For foliage build issues, see Foliage Not Rendering. For asset registry, see Asset Registry Empty.

VT.PoolSizeMB up. Auto-grow on. Mobile fallback. The textures sharpen.