> [!abstract] Summary > To fix noise in Arnold, first identify **which ray type** is causing it by isolating AOVs. Each AOV corresponds to a specific sample type — once you know which one is noisy, you can increase only that sample count rather than brute-forcing the whole scene. --- # Identifying the Source of Noise The key principle: **don't increase global samples blindly**. Instead, isolate the problem by outputting individual light transport AOVs and checking which one is noisy. ![[ac-removing-noise-1-sample-1.jpg]] ## AOVs to Output for Diagnosis Enable these AOVs in your render settings and compare them: | AOV | What it Shows | Corresponding Sample | | --- | ------------- | -------------------- | | `diffuse_direct` | Direct diffuse from lights | Diffuse samples | | `diffuse_indirect` | Indirect diffuse / GI bounces | Diffuse samples | | `specular_direct` | Direct specular / glossy highlights | Specular samples | | `specular_indirect` | Indirect specular / reflections | Specular samples | | `sss` | Subsurface scattering | SSS samples | | `transmission` | Refraction and transparency | Transmission samples | > [!tip] The noisiest AOV points directly to the sample type you need to increase. This avoids oversampling clean channels unnecessarily. --- # Fixing the Noise Once the noisy AOV is identified, increase only the corresponding sample parameter in the Arnold render settings: | Noisy AOV | Parameter to Increase | | --------- | --------------------- | | `diffuse_direct` / `diffuse_indirect` | **Diffuse** samples | | `specular_direct` / `specular_indirect` | **Specular** samples | | `sss` | **SSS** samples | | `transmission` | **Transmission** samples | | Everything | Increase **AA** (global) or switch to Adaptive Sampling | --- # Adaptive Sampling (Recommended) Rather than tuning samples per ray type manually, use **Adaptive Sampling** to let Arnold allocate samples automatically based on per-pixel noise levels. > [!tip] See [[../../../OUT OF PUBLISH/BHGC Arnold optimization]] for a detailed breakdown of adaptive sampling settings and recommended values. Key settings: - **Max AA Samples**: ~15 for a solid baseline - **Noise Threshold**: ~0.02 for production, 0.05 for drafts, 0.015 for ultra-clean Adaptive sampling is especially valuable for **animations**, where inconsistent per-material noise levels cause flickering between frames.