Warning Num Samples Per Thread Reduced To 32768 Rendering Might Be Slower -

| Software/Renderer | How Warning Appears | |------------------|----------------------| | | In system console or status log when using GPU rendering with high tile sizes or sample counts. | | LuxCoreRender | Visible in console when OpenCL device limits are hit. | | Mitsuba 3 | Logs as info/warning, especially with large sampler configurations. | | Custom CUDA/Optix renderers | Can be user-defined; often hardcoded limit to 32768 for safety. | | V-Ray GPU | Less common, but equivalent "per-thread sample buffer reduced" message may appear. |

A: No. The final image samples are identical. Only performance is affected.

He pressed Y.

Limit the number of extra render passes (like AO, shadows, or reflections) you are outputting at once.

Select for excellent CPU/GPU results, or OptiX if you are using an NVIDIA RTX graphics card. | | Custom CUDA/Optix renderers | Can be

Understanding the "Warning: num samples per thread reduced to 32768" Error

Older GPU generations (like the Pascal or Maxwell series) hit these limits much faster than newer RTX cards with dedicated RT cores. How to Fix the Warning 1. Enable Adaptive Sampling The final image samples are identical

High-resolution renders (like 4K) require larger internal buffers, which consume more VRAM and can trigger the reduction. How to Fix It