Noise in VRay bucket rendering?

V-Ray V-Ray Application SDK Issues
1

Bucket mode is faster than progressive, however, it has more noise.

img_v2_eed2986d-7b44-4574-b262-bed957c06a2g.jpg
img_v2_eed2986d-7b44-4574-b262-bed957c06a2g.jpg924×483 68.2 KB
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app sdk version:
appsdk-win_qt5-nightly-vray_v5.20.24-20230208

here is my vrscene settings:

SettingsImageSampler settingsIS {
type=1;
min_shade_rate=6;
fixed_subdivs=1;
dmc_minSubdivs=2;
dmc_maxSubdivs=4;
dmc_threshold=0.005;
subdivision_minRate=-1;
subdivision_maxRate=2;
subdivision_jitter=1;
subdivision_threshold=0.1;
subdivision_edges=0;
subdivision_normals=0;
subdivision_normals_threshold=0.05;
progressive_minSubdivs=1;
progressive_maxSubdivs=100;
progressive_threshold=0.01;
progressive_maxTime=0;
progressive_bundleSize=128;
progressive_showMask=0;
progressive_progNoiseThreshold=80;
progressive_effectsUpdate=10;
render_mask_mode=0;
render_mask_clear=0;
progressive_autoswitch_effectsresult=1;
}​

SettingsRTEngine rtEngine_settings {
trace_depth=5;
gi_depth=3;
cpu_bundle_size=128;
cpu_samples_per_pixel=4;
gpu_bundle_size=192;
gpu_samples_per_pixel=16;
low_gpu_thread_priority=0;
coherent_tracing=0;
stereo_mode=0;
stereo_eye_distance=6.5;
stereo_focus=2;
opencl_texsize=512;
opencl_resizeTextures=0;
opencl_textureFormat=2;
progressive_samples_per_pixel=1;
undersampling=2;
disable_render_elements=0;
max_render_time=0;
max_sample_level=5000;
noise_threshold=0.001;
enable_mask=0;
max_draw_interval=150;
min_draw_interval=50;
interactive=0;
enable_cpu_interop=0;
enable_bucket_sampler=0;
out_of_core=0;
gpu_light_cache=0;
}
```​
How to lower the noise in bucket mode?
2

The settings for the bucket (adaptive) and progressive sampler are different - in your case, dmc_maxSubdivs for example is quite low, which is probably why buckets are way faster and noisier.

You can read the basics for the difference between the samplers here. Or for a deeper dive - here.