lin-depth on the sky looks faceted because the sky is a box (12 tris) with a far-depth hack — use lin-depth-geom to mask sky. rm-alpha / sample count: transmittance often changes little once the integral has converged; try rm-optical-depth-frac or rm-transmittance for finer contrast. Log-Z (default) follows the three.js WebGPU log-depth example — use the checkbox or ?logDepth=0 to A/B.