The decoded float cloud.
Cutoff multiple of the 90th-percentile distance. Default 1.5 (matches the look of a stray-culled BVC transcode; a compact capture's farthest real point sits near ~1.04 × r90, so genuine content survives with margin).
The keep-mask, or null when nothing would be culled.
3DGS captures surround their subject with a sparse ball of huge far-field
background/sky splats (±200 m around an 8 m subject is typical) that
renders as ghost fog over the map. The rule is self-scaling: on halo-free
captures the maximum distance sits well inside factor × r90, so nothing
is culled (and null is returned). The runtime analog of the Bitruvius
BVC encoder's stray-cull transcode (which is why a culled .spz matches
its .bvc transcode visually). Costs a few sorted copies of the position
planes — load-time only.
Compute the stray-splat keep-mask: cull splats farther from the robust (per-axis MEDIAN) center than
factor ×the 90th-percentile distance.