Simulation · the paths a person touches

Ray atlas.

A transmitter fills a room with radio waves that bounce off walls, pass through them and scatter before they reach each receiver. A person reading at a table or walking to a shelf touches only a few of those paths. This page draws every path the ray tracer kept, frame by frame, in the room it solved them in, so you can watch which ones the people cut.

In plain words A transmitter fills a room with radio waves that bounce off walls, pass through them and scatter off furniture before they reach each receiver. A person reading at a table or walking to a shelf touches only a few of those paths. This page draws every path a ray tracer found, frame by frame, in 3D, so you can watch which ones the people cut.

The rate ladder Corpus

Snapshots solved offline with Sionna RT 2.0.1 from simulation runs, by notebooks/studies/2026-10-18-ray-visualization/solve_rays.py --web-out, and committed with the site. No request reaches S3 or runs the ray tracer. Simulated data throughout.

FIIT library, five readers and browsersfiit-ground-0 · run 01M5B21JR7B2ED030HT5Z9A9W0

The 3D view needs JavaScript. These are the numbers it draws.

5 simulated people, 60 frames over 59 s. The snapshot keeps the strongest paths to each receiver in each frame: 13500 paths in all, of which 1010 (7.5 %) touch a person. A path's colour is its last interaction, and it fades into the page as its power falls. A person's colour is the state their walker was in. The room is the scene the ray tracer solved: its walls, and 143 furniture pieces as boxes turned to their footprints at their stored heights. Library-mix pilot v3, seed 920: three readers and two browsers on the corrected furniture layers, with the walk-slit closure on. Over the whole 180 s run no person stood still for 45 s and all nine link bands were entered; this snapshot is its first 59 s.

Last interaction	Paths	Share
Line of sight	408	3.0 %
Reflected	2055	15.2 %
Through a wall	645	4.8 %
Scattered	10392	77.0 %
Touching a person	1010	7.5 %

Simulation input	Value
Run	`01M5B21JR7B2ED030HT5Z9A9W0`
Floor	`fiit-ground-0`
Furniture layers	`roomplan-open-2026-10-19`, `may-gapfill-2026-10-19`, `lidar-silent-2026-08-19`
Furniture pieces	143

Snapshot fiit-library-mix-v3, built 2026-10-20.

Until 2026-10-19 this page showed a three-walker run (01M57PNEA7YX0FPCE6TSR08KAW) whose people each stood wedged for 45 s or more at the passage between the two rooms, and four of its nine links were never entered. It was withdrawn because it did not show people walking. The cause and the fix are in notebooks/studies/2026-10-19-library-mix/README.md.