Deterministic / bit-for-bit identical output across runs (seed or deterministic mode?)

[LeandreSassi]

I’m trying to get bit-for-bit identical geometry from two runs with exactly the same inputs and config, but I still see differences between runs. I’m looking for guidance on whether fully deterministic output is possible today, and how to achieve it (e.g., via a seed or a deterministic mode).

What I’m doing

Host: Windows (Docker Desktop)

Image: 3dgi/roofer:develop

Command (single-threaded + pinned math libs):

docker run --rm ^
  -v C:\Users\XXX\Github\LOD2\data\docker_test:/data ^
  -e RANDOM_SEED=42 ^
  -e PYTHONHASHSEED=42 ^
  -e OMP_NUM_THREADS=1 ^
  -e OPENBLAS_NUM_THREADS=1 ^
  -e MKL_NUM_THREADS=1 ^
  -e NUMEXPR_NUM_THREADS=1 ^
  3dgi/roofer:develop roofer \
    -c /data/config.toml \
    --jobs 1 \
    --loglevel info

What I’ve tried:

Single-threaded Roofer: --jobs 1

Env vars to avoid hidden parallelism: OMP_NUM_THREADS=1, OPENBLAS_NUM_THREADS=1, MKL_NUM_THREADS=1, etc.

Fixed locale: LC_ALL=C

Fixed “seed” envs (RANDOM_SEED, PYTHONHASHSEED) — I understand Roofer doesn’t expose a --seed, so these may not affect core steps.

Ensured byte-identical inputs and stable layer selection in config.toml.

Is it even possible to get to that point or are the random seeds generated too deep in the code?

Thanks :)

Léandre

[Ylannl]

FYI those environment variables will have zero effect on roofer.

Deterministic / bit-for-bit identical output has not been a hard design goal, so this is not guaranteed at the moment. May I ask why do you need this?

[LeandreSassi]

Thanks! This would help with end-to-end tests, we could run Roofer a few times with the same params/inputs and just deep-compare the outputs to make sure it’s consistent.