Parley Hatch
53cd1023e0
sweep_strength.py renders one open + one closed FPV frame across a
ControlNet strength matrix at fixed seed/prompt and montages them beside
the depth map — the GPU experiment to find the right strength now that
rev-3 depth maps carry a full-range signal (018909b). Findings/plan in
.dev/2026-06-15-diffusion-pipeline-reliability.md.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
64 lines
3.4 KiB
Markdown
64 lines
3.4 KiB
Markdown
# Diffusion pipeline reliability — making the depth ControlNet actually followed
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**Started:** 2026-06-15 · ongoing (`/loop`)
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**Problem (user):** "controlnet maps generated are barely followed; images of the
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dungeons are very hit and miss."
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## Root cause found (iteration 1)
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The FPV depth maps fed to the Z-Image Fun depth ControlNet used only a sliver of
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the tonal range. Histogram over all 68 baked seed-7 frames:
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- median dynamic range **193 / 255**, worst frame only **54**
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- **0/68** frames reached true black (`<32`); the deepest recesses topped out ~mid-gray
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- only **35/68** reached near-white at the near surfaces
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Cause in `reikhelm-web/fpv.js`: a fixed `t = dpix / maxView` with `maxView = 12`.
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The nearest floor sits ~1 cell away (never hit white) and a wall 3 cells ahead
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landed at mid-gray (never black), so small rooms collapsed into the 160–214 band.
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Depth ControlNets are trained on full-range MiDaS / depth-anything maps, so a
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washed-out map gives almost no structural signal → the model freelances.
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## Fix shipped — commit `018909b`
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Two-pass raycast in `computeFPVDepth`:
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- Pass 1 records each column's wall distance + the frame's true near/far.
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- Pass 2 maps depth through a **per-frame window**: near → white, deepest visible
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recess → black, every frame.
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- Far plane tracks the deepest *real* surface but is clamped to `minSpan` (5 cells)
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so a shallow dead-end nook is NOT stretched into a fake tunnel — its faced wall
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stays an honest mid-gray slab (no black recess → no phantom-door bait).
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- `gamma` 2.0 → 1.5 (normalization now owns the range). `nearPlane`/`minSpan` are opts.
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**Verified offline** (headless `bakeAtlasDepths(7)`, 68 frames):
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median range 193 → **255**; near-white frames 35/68 → **68/68**; worst range 54 → 106.
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Visual before/after (`/tmp/ba.png` during the session): open frames now frame a
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black passage; closed frames a clean mid-gray wall.
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## Next — needs the render workstation (192.168.1.26:8188, was OFFLINE this iteration)
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The depth signal is now strong, so the old strength is almost certainly wrong.
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With a weak signal you crank strength to force adherence; a strong signal wants
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*less*. `bake_atlas.py` defaults `--strength 0.85`.
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1. Re-probe the workstation: `python3 tools/comfy-spike/comfy.py probe http://192.168.1.26:8188`
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2. **Strength sweep** (tool already written, validated):
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```
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python3 tools/comfy-spike/sweep_strength.py http://192.168.1.26:8188 \
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--seed-dir tools/out/atlas/7 --open r8_N --closed r0_N \
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--strengths 0.55,0.7,0.85,1.0
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```
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→ `tools/out/compare/sweep_<run>.png`. Read adherence: does the rendered passage
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land on the black recess? does the closed wall stay a wall (no phantom door)?
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Pick the lowest strength that still honors geometry, update `bake_atlas.py` default.
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3. Then re-bake a full atlas at the chosen strength and spot-check a montage vs the
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old `acc8137`/`a12bcbb` bakes.
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## Open levers if still hit-and-miss after strength tuning
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- `nearPlane`/`minSpan`/`gamma` are now tunable per-export — A/B if near surfaces
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read too blown-out (the AFTER maps are ~47% near-white; may want a slightly
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deeper nearPlane to retain near-field texture).
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- Subtle masonry-block relief on closed-wall slices so flat walls render as detailed
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stone (offline-buildable, but verify on GPU it doesn't read as structure).
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- Strength `start_percent`/`end_percent` scheduling (currently 0→1 full) — easing
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control off in late steps frees texture while locking composition.
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