Commit Graph
3 Commits
Author SHA1 Message Date
dtourolle 5a8c3e4c40 Run each model on the Hexagon in the form measured to hold it
The engine knew f32 and int8, and gave the Hexagon int8 for every role it
served. Measured on the tablet itself (inference.md §1.5), int8 lost
5% of the detector's faces at 40-80 px, moved the landmarks 1.5 px,
emptied the segmenter's scores and cost the denoiser 5-9 dB; fp16 the HTP
refuses outright. `Form` gains A16W8 and A16W16, and `Rung::form` now
names one per role: detectors and landmarks A16W8, the segmenter, scene
model, border filler and denoiser A16W16, XFeat int8. The embedder and
the eye classifiers stay on the CPU.

Each loader resolves its `<stem>.<form>.onnx` sibling; the segmenter and
XFeat, compiled into the binary, embed their quantised forms on Android
only and pick through `choose_embedded`. The probe, the compile step and
the cache fingerprint follow the form instead of assuming int8. Detectors
on the new form write `scrfd_*_a16+w600k_mbf`, and `model_ids` answers
for all three spellings.

On the tablet (ORT 1.29 + QNN 2.42), each shipped file against f32 on the
same inputs, and against the CPU's f32 time:
  SCRFD 500m/2.5g/10g  A16W8   100% of faces in every band   4.2/5.1/9.0 ms vs 17/56/198
  landmarks            A16W8   0.25 px in the 192 crop        0.5 ms vs 2.8
  YOLO26n-seg          A16W16  98.2% found, mask IoU 0.994    12.9 ms vs 90
  scene model          A16W16  98.9% of cells agree           15 ms vs 151
  MI-GAN               A16W16  41 dB from f32 in the fill     87 ms vs 488
  XFeat                int8    pano alignment 0.45 px (f32's own spread 0.41)  6.5 ms vs 58
  denoiser             A16W16  0.00 dB at every ISO            95 ms vs 1510 a tile
Face numbers are over public COCO val2017 photographs, not a library.

The APK carries the siblings (BUNDLED 15 -> 19; the old int8 detectors
removed), about 43 MB more. The Windows installer and its CI count skip
them; the Arch and Flatpak packages list their files and never had them.
The ladder example takes a role per model, which is how the per-role
forms above were seen landing on the NPU from the real probe.
2026-10-04 03:45:46 -04:00
dtourolleandClaude Opus 5 8df6000e4b Decode the scene model into per-category weights
The weights landed last commit with nothing to read them. This is the
decoder, and the shape of it follows from one property worth stating
before the code: the categories must partition the image.

## Why a partition, and not a mask per category

The scene tab applies one grade to every pixel of a category — lift the
sky, desaturate foliage — and both grades meet at the horizon. If each
category carried an independent mask, feathering them outward would make
the boundary band belong to both, so both grades would land there and
every horizon would acquire a visible seam. Feathering has to *blend*
there, not accumulate.

So `marginalise` takes one softmax over all 150 channels and sums within
each category. Grouping cannot change a total of one, so the listed
categories plus the unlisted remainder sum to one at every pixel, by
construction rather than by normalising afterwards. `parse_categories`
refuses a descriptor that claims a class twice, because that is the one
input that would quietly make the property untrue.

## The descriptor is data, and hand-written

`models/scene/categories.txt` groups ADE20K's 150 classes into the eight
a photographer would recognise. It is a file rather than a table in Rust
for the reason `models/LICENCE.md` predicted — a vocabulary is model
metadata — and it is line-oriented with comments rather than JSON like
the `.classes.json` beside it, because that file is generated and this
one is argued. Why `swimming pool` is water and not architecture belongs
next to the line that says so.

Classes are named, not indexed. An index is silently wrong after a
re-export; a name is loudly wrong, and the loader refuses one the model
does not have.

## Resolution, kept visible

`Scene` holds the native 80×80 logit grid and resamples on demand rather
than upsampling once at load. The coarseness is real — it is what the
graph produces — and a type that hides it behind an early resize invites
callers to expect detail that was never there. `rasterise` is where the
letterbox inverse lives, once.

`Letterbox` and `Window` become `pub(crate)` and `to_proto` generalises
to `to_grid`, because both dense outputs this crate reads are an even
fraction of the same letterboxed square and differ only in the divisor.

## Verified by looking, which is the only way this gets verified

`examples/scene.rs` writes the photograph dimmed outside each category. A
transposed axis or an off-by-one in the inverse produces perfectly
plausible weights over slightly the wrong pixels, and no unit test
catches that. On an indoor frame the person mask lands on the person,
including the outstretched arm, and sky reads ~5% against a bright
ceiling.

It doubles as the benchmark, because every timing quoted while this model
was chosen came off a laptop compiling other things and none of them
belong in a document.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-30 10:48:37 +02:00
dtourolleandClaude Opus 5 9a2b39b8e5 Add the ADE20K scene model beside the instance one
`models/LICENCE.md` recorded, on 2026-08-21, that no YOLO model trained on
ADE20K existed in usable form — the stuff classes photography cares about,
sky and vegetation and water, had no model to come from. Re-checked
2026-08-30: Ultralytics now ships a `semantic` task with ADE20K
checkpoints, so `models/scene/` holds `yolo26s-sem-ade20k`.

This is an addition, not a replacement. A semantic model labels every
pixel but merges same-class pixels into one region, so it cannot tell
three people apart — which is exactly what clicking a subject needs, and
exactly what `segment/`'s COCO instance model already does. The scene tab
grades per category and does not care that instances are merged. Keeping
both is the point.

## The export is truncated, deliberately

Ultralytics ends the graph with `Resize -> ArgMax -> Cast` and hands back
a `[1, 640, 640]` u8 label map. The script cuts that tail and exposes the
classifier's `[1, 150, 80, 80]` f32 logits instead, for two reasons.

Cost: the Resize materialises 150 x 640 x 640 x f32, 246 MB, and ArgMax
then reduces across the channel axis, striding 409,600 elements per
comparison. On one loaded machine the full graph ran ~1160 ms against
~500 ms truncated — roughly four fifths of the time spent on work the
application discards. Those numbers were measured under contention and
are upper bounds, but the ratio is structural.

Softness: ArgMax destroys the per-class scores, and the scene tab needs
them. Softmax over the 150 channels, summed within each photographic
category, yields per-category weights summing to 1 at every pixel.
Feathering a partition of unity cannot double-grade a boundary, whereas
feathering hard labels outward from two adjacent categories paints both
grades into the overlap and haloes every horizon.

The discarded upsample was never information: the graph's true spatial
resolution is the 80x80 logit grid, and the application can resample from
that itself.

The tail is matched by op type and asserted before cutting, so an
upstream graph change fails loudly in the exporter rather than quietly
shipping a differently-shaped model.

Nothing reads these weights yet — the decode path, the category
descriptor grouping 150 classes into ~8 photographic ones, and the scene
tab are still to come. At 24 MB this model also wants the runtime-asset
treatment `models/face/` already gets on Android rather than
`include_bytes!`; embedding it would put ~35 MB of weights in the binary.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-30 10:05:44 +02:00