a01 Composition Convergence — a Study

Can a hand-drawn concept — A01, the gold salvage-mech — be reached by machine? This page follows the full arc: from a composition echo of the concept, through the dead ends that taught us where composition tops out, to a validated forge → fuse → rig → animate pipeline that produced a coherent, rigged, animated a01. Measured evidence at every step. This is the prototype study behind the automated convergence pipeline (task-614).
The measured arc.
Composition-only convergence topped out at a stylized echo (~0.75 CLIP) — clean but generic, unable to reach the concept's mass. Dissecting a01 and recomposing it metric-gamed higher but looked visibly worse — an incoherent slab-pile. The breakthrough was a different shape of solution: forge a coherent whole, fuse + remesh it watertight, then rig-from-base by weight-transfer from the golden skeleton. That full pipeline is now validated end-to-end — a coherent, rigged, animated a01 at CLIP 0.769.
Current state: the shipped a01 stays the clean chunky Quaternius; the fuse → rig pipeline is validated and being polished (cut the mesh at the arm joints to kill the 7.28% tear, then texturing).

The finale — a coherent, rigged, animated a01

Five panels: concept driver, then rest pose and three walk-cycle frames of the fused, rigged a01 mech
The full pipeline's output. Concept driver (left) → Hunyuan3D-2.1 forgefuse+remesh (one coherent watertight body, legs intact) → rig-from-base (the golden CMU skeleton fitted by bbox match, rigid weight-transfer) → walk clip. Rest pose is a coherent chunky biped, both legs present; the walk frames articulate — legs stride, arms swing, plates rotate rigidly. concept_match CLIP (ViT-L) 0.769. One measured defect: arm-joint tearing 7.28% — rigid weight-transfer on a continuous fused skin can't separate at a joint, so spanning triangles stretch (legs hold at 2.96%, torso 1.04%). The fix is cutting the mesh at the joint bands.

The journey — six stages

Each stage is a real attempt with a real result. Stages 1–4 are the dead ends that mapped the problem; stages 5–6 are the path that worked. Ratings and metrics are cited, not rounded up.

Composition-echo ceiling ~0.75

a01 as a Quaternius biped base recolored gold, with small forge-grafted parts (head / chest / shoulder-dome / claw / boot) seated on top. Six manual iterations moved the palette, hooded head, grounded boots and clawed hands toward the concept — a real but limited gain. It stays clean but generic: the signature huge gold shoulder domes and the hunched, top-heavy mass never land, because the base is one shared-surface mesh with a fixed pose. This is a ceiling of the method, not a tuning miss. Full stage-1 study below ↓

Dissect → compose incoherent

Broke a01 into parts and recomposed them on the base skeleton. Result: a slab-pile — broken legs, seam gaps, floating blocks. It metric-gamed HIGHER on CLIP but looked visibly worse. Verdict: dissect → compose fails for mechs — a coherent pre-rigged mech beats a modular slab-pile at the same score.

Golden-frame (slim base + dissected armor) regressed 0.649

Fit dissected a01 armor onto the slim golden body. Regressed to slim / ragged, CLIP 0.649. Lesson: dissecting an existing model only yields what the source already has — you cannot dissect mass that was never in the source.

Forge + multi-view tests source-bound

The forge was never the bottleneck. Multi-view generation (zero123plus's 6 views) is good and consistent — it solves single-view hallucination — but the reconstructor resolution blobs detail: InstantMesh's low-res LRM smooths everything to a soft blob (CLIP 0.698, mitten hands, no panel lines). Single-view Hunyuan stays crispest at 0.768; the new H3D-2.1 chunky forge holds crispness at 0.759. Crispness needs a higher-res reconstructor, not more views.

Contact sheet comparing the concept to Quaternius, golden-dissect slim, and new H3D-2.1 chunky forge, with CLIP scores
Forge / dissect comparison. Concept, then the current Quaternius a01 (CLIP 0.753, cited 0.692), the golden-dissect slim regression (0.649), and the new Hunyuan3D-2.1 chunky forge (0.759 front). The dissected variants are small and ragged; the coherent forge is the better source to build on.

Fuse + remesh validated

Boolean-union + remesh fuses the composite into ONE coherent watertight whole — this fixes the slab-pile: broken legs and floating blocks become a single closed body. Cost: the surface is smoother (remesh softens panel detail), it collapses to a single material, and it must be re-rigged — but re-rig is CHEAP via weight-transfer from the golden base. Two confirmed limits: a voxel union only merges geometry that touches (it won't bridge a genuine void), and it doesn't fix bad source proportions — so it needs a good, well-proportioned, mostly-touching source.

Concept target beside before (dissect-compose slab-pile) and after (watertight fused whole), front and three-quarter
The coherence win. Before (dissect → compose): a slab-pile with broken legs, gaps and floating blocks. After (fuse + remesh): one watertight whole, legs continuous — front and three-quarter.

Full pipeline validated end-to-end

The whole chain in one pass: Hunyuan3D-2.1 forge (octree 384, 50 steps, ~60s on the 5090 → 420k-vert mesh, 17 components, legs intact) → fuse+remesh (detail 200 → 40k faces, 0 holes, legs verified intact) → rig-from-base (fit the golden CMU skeleton by bbox match, scale 0.687; rigid weight-transfer, each vertex to its single nearest major bone) → animate the base's walk clip. Result: coherent, rigged, animated a01, CLIP 0.769 — see the finale above. The forge is model-agnostic (2.1 on the 5090, 2.0 as a low-mem fallback; downstream never changes). Remaining levers: cut the mesh at the arm joints (the measured 7.28% tear), then texturing; a crispness upgrade awaits a higher-res TRELLIS reconstructor (built on the 5090, pending a gated aux model).

Stage 1 in depth — the composition-echo study

The origin of the arc, kept in full because it is what proved composition-only convergence has a hard ceiling — and told the pipeline when to stop nudging and start re-forging (stages 2–6). a01 here is a Quaternius mike biped-mech base, recolored by the a01_salvage preset, with five small forge-grafted a01 parts. The only convergence levers are per-part scale / rot / pos, base proportions, and gold material values — the base body mesh itself cannot be reshaped. Each iteration edited the manifest, re-rendered front + three-quarter in a neutral grey studio (godot4 --rendering-driver opengl3, matching the concept's lighting), and scored the result against the target by region.

Contact sheet: concept target at left, then iter0 through iter5, front row and three-quarter row
Left column: the concept target (massive rounded gold shoulder domes with dark circular vents, a small angular gold-crested head hunched between them, gold chest plates over a dark mechanical core, thin dark clawed arms, heavy dark tread boots, top-heavy hunched stance). Then iter0 → iter5 across; top row front, bottom row three-quarter. The palette and mass shift over the run; the domes and hunched proportions do not.
a01 iteration 0, front view iter0 — baseline
a01 iteration 5, front view iter5 — final

Before / after, front. The head reads as a gold hood rather than a flat box with googly eyes; the feet are grounded boots rather than thin spikes; the gold is brighter and closer to the concept's construction-yellow. The wide upright biped proportions are unchanged.

Per-iteration change log

iter0 — baseline (composition as-is)

Rendered the manifest unchanged. Gold hue already close, but: head is a round box with two googly eyes and a stray spike; shoulders read as small dark caps, not the concept's clean domes; torso is all-gold (no dark core); arms short & chunky; feet are thin black spikes half-underground; stance upright and even. Starting point: a generic recolored biped.

iter1 — head

Seated the head chunk as a forward crest. An aggressive cant (scale 4.6 / 18°) drooped over the face — a defect; landed on scale 4.4, pos [0,0.16,0.02], rot [6,0,0]. The head now reads as a rounded gold hood over the brow, more top-heavy. Still not a sharp angular crest, and mike's two round eyes still show.

iter2 — torso

Enlarging the shoulder-dome & chest grafts regressed — the a01 grafts are jagged forge chunks, so scaling them made spiky gold wings, not domes. Reverted; kept a modest chest nudge (scale 5.2→5.7) for a fuller central plate. Constraint found: a matmap probe showed mike's whole body is one mesh with six shared surfaces — the dark shoulder caps share the "Black" surface with the shins, so the concept's gold-shoulders / dark-legs split and its dark chest core cannot be recolored independently.

iter3 — arms

Enlarged the claw grafts (scale 3.2→4.2) to emphasize the skeletal hands. Arm length can't change (fixed by mike). Claws are more prominent (good), but they stay gold (the graft is unnamed and picks up the gold fallback, not the concept's dark metal), and one claw shows a pale-facing artifact from a bad normal on the chunk.

iter4 — feet

Baseline boots sat half-underground as thin spikes. Landed on scale 4.5, rot [-90,0,0] (lay the tall chunk flat/forward), pos [0,-0.12,0.12] — a bulkier mass at the foot. Ground shadows go from slivers to broad boot shapes. The single biggest silhouette gain — the stance reads grounded and boot-like. Still not detailed treads, and dark-on-dark so subtle in render.

iter5 — proportions + gold material + cleanup

Bumped gold saturation toward the concept's bright construction-yellow (Main [0.8,0.45,0.09]→[0.86,0.52,0.06], etc.), reduced the head stray chunk (scale 4.4→4.1), and split the mirrored claw entry (did not fix the pale facing; kept, no regression). Gold hue is now the closest it has been to the concept.

Per-region match vs. concept

Ratings are a judgement call against the target render, not a metric — but they are deliberately unflattering where the method fell short.

RegionMatchNotes
Head5/10iter0 flat box + spike + googly eyes → gold hooded dome, more top-heavy. Not the sharp angular crest; still shows mike's round eyes + a minor stray chunk.
Torso4/10Solid bright-gold plate — close on colour/plating. Misses the concept's exposed DARK mechanical core (can't isolate it in the shared mesh).
Shoulders3/10The concept's SIGNATURE huge gold domes never landed — enlarging the jagged graft made spiky wings (reverted); the clean dark caps are mike's own mesh sharing the "Black" surface with the shins, so they can't be gold-ised without golding the legs. Weakest region.
Arms4/10Prominent clawed gauntlets (good), but arm length is fixed by mike, claws are gold not dark, and one claw has a pale-facing artifact.
Feet5/10Biggest gain — thin spikes → grounded bulky boots (broad boot-shaped shadows). Still not detailed treads, and dark-on-dark subtle.
Colour7/10Bright construction-yellow gold reads clearly like the concept. Best-matching axis.
Stance / proportions3/10Upright even biped vs. the concept's hunched, top-heavy, gorilla-like hulk — unchanged (base pose is fixed).

Why composition-only hit a ceiling

Stage 1's convergence is real but modest — a stylized gold salvage-mech echo, not a close likeness. The failure is not tuning; it is structural. Three concrete reasons composition-only tops out on a complex mech:

That is exactly why the arc moved off composition. Real convergence on a mech like this needs a coherent forged whole, fused and re-rigged — the re-forge action that task-614's automated pipeline is scoped to trigger when composition-only stalls. Stages 5–6 above are that path, now validated end-to-end. This study is what tells the pipeline when to stop nudging and start re-forging.

Current state — no overclaim.
The shipped a01 in the game is still the clean chunky Quaternius composition. The fuse → rig → animate pipeline is validated (coherent, rigged, animated, CLIP 0.769) and being polished, not yet shipped: next is cutting the mesh at the arm joints to remove the 7.28% joint tear, then texturing. The crispness upgrade (higher-res TRELLIS) is pending a gated auxiliary model.

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