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name: scenario-maya-retopology-uv description: 'Use when turning a dense sculpt, scan, ZBrush export or AI-generated mesh into animation-ready or game-ready topology in Maya without a mouse ("clean up this AI mesh", "retopo this character", Quad Draw, Retopologize), testing it deforms before rigging (bad elbow or wrist bend, lids popping through the eyes), or unwrapping UVs, cutting seams, setting texel density, mip-safe padding, UDIMs, lightmap UVs, stacking mirrored shells, or preparing a low poly and cage for baking. Keywords: edge flow, eye and mouth loops, Unfold3D, bake prep.' license: MIT

Maya retopology and UVs

Expert retopology is a loop plan with the fewest polygons that still deform: landmarks first, rings around eyes and mouth, three loops per joint, poles where nothing moves, a bend test that says whose fault a bad crease is. Expert UVs spend texels where the camera looks, at a density derived from the closest shot, with padding that survives mips. Without a mouse the agent reuses approved topology, builds from data, and measures then renders every stage. If a sibling skill named here is missing from your available skills, ask the user to install it (npx skills add scenario-labs/skills --skill <name>); unattended, proceed from tool schemas and flag the gap.

REQUIRED BACKGROUND: scenario-maya-expert (execution channel, review loop, 2027 version traps). Toolkit: scripts/mx_retopology_uv.py (import mx_retopology_uv as RU), built on mx_audit, mx_review and mx_run.

Status (2026-09-24): every Maya call is not yet run in Maya (not installed); 99 pure and 40 fake-Maya checks pass offline. First run tests/code/maya-retopology-uv/run_all.sh, then fix what job_probe_commands reports.

Stance (the expert delta)

• Landmarks first, big polygons, then fill like a puzzle. FlippedNormals: starting small is "a terrible way to work"; loose is recoverable, tight is not (9N4rG5qHWgk [00:01:05] [00:02:07]). The loop map is data before any vertex; a template fit is gated at base density before spans are added.
• Reuse approved topology. FlippedNormals carry one perfect hand, ear or base mesh to every model ([00:10:11]); Jessica Dru Johnson's standard base cut face skinning from three days to 30 minutes (ZiYEO49B768 [00:58:51]). Quad Draw substitute: RU.fit_template.
• No automatic topology on what deforms. On a face it "will look normal, but it's not" (FlippedNormals [00:23:15]); automatic is for parts that do not animate ([00:22:13]). Retopologize serves props, armor plates, static cloth; on a torso or loose coat it is a flagged start that must pass the deformation gate.
• Isolate and bound deformation. Concentric rings around eyes and mouth, one control plus two support loops per joint, a flat loop from lip corner to jaw corner against shearing (Jessica [01:15:51] [01:30:10]), equal lid loop counts (FlippedNormals [00:21:41]). Poles in still areas or skin folds ([00:12:45]); triangles only in cavities; never n-gons: ZBrush triangulates them and blend shapes break ([00:05:31]).
• Test the bend before handoff, blame the right artist. antCGi: loops running along a joint (wrist, ankle, hip crease) are the modeler's fix; volume lost at a correctly looped hinge is the rig's, for correctives; prove it by swapping topology under identical weights (x07USYlvu2o [00:10:27] [00:16:24]). Fit lids over the real eyeballs, with enough loops to curve over the cornea on a blink ([00:15:18]; RlNnp4qQIrU [00:08:24]). Shear (Jessica [01:13:06]) judges face hinges; on limbs a linear blend shears even perfect rings [added, measured].
• Retopologize traps (Maya 2027 Help). polyRetopo re-runs on edits and file open: delete history; Pause the node while changing several attributes. Preprocess Mesh (default on) smooths detail: noisy 100k+ triangle input only. Hard surface 1 / 1 / 0. Never half a mesh. Edge component tags steer flow.
• Texel density from the closest camera. Paulino: frame the reference piece at the closest shot, double its screen pixels, round to a power of two, Get/Set on every shell (iL2iXizf9xM [00:02:33]). Film: one density, UDIMs. Games: uniform, scale up the head, stack mirrored shells (MLC s_KLbTUdKms [00:10:57]).
• Padding is a mip problem; bake prep is geometry. 4 px between shells, 2 px to the border, doubled per mip step; Room space stays 2 px (Maya 2027 Help). Hard edges on UV seams, one triangulation for bake and export, the whole mirrored model baked with mirrored UVs one tile over (Polycount), a low that hugs the high (On Mars YDu9pYMkkSM [00:17:45]).

Establish first

Input	Why it changes the plan	Default when the brief is silent
Purpose	film cage subdivided at render vs real-time triangles plus bakes	real-time
Deformation, engine	face rig, blend shapes; one extra mouth-corner span forced a fifth influence (Jessica [00:59:24])	face and limbs deform; 4 influences, confirm with scenario-maya-rigging
Budget	triangles from the lead (Polycount); "exactly as high as needed" (FlippedNormals [00:13:46])	propose one from screen coverage, as an assumption
Closest shot	texel density	1920 x 1080, 85 mm on the head (Paulino)
Textures	map size, 0-1 or UDIM, lowest mip, strategy (optimized, technical, continuous)	games: 0-1 seen at a quarter size; film: 4K UDIMs; characters continuous
Template, eyes	base mesh; eyeballs to fit lids on	ask scenario-maya-modeling for a primitive-blocked base and eyeballs
Pose	neutral face, relaxed A-pose, eyes forward (Jessica [01:00:30]; antCGi e74KphYwMww [00:07:39])	report a posed source

Clothes fused to the body (AI meshes). Tight garments become body topology with loops on the garment lines; loose layers get their own tube or template projected onto the fused source [added]; plates may slide but the torso stays one piece (Jessica [00:44:17]); wrinkles that never animate go to Retopologize or the bake (FlippedNormals [00:22:13]).

Workflow

1. Intake, read only. mx_audit.audit(source); the source stays the bake source. RU.prep_source makes the working copy (weld, soften, report non-manifold); a broken source is rebuilt or used only as projection target (P2). Orient by the transform (cm, Y-up, +Z front, feet at 0). GATE: numbers written; clay sheet looked at.

2. Map. Landmarks, ring counts per opening, joint stations, flows (mouth corner under the cheek; neck along the sternocleidomastoid, clavicle to skull back, antCGi RlNnp4qQIrU [00:09:32] [00:37:43]), a method per part. GATE: the map is JSON before any geometry.

3. Build per part.

   Part	Method	Call
   Face, head, hands, body with a base	landmark fit	RU.fit_template
   Limbs, fingers, sleeves, skirts, tails	plane sections, 1 + 2 loops per joint	RU.limb_stations, RU.build_tube
   Props, armor plates, static cloth	Retopologize	RU.retopologize(mesh, faces, hard_surface=...)
   Torso or face without a base	primitive base from scenario-maya-modeling, then fit	Retopologize only as a flagged start for Quad Draw (gui-paths.md)

   Then cavities: mouth bag, nostrils, eye pouch (FlippedNormals [00:25:16] [00:27:22]). GATE: mx_audit.verdict clean per part.

4. Relax, center, mirror. RU.relax_project, RU.snap_center, RU.mirror_half (weld 0.001, antCGi QW8w15J00Ok [00:02:56]); combine symmetric parts (e74KphYwMww [00:24:32]). GATE: no center drift, symmetry 100%.

5. Gate the topology. RU.retopo_report plus wire and clay sheets in the source's views.

6. Deformation-ready gate, before UVs (antCGi unwraps after it). RU.deform_test(mesh, chain, bends, review_dir=...) per limb (elbow and knee at 90 and 130 degrees, wrist, ankle, hip; twist judged mid-limb, never at shoulder or wrist, x07USYlvu2o [00:08:40]), kind="hinge" for jaw open, RU.lid_check(head, eyeball). Proxy weights, no skinCluster: binds are scenario-maya-deformation's. GATE: no topology verdict, lids ok, pose sheets looked at; rig verdicts travel as notes; prove a fix with RU.compare_variants (P19, P20).

7. UVs. Seams as edge loops (RU.loop_keys, RU.cut_seams): neck base, head slits, inside the mouth, sleeve line, back of the arm, wrists, waist, inner legs, boot tops, soles (MLC [00:01:37] to [00:08:05]); cloth on its real seams (Paulino [00:05:16]). RU.unfold, RU.optimize; limb shells RU.orient_shell then RU.straighten_rows (MLC [00:04:49]); RU.mirror_uvs(mode="mirror"). GATE: planned shells, no folds, distortion in band.

8. Density and packing. RU.density_from_camera (film) or RU.density_for_budget (games); RU.set_texel_density (head bias in games); RU.layout(scale_mode="off") with RU.mip_padding; UDIMs, or RU.mirror_uvs(mode="stack", offset_u=1.0) for game bakes, never where AO or a logo differs; RU.lightmap_set. GATE: RU.uv_report ok; UV and RU.checker_review sheets looked at.

9. Bake prep. RU.harden_uv_borders, RU.bake_check, RU.make_cage or RU.project_to_surface, RU.bake_copy, RU.overlap_review(low, high, out) (P21). GATE: high inside the cage, hard edges only on seams, one triangulation, silhouettes match.

AI character end to end: procedure P18.

Numbers

Item	Value	Relative to, source
Joint loops	1 control + 2 support; knuckles 3 each	each bend (Jessica [01:15:51] [01:17:34])
Lids, lips	upper count = lower count	FlippedNormals [00:21:41]; antCGi RlNnp4qQIrU [00:05:22]
Mirror, center	weld custom 0.001; drift band 1e-4 to 1e-2 cm, snap to 0	antCGi QW8w15J00Ok [00:02:24]; FlippedNormals [00:19:06]
Retopologize	hard surface 1 / 1 / 0; Preprocess for 100k+ tris; tolerance under 10% is slow	Maya 2027 Help
Texel density	2 x screen px at the closest shot, power of two	Paulino [00:02:33]
Maps, padding	4K tiles, odd shell at half scale on 8K; 4 / 2 px, x2 per mip (2048 seen at 512: 16 / 8)	Paulino [00:05:48]; Maya 2027 Help
Hard edges, mirror	every UV seam, bends over ~45°; mirrored UVs 1 unit over	Polycount
Deformation [added]	joint loop within 20° of the bone, no spiral over 15°, 0.8 of an ideal ring's area kept; hinge mean shear under 10°; faces under 0.3 area collapse; an ideal ring under 0.7 is a rig note	organic digest; scenario-maya-deformation
Lids [added]	nothing inside the eyeball at rest or blink, vertices and edge midpoints; gap under 0.1 eye radius	antCGi x07USYlvu2o [00:15:18]
Gates [added]	deviation under 10% of mean edge; UV area ratio 0.5 to 2, anisotropy under 2; density within 10%; packing 0.7; 3+ clean rings per opening; silhouettes differ under 2%	this skill

Quality gates

In code (MAYA, not yet run in Maya):

rep = RU.retopo_report("body_geo", "scan_high", openings={"eye_L": {"point": (3.2, 163, 8.5)}},
                       joints={"elbow_L": {"center": (45, 140, -2), "axis": (1, 0, 0), "radius": 6}})
dt = RU.deform_test("body_geo", [shoulder, elbow, wrist, hand_tip],
                    [{"name": "elbow_130", "joint": 1, "angle": 130, "axis": (0, 1, 0)}])
lid = RU.lid_check("body_geo", "eyeL_geo")
uv = RU.uv_report("body_geo", 4096, smallest_mip=1024, target_density=20.48, images_dir="/abs/out/uv")
print(rep["fails"], dt["verdict"], lid["fails"], uv["fails"])     # full arguments: procedures.md

Topology: 0 n-gons, no polyRetopo history, 3+ clean rings and equal halves per opening, 3 loops per joint band, triangles only in cavities, eyes denser than the cranium, no center drift, no topology verdict. UVs: all faces mapped, no unintended overlap, padding at the lowest mip, density on target, hard edges only on seams (games). Visual: wire and clay sheets (rings close, even squares); pose sheets (creases where anatomy creases, no pinching); UV sheets; checker in three views plus the closest shot; overlap diff images (red: high outside the low). Score with references/critique.md.

Common mistakes

Mistake	Looks like	Fix
Retopologize on a face	plausible grid, no rings	template fit; openings gate
polyRetopo history kept	mesh re-solves on edit or open	RU.retopologize deletes it
All hard edges on a scan or AI mesh	Retopologize fails or crawls	prep_source softens all
Cleanup and Merge on internal faces	endless non-manifold loop	select-mode Cleanup, delete by hand, or Boolean Volume (P2)
Wrist or ankle bend sent to the rigger	loops along the joint patched with correctives	topology verdict: reroute loops across it, A/B
Clean rings rebuilt for volume loss	same elbow collapse	rig verdict: corrective note for scenario-maya-deformation
Lids modeled without the eyeball	lid pops through on a blink	lid_check, add lid loops, refit
Center drift; relax after UVs	mirror seam; textures swim	snap_center first; relax before UVs or transfer_uvs
Straighten UVs on a whole shell	"this mess"	orient, align rows, pin, optimize the interior (MLC)
Unfold refuses a mesh that audits manifold	Unfold3D aborts	it unfolds a triangulated copy: triangulate a duplicate, select-mode Cleanup
Layout Uniform after density; stacked unique bakes	density changed; mirrored AO	scale_mode="off"; stack by strategy, offset 1 tile
Half model baked, two triangulations	center seam, zig-zag shading	whole mirrored model; bake_copy

Handoffs

• Receives from scenario-maya-modeling (base meshes, eyeballs, mx_validate(profile="model") clean), scenario-zbrush-expert (real scale, neutral; posed sources go back), scenario-3d (FBX or OBJ [verify glTF]; its remesh only for static parts); loop faults back from scenario-maya-deformation with pose and numbers.
• Delivers to scenario-maya-rigging and scenario-maya-deformation: a new version, <part>_geo frozen without history, cm, Y-up, centered, feet on the grid, eyes separate and forward, mouth bag, symmetric parts combined; retopo_report, deform_test (rig notes: hinges needing correctives) and lid_check JSON, wire and pose sheets.
• Delivers to scenario-maya-lookdev: UV sets, px/cm, UDIM table, the bake package (high, triangulated bake copy, cage, offsets, tangent basis: MikkTSpace for Unreal and Unity; Arnold normal_map has a MikkTSpace mode from MtoA 5.6.1.1, Maya 2027.1), uv_report JSON.

Maya 2027 notes

• Quad Draw is interactive only (Make Live first); its 2027 hotkey table is lost, so gui-paths.md's 2018 panel is [verify]. polyRetopo flags are unsaved: RU.call passes only flags cmds.help lists. Flow Retopology (cloud, 2027.1) needs a sign-in: not headless. Reduce is decimation.
• Broken source: Mesh > Booleans Volume mode with a Voxel size (2026) rebuilds watertight but needs a second input; Mesh > Remesh evens the spread before Retopologize.
• Unfold3D is the default, refuses non-manifold meshes, pins unselected UVs (Legacy: selected only). Relax is Optimize > Legacy. Texel Density needs Map Size first; Measure has Pixel Distance.
• dgaTension (2026.3) measures stretch against a reference mesh for a heat map (RU.tension_node, attributes [verify]). A hand-made test bind leaves Skin Tools layers uninitialized (the default), so skinPercent floods work; on a skinned mesh delete Non-Deformer History, never History (antCGi [00:12:41]).

References

• references/procedures.md: full code P0 to P21 with test paths. Load before writing code.
• references/expert-notes.md: principles by expert, disagreements, deciding conditions. Load when planning a face, body, clothes, a deformation test or a mapping strategy.
• references/critique.md: the self-review rubric. Load at every review.
• references/gui-paths.md: menus, hotkeys, tool settings (Quad Draw, Retopologize, test bind, UV Toolkit).
• references/sources.md: every source with credentials, URL and timestamps.