Scenario Zbrush Retopology Export

ZBrush retopology and export (pipeline sculptor)

Expert level means the sculpt leaves ZBrush as a light, clean exchange mesh at its lowest level, detail kept on a rebuilt subdivision stack or in maps, at real size, every file proved by parsing it. Most of it is deterministic palette work an agent does well; click-by-click topology, modifier clicks and a few dialogs stay with a human or computer-use agent. 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-zbrush-expert (bridge, stroke engine, review loop, 2026 traps).

Toolkit: scripts/zb_retopology_export.py (rx) on top of the lead's zb_ops, zb_audit and zb_launch: rx.zcall("func", ...) inside ZBrush, audits on the agent side. Every projection pass is the lead's safe zb_ops.project_all (versioned checkpoint, nets, gate). Not yet run in ZBrush (88 offline tests pass; live tests in references/procedures.md).

Stance (the expert delta)

• Set symmetry on purpose before every ZRemesher run. With symmetry on, ZRemesher remeshes half and mirrors it: a silent Mirror And Weld that ruins posed or asymmetric meshes (Drust, Kjce71jjWJU 00:01:11). rx.zremesh makes symmetric a required argument.
• Give ZRemesher an easy problem. A face that will animate goes in neutral, folds relaxed, the expression sculpted back on the new topology (Pavlovich n5_cZK-9peg 00:01:39). Ears and hands are remeshed alone, open borders polished first (00:44:36). Unintended holes are closed first: they survive and inflate the count (ZRemesher doc).
• ZRemesher is for flow; detail comes back by projection. Aim low (Gaboury: 5k to 18k for an arm, 34D6VljTjBs 00:02:18), then Project All with Dist 0.1, which fixes "90 percent" of artifacts (Drust nxMYYsyJt3o 00:02:19). Only source and target visible, even in Solo (Pavlovich 01:07:26). With Adapt on and Keep Groups, Target 5 gave 8.0k to 9.4k points (frames 00:18:50, 00:22:09); Adapt off hits the count.
• Projection has danger zones: eyes, mouth, armpits, between fingers, crotch; what is left there becomes hard lines in displacement (FlippedNormals Zp07GW3rND0 00:07:43). Mask an eye-interior group grown just past the lid; repair with the morph target or a masked reprojection, never smoothing (00:05:31, 00:06:36).
• Steer with polygroups, borders smoothed first: ZRemesher builds jagged borders into the loops (Pavlovich 00:05:27). Smooth Groups 0 on clean borders, 1 for ragged DynaMesh groups (Drust 8D-xqasgUws 00:02:17). Failed eyelids, mouth corners and nostrils are deleted and rebuilt (Pavlovich 00:21:36); the Retopo brush's "No" answer makes a light ZRemesher mesh editable (Pablo Munoz Gomez, I4nePXDTrhQ 00:06:36).
• The lowest level is the exchange mesh. UVs are made there (Gaboury cemmalvugFk 00:00:51). Maps compare the current level with the top of the same SubTool, never two SubTools (Drust n0qqpwvn-jA 00:01:14); level 1 carries forms, max-1 micro detail only (2zDAtaQqwh8 00:02:53).
• Film displacement is a fixed recipe (FlippedNormals -ThBTEc8L_M): Flip V on ("an absolute must"), Adaptive off (100 UDIMs in about 1 h, not 24 h), DpSubPix 0, 32-bit EXR, 3 Channels off, renderer zero value = Mid (MME doc: Mid 0 for 32-bit; FlippedNormals keep 0.5; record it).
• Exported size = internal extent x Export Scale (Drust n2xPrwI9o1U 00:04:19). Keep XYZ Size between 1 and 4 (Gallagher EXjfH_X2hkM 00:28:23). Export Scale and offsets live per SubTool, so the same values go on every SubTool [added].
• A generated or scanned mesh is a form reference, not topology to repair. DynaMesh early, after thickening thin shells, which DynaMesh's hole fill "shoots straight across" (Drust PrFQXjs_6_w 00:02:53). Rebuild the stack from the cleaned DynaMesh, never the noisy original [added].

Establish first

Workflow

1. Preflight, checkpoint. rx.zcall("preflight", 180.0); zb_ops.save_ztl. GATE: flags resolved (over 8M vertices, XYZ Size outside 1 to 4, Export Scale 0, duplicate names).
2. ZRemesher input. remesh_input("auto", max_points=2_000_000) duplicates the sculpt and hides the original (the projection source); fill_holes=True adds Close Holes and Fix Mesh when holes are unintended. DynaMesh and Close Holes also shut eye sockets and mouth bags: openings_closed sets the hole gate (0, else the intended openings). GATE: copy under 8M vertices, source intact, face neutral.
3. Guides. Polygroups by buttons (Auto Groups, Groups By Normals, From Polypaint); a mask a human drew becomes a group with support loops through Edgeloop Masked Border (Drust IpTYcGxxsdM 00:05:08); polish_band("groups"). Ears and hands: own SubTools (Groups Split, Split Hidden), polish_band("border"), own runs (hand Adaptive Size about 14: Pavlovich 00:59:42), then merge_down_run(..., weld=True); Freeze Border only where borders must re-weld exactly, after remeshing the whole limb, at a cost to animation (01:03:44). GATE: Polyframe sheet shows closed, smooth rings; no seam loops after the re-join.
4. ZRemesher. zremesh(target_k, symmetric, keep_groups=True, smooth_groups=0) (Half, Same, Double off), then retry(adaptive_size=...) over 0, 5, 21. Keep Groups, Keep Creases, Smooth Groups or a sculpt break the Retry cache. The sweep leaves the LAST variant: pick_retry, retry(**pick["retry"]), confirm_retry. Optional Half pass with Adapt off, or a retopology over the retopology (Drust R2MzFqWMaWY 00:01:44). Poor center line at nape or brow: Alt+ZRemesher, a modifier click press cannot send: ask computer use, compare centre_line_components (Pavlovich 00:48:31). When snap_back is true, project_stack(copy, source, levels=0, checkpoint=ztl) before judging (00:22:05). GATE: in_band; topo_report + retopo_verdict(purpose="rig", expected_holes=...) on a Grp-on QA export; loops follow forms. Failed orifices: the script stops for a human Retopo pass.
5. Rebuild the stack. project_stack(target, source, checkpoint=ztl): two visible, Dist 0.1, level 1 then Divide + Project All per level up to half the source count, a morph target per pass, color last with Colorize on for both SubTools (Drust PrFQXjs_6_w 00:16:35). Danger zones or a film face: order="top_first", stop_after="nets" (divisions, then StoreMT and a layer at the top: FlippedNormals 00:02:13), a human isolates the eye-interior group, protect_isolated(grow=1), project_levels(..., nets_done=True). GATE: projection_from_stack (level 1 unchanged, bbox 0.5 percent, volume 2 percent [added]); same-view sheet plus danger-zone close-ups per level. Busted areas: zb_ops.morph_repair; a target inside the source: masked Inflate, or ProjectionShell with Inner and Dist 1 (Gaboury pQbPtH0p5Bg 00:02:30). Then drop_morph_target(): bakes refuse a stored morph target, a possible map base (Drust 2zDAtaQqwh8 00:01:44) [verify].
6. UVs at level 1 (they carry through the levels, Gaboury cemmalvugFk 00:03:30). Quick: zb_ops.uv_unwrap("native"). Explicit seams: unwrap_creases() (Pavlovich cvqoVUX5aBw). Painter islands: uvmaster_roundtrip(). Eyes get their own simple UVs. GATE: uv_verdict on the Txr export; seams hidden, face uncut.
7. Maps. mme_create_all(dir, name, settings="arnold") or bake_normal_map / bake_displacement_map. GATE: map_verdict per file (size, bits, flat at Mid, normal flat at 128/128/255: Polycount); orientation calibrated once per build (live_rx_04 fixture).
8. Scale, names, export. set_export_scale(180, axis=1) (every SubTool); set_export_switches(quads=True, uvs=True, groups=False); export_subtools(dir, level="lowest"). FBX: ZScript could not suppress its options window, Python is unverified (Maxon forum), AppleScript System Events clicks ZBrush dialogs on this Mac [verify for it]; default: OBJ, converted by scenario-maya-expert or scenario-blender-expert. GATE: obj_header reads the Export Scale back from #Auto scale (written by 2026.2.1, lead v03 export); scale_report passes (1 percent, feet at 0, centered).
9. Handoff. handoff_report(json, ...): meshes, maps, unit, axis, Mid and scale, normal convention, audits, sheets, not-verified list.