AI-driven head rework: judge picks the decimated MakeHuman head over the displacement shell

TODO.md

@@ -80,16 +80,18 @@ the rest of §C remains the broad review checklist.
 
 ### 3. Head and face prototype
 
+### 3. Head and face prototype
+
 - [x] Build one `npc_casual` head/face prototype as a connected head shell plus intentional feature
       geometry — not a sphere with floating facial balls. Use loop-based eye sockets/lids, a
       readable nose bridge/tip/ala, a mouth with upper/lower lip volumes, ears with concha depth,
       and brow/cheek/jaw planes that survive the 256² AO bake.
-      `tools/npc_parts.py build --part head_proto` displaces a seg-48 shell into eye sockets with
-      an orbital rim, a nose bridge/tip/ala, upper/lower lips, a chin bump, a brow step, a sloped
-      forehead and extruded ears (helix + concha + lobe); the eyeballs stay separate. Objective
-      centre-profile evidence: nose tip −0.192, brow −0.150, chin −0.149, jaw step −0.11, forehead
-      −0.126→−0.078. Vision-judged ~3/5; remaining polish (forehead/ear/jawline read) is folded
-      into §3.2 comparison.
+      `tools/npc_parts.py build --part head_proto` built the displacement shell (sockets, nose,
+      lips, chin, brow, ears) but the AI-judged rework (concept + judge, see
+      `docs/3d-model-review.md` §AI-driven head rework) shows it oscillates between "egg" and
+      "spiky" at ~3/5. The judge's decisive result: **ship the decimated MakeHuman head**
+      (1,573 tris, nose/chin/jaw landmarks) plus the project's separate eye/mouth/brow pieces. The
+      displacement `_head_proto` is a rejected variant; the MakeHuman head is the new base.
 - [x] Compare two or three subdivision/loop variants at 1.85 m front/three-quarter/profile and a
       1.5 m portrait. Pick the variant that reads best before changing all 12 characters; keep the
       rejected variants local.

docs/3d-model-review.md

@@ -232,6 +232,24 @@ brow −0.150, chin −0.149, jaw step −0.11, forehead −0.126→−0.078. Th
 forehead, a defined ear helix/lobe, a jawline that steps to the neck) is folded into the §3.2
 variant comparison; the neck is part of `_skin_body`, so the standalone head always lacks it.
 
+### AI-driven head rework (2026-11-04)
+
+The head was reworked against an AI-generated target concept (front + profile, saved under
+`tmp/npc-parts/head_concept_*.png`) and judged with `describe_image.py` across several iterations.
+The displacement-on-sphere approach oscillates between "decorated egg" (too subtle) and
+"spiky wedges" (too aggressive) and settles at ~3/5 — the coarse s48 sphere cannot resolve the
+nose/lip/chin relief cleanly.
+
+The judge then compared the displacement head against the **decimated MakeHuman head**
+(extracted from `makehuman_retargeted.glb`, 2,009 verts / 1,573 tris, saved as
+`tmp/npc-parts/makehuman_head.glb`) and returned a decisive result: **ship the MakeHuman head** —
+it keeps the nose/chin/jaw landmarks at a fraction of the cost, while the procedural head's
+"clean ellipse outline instantly screams procedural sphere".
+
+**Conclusion:** the next head asset is the MakeHuman head shape (1,573 tris) plus the project's
+separate eye/mouth/brow pieces for readability, not the displacement shell. The displacement
+`_head_proto` stays local as a rejected variant.
+
 ### Head subdivision comparison (2026-11-04)
 
 Three `head_proto` variants at UV-sphere segments 24/48/64 were rendered at 1.85 m and 1.5 m in

tools/blender_assets.py

@@ -869,7 +869,7 @@ def _head_proto(mats, spec, subdiv=48):
     white = material("eye_white", textured_solid=True)
     rings = max(14, subdiv // 2 + 2)
     head = sphere("HeadShell", 0.155, (0, 0, 1.635), skin, seg=subdiv, rings=rings,
-                  scale=(0.90, 0.96, 1.08))
+                  scale=(0.88, 0.95, 1.18))
     _shape_head_mesh(head)  # brow ridge + cheekbone + jaw/chin planes
     bm = bmesh.new()
     bm.from_mesh(head.data)
@@ -877,10 +877,10 @@ def _head_proto(mats, spec, subdiv=48):
     # Pass 1: skull shape — flatten the face plane and taper the jaw/chin.
     for v in bm.verts:
         x, y, z = v.co
-        if y < -0.03 and 1.44 < z < 1.76:
-            v.co.y = -0.13 + (y + 0.13) * 0.10  # flatten the forward bulge
+        if y < -0.03 and 1.42 < z < 1.80:
+            v.co.y = -0.13 + (y + 0.13) * 0.05  # flatten the forward bulge
         if y < -0.03 and z > 1.70:
-            v.co.y += (z - 1.70) * 0.35  # forehead slopes back to the crown
+            v.co.y += (z - 1.70) * 0.45  # forehead slopes back to the crown
         if z < 1.58:
             taper = max(0.0, 1.0 - (1.58 - z) / 0.12)
             v.co.x *= 1.0 - 0.16 * taper  # narrow the lower face
@@ -889,11 +889,11 @@ def _head_proto(mats, spec, subdiv=48):
     for v in bm.verts:
         x, y, z = v.co
         ax = abs(x)
-        # --- brow step ---
-        brow = (max(0.0, 1.0 - abs(z - 1.695) / 0.022)
+        # --- brow ledge: a clear ridge where the forehead meets the nose ---
+        brow = (max(0.0, 1.0 - abs(z - 1.695) / 0.024)
                 * max(0.0, 1.0 - abs(ax - 0.050) / 0.045))
         if brow > 0:
-            v.co.y -= 0.016 * brow
+            v.co.y -= 0.028 * brow
         # --- eye sockets: recess the floor, leave a raised orbital rim ---
         for s in (-1.0, 1.0):
             r = math.hypot(x - 0.052 * s, z - 1.664)
@@ -902,46 +902,46 @@ def _head_proto(mats, spec, subdiv=48):
             elif r < 0.046:
                 v.co.y -= 0.010 * (1.0 - (r - 0.036) / 0.010)
         # --- nose: a wide bridge/tip with ala wings ---
-        if y < 0 and ax < 0.075:
+        if y < 0 and ax < 0.080:
             band = max(0.0, 1.0 - abs(z - 1.632) / 0.055)
             if band > 0:
-                tip = max(0.0, 1.0 - abs(z - 1.615) / 0.032)
-                v.co.y -= (0.060 * tip + 0.018 * max(0.0, band - tip)) \
-                          * (1.0 - ax / 0.075)
+                tip = max(0.0, 1.0 - abs(z - 1.615) / 0.034)
+                v.co.y -= (0.062 * tip + 0.020 * max(0.0, band - tip)) \
+                          * (1.0 - ax / 0.080)
             for s in (-1.0, 1.0):
-                ar = math.hypot((x - 0.024 * s) / 0.014, (z - 1.604) / 0.013)
+                ar = math.hypot((x - 0.026 * s) / 0.015, (z - 1.604) / 0.014)
                 if ar < 1.0:
-                    v.co.y -= 0.022 * (1.0 - ar)
-        # --- chin bump + jaw step ---
-        if y < 0 and ax < 0.040:
-            chin = max(0.0, 1.0 - abs(z - 1.548) / 0.022)
+                    v.co.y -= 0.024 * (1.0 - ar)
+        # --- chin wedge + jaw step ---
+        if y < 0 and ax < 0.044:
+            chin = max(0.0, 1.0 - abs(z - 1.548) / 0.024)
             if chin > 0:
-                v.co.y -= 0.030 * chin
+                v.co.y -= 0.034 * chin
             step = max(0.0, 1.0 - abs(z - 1.516) / 0.016)
             if step > 0:
-                v.co.y += 0.024 * step
-        # --- mouth: recessed line + upper/lower lip volumes ---
-        if y < 0 and ax < 0.030:
-            if abs(z - 1.583) < 0.012:
-                v.co.y += 0.008
-            if abs(z - 1.590) < 0.008:
-                v.co.y -= 0.014
-            if abs(z - 1.577) < 0.010:
-                v.co.y -= 0.018
-    # --- ears: helix rim + concha recess + a lobe ---
+                v.co.y += 0.026 * step
+        # --- mouth: recessed line + smooth protruding upper/lower lip block ---
+        if y < 0 and ax < 0.036:
+            if abs(z - 1.583) < 0.014:
+                v.co.y += 0.006
+            if abs(z - 1.590) < 0.012:
+                v.co.y -= 0.016
+            if abs(z - 1.577) < 0.014:
+                v.co.y -= 0.020
+    # --- ears: raised C-shape helix + concha recess + a lobe ---
     for v in bm.verts:
         x, y, z = v.co
-        r = math.hypot((z - 1.60) / 0.055, (y - 0.002) / 0.045)
+        r = math.hypot((z - 1.62) / 0.062, (y - 0.002) / 0.048)
         near = abs(x) - 0.138
         sign = 1.0 if x >= 0 else -1.0
-        if -0.02 < near < 0.06 and r < 1.0:
-            if r < 0.30:
-                v.co.x -= 0.018 * (1.0 - r / 0.30) * sign
+        if -0.02 < near < 0.07 and r < 1.0:
+            if r < 0.36:
+                v.co.x -= 0.016 * (1.0 - r / 0.36) * sign
             else:
-                v.co.x += 0.045 * (1.0 - r) * sign
-        lr = math.hypot((z - 1.575) / 0.016, (y + 0.012) / 0.016)
-        if -0.02 < near < 0.05 and lr < 1.0:
-            v.co.x += 0.032 * (1.0 - lr) * sign
+                v.co.x += 0.048 * (1.0 - r) * sign
+        lr = math.hypot((z - 1.585) / 0.018, (y + 0.012) / 0.017)
+        if -0.02 < near < 0.06 and lr < 1.0:
+            v.co.x += 0.034 * (1.0 - lr) * sign
     bm.normal_update()
     bm.to_mesh(head.data)
     bm.free()
@@ -949,7 +949,7 @@ def _head_proto(mats, spec, subdiv=48):
     # Eyeballs stay separate for readability; lids wrap the socket rim.
     parts = [head]
     for s in (-1.0, 1.0):
-        ex, ey, ez = 0.052 * s, -0.134, 1.664
+        ex, ey, ez = 0.052 * s, -0.127, 1.664
         parts.append(sphere("EyeWhite", 0.019, (ex, ey, ez), white, seg=10,
                             rings=6, scale=(1.25, 0.62, 0.85)))
         parts.append(sphere("Iris", 0.0105, (ex, ey - 0.007, ez), acc, seg=8,
@@ -960,7 +960,7 @@ def _head_proto(mats, spec, subdiv=48):
         parts.append(sphere("LowerLid", 0.017, (ex, ey - 0.004, ez - 0.012),
                             skin, seg=8, rings=4, scale=(1.10, 0.22, 0.18),
                             rot=(math.radians(6), 0, 0)))
-        parts.append(box("Brow", (0.055, 0.014, 0.012), (0.052 * s, -0.143, 1.699),
+        parts.append(box("Brow", (0.055, 0.014, 0.012), (0.052 * s, -0.137, 1.699),
                          hair, rot=(0, 0.14 * s, 0.0)))
     return parts