xsl
a3fddbbc34
按 MediaPipe 左右对应额头点协调模板延伸距离，保留人脸姿态与头部轮廓钳制，统一预览白线和生发遮罩的几何。补充对齐回归测试并更新贴图顺序测试及实现说明。 验证：13 项相关测试通过；两张用户图片完成前后对比，新图男性 7 型接口与生发图均成功返回。
178 lines
7.8 KiB
Python
178 lines
7.8 KiB
Python
"""Shared constants for the hairline-extension pipeline.
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These define the topology of the extended mesh and must stay in sync with
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the C++ side (see sdk/ExtensionConstants.h). If you change anything here,
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regenerate face_ext.obj and update the C++ header.
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"""
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from __future__ import annotations
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# Number of MediaPipe FaceMesh landmarks (no iris refinement).
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N_MP = 468
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# Anchors along the upper boundary of the MediaPipe face mesh,
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# ordered left-to-right when viewing the face frontally.
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# Each anchor will get a paired hairline sample directly "above" it.
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#
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# Verify visually with scripts/show_anchors.py before locking these in.
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MP_TOP_ANCHORS: list[int] = [
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127, 234, 162, 21, 54, 103, 67, 109, 10,
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338, 297, 332, 284, 251, 389, 356, 454,
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]
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N_ANCHORS = len(MP_TOP_ANCHORS) # 17
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# Anatomical left/right pairs, in MediaPipe indices. The anchor list is
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# NOT mirror-ordered at its ends: 127 pairs with 356, 234 with 454.
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MP_TOP_ANCHOR_PAIRS = [
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(127, 356), (234, 454), (162, 389), (21, 251),
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(54, 284), (103, 332), (67, 297), (109, 338),
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]
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# Vertex ID layout in the extended array of length 468 + 2*N_ANCHORS.
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# [0 .. 468) : MediaPipe canonical landmarks
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# [468 .. 468+N) : middle row (between MP boundary and hairline)
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# [468+N .. 468+2N) : hairline row
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N_EXT = 2 * N_ANCHORS # 34
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N_TOTAL = N_MP + N_EXT # 502
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MIDDLE_START = N_MP # 468
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HAIRLINE_START = N_MP + N_ANCHORS # 485
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# Saggital head-curvature radius (in MediaPipe normalized-Y units),
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# expressed as a fraction of face height. The head's mid-line cross
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# section is treated locally as a circular arc; for a hairline / middle
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# vertex located dy=(y_hair - y_anchor) above an MP top anchor (dy < 0
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# since hairline y < anchor y) we compute its Z by
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#
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# z_hair = z_anchor + dy² / (2 R), R = HEAD_ARC_RADIUS_FRAC × face_h
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#
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# This always pushes the added vertex BACKWARD (toward +z in MP / face.obj
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# convention, i.e. toward the back of the head), matching the actual
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# anatomy. See README for the derivation.
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#
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# Smaller fraction = more pronounced backward bulge. 0.30 produces a
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# moderate offset (~0.024 in normalized z for a 0.08-y hairline lift on
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# a typical face).
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HEAD_ARC_RADIUS_FRAC = 0.30
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# Extra lift applied to the detected hairline along the face-up direction,
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# expressed as a fraction of the MP face height. The 2D hairline detector
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# stops at the hair-skin boundary (start of the visible hair); the mesh
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# ribbon's top row should sit at the crown of the head instead, so the
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# texture-overlay band can cover the whole forehead → crown region.
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#
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# 0.06 ≈ moves the hairline row up by 6% of face height, which on the
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# reference photos lands the top row just above the visible hairline and
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# below the crown — empirically tuned with the /preview slider and locked
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# in as the project default. Bump to 0.10..0.15 for taller foreheads /
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# higher crowns; drop to 0.03 to keep the ribbon hugging the hair-skin
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# boundary.
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HAIRLINE_CROWN_LIFT_FRAC = 0.06
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# Pure-geometry hairline offset for the /preview 502-point pipeline.
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#
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# When placing the hairline row WITHOUT hair detection (works for bald /
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# with-hair / hat — all head types), each anchor is offset upward along
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# face-up by GEOMETRIC_HAIRLINE_OFFSET_FRAC × face_h in normalised
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# image space. The sagittal-arc model then derives Z.
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#
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# 0.25 × face_h ≈ 0.12 normalised on a typical face (face_h ≈ 0.48),
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# giving dz ≈ 0.05 — matches the real hairline distance observed on
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# reference photos where hair detection succeeds.
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GEOMETRIC_HAIRLINE_OFFSET_FRAC = 0.25
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# UV layout for the 34 forehead-extension vertices.
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#
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# The texture (imgs/texture0.png, 512×512) is laid out with the original
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# MediaPipe face skin in V_raw ≈ 0.00..0.77 (image y ≈ 117..511) and a
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# horizontal stack of 5 hairline-design arcs at the TOP of the image
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# (image y ≈ 30..170, i.e. V_raw ≈ 0.67..0.94). Those 5 arcs are the
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# content that the extension strip is supposed to display: hairline row
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# samples the topmost arc (blue), middle row samples the bottom arc
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# (orange), and the 3 arcs in between fall out automatically because the
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# ribbon triangle interpolates V linearly between the two rows.
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#
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# V conventions
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# -------------
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# uv_template.py / Three.js (with texture.flipY=true) treat V_raw=1 as
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# the TOP of the image (image y=0) and V_raw=0 as the BOTTOM.
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#
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# U conventions — IMPORTANT
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# -------------------------
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# The 17 MP_TOP_ANCHORS in face.obj have NON-uniform u (≈ 0.00 at the
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# temples, ≈ 0.50 at the forehead center, ≈ 1.00 at the other temple).
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# Each ribbon triangle (anchor[i] → middle[i] → anchor[i+1] etc.) is a
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# vertical column in UV space ONLY when the middle/hairline vertex
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# inherits its U from the corresponding anchor. If we used a uniform
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# 0.05..0.95 U for the strip the columns would slant relative to the
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# anchor U values, warping the texture's 5 horizontal arcs into
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# zig-zags. So `extension_uv_for` takes `anchor_u` and copies it.
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UV_MIDDLE_DV = 0.110 # middle 行 V_raw 相对该列 anchor V_raw 上移这么多
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UV_HAIRLINE_DV = 0.220 # hairline 行 V_raw 相对该列 anchor V_raw 上移这么多
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# 为什么是"相对 anchor 平行偏移"而不是固定常数:
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#
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# face.obj 中 17 个 MP_TOP_ANCHORS 的 V_raw 是**非均匀弧形** (额头中央 MP 10
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# = 0.7724, 太阳穴 MP 127 = 0.4668, 横跨 0.30 V 单位)。 如果 middle/hairline
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# 用固定常数 V_raw (例如 0.82 / 0.998), 那每个 ribbon quad 的 V 跨度
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# (= middle.V − anchor[i].V) 在 17 列之间差异巨大 (中央列 0.05, 两端列 0.35,
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# 差了 7 倍)。 贴图最底部的弧线 (V_raw ≈ 0.76) 正好落在 V 跨度大的列上 →
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# 被拉伸成粗大色块, 而顶部弧线 (V_raw ≈ 0.93) 落在 V 跨度小的列上 → 被压
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# 缩成细线。 这就是"最下面那条线特别粗、上面 4 根都细"的根因。
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#
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# 把 middle/hairline 的 V 也设成"anchor V + 固定 Δ", 每列的 V 跨度变成恒定
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# 的 Δm / (Δh − Δm), ribbon 在贴图上是上下都跟随 anchor 弧度的弯月形带,
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# 贴图 5 条弧线在 mesh 上粗细均匀。
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#
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# 硬约束:
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# 1. Δm > 0 且 Δm < Δh (顺序保持 anchor < middle < hairline, 防 V 反向)
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# 2. anchor.V_max + Δh ≤ 1.0 (即 Δh ≤ 1 − 0.7724 = 0.2276)
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# 否则中央列 hairline V 溢出, 采到贴图边缘的抗锯齿像素。
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# 当前 Δh = 0.220 留 ≈ 0.008 V 单位 buffer; Δm = Δh / 2 让上下两段等宽。
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def extension_uv_for(row: int, anchor_u: float, anchor_v: float) -> tuple[float, float]:
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"""Return (u, v_raw) UV for an extension vertex.
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row: 0 = middle, 1 = hairline.
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anchor_u: U of the corresponding MP anchor (copy verbatim → ribbon column
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is vertical in UV space).
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anchor_v: V_raw of the corresponding MP anchor (we add a constant Δ to
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it → ribbon row stays parallel to anchor row in UV space, so
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each quad has the same V span and texture arcs render at the
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same thickness across all 17 columns).
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"""
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dv = UV_MIDDLE_DV if row == 0 else UV_HAIRLINE_DV
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return (anchor_u, anchor_v + dv)
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# Face-parsing class indices for the jonathandinu/face-parsing
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# SegFormer model (matches CelebAMask-HQ labels):
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PARSE_BG = 0
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PARSE_SKIN = 1
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PARSE_NOSE = 2
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PARSE_EYE_G = 3
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PARSE_L_EYE = 4
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PARSE_R_EYE = 5
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PARSE_L_BROW = 6
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PARSE_R_BROW = 7
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PARSE_L_EAR = 8
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PARSE_R_EAR = 9
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PARSE_MOUTH = 10
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PARSE_U_LIP = 11
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PARSE_L_LIP = 12
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PARSE_HAIR = 13
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PARSE_HAT = 14
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PARSE_EAR_R = 15
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PARSE_NECK_L = 16
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PARSE_NECK = 17
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PARSE_CLOTH = 18
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# 内网/离线：指向本地权重目录（transformers from_pretrained 支持本地路径）。
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# 在线 id 为 "jonathandinu/face-parsing"，权重已放到 hairline/models/face-parsing/。
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import os as _os
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HF_FACE_PARSER_MODEL = _os.path.join(
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_os.path.dirname(_os.path.abspath(__file__)), "models", "face-parsing"
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)
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