generate_mediapipe_face_symmetry_map.py

source scripts mediapipe mathematics

File Path: scripts/generate_mediapipe_face_symmetry_map.py

Purpose: Generates a bidirectional mapping of MediaPipe Face Mesh landmarks to their mirror equivalents (left side to right side).

Overview

This script uses a reference image of a front-facing face to detect 478 landmarks. It then applies the Hungarian Algorithm (via scipy.optimize.linear_sum_assignment) to find the optimal mirror pairs by minimizing the Euclidean distance between points and their horizontally flipped versions.

Functions

init_face_model()

Initializes the MediaPipe Face Landmarker task.

get_face_mesh_symmetry_indices(...)

Detects landmarks and calculates the symmetry map using cdist and linear_sum_assignment.

gen_symmetry_map(...)

Wraps the detection with sanity checks:

• Verifies all 478 points are mapped uniquely.
• Checks specific known pairs (e.g., eye corners).
• Ensures the mapping is bidirectional ($A\to B⟹B\to A$).

Execution

When run directly, it:

1. Loads two reference images (frontal-face-1.jpg, frontal-face-2.jpg).
2. Confirms the symmetry map is identical for both.
3. Saves the mapping as a .npy file to FACE_SYMMETRY_MAP_PATH.

Related Documentation

Used By:

• generate_mediapipe_simplified_face_kps.py - To ensure simplified contours remain symmetric.