human/src/blazeface/facepipeline.ts

/* eslint-disable class-methods-use-this */
import * as tf from '../../dist/tfjs.esm.js';
import * as bounding from './box';
import * as util from './util';
import * as coords from './coords';

const LANDMARKS_COUNT = 468;
const MESH_MOUTH_INDEX = 13;
const MESH_KEYPOINTS_LINE_OF_SYMMETRY_INDICES = [MESH_MOUTH_INDEX, coords.MESH_ANNOTATIONS['midwayBetweenEyes'][0]];
const BLAZEFACE_MOUTH_INDEX = 3;
const BLAZEFACE_NOSE_INDEX = 2;
const BLAZEFACE_KEYPOINTS_LINE_OF_SYMMETRY_INDICES = [BLAZEFACE_MOUTH_INDEX, BLAZEFACE_NOSE_INDEX];
const LEFT_EYE_OUTLINE = coords.MESH_ANNOTATIONS['leftEyeLower0'];
const LEFT_EYE_BOUNDS = [LEFT_EYE_OUTLINE[0], LEFT_EYE_OUTLINE[LEFT_EYE_OUTLINE.length - 1]];
const RIGHT_EYE_OUTLINE = coords.MESH_ANNOTATIONS['rightEyeLower0'];
const RIGHT_EYE_BOUNDS = [RIGHT_EYE_OUTLINE[0], RIGHT_EYE_OUTLINE[RIGHT_EYE_OUTLINE.length - 1]];
const IRIS_UPPER_CENTER_INDEX = 3;
const IRIS_LOWER_CENTER_INDEX = 4;
const IRIS_IRIS_INDEX = 71;
const IRIS_NUM_COORDINATES = 76;

// Replace the raw coordinates returned by facemesh with refined iris model coordinates
// Update the z coordinate to be an average of the original and the new.
function replaceRawCoordinates(rawCoords, newCoords, prefix, keys) {
  for (let i = 0; i < coords.MESH_TO_IRIS_INDICES_MAP.length; i++) {
    const { key, indices } = coords.MESH_TO_IRIS_INDICES_MAP[i];
    const originalIndices = coords.MESH_ANNOTATIONS[`${prefix}${key}`];
    // @ts-ignore
    if (!keys || keys.includes(key)) {
      for (let j = 0; j < indices.length; j++) {
        const index = indices[j];
        rawCoords[originalIndices[j]] = [
          newCoords[index][0], newCoords[index][1],
          (newCoords[index][2] + rawCoords[originalIndices[j]][2]) / 2,
        ];
      }
    }
  }
}
// The Pipeline coordinates between the bounding box and skeleton models.
export class Pipeline {
  storedBoxes: any;
  boundingBoxDetector: any;
  meshDetector: any;
  irisModel: any;
  meshWidth: number;
  meshHeight: number;
  irisSize: number;
  irisEnlarge: number;
  skipped: number;
  detectedFaces: number;

  constructor(boundingBoxDetector, meshDetector, irisModel, config) {
    // An array of facial bounding boxes.
    this.storedBoxes = [];
    this.boundingBoxDetector = boundingBoxDetector;
    this.meshDetector = meshDetector;
    this.irisModel = irisModel;
    this.meshWidth = config.face.mesh.inputSize;
    this.meshHeight = config.face.mesh.inputSize;
    this.irisSize = config.face.iris.inputSize;
    this.irisEnlarge = 2.3;
    this.skipped = 0;
    this.detectedFaces = 0;
  }

  transformRawCoords(rawCoords, box, angle, rotationMatrix) {
    const boxSize = bounding.getBoxSize({ startPoint: box.startPoint, endPoint: box.endPoint });
    const scaleFactor = [boxSize[0] / this.meshWidth, boxSize[1] / this.meshHeight];
    const coordsScaled = rawCoords.map((coord) => ([
      scaleFactor[0] * (coord[0] - this.meshWidth / 2),
      scaleFactor[1] * (coord[1] - this.meshHeight / 2), coord[2],
    ]));
    const coordsRotationMatrix = (angle !== 0) ? util.buildRotationMatrix(angle, [0, 0]) : util.IDENTITY_MATRIX;
    const coordsRotated = (angle !== 0) ? coordsScaled.map((coord) => ([...util.rotatePoint(coord, coordsRotationMatrix), coord[2]])) : coordsScaled;
    const inverseRotationMatrix = (angle !== 0) ? util.invertTransformMatrix(rotationMatrix) : util.IDENTITY_MATRIX;
    const boxCenter = [...bounding.getBoxCenter({ startPoint: box.startPoint, endPoint: box.endPoint }), 1];
    return coordsRotated.map((coord) => ([
      coord[0] + util.dot(boxCenter, inverseRotationMatrix[0]),
      coord[1] + util.dot(boxCenter, inverseRotationMatrix[1]),
      coord[2],
    ]));
  }

  getLeftToRightEyeDepthDifference(rawCoords) {
    const leftEyeZ = rawCoords[LEFT_EYE_BOUNDS[0]][2];
    const rightEyeZ = rawCoords[RIGHT_EYE_BOUNDS[0]][2];
    return leftEyeZ - rightEyeZ;
  }

  // Returns a box describing a cropped region around the eye fit for passing to the iris model.
  getEyeBox(rawCoords, face, eyeInnerCornerIndex, eyeOuterCornerIndex, flip = false) {
    const box = bounding.squarifyBox(bounding.enlargeBox(this.calculateLandmarksBoundingBox([rawCoords[eyeInnerCornerIndex], rawCoords[eyeOuterCornerIndex]]), this.irisEnlarge));
    const boxSize = bounding.getBoxSize(box);
    let crop = tf.image.cropAndResize(face, [[
      box.startPoint[1] / this.meshHeight,
      box.startPoint[0] / this.meshWidth, box.endPoint[1] / this.meshHeight,
      box.endPoint[0] / this.meshWidth,
    ]], [0], [this.irisSize, this.irisSize]);
    if (flip) {
      crop = tf.image.flipLeftRight(crop);
    }
    return { box, boxSize, crop };
  }

  // Given a cropped image of an eye, returns the coordinates of the contours surrounding the eye and the iris.
  getEyeCoords(eyeData, eyeBox, eyeBoxSize, flip = false) {
    const eyeRawCoords: Array<any[]> = [];
    for (let i = 0; i < IRIS_NUM_COORDINATES; i++) {
      const x = eyeData[i * 3];
      const y = eyeData[i * 3 + 1];
      const z = eyeData[i * 3 + 2];
      eyeRawCoords.push([
        (flip ? (1 - (x / this.irisSize)) : (x / this.irisSize)) * eyeBoxSize[0] + eyeBox.startPoint[0],
        (y / this.irisSize) * eyeBoxSize[1] + eyeBox.startPoint[1], z,
      ]);
    }
    return { rawCoords: eyeRawCoords, iris: eyeRawCoords.slice(IRIS_IRIS_INDEX) };
  }

  // The z-coordinates returned for the iris are unreliable, so we take the z values from the surrounding keypoints.
  getAdjustedIrisCoords(rawCoords, irisCoords, direction) {
    const upperCenterZ = rawCoords[coords.MESH_ANNOTATIONS[`${direction}EyeUpper0`][IRIS_UPPER_CENTER_INDEX]][2];
    const lowerCenterZ = rawCoords[coords.MESH_ANNOTATIONS[`${direction}EyeLower0`][IRIS_LOWER_CENTER_INDEX]][2];
    const averageZ = (upperCenterZ + lowerCenterZ) / 2;
    // Iris indices: 0: center | 1: right | 2: above | 3: left | 4: below
    return irisCoords.map((coord, i) => {
      let z = averageZ;
      if (i === 2) {
        z = upperCenterZ;
      } else if (i === 4) {
        z = lowerCenterZ;
      }
      return [coord[0], coord[1], z];
    });
  }

  async predict(input, config) {
    let useFreshBox = false;
    // run new detector every skipFrames unless we only want box to start with
    let detector;
    if ((this.skipped === 0) || (this.skipped > config.face.detector.skipFrames) || !config.face.mesh.enabled || !config.videoOptimized) {
      detector = await this.boundingBoxDetector.getBoundingBoxes(input);
      this.skipped = 0;
    }
    if (config.videoOptimized) this.skipped++;

    // if detector result count doesn't match current working set, use it to reset current working set
    if (detector && detector.boxes && (!config.face.mesh.enabled || (detector.boxes.length !== this.detectedFaces) && (this.detectedFaces !== config.face.detector.maxFaces))) {
      this.storedBoxes = [];
      this.detectedFaces = 0;
      for (const possible of detector.boxes) {
        this.storedBoxes.push({ startPoint: possible.box.startPoint.dataSync(), endPoint: possible.box.endPoint.dataSync(), landmarks: possible.landmarks, confidence: possible.confidence });
      }
      if (this.storedBoxes.length > 0) useFreshBox = true;
    }

    if (config.face.detector.skipInitial && this.detectedFaces === 0) this.skipped = 0;

    if (useFreshBox) {
      if (!detector || !detector.boxes || (detector.boxes.length === 0)) {
        this.storedBoxes = [];
        this.detectedFaces = 0;
        return null;
      }
      for (let i = 0; i < this.storedBoxes.length; i++) {
        const scaledBox = bounding.scaleBoxCoordinates({ startPoint: this.storedBoxes[i].startPoint, endPoint: this.storedBoxes[i].endPoint }, detector.scaleFactor);
        const enlargedBox = bounding.enlargeBox(scaledBox);
        const squarifiedBox = bounding.squarifyBox(enlargedBox);
        const landmarks = this.storedBoxes[i].landmarks.arraySync();
        const confidence = this.storedBoxes[i].confidence;
        this.storedBoxes[i] = { ...squarifiedBox, confidence, landmarks };
      }
    }
    if (detector && detector.boxes) {
      detector.boxes.forEach((prediction) => {
        prediction.box.startPoint.dispose();
        prediction.box.endPoint.dispose();
        prediction.landmarks.dispose();
      });
    }

    let results = tf.tidy(() => this.storedBoxes.map((box, i) => {
      // The facial bounding box landmarks could come either from blazeface (if we are using a fresh box), or from the mesh model (if we are reusing an old box).
      let face;
      let angle = 0;
      let rotationMatrix;
      if (config.face.detector.rotation && config.face.mesh.enabled) {
        const [indexOfMouth, indexOfForehead] = (box.landmarks.length >= LANDMARKS_COUNT) ? MESH_KEYPOINTS_LINE_OF_SYMMETRY_INDICES : BLAZEFACE_KEYPOINTS_LINE_OF_SYMMETRY_INDICES;
        angle = util.computeRotation(box.landmarks[indexOfMouth], box.landmarks[indexOfForehead]);
        const faceCenter = bounding.getBoxCenter({ startPoint: box.startPoint, endPoint: box.endPoint });
        const faceCenterNormalized = [faceCenter[0] / input.shape[2], faceCenter[1] / input.shape[1]];
        const rotatedImage = tf.image.rotateWithOffset(input, angle, 0, faceCenterNormalized);
        rotationMatrix = util.buildRotationMatrix(-angle, faceCenter);
        face = bounding.cutBoxFromImageAndResize({ startPoint: box.startPoint, endPoint: box.endPoint }, rotatedImage, [this.meshHeight, this.meshWidth]).div(255);
      } else {
        rotationMatrix = util.IDENTITY_MATRIX;
        const cloned = input.clone();
        face = bounding.cutBoxFromImageAndResize({ startPoint: box.startPoint, endPoint: box.endPoint }, cloned, [this.meshHeight, this.meshWidth]).div(255);
      }

      // if we're not going to produce mesh, don't spend time with further processing
      if (!config.face.mesh.enabled) {
        const prediction = {
          coords: null,
          box,
          faceConfidence: null,
          boxConfidence: box.confidence,
          confidence: box.confidence,
          image: face,
        };
        return prediction;
      }

      const [, confidence, contourCoords] = this.meshDetector.predict(face); // The first returned tensor represents facial contours which are already included in the coordinates.
      const faceConfidence = confidence.dataSync()[0];
      if (faceConfidence < config.face.detector.minConfidence) return null; // if below confidence just exit
      const coordsReshaped = tf.reshape(contourCoords, [-1, 3]);
      let rawCoords = coordsReshaped.arraySync();

      if (config.face.iris.enabled) {
        const { box: leftEyeBox, boxSize: leftEyeBoxSize, crop: leftEyeCrop } = this.getEyeBox(rawCoords, face, LEFT_EYE_BOUNDS[0], LEFT_EYE_BOUNDS[1], true);
        const { box: rightEyeBox, boxSize: rightEyeBoxSize, crop: rightEyeCrop } = this.getEyeBox(rawCoords, face, RIGHT_EYE_BOUNDS[0], RIGHT_EYE_BOUNDS[1]);
        const eyePredictions = this.irisModel.predict(tf.concat([leftEyeCrop, rightEyeCrop]));
        const eyePredictionsData = eyePredictions.dataSync();
        const leftEyeData = eyePredictionsData.slice(0, IRIS_NUM_COORDINATES * 3);
        const { rawCoords: leftEyeRawCoords, iris: leftIrisRawCoords } = this.getEyeCoords(leftEyeData, leftEyeBox, leftEyeBoxSize, true);
        const rightEyeData = eyePredictionsData.slice(IRIS_NUM_COORDINATES * 3);
        const { rawCoords: rightEyeRawCoords, iris: rightIrisRawCoords } = this.getEyeCoords(rightEyeData, rightEyeBox, rightEyeBoxSize);
        const leftToRightEyeDepthDifference = this.getLeftToRightEyeDepthDifference(rawCoords);
        if (Math.abs(leftToRightEyeDepthDifference) < 30) { // User is looking straight ahead.
          replaceRawCoordinates(rawCoords, leftEyeRawCoords, 'left', null);
          replaceRawCoordinates(rawCoords, rightEyeRawCoords, 'right', null);
          // If the user is looking to the left or to the right, the iris coordinates tend to diverge too much from the mesh coordinates for them to be merged
          // So we only update a single contour line above and below the eye.
        } else if (leftToRightEyeDepthDifference < 1) { // User is looking towards the right.
          replaceRawCoordinates(rawCoords, leftEyeRawCoords, 'left', ['EyeUpper0', 'EyeLower0']);
        } else { // User is looking towards the left.
          replaceRawCoordinates(rawCoords, rightEyeRawCoords, 'right', ['EyeUpper0', 'EyeLower0']);
        }
        const adjustedLeftIrisCoords = this.getAdjustedIrisCoords(rawCoords, leftIrisRawCoords, 'left');
        const adjustedRightIrisCoords = this.getAdjustedIrisCoords(rawCoords, rightIrisRawCoords, 'right');
        rawCoords = rawCoords.concat(adjustedLeftIrisCoords).concat(adjustedRightIrisCoords);
      }

      const transformedCoordsData = this.transformRawCoords(rawCoords, box, angle, rotationMatrix);
      const landmarksBox = bounding.enlargeBox(this.calculateLandmarksBoundingBox(transformedCoordsData));
      const squarifiedLandmarksBox = bounding.squarifyBox(landmarksBox);
      const transformedCoords = tf.tensor2d(transformedCoordsData);
      const prediction = {
        coords: transformedCoords,
        box: landmarksBox,
        faceConfidence,
        boxConfidence: box.confidence,
        image: face,
        rawCoords,
      };
      this.storedBoxes[i] = { ...squarifiedLandmarksBox, landmarks: transformedCoordsData, confidence: box.confidence, faceConfidence };

      return prediction;
    }));

    results = results.filter((a) => a !== null);
    // remove cache entries for detected boxes on low confidence
    if (config.face.mesh.enabled) this.storedBoxes = this.storedBoxes.filter((a) => a.faceConfidence > config.face.detector.minConfidence);
    this.detectedFaces = results.length;

    return results;
  }

  calculateLandmarksBoundingBox(landmarks) {
    const xs = landmarks.map((d) => d[0]);
    const ys = landmarks.map((d) => d[1]);
    const startPoint = [Math.min(...xs), Math.min(...ys)];
    const endPoint = [Math.max(...xs), Math.max(...ys)];
    return { startPoint, endPoint, landmarks };
  }
}