findSeedPointOnCentralSlice()

in src/engine/actvolume/lungsfill/seedPoints.js [27:149]

• 110 lines of code
• 25 McCabe index (conditional complexity)

  findSeedPointOnCentralSlice(vSeed) {
    const TWO = 2;
    const zCenter = Math.floor(this.m_zDim / TWO);
    const yCenter = Math.floor(this.m_yDim / TWO);
    let yMin = -1,
      yMax = -1;
    const zOff = zCenter * this.m_xDim * this.m_yDim;
    let yOff = -1;

    // detect min, max y
    let x, y;
    const NUM_170 = 170.0;
    const NUM_512 = 512.0;
    const MIN_LINE_RATIO = NUM_170 / NUM_512;

    for (y = 0; y < yCenter; y++) {
      yOff = y * this.m_xDim;
      let numWhitePixels = 0;
      for (x = 0; x < this.m_xDim; x++) {
        numWhitePixels += this.m_volTexSrc[x + yOff + zOff] > TOO_MIN_VAL ? 1 : 0;
      }
      // how much percents of non-black pixels can be in line
      const isBlackLine = numWhitePixels / this.m_xDim < MIN_LINE_RATIO ? 1 : 0;
      if (!isBlackLine) {
        break;
      }
      yMin = y;
    }

    for (y = this.m_yDim - 1; y > yCenter; y--) {
      yOff = y * this.m_xDim;
      let numWhitePixels = 0;
      for (x = 0; x < this.m_xDim; x++) {
        numWhitePixels += this.m_volTexSrc[x + yOff + zOff] > TOO_MIN_VAL ? 1 : 0;
      }
      // how much percetns non-black pixels can be in line
      const isBlackLine = numWhitePixels / this.m_xDim < MIN_LINE_RATIO ? 1 : 0;
      if (!isBlackLine) {
        break;
      }
      yMax = y;
    }
    // console.log(`yMin = ${yMin}, yMax = ${yMax}`);
    // shift range [yMin .. yMax] to mire narrow search area
    const NUM_45 = 45.0;
    const NUM_60 = 60.0;
    const NUM_339 = 339.0;
    const ADD_RATIO_MIN = NUM_45 / NUM_339;
    const ADD_RATIO_MAX = NUM_60 / NUM_339;

    const yMinNew = Math.floor(yMin + (yMax - yMin) * ADD_RATIO_MIN);
    const yMaxNew = Math.floor(yMax - (yMax - yMin) * ADD_RATIO_MAX);
    yMin = yMinNew;
    yMax = yMaxNew;
    const NUM_COLORS = 8;
    const histogram = new Float32Array(NUM_COLORS);
    let goodHistogramDetected = false;
    for (y = yMin; y <= yMax && !goodHistogramDetected; y++) {
      // clear histogram
      for (x = 0; x < NUM_COLORS; x++) {
        histogram[x] = 0;
      }
      // collect histogram
      yOff = y * this.m_xDim;

      const SHIFT_5 = 5;
      for (x = 0; x < this.m_xDim; x++) {
        // get value in [0..7]
        const val = this.m_volTexSrc[x + yOff + zOff] >> SHIFT_5;
        histogram[val] += 1.0;
      }
      // get color probability
      for (x = 0; x < NUM_COLORS; x++) {
        histogram[x] /= this.m_xDim;
      }
      // black color should be largely presented
      // but we should have enough whites
      const BARRIER = 0.7;
      if (histogram[0] < BARRIER) {
        goodHistogramDetected = true;
        break;
      }
    } // for (y) all possible hor lines
    // console.log(`found y = ${y}`);
    // search seed point in line: zCenter, y
    let valThreshold = 0;
    // search first white point on line
    const xCenter = Math.floor(this.m_xDim / TWO);
    for (x = 0; x < xCenter; x++) {
      valThreshold = this.m_volTexSrc[x + yOff + zOff];
      if (valThreshold > TOO_MIN_VAL) {
        break;
      }
    }
    // search first black point
    const ADD_RANGE = 8;
    x += ADD_RANGE;
    for (; x < xCenter; x++) {
      valThreshold = this.m_volTexSrc[x + yOff + zOff];
      if (valThreshold < TOO_MIN_VAL) {
        break;
      }
    }
    if (x === xCenter) {
      return 1;
    }

    // check that next 8 pixels are black
    for (let dx = 0; dx < ADD_RANGE; dx++) {
      valThreshold = this.m_volTexSrc[x + yOff + zOff];
      if (valThreshold > TOO_MIN_VAL) {
        break;
      }
      x++;
    }
    if (valThreshold > TOO_MIN_VAL) {
      return 1;
    }
    vSeed.x = x;
    vSeed.y = y;
    vSeed.z = zCenter;
    return 0;
  } //findSeedPointOnCentralSlice