TrackOffical/node_modules/geotiff/dist-module/resample.js

/**
 * @module resample
 */

function copyNewSize(array, width, height, samplesPerPixel = 1) {
  return new (Object.getPrototypeOf(array).constructor)(width * height * samplesPerPixel);
}

/**
 * Resample the input arrays using nearest neighbor value selection.
 * @param {TypedArray[]} valueArrays The input arrays to resample
 * @param {number} inWidth The width of the input rasters
 * @param {number} inHeight The height of the input rasters
 * @param {number} outWidth The desired width of the output rasters
 * @param {number} outHeight The desired height of the output rasters
 * @returns {TypedArray[]} The resampled rasters
 */
export function resampleNearest(valueArrays, inWidth, inHeight, outWidth, outHeight) {
  const relX = inWidth / outWidth;
  const relY = inHeight / outHeight;
  return valueArrays.map((array) => {
    const newArray = copyNewSize(array, outWidth, outHeight);
    for (let y = 0; y < outHeight; ++y) {
      const cy = Math.min(Math.round(relY * y), inHeight - 1);
      for (let x = 0; x < outWidth; ++x) {
        const cx = Math.min(Math.round(relX * x), inWidth - 1);
        const value = array[(cy * inWidth) + cx];
        newArray[(y * outWidth) + x] = value;
      }
    }
    return newArray;
  });
}

// simple linear interpolation, code from:
// https://en.wikipedia.org/wiki/Linear_interpolation#Programming_language_support
function lerp(v0, v1, t) {
  return ((1 - t) * v0) + (t * v1);
}

/**
 * Resample the input arrays using bilinear interpolation.
 * @param {TypedArray[]} valueArrays The input arrays to resample
 * @param {number} inWidth The width of the input rasters
 * @param {number} inHeight The height of the input rasters
 * @param {number} outWidth The desired width of the output rasters
 * @param {number} outHeight The desired height of the output rasters
 * @returns {TypedArray[]} The resampled rasters
 */
export function resampleBilinear(valueArrays, inWidth, inHeight, outWidth, outHeight) {
  const relX = inWidth / outWidth;
  const relY = inHeight / outHeight;

  return valueArrays.map((array) => {
    const newArray = copyNewSize(array, outWidth, outHeight);
    for (let y = 0; y < outHeight; ++y) {
      const rawY = relY * y;

      const yl = Math.floor(rawY);
      const yh = Math.min(Math.ceil(rawY), (inHeight - 1));

      for (let x = 0; x < outWidth; ++x) {
        const rawX = relX * x;
        const tx = rawX % 1;

        const xl = Math.floor(rawX);
        const xh = Math.min(Math.ceil(rawX), (inWidth - 1));

        const ll = array[(yl * inWidth) + xl];
        const hl = array[(yl * inWidth) + xh];
        const lh = array[(yh * inWidth) + xl];
        const hh = array[(yh * inWidth) + xh];

        const value = lerp(
          lerp(ll, hl, tx),
          lerp(lh, hh, tx),
          rawY % 1,
        );
        newArray[(y * outWidth) + x] = value;
      }
    }
    return newArray;
  });
}

/**
 * Resample the input arrays using the selected resampling method.
 * @param {TypedArray[]} valueArrays The input arrays to resample
 * @param {number} inWidth The width of the input rasters
 * @param {number} inHeight The height of the input rasters
 * @param {number} outWidth The desired width of the output rasters
 * @param {number} outHeight The desired height of the output rasters
 * @param {string} [method = 'nearest'] The desired resampling method
 * @returns {TypedArray[]} The resampled rasters
 */
export function resample(valueArrays, inWidth, inHeight, outWidth, outHeight, method = 'nearest') {
  switch (method.toLowerCase()) {
    case 'nearest':
      return resampleNearest(valueArrays, inWidth, inHeight, outWidth, outHeight);
    case 'bilinear':
    case 'linear':
      return resampleBilinear(valueArrays, inWidth, inHeight, outWidth, outHeight);
    default:
      throw new Error(`Unsupported resampling method: '${method}'`);
  }
}

/**
 * Resample the pixel interleaved input array using nearest neighbor value selection.
 * @param {TypedArray} valueArrays The input arrays to resample
 * @param {number} inWidth The width of the input rasters
 * @param {number} inHeight The height of the input rasters
 * @param {number} outWidth The desired width of the output rasters
 * @param {number} outHeight The desired height of the output rasters
 * @param {number} samples The number of samples per pixel for pixel
 *                         interleaved data
 * @returns {TypedArray} The resampled raster
 */
export function resampleNearestInterleaved(
  valueArray, inWidth, inHeight, outWidth, outHeight, samples) {
  const relX = inWidth / outWidth;
  const relY = inHeight / outHeight;

  const newArray = copyNewSize(valueArray, outWidth, outHeight, samples);
  for (let y = 0; y < outHeight; ++y) {
    const cy = Math.min(Math.round(relY * y), inHeight - 1);
    for (let x = 0; x < outWidth; ++x) {
      const cx = Math.min(Math.round(relX * x), inWidth - 1);
      for (let i = 0; i < samples; ++i) {
        const value = valueArray[(cy * inWidth * samples) + (cx * samples) + i];
        newArray[(y * outWidth * samples) + (x * samples) + i] = value;
      }
    }
  }
  return newArray;
}

/**
 * Resample the pixel interleaved input array using bilinear interpolation.
 * @param {TypedArray} valueArrays The input arrays to resample
 * @param {number} inWidth The width of the input rasters
 * @param {number} inHeight The height of the input rasters
 * @param {number} outWidth The desired width of the output rasters
 * @param {number} outHeight The desired height of the output rasters
 * @param {number} samples The number of samples per pixel for pixel
 *                         interleaved data
 * @returns {TypedArray} The resampled raster
 */
export function resampleBilinearInterleaved(
  valueArray, inWidth, inHeight, outWidth, outHeight, samples) {
  const relX = inWidth / outWidth;
  const relY = inHeight / outHeight;
  const newArray = copyNewSize(valueArray, outWidth, outHeight, samples);
  for (let y = 0; y < outHeight; ++y) {
    const rawY = relY * y;

    const yl = Math.floor(rawY);
    const yh = Math.min(Math.ceil(rawY), (inHeight - 1));

    for (let x = 0; x < outWidth; ++x) {
      const rawX = relX * x;
      const tx = rawX % 1;

      const xl = Math.floor(rawX);
      const xh = Math.min(Math.ceil(rawX), (inWidth - 1));

      for (let i = 0; i < samples; ++i) {
        const ll = valueArray[(yl * inWidth * samples) + (xl * samples) + i];
        const hl = valueArray[(yl * inWidth * samples) + (xh * samples) + i];
        const lh = valueArray[(yh * inWidth * samples) + (xl * samples) + i];
        const hh = valueArray[(yh * inWidth * samples) + (xh * samples) + i];

        const value = lerp(
          lerp(ll, hl, tx),
          lerp(lh, hh, tx),
          rawY % 1,
        );
        newArray[(y * outWidth * samples) + (x * samples) + i] = value;
      }
    }
  }
  return newArray;
}

/**
 * Resample the pixel interleaved input array using the selected resampling method.
 * @param {TypedArray} valueArray The input array to resample
 * @param {number} inWidth The width of the input rasters
 * @param {number} inHeight The height of the input rasters
 * @param {number} outWidth The desired width of the output rasters
 * @param {number} outHeight The desired height of the output rasters
 * @param {number} samples The number of samples per pixel for pixel
 *                                 interleaved data
 * @param {string} [method = 'nearest'] The desired resampling method
 * @returns {TypedArray} The resampled rasters
 */
export function resampleInterleaved(valueArray, inWidth, inHeight, outWidth, outHeight, samples, method = 'nearest') {
  switch (method.toLowerCase()) {
    case 'nearest':
      return resampleNearestInterleaved(
        valueArray, inWidth, inHeight, outWidth, outHeight, samples,
      );
    case 'bilinear':
    case 'linear':
      return resampleBilinearInterleaved(
        valueArray, inWidth, inHeight, outWidth, outHeight, samples,
      );
    default:
      throw new Error(`Unsupported resampling method: '${method}'`);
  }
}