planning

node_modules/geotiff/dist-module/resample.js

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+/**
+ * @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}'`);
+  }
+}