diff --git a/modules/dynamic/heightmap-selection.js b/modules/dynamic/heightmap-selection.js
index 5b3f6484..8bc8b9d5 100644
--- a/modules/dynamic/heightmap-selection.js
+++ b/modules/dynamic/heightmap-selection.js
@@ -323,14 +323,14 @@ async function drawPrecreatedHeightmap(id) {
 }
 
 function drawTemplatePreview(id) {
-  const heights = generateHeightmap(id);
+  const heights = HeightmapGenerator.fromTemplate(graph, id);
   const dataUrl = drawHeights(heights);
   const article = byId("heightmapSelection").querySelector(`[data-id="${id}"]`);
   article.querySelector("img").src = dataUrl;
 }
 
 async function drawPrecreatedHeightmap(id) {
-  const heights = await HeightmapGenerator.fromPrecreated(id);
+  const heights = await HeightmapGenerator.fromPrecreated(graph, id);
   const dataUrl = drawHeights(heights);
   const article = byId("heightmapSelection").querySelector(`[data-id="${id}"]`);
   article.querySelector("img").src = dataUrl;
diff --git a/modules/heightmap-generator.js b/modules/heightmap-generator.js
index cb297f2e..66696953 100644
--- a/modules/heightmap-generator.js
+++ b/modules/heightmap-generator.js
@@ -510,7 +510,6 @@ window.HeightmapGenerator = (function () {
       const powered = lightness < 0.2 ? lightness : 0.2 + (lightness - 0.2) ** 0.8;
       heights[i] = minmax(Math.floor(powered * 100), 0, 100);
     }
-    return heights;
   }
 
   return {
diff --git a/modules/submap.js b/modules/submap.js
index 85408487..263d3294 100644
--- a/modules/submap.js
+++ b/modules/submap.js
@@ -41,7 +41,6 @@ window.Submap = (function () {
     // create new grid
     applyMapSize();
     grid = generateGrid();
-
     drawScaleBar(scale);
 
     const resampler = (points, qtree, f) => {
diff --git a/utils/arrayUtils.js b/utils/arrayUtils.js
index 9c7dc121..241d2fac 100644
--- a/utils/arrayUtils.js
+++ b/utils/arrayUtils.js
@@ -96,3 +96,19 @@ function deepCopy(obj) {
 
   return dcAny(obj);
 }
+
+function getTypedArray(maxValue) {
+  console.assert(
+    Number.isInteger(maxValue) && maxValue >= 0 && maxValue <= 4294967295,
+    `Array maxValue must be an integer between 0 and 4294967295, got ${maxValue}`
+  );
+
+  if (maxValue <= 255) return Uint8Array;
+  if (maxValue <= 65535) return Uint16Array;
+  if (maxValue <= 4294967295) return Uint32Array;
+  return Uint32Array;
+}
+
+function createTypedArray({maxValue, length}) {
+  return new (getTypedArray(maxValue))(length);
+}