Vertical exaggeration control

examples/shaded-relief.css

@@ -0,0 +1,4 @@
+table.controls td {
+  text-align: center;
+  padding: 2px 5px;
+}

examples/shaded-relief.html

@@ -28,11 +28,19 @@ tags: "raster, shaded relief"
 <div class="row-fluid">
   <div class="span12">
     <div id="map" class="map"></div>
-    <div id="controls">
-      <label for="sun-el">sun elevation</label>
-      <input id="sun-el" type="range" min="0" max="90" value="45"/>
-      <label for="sun-az">sun azimuth</label>
-      <input id="sun-az" type="range" min="0" max="360" value="45"/>
-    </div>
+    <table class="controls">
+      <tr>
+        <td>vertical exaggeration: <span id="vertOut"></span>x</td>
+        <td><input id="vert" type="range" min="1" max="5" value="1"/></td>
+      </tr>
+      <tr>
+        <td>sun elevation: <span id="sunElOut"></span>°</td>
+        <td><input id="sunEl" type="range" min="0" max="90" value="45"/></td>
+      </tr>
+      <tr>
+        <td>sun azimuth: <span id="sunAzOut"></span>°</td>
+        <td><input id="sunAz" type="range" min="0" max="360" value="45"/></td>
+      </tr>
+    </table>
   </div>
 </div>

examples/shaded-relief.js

@@ -1,8 +1,9 @@
 goog.require('ol.Map');
 goog.require('ol.View');
+goog.require('ol.layer.Image');
 goog.require('ol.layer.Tile');
-goog.require('ol.source.TileJSON');
 goog.require('ol.source.Raster');
+goog.require('ol.source.TileJSON');
 goog.require('ol.source.XYZ');
 
 
@@ -10,7 +11,7 @@ goog.require('ol.source.XYZ');
  * Generates a shaded relief image given elevation data.  Uses a 3x3
  * neighborhood for determining slope and aspect.
  * @param {Array.<ImageData>} inputs Array of input images.
- * @param {Object} data Data with resolution property.
+ * @param {Object} data Data added in the "beforeoperations" event.
  * @return {Array.<ImageData>} Output images (only the first is rendered).
  */
 function shade(inputs, data) {
@@ -19,14 +20,16 @@ function shade(inputs, data) {
   var height = elevationImage.height;
   var elevationData = elevationImage.data;
   var shadeData = new Uint8ClampedArray(elevationData.length);
-  var dx = dy = data.resolution * 2;
+  var dp = data.resolution * 2;
   var maxX = width - 1;
   var maxY = height - 1;
   var pixel = [0, 0, 0, 0];
   var twoPi = 2 * Math.PI;
   var halfPi = Math.PI / 2;
-  var cosSunEl = Math.cos(data.sunEl);
-  var sinSunEl = Math.sin(data.sunEl);
+  var sunEl = Math.PI * data.sunEl / 180;
+  var sunAz = Math.PI * data.sunAz / 180;
+  var cosSunEl = Math.cos(sunEl);
+  var sinSunEl = Math.sin(sunEl);
   var pixelX, pixelY, x0, x1, y0, y1, offset,
       z0, z1, dzdx, dzdy, slope, aspect, cosIncidence, scaled;
   for (pixelY = 0; pixelY <= maxY; ++pixelY) {
@@ -42,7 +45,7 @@ function shade(inputs, data) {
       pixel[1] = elevationData[offset + 1];
       pixel[2] = elevationData[offset + 2];
       pixel[3] = elevationData[offset + 3];
-      z0 = pixel[0] + pixel[1] * 2 + pixel[2] * 3;
+      z0 = data.vert * (pixel[0] + pixel[1] * 2 + pixel[2] * 3);
 
       // determine elevation for (x1, pixelY)
       offset = (pixelY * width + x1) * 4;
@@ -50,9 +53,9 @@ function shade(inputs, data) {
       pixel[1] = elevationData[offset + 1];
       pixel[2] = elevationData[offset + 2];
       pixel[3] = elevationData[offset + 3];
-      z1 = pixel[0] + pixel[1] * 2 + pixel[2] * 3;
+      z1 = data.vert * (pixel[0] + pixel[1] * 2 + pixel[2] * 3);
 
-      dzdx = (z1 - z0) / dx;
+      dzdx = (z1 - z0) / dp;
 
       // determine elevation for (pixelX, y0)
       offset = (y0 * width + pixelX) * 4;
@@ -60,7 +63,7 @@ function shade(inputs, data) {
       pixel[1] = elevationData[offset + 1];
       pixel[2] = elevationData[offset + 2];
       pixel[3] = elevationData[offset + 3];
-      z0 = pixel[0] + pixel[1] * 2 + pixel[2] * 3;
+      z0 = data.vert * (pixel[0] + pixel[1] * 2 + pixel[2] * 3);
 
       // determine elevation for (pixelX, y1)
       offset = (y1 * width + pixelX) * 4;
@@ -68,9 +71,9 @@ function shade(inputs, data) {
       pixel[1] = elevationData[offset + 1];
       pixel[2] = elevationData[offset + 2];
       pixel[3] = elevationData[offset + 3];
-      z1 = pixel[0] + pixel[1] * 2 + pixel[2] * 3;
+      z1 = data.vert * (pixel[0] + pixel[1] * 2 + pixel[2] * 3);
 
-      dzdy = (z1 - z0) / dy;
+      dzdy = (z1 - z0) / dp;
 
       slope = Math.atan(Math.sqrt(dzdx * dzdx + dzdy * dzdy));
 
@@ -84,7 +87,7 @@ function shade(inputs, data) {
       }
 
       cosIncidence = sinSunEl * Math.cos(slope) +
-          cosSunEl * Math.sin(slope) * Math.cos(data.sunAz - aspect);
+          cosSunEl * Math.sin(slope) * Math.cos(sunAz - aspect);
 
       offset = (pixelY * width + pixelX) * 4;
       scaled = 255 * cosIncidence;
@@ -124,27 +127,31 @@ var map = new ol.Map({
   ],
   view: new ol.View({
     extent: [-13675026, 4439648, -13580856, 4580292],
-    center: [-13606539, 4492849],
+    center: [-13615645, 4497969],
     minZoom: 10,
     maxZoom: 16,
-    zoom: 12
+    zoom: 13
   })
 });
 
-var sunElevationInput = document.getElementById('sun-el');
-var sunAzimuthInput = document.getElementById('sun-az');
-
-sunElevationInput.addEventListener('input', function() {
-  raster.changed();
-});
-
-sunAzimuthInput.addEventListener('input', function() {
+var controlIds = ['vert', 'sunEl', 'sunAz'];
+var controls = {};
+controlIds.forEach(function(id) {
+  var control = document.getElementById(id);
+  var output = document.getElementById(id + 'Out');
+  control.addEventListener('input', function() {
+    output.innerText = control.value;
     raster.changed();
+  });
+  output.innerText = control.value;
+  controls[id] = control;
 });
 
 raster.on('beforeoperations', function(event) {
   // the event.data object will be passed to operations
-  event.data.resolution = event.resolution;
-  event.data.sunEl = Math.PI * sunElevationInput.value / 180;
-  event.data.sunAz = Math.PI * sunAzimuthInput.value / 180;
+  var data = event.data;
+  data.resolution = event.resolution;
+  for (var id in controls) {
+    data[id] = Number(controls[id].value);
+  }
 });