Rendering raster tiles with WebGL

examples/cog-math.js

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+import GeoTIFF from '../src/ol/source/GeoTIFF.js';
+import Map from '../src/ol/Map.js';
+import Projection from '../src/ol/proj/Projection.js';
+import TileLayer from '../src/ol/layer/WebGLTile.js';
+import View from '../src/ol/View.js';
+import proj4 from 'proj4';
+import {getCenter} from '../src/ol/extent.js';
+import {register} from '../src/ol/proj/proj4.js';
+
+proj4.defs('EPSG:32636', '+proj=utm +zone=36 +datum=WGS84 +units=m +no_defs');
+register(proj4);
+
+const projection = new Projection({
+  code: 'EPSG:32636',
+  extent: [166021.44, 0.0, 534994.66, 9329005.18],
+});
+
+// metadata from https://s3.us-west-2.amazonaws.com/sentinel-cogs/sentinel-s2-l2a-cogs/2020/S2A_36QWD_20200701_0_L2A/S2A_36QWD_20200701_0_L2A.json
+const sourceExtent = [499980, 1790220, 609780, 1900020];
+
+const map = new Map({
+  target: 'map',
+  layers: [
+    new TileLayer({
+      style: {
+        color: [
+          'interpolate',
+          ['linear'],
+          // calculate NDVI, bands come from the sources below
+          [
+            '/',
+            ['-', ['band', 2], ['band', 1]],
+            ['+', ['band', 2], ['band', 1]],
+          ],
+          // color ramp for NDVI values, ranging from -1 to 1
+          -0.2,
+          [191, 191, 191],
+          -0.1,
+          [219, 219, 219],
+          0,
+          [255, 255, 224],
+          0.025,
+          [255, 250, 204],
+          0.05,
+          [237, 232, 181],
+          0.075,
+          [222, 217, 156],
+          0.1,
+          [204, 199, 130],
+          0.125,
+          [189, 184, 107],
+          0.15,
+          [176, 194, 97],
+          0.175,
+          [163, 204, 89],
+          0.2,
+          [145, 191, 82],
+          0.25,
+          [128, 179, 71],
+          0.3,
+          [112, 163, 64],
+          0.35,
+          [97, 150, 54],
+          0.4,
+          [79, 138, 46],
+          0.45,
+          [64, 125, 36],
+          0.5,
+          [48, 110, 28],
+          0.55,
+          [33, 97, 18],
+          0.6,
+          [15, 84, 10],
+          0.65,
+          [0, 69, 0],
+        ],
+      },
+      source: new GeoTIFF({
+        sources: [
+          {
+            // visible red, band 1 in the style expression above
+            url:
+              'https://sentinel-cogs.s3.us-west-2.amazonaws.com/sentinel-s2-l2a-cogs/2020/S2A_36QWD_20200701_0_L2A/B04.tif',
+            nodata: 0,
+            max: 10000,
+          },
+          {
+            // near infrared, band 2 in the style expression above
+            url:
+              'https://sentinel-cogs.s3.us-west-2.amazonaws.com/sentinel-s2-l2a-cogs/2020/S2A_36QWD_20200701_0_L2A/B08.tif',
+            nodata: 0,
+            max: 10000,
+          },
+        ],
+      }),
+      extent: sourceExtent,
+    }),
+  ],
+  view: new View({
+    center: getCenter(sourceExtent),
+    extent: sourceExtent,
+    zoom: 9,
+    projection: projection,
+  }),
+});