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Get pixel data

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This commit is contained in:
Tim Schaub
2022-02-06 16:46:01 -07:00
parent cd45663996
commit eb4d5e0784
23 changed files with 721 additions and 101 deletions
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125
examples/cog-math.js
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@@ -17,65 +17,74 @@ const source = new GeoTIFF({
],
});
const layer = 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: source,
});
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: source,
}),
],
layers: [layer],
view: source.getView(),
});
const output = document.getElementById('output');
function displayPixelValue(event) {
const data = layer.getData(event.pixel);
if (!data) {
return;
}
const red = data[0];
const nir = data[1];
const ndvi = (nir - red) / (nir + red);
output.textContent = ndvi.toFixed(2);
}
map.on(['pointermove', 'click'], displayPixelValue);