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| import GeoTIFF from 'ol/source/GeoTIFF.js';
import Map from 'ol/Map.js';
import TileLayer from 'ol/layer/WebGLTile.js';
const segments = 10;
const defaultMinColor = '#0300AD';
const defaultMaxColor = '#00ff00';
const defaultMinValue = -0.5;
const defaultMaxValue = 0.7;
const minColorInput = document.getElementById('min-color');
minColorInput.value = defaultMinColor;
const maxColorInput = document.getElementById('max-color');
maxColorInput.value = defaultMaxColor;
const minValueOutput = document.getElementById('min-value-output');
const minValueInput = document.getElementById('min-value-input');
minValueInput.value = defaultMinValue.toString();
const maxValueOutput = document.getElementById('max-value-output');
const maxValueInput = document.getElementById('max-value-input');
maxValueInput.value = defaultMaxValue.toString();
function getVariables() {
const variables = {};
const minColor = minColorInput.value;
const maxColor = maxColorInput.value;
const scale = chroma.scale([minColor, maxColor]).mode('lab');
const minValue = parseFloat(minValueInput.value);
const maxValue = parseFloat(maxValueInput.value);
const delta = (maxValue - minValue) / segments;
for (let i = 0; i <= segments; ++i) {
const color = scale(i / segments).rgb();
const value = minValue + i * delta;
variables[`value${i}`] = value;
variables[`red${i}`] = color[0];
variables[`green${i}`] = color[1];
variables[`blue${i}`] = color[2];
}
return variables;
}
function colors() {
const stops = [];
for (let i = 0; i <= segments; ++i) {
stops[i * 2] = ['var', `value${i}`];
const red = ['var', `red${i}`];
const green = ['var', `green${i}`];
const blue = ['var', `blue${i}`];
stops[i * 2 + 1] = ['color', red, green, blue];
}
return stops;
}
const ndvi = [
'/',
['-', ['band', 2], ['band', 1]],
['+', ['band', 2], ['band', 1]],
];
const source = new GeoTIFF({
sources: [
{
url: 'https://sentinel-cogs.s3.us-west-2.amazonaws.com/sentinel-s2-l2a-cogs/36/Q/WD/2020/7/S2A_36QWD_20200701_0_L2A/B04.tif',
max: 10000,
},
{
url: 'https://sentinel-cogs.s3.us-west-2.amazonaws.com/sentinel-s2-l2a-cogs/36/Q/WD/2020/7/S2A_36QWD_20200701_0_L2A/B08.tif',
max: 10000,
},
],
});
const layer = new TileLayer({
style: {
variables: getVariables(),
color: ['interpolate', ['linear'], ndvi, ...colors()],
},
source: source,
});
function update() {
layer.updateStyleVariables(getVariables());
minValueOutput.innerText = parseFloat(minValueInput.value).toFixed(1);
maxValueOutput.innerText = parseFloat(maxValueInput.value).toFixed(1);
}
minColorInput.addEventListener('input', update);
maxColorInput.addEventListener('input', update);
minValueInput.addEventListener('input', update);
maxValueInput.addEventListener('input', update);
update();
const map = new Map({
target: 'map',
layers: [layer],
view: source.getView(),
});
|
)
