given the below posted request, and referring to Normalized Difference Vegetagtion Indeceswhen i try to execute it in request-builder it does not work, and when i try to run it in my code, i receive bad-reuqest.
i am trying to get the ndvi from landsat-8 which identified via the indentifier landsat-ot-l1.
please let me know what is wrong in the below posted request or what i am missing
request:
"input": {
"bounds": {
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
1216491.6636585994,
6596655.883092916
],
[
1210613.043299023,
6580154.492609894
],
[
1233096.18783214,
6590674.129042821
],
[
1216491.6636585994,
6596655.883092916
]
]
]
},
"properties": {
"crs": "http://www.opengis.net/def/crs/EPSG/0/3857"
}
},
"data": [
{
"dataFilter": {
"timeRange": {
"from": "2022-01-01T00:00:00Z",
"to": "2022-01-15T23:59:59Z"
}
},
"type": "landsat-ot-l1"
}
]
},
"output": {
"width": 512,
"height": 375.402,
"responses": [
{
"identifier": "default",
"format": {
"type": "image/tiff"
}
}
]
},
"evalscript": `
//VERSION=3
// Script to extract a time series of NDVI values using
// Sentinel 2 Level 2A data and metadata file.
function setup() {
return {
input: [{
bands: ["B04", "B05"],
units: "DN"
}],
output: {
bands: 1,
sampleType: SampleType.FLOAT32
},
mosaicking: Mosaicking.ORBIT
}
}
// The following function is designed to update the number of
// output bands without knowing beforehand how many there are
function updateOutput(outputs, collection) {
Object.values(outputs).forEach((output) => {
output.bands = collection.scenes.length;
});
}
// function to generate a json file with a list of the NDVI
// dates used in the analysis.
function updateOutputMetadata(scenes, inputMetadata, outputMetadata) {
var dds = [];
for (i=0; i<scenes.length; i++){
dds.push(scenes[i].date)
}
outputMetadata.userData = { "acquisition_dates": JSON.stringify(dds) }
}
function evaluatePixel(samples) {
// Precompute an array to contain NDVI observations
var n_observations = samples.length;
let ndvi = new Array(n_observations).fill(0);
// Fill the array with NDVI values
samples.forEach((sample, index) => {
ndvi[index] = (sample.B05 - sample.B04) / (sample.B05 + sample.B04) ;
});
return ndvi;
}'
