for the below posted evalscript and request object, i am calculating the ndvi and then calculate the averags.
i want to visualize the band that contain the averages, but response i receive in the request builder is a completly black tiff file.
would you please let me know why that is happeing and how to fix this issue?
request object:
{
"input": {
"bounds": {
"bbox": [
12.44693,
41.870072,
12.541001,
41.917096
]
},
"data": [
{
"dataFilter": {
"timeRange": {
"from": "2024-06-26T00:00:00Z",
"to": "2024-07-26T23:59:59Z"
}
},
"type": "sentinel-2-l2a"
}
]
},
"output": {
"width": 512,
"height": 343.697,
"responses": [
{
"identifier": "default",
"format": {
"type": "image/jpeg"
}
}
]
},
"evalscript": "\n//VERSION=3\n\nfunction setup() {\n return {\n input: [\"B04\", \"B08\", \"CLD\"],\n output: {\n id: \"default\",\n bands: 1,\n sampleType: \"FLOAT32\",\n nodataValue: NaN,\n },\n };\n}\n\nfunction samplesParser(samples) {\n const cloudFreeSamples = new Array();\n const cloudySamples = new Array();\n\n for (let i = 0; i < samples.length; i++){\n if (samples[i].CLD > 0) {\n cloudySamples.push(samples[i]);\n } else {\n cloudFreeSamples.push(samples[i]);\n }\n }\n return [cloudySamples, cloudFreeSamples];\n }\n\n function calcAverage(samples) {\n let sum = 0;\n for(let i = 0;i < samples.length; i++) {\n sum += samples[i];\n }\n let avg = sum / samples.length;\n return avg;\n }\n \n function calcNDVIForSamples(samples) {\n const ndvis = new Array(samples.length).fill(NaN);\n\n for(let i = 0;i < samples.length; i++) {\n ndvis[i] = (samples[i].B08 - samples[i].B04) / (samples[i].B08 + samples[i].B04) ;\n }\n return ndvis;\n }\n\nfunction evaluatePixel(samples) {\n const parsedSamples = samplesParser(samples);\n const ndvis = calcNDVIForSamples(parsedSamples[1]);\n const averages = calcAverage(ndvis);\n return [averages]\n}"
}
evalscript:
//VERSION=3
function setup() {
return {
input: ["B04", "B08", "CLD"],
output: {
id: "default",
bands: 1,
sampleType: "FLOAT32",
nodataValue: NaN,
},
};
}
function samplesParser(samples) {
const cloudFreeSamples = new Array();
const cloudySamples = new Array();
for (let i = 0; i < samples.length; i++){
if (samples[i].CLD > 0) {
cloudySamples.push(samples[i]);
} else {
cloudFreeSamples.push(samples[i]);
}
}
return [cloudySamples, cloudFreeSamples];
}
function calcAverage(samples) {
let sum = 0;
for(let i = 0;i < samples.length; i++) {
sum += samples[i];
}
let avg = sum / samples.length;
return avg;
}
function calcNDVIForSamples(samples) {
const ndvis = new Array(samples.length).fill(NaN);
for(let i = 0;i < samples.length; i++) {
ndvis[i] = (samples[i].B08 - samples[i].B04) / (samples[i].B08 + samples[i].B04) ;
}
return ndvis;
}
function evaluatePixel(samples) {
const parsedSamples = samplesParser(samples);
const ndvis = calcNDVIForSamples(parsedSamples[1]);
const averages = calcAverage(ndvis);
return [averages]
}