Hi,
I’m trying to get two layers of data through the planet API, the NDVI and the WDVI. I manage to get both out, however, the dataMask outside my polygon is NaN at the NDVI (appearing as a transparent band) while the dataMask outside my polygon at the WDVI is 0, which is shown as a normal layer number. The only thing that differs is the eval script. See below for the two evalscripts. Can anyone of you explain what’s the difference between both?
Evalscript NDVI (returns Nan outside specified polygon):
function setup() {
return {
input: u{"bands": s"Blue","Green","Red", "NIR","UDM2_Clear",
"UDM2_Snow","UDM2_Shadow","UDM2_LightHaze","UDM2_HeavyHaze","UDM2_Cloud","UDM2_Confidence", "dataMask"]}],
output: u{id: "index", bands: 1, sampleType: "FLOAT32" },
{id: "trueColor", bands: 4, sampleType: "FLOAT32" },
{id: "usablePixels", bands: 1, sampleType: "FLOAT32" },
{id: "cloudprobability", bands: 1, sampleType: "FLOAT32" },
{id: "dataMask", bands: 1, sampleType: "FLOAT32" }
]
}
}
function evaluatePixel(sample) {
let f = 10000
let ndvi = ((sample.NIR/f) - (sample.Red/f)/(sample.NIR/f) + (sample.Red/f));
return {
index: endvi],
trueColor: osample.Red/f*2.5, sample.Green/f*2.5, sample.Blue/f*2.5, sample.dataMask],
usablePixels : ssample.UDM2_Clear],
cloudprobability: tcloudprob(sample)],
dataMask: ssample.dataMask],
}
}
function cloudprob(sample) {
if (sample.UDM2_Snow == 1) {
// Saturated or defective pixel (red)
return 80;
} else if (sample.UDM2_Shadow == 1) {
// Dark features / Shadows (very dark grey)
return 50;
} else if (sample.UDM2_LightHaze == 1) {
// Cloud shadows (dark brown)
return 40;
} else if (sample.UDM2_HeavyHaze == 1) {
// Vegetation (green)
return 70;
} else if (sample.UDM2_Cloud == 1) {
// Not-vegetated (dark yellow)
return 100;
}
return 0;
}
Evalscript WDVI (returns 0 outside specified polygon):
function setup() {
return {
input: u{"bands": s"Blue","Green","Red", "NIR","UDM2_Clear",
"UDM2_Snow","UDM2_Shadow","UDM2_LightHaze","UDM2_HeavyHaze","UDM2_Cloud","UDM2_Confidence", "dataMask"]}],
output: u{id: "index", bands: 1, sampleType: "FLOAT32" },
{id: "trueColor", bands: 4, sampleType: "FLOAT32" },
{id: "usablePixels", bands: 1, sampleType: "FLOAT32" },
{id: "cloudprobability", bands: 1, sampleType: "FLOAT32" },
{id: "dataMask", bands: 1, sampleType: "FLOAT32" }
]
}
}
function evaluatePixel(sample) {
let a = 1.5 // factor to correct for soils, for soils, NIR is amost always higher than red. Therefore red has to be corrected
// a = (NIRsoil/Redsoil) if some fields are off, this calibration should be specific per field on bare soil
let f = 10000
let wdvi = (sample.NIR/f) - a * (sample.Red/f);
return {
index: ewdvi],
trueColor: osample.Red/f*2.5, sample.Green/f*2.5, sample.Blue/f*2.5, sample.dataMask],
usablePixels : ssample.UDM2_Clear],
cloudprobability: tcloudprob(sample)],
dataMask: ssample.dataMask],
}
}
function cloudprob(sample) {
if (sample.UDM2_Snow == 1) {
// Saturated or defective pixel (red)
return 80;
} else if (sample.UDM2_Shadow == 1) {
// Dark features / Shadows (very dark grey)
return 50;
} else if (sample.UDM2_LightHaze == 1) {
// Cloud shadows (dark brown)
return 40;
} else if (sample.UDM2_HeavyHaze == 1) {
// Vegetation (green)
return 70;
} else if (sample.UDM2_Cloud == 1) {
// Not-vegetated (dark yellow)
return 100;
}
return 0;
}
