GEE: Draw a pixel with 500m x 500m resolution

Question

Now I'm drawing some pixels sampled from map, the code can be run easily:

var first = ee.ImageCollection('COPERNICUS/S2_SR')
  .filterBounds(ee.Geometry.Point(-70.48, 43.3631))
  .filterDate('2019-01-01', '2019-12-31')
  .sort('CLOUDY_PIXEL_PERCENTAGE')
  .first()

var samples = first
  .sample({
    numPixels: 10,
    geometries: true,
  })
  .map(function(feature) {
    var min = 0
    var max = 300
    var opacity = toHex(min, max, feature.getNumber('B2'))
    var fillColor = ee.String('#ff0000').cat(opacity)
    return feature
      .set('style', {
        fillColor: fillColor
      })
  })

var styled = samples.style({
  pointSize: 40,
  width: 0,
  styleProperty: 'style'
})

Map.addLayer(styled, null, 'samples')
Map.centerObject(samples)


function toHex(min, max, value) {
  return ee.Number(value)
    .unitScale(min, max)
    .multiply(255)
    .round()
    .clamp(0, 255)
    .format('%x')
}

But now I want to draw the pixel size with (500m x 500m) on the map, or you can regard it as a 500x500 size mask. I try to tune the pointSize=500 in fucntion samples.style(), but it seems to be wrong. How can I do it?

Answer 1

You can turn the points into polygons by buffering the points with half the size you want, then take the bounds of the resulting circle. They will be hard to spot when you're zoomed out though, as they actually will be 500x500 meters.

var styled = samples
  // Turning samples into polygons separately, in case you need the original points for something
  .map(function (feature) {
    var size = 500
    return ee.Feature(
      feature.geometry().buffer(size / 2).bounds(), 
      feature.toDictionary()
    )
  })
  .style({
    width: 0,
    styleProperty: 'style'
  })

https://code.earthengine.google.com/e627bc186d8e890709cf256489f3bd01