How do I visualize values at given lat/lon points and a given pix resolution from a Google Earth Engine FeatureCollection?

Question

I'm new to GEE and Java Script but hopefully I can be clear in describing my question. I've been looking through the tutorials and stack overflow but I'm still having difficulty.

I have a csv file consisting of lat/lon locations that I have uploaded with Google Fusion Tables. With my script, I have successfully been able to bin my data into user-defined bins. I wish to display the column truthCloudCover at the resolution from which my data was derived, i.e., 12 km, with a gray-scaled color palette. I am assuming that as I zoom in and out of the visualization, the glyph used to describe the lat/lon point maintains the 12 km resolution. Is this even possible? If so, can you please provide some example? Below I provide my script up to the point where I can bin my data. If you can point me to helpful examples of plotting FeatureCollections at their specified resolutions, I would be very grateful.

I believe you should be able to access my sample data from https://drive.google.com/open?id=1czdOaBYVyu0GA1mcNKIpwEdImsuQqwc0hGudCqv3.

My script for accessing the data and binning it is as follows:

// Load a FeatureCollection from a Fusion Table.
var fromFT = ee.FeatureCollection('ft:1czdOaBYVyu0GA1mcNKIpwEdImsuQqwc0hGudCqv3');
//var selection = fromFT.select('truthCloudCover');

var computePct = function(feature) {
  var trPct = ee.Number(feature.get('truthCloudCover')).divide(100.0);
  var bin = ee.Number(-99);
  if (trPct >= 0.9) {
    bin = ee.Number(3);
  }
  else if (trPct <= 0.1) {
    bin = ee.Number(1);
  }
  else {
    bin = ee.Number(2);
  }  
  return feature.set({bin: bin});
};

var fromFT = fromFT.map(computePct);
// show new property values
print('fromFT', fromFT.limit(6));

var foo = fromFT.select('bin');
print('bin', foo);

var getDict = function(feature) {
  var foo = feature.get('bin'); 
};

var binDict = ee.List.add()

var binDict = fromFT.toDictionary(['name']);
print('binDict', binDict);

user1745564 · Answer 1 · 2018-12-01T15:22:48.450

Finally figured it out. Since I'm new to this, it may not be the most elegant way but posting it anyway. The truthCloudCover column is stratified into bins as follows:

    if truthCloudCover < 0.0 then bin = 0, color is "ffffff"
    if 0.0 <= truthCloudCover <= 10.0 then bin = 1, color is "636363"
    if 10.0 < truthCloudCover < 70.0 then bin = 2, color is "bdbdbd" 
    if truthCloudCover >= 70.0 then bin = 3, color is "f0f0f0"

Solution starts here:

// Load a FeatureCollection from a Fusion Table.
var fromFT = ee.FeatureCollection('ft:1czdOaBYVyu0GA1mcNKIpwEdImsuQqwc0hGudCqv3');

var stratify = function(feature) {
   var val = ee.Number(feature.get('truthCloudCover'));
   val = val.float();
   var bin = ee.Algorithms.If(val.lt(0), 0, 
                              ee.Algorithms.If(val.gte(70), 3,
                                               ee.Algorithms.If(val.lte(10), 1, 2)));
   return feature.set({bin: bin, val: val});
};

var resolution = 12191;

var fromFT = fromFT.map(stratify);

var palette = ee.List(["ffffff", "636363", "bdbdbd", "f0f0f0"]);
var values = ee.List([0,1,2,3]);

var features = fromFT.map(function(f) {
    var bin = f.get("bin");
    // Can't set opacity for a Feature here.  Give buffer radius of resolution
    return f.set({style: {color: palette.get(bin)}}).buffer(resolution/2.0);
});

var layer = Map.addLayer(features.style({styleProperty: "style"}));

layer.setOpacity(0.5);

How do I visualize values at given lat/lon points and a given pix resolution from a Google Earth Engine FeatureCollection?

1 Answers1