Google Earth Engine Apps – How to Upload Shapefile and Download Raster Layer for Area

google-earth-enginegoogle-earth-engine-javascript-api

My Google Earth Engine app allows you to select a raster layer and then download that layer as a zip containing a tif. Here is the javascript code in the GEE IDE for the downloading part:

function downloadImg() {
  var viewBounds = ee.Geometry.Rectangle(Map.getBounds()); // CHANGE BOUNDARIES TO SHAPEFILE
  var downloadArgs = {
    name: 'sample_image',
    crs: 'EPSG:4326',
    region: viewBounds.toGeoJSONString()
 };

 var img = imgCol.first(); 

 var url =img.getDownloadURL(downloadArgs);
 urlLabel.setUrl(url);
 urlLabel.style().set({shown: true});
}

// Add UI elements to the Map.
var downloadButton = ui.Button('Get download link', downloadImg);
var urlLabel = ui.Label('Download', {shown: false});
var buttons = ui.Panel([downloadButton, urlLabel]);
c.controlPanel.add(buttons);

This protoype just auto-selects the first layer in my ImageCollection right now.

I want to add widgets to allow the user to upload a shapefile and only download the raster data within that shapefile. It would also be great to be able to draw a polygon and download that shape.

Best Answer

Apps can't do upload and can only do download through getDownloadUrl or getThumbnail.

Related Solutions

Google Earth Engine – Difference Between reduce(ee.Reducer.mean()) and mean() for ImageCollection

Did you look at the Earth Engine documentation for ImageCollection reductions?

For basic statistics like min, max, mean, etc., ImageCollection has shortcut methods like min(), max(), mean(), etc. They function in exactly the same way as calling reduce(), except the resultant band names will not have the name of the reducer appended.

In other words, the result is the same if you use .mean() or .reduce(ee.Reducer.mean()) but the latter method will append _mean to the band names.

Google Earth Engine – Exporting 10 Mb Raster Image Took 2 Days

I exported and downloaded as shapefile your polygons vector layer. As it can be observed in following image with QGIS, it has not an id in its attributes table; totaling 127,433 features.

So, I added one and imported to my assets an arbitrary little selection of 27 features, as follows, for exploring where issues could be presents.

I tried out your code with this very low quantity of features and it was impossible to get an useful image for sum_image. So, issues probably are related to firepolygoncountperpixel function.

For this reason, I modified your code and ran it by using the following selection of 27,174 features.

Code looks as follows:

//  Insert MSEA country boundaries
var msea = ee.FeatureCollection('users/jjohanness1992/GADM/mainland_SEA');
var country = msea.filter(ee.Filter.eq('ISO','LAO'));
//print('country metadata',country);

//  Load image
var image = ee.Image('users/jjohanness1992/Fire_and_LCC/clip_lcc_2011_2012_templateLCC').clip(country);
// this is a 30 m raster for the entire mainland SE Asia

//  Create reclassification codes
//  Here I reclassify the land cover map to a raster of 0's
//  This is because I want to preserve this raster grid when performing the polygon count
var oldgroup = ee.List([18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303,304,305,306
]);
var newgroup = ee.List([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
]);

//  Reclassify lcc image to an image of 0 values
var image2 = image.remap(oldgroup,newgroup).select('remapped').rename('b1');

var pol_list = polygons4.toList(polygons4.size());

var coll = ee.ImageCollection(pol_list.map(function (ele){
  
  return image2.add(1)
          .clip(ele);
  
})).sum().toInt();

print(coll);

Map.centerObject(polygons1);
//Map.addLayer(coll);

Export.image.toDrive({
  image: coll, 
  description: 'percountry_LAO_firepolygoncount_2012',
  folder: 'GEE_Folder',
  region: polygons4, //box
  scale: 30, // This is the scale of the original land cover map
  maxPixels: 1e13,
});

After running above code in GEE code editor, exported image (in only 29 minutes with my slow speed Internet service) with Zoom in an area where features represent a very high overlapping, looks as follows. Cursor is pointing out a pixel with a value of 35 in blue area. Red areas represent zero overlapping.

Below image results when it is marked polygons4. It can be corroborated that red areas represent no overlapping.

Best Answer

Related Solutions

Google Earth Engine – Difference Between reduce(ee.Reducer.mean()) and mean() for ImageCollection

Google Earth Engine – Exporting 10 Mb Raster Image Took 2 Days

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