Generating 1 km x 1 km Square Polygons Automatically in Google Earth Engine

 Introduction:

Google Earth Engine (GEE) is a powerful platform that allows users to analyze and visualize geospatial data at an unprecedented scale. In this tutorial, we'll explore how to create 1 km x 1 km square polygons automatically using Google Earth Engine. This can be incredibly useful for tasks such as defining study areas, generating sample regions, or creating consistent spatial units for analysis. Let's dive in!

Step 1: Setting Up Google Earth Engine Environment

If you haven't already, sign up for a Google Earth Engine account and access the GEE Code Editor. This cloud-based platform provides an interactive environment to write and run code for geospatial analysis.

Step 2: Defining the Area of Interest (AOI)

Start by defining the geographical coordinates or a region of interest where you want to create the 1 km x 1 km square polygons. For instance, you might be interested in a specific location for a study.

Figure 1: Autogenerate 1sq km polygon

Step 3: Writing the Code

In the GEE Code Editor, use JavaScript to write the code for generating the square polygons.

CODE:--------------------------------------------------------

var targetArea = ee.Number(1e6)

function toSquare(buffer) {

  return point.buffer(buffer, 1).bounds()

}

function getBuffer(area) {

  return ee.Number(area).sqrt().divide(2)

}

var buffer = getBuffer(targetArea)

var minBuffer = buffer.multiply(0.99)

var maxBuffer = buffer.multiply(1.01)

var square, area

for (var i = 0; i < 100; i++) {

  var buffer = minBuffer.add(maxBuffer).divide(2)

  square = toSquare(buffer)

  area = square.area(1)

  minBuffer = ee.Number(ee.Algorithms.If(area.lt(targetArea), buffer, minBuffer))

  maxBuffer = ee.Number(ee.Algorithms.If(area.gt(targetArea), buffer, maxBuffer))

}

print(square)

print("Area of Square", area)

Map.addLayer(square)

Map.centerObject(square)

//Export to Drive

var generatedGeometry = square;

var geojsonFeature = ee.Feature(generatedGeometry);

var geojson = geojsonFeature.toGeoJSONString();

Export.string.toDrive({

  data: geojson,

  description: '1sq_km',

  folder: 'GEE',

  fileFormat: 'GeoJSON'

});

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Step 4: Customizing the Output

You can customize the appearance of the generated square polygon by adjusting the visualization parameters. For instance, you can change the color, opacity, and border properties of the polygon to suit your needs.

Step 5: Exporting and Sharing

Once you're satisfied with the generated square polygon, you can explore further analyses within Google Earth Engine or export the polygon for use in other GIS software. Here I export the polygon in GeoJSON format in my google drive.

Conclusion:

Automatically generating 1 km x 1 km square polygons in Google Earth Engine is a straightforward process that can assist in various geospatial tasks. This tutorial demonstrated the basic steps to create a square polygon around a given center point. As you become more familiar with Google Earth Engine's capabilities, you can build on this foundation to create more complex polygons, integrate other datasets, and perform advanced spatial analyses.

Remember that Google Earth Engine's extensive documentation and user community are excellent resources for expanding your knowledge and exploring the platform's full potential. 

Happy mapping!