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Last edited by Ramices Silva
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transects

Code Overview

This code is designed to generate transects orthogonal to a specified polygon and expand them horizontally. It utilizes the Google Earth Engine (GEE) library and some geodesic computations to achieve this.

Dependencies

  • Google Earth Engine (ee)
  • Geodesy utilities (computeBearing, computeDisplacement)
  • Metadata constants (INTERNALS)

Functions

offsetMapper(extent, origin, theta)

Creates a function that maps offsets to transects.

Parameters

  • extent (Number): The extent of the transect.
  • origin (List): The origin point for the transect.
  • theta (Number): The angle for the transect.

Returns

  • Function: A function that takes an offset and returns a transect as an ee.Feature.

transectAccumulator(step, extent)

Creates a function that accumulates transects along a path.

Parameters

  • step (Number): The step size for the transects.
  • extent (Number): The extent of the transect.

Returns

  • Function: A function that takes the current and last points and returns an accumulated list of transects.

generateOrthogonalTransects(coordinates, step, extent)

Generates transects orthogonal to the specified polygon.

Parameters

  • coordinates (ee.List): A list of coordinates defining the polygon.
  • step (Number): The step size for the transects.
  • extent (Number): The extent of the transect.

Returns

  • ee.List: A list of transects as ee.FeatureCollection.

Example Usage

const coordinates = ee.List([
  [0, 0],
  [1, 1],
  [2, 2],
]);
const step = 10;
const extent = 5;
const transects = generateOrthogonalTransects(coordinates, step, extent);

expandHorizontally(transects, amount)

Expands the transects horizontally by a specified amount.

Parameters

  • transects (ee.List): A list of transects as ee.FeatureCollection.
  • amount (Number): The amount to expand the transects.

Returns

  • ee.List: A list of expanded transects as ee.FeatureCollection.

Example Usage

const expandedTransects = expandHorizontally(transects, 10);

Edge Cases and Assumptions

  • Assumes that the input coordinates are in a valid format and order.
  • Assumes that the step and extent values are positive numbers.
  • Handles cases where the space between transects is greater than the length of the segment.

References