GitLab

# Earth Engine Utilities

This code file provides a set of utilities for working with Google Earth Engine (GEE) to process satellite imagery. It includes functions for cloud masking, date slicing, and metadata management.

## Dependencies
- `ee` from `../../services/earth-engine`
- Utility functions from `../utils`
- Cloud scoring from `../imagery`
- Metadata constants from `../../common/metadata`

## Functions

### addGridPosition
Adds a grid position to an image based on its WRS path and row.

**Parameters:**
- `element` (Object): The image element to which the grid position will be added.

**Returns:**
- `ee.Image`: The image with the added grid position.

### sliceByRevisit
Slices an image collection by a given revisit period starting from a specific date.

**Parameters:**
- `collection` (ee.ImageCollection): The image collection to slice.
- `startingDate` (String): The starting date for the slice.
- `days` (Number): The number of days for the revisit period.

**Returns:**
- `ee.ImageCollection`: The sliced image collection.

### maskTOAClouds
Masks clouds in an image based on the Top of Atmosphere (TOA) reflectance.

**Parameters:**
- `image` (ee.Image): The image to mask.
- `bandName` (String): The name of the band to use for cloud masking.

**Returns:**
- `ee.Image`: The cloud-masked image.

### acquireFromDate
Acquires an image from a specific date, mission, and geometry, and calculates the cloud ratio.

**Parameters:**
- `date` (String): The date to acquire the image.
- `mission` (Object): The mission details including name, cycle, and bands.
- `geometry` (ee.Geometry): The geometry to clip the image to.

**Returns:**
- `ee.Image`: The processed image with cloud ratio metadata.

### processCollection
Processes an image collection to compute valid dates for image acquisition.

**Parameters:**
- `mission` (Object): The mission details including name and cycle.
- `geometry` (ee.Geometry): The geometry to filter the image collection.

**Returns:**
- `ee.List`: A list of valid dates for image acquisition.

### generateCloudMap
Generates a cloud map for a list of dates, mission, and geometry.

**Parameters:**
- `dates` (ee.List): The list of dates to generate the cloud map for.
- `mission` (Object): The mission details including name and bands.
- `geometry` (ee.Geometry): The geometry to clip the images to.

**Returns:**
- `ee.List`: A list of cloud ratios for each date.

### queryAvailable
Queries available images for a given mission and geometry.

**Parameters:**
- `mission` (Object): The mission details including name and cycle.
- `geometry` (ee.Geometry): The geometry to filter the image collection.

**Returns:**
- `ee.Dictionary`: A dictionary mapping dates to cloud ratios.

### getAvailable
Placeholder function for getting available images.

**Parameters:**
- `mission` (Object): The mission details.
- `geometry` (ee.Geometry): The geometry to filter the image collection.

### acquire
Acquires an image for a given date, mission, and geometry.

**Parameters:**
- `mission` (Object): The mission details.
- `date` (String): The date to acquire the image.
- `geometry` (ee.Geometry): The geometry to clip the image to.

**Returns:**
- `ee.Image`: The acquired image.

### format
Formats properties into a string.

**Parameters:**
- `properties` (Object): The properties to format.

**Returns:**
- `String`: The formatted string.

## Usage Example

```javascript
import EarthEngineUtils from './path/to/earth-engine-utils';

const mission = {
  name: 'LANDSAT/LC08/C01/T1_TOA',
  cycle: 16,
  bands: {
    qa: 'BQA'
  }
};

const geometry = ee.Geometry.Point([102.0, 17.0]);

// Query available images
const availableImages = EarthEngineUtils.queryAvailable(mission)(geometry);

// Acquire an image for a specific date
const date = '2021-01-01';
const image = EarthEngineUtils.acquire(mission)(date, geometry);

// Format properties
const properties = { 'system:time_start': '2021-01-01', 'cloud': 0.1 };
const formatted = EarthEngineUtils.format(properties);
console.log(formatted);