https://github.com/jessjaco/gee-blend

Various blending functions for Google Earth Engine
https://github.com/jessjaco/gee-blend

Last synced: about 1 month ago
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Various blending functions for Google Earth Engine

• Host: GitHub
• URL: https://github.com/jessjaco/gee-blend
• Owner: jessjaco
• Created: 2022-02-24T20:42:10.000Z (almost 3 years ago)
• Default Branch: main
• Last Pushed: 2022-03-03T22:19:09.000Z (almost 3 years ago)
• Last Synced: 2024-08-03T18:15:25.414Z (5 months ago)
• Size: 5.86 KB
• Stars: 34
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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• Awesome-GEE - gee-blend - Various blending functions for Google Earth Engine. (JavaScript API / Repositories)

README

        
# gee-blend

#### _Jesse Anderson_

## About

_gee-blend_ is a code module for using blended visualizations in [Google Earth Engine](https://earthengine.google.com). It can be loaded in the playground by clicking [here](https://code.earthengine.google.com/?accept_repo=users/jja/public), which will add the repository containing the code to the _Reader_ section of the _Scripts_ tab, under `users/jja/public`. The script _blend_demo.js_ illustrates some of its basic functionality.

## Using the Module

You can load the module in your code by running

```javascript

var blend = require('users/jja/public:blend.js');

```

Blend functions can be applied using the following pattern: `blend.(top_image, bottom_image);`

Where `` is one of the following:

- addition

- burn

- darken

- difference

- dodge

- hard_light

- lighten

- multiply

- normal

- overlay

- screen

- subtract

`

Here is an example blend operation and output.

Code:

```javascript

// First, add the module to your account by going to https://code.earthengine.google.com/?accept_repo=users/jja/public

// Load the module

var blend = require('users/jja/public:blend.js');

// Load and visualize a digital elevation model

var dem = ee.Image("CGIAR/SRTM90_V4");

var dem_rgb = dem.visualize({

  min:100, 

  max:6000, 

  palette: ['#000004', '#50127b', '#b63679', '#fc8761', '#fdfd65'],

  forceRgbOutput:true

});

// Derive and visualize a slope image

var slope_rgb = ee.Terrain.slope(dem).visualize({

  min:0, 

  max:90, 

  palette: ['#000000', '#ffffff'],

  forceRgbOutput:true

});

// Use the `difference` blend function and add to the map

Map.addLayer(blend.difference(dem_rgb, slope_rgb), {min:-41, max:163});

// Zoom to an interesting location

Map.setCenter(71.2, 36, 9);

```

Image:

![blend_ex_1](https://user-images.githubusercontent.com/1250693/155811215-dbba64db-30ab-4fcf-9472-be7425a99e54.png)

### Some other examples

NLCD over hillshade, in northern New Mexico (using blend.multiply):

![nlcd_hillshade](https://user-images.githubusercontent.com/1250693/156436778-ae20e293-cf88-4448-b62b-82617bf3b541.png)

Elevation over slope, using blend.dodge (Grand Canyon):

![gc](https://user-images.githubusercontent.com/1250693/156437236-14159e49-3d80-46de-a8b6-8531ba57a826.png)

## License

The blend code is licensed under the terms of the [MIT license](https://opensource.org/licenses/MIT).