deck.gl-extended-layers

A collection of custom Deck.gl layers

Overview

Deck.gl is a great geospatial rendering engine for the browser. Deck.gl layers are designed to be composable and easy to extend. As such, small variations of the pre-built layers can do amazing new things, while not being fit for inclusion in the standard layer library.

This repository is a handful of custom layers I've created for my own use, which I've put into a single repository.

Install

yarn add @kylebarron/deck.gl-extended-layers

Layers

BandsBitmapLayer

This is a subclass of the BitmapLayer from the Deck.gl standard library to enable image operations on individual satellite image bands. You can combine RGB bands in true color or false color manners, or run a simple calculation and apply a colormap. With true color imagery, you can optionally apply pansharpening on the GPU. This layer allows for image bands to be requested and loaded in parallel, which can sometimes speed up image loading.

Props

Images:

Images to render in the layer. All of these must be passed to the class as Texture2D objects.

• image_r: (Texture2D) Image corresponding to the red band.

• image_g: (Texture2D) Image corresponding to the green band.

• image_b: (Texture2D) Image corresponding to the blue band. Required when band_combination is rgb or evi.

• image_pan: (Texture2D) Optional. Image corresponding to the pansharpening band. Will be ignored if not provided or if usePan is false.

• colormap: (Texture2D) Required when band_combination is anything other than rgb. Not used when band_combination is rgb. Many colormaps are in assets/colormaps in PNG format, derived from Matplotlib and rio-tiler.

  To use them, you can use the jsdelivr CDN, e.g.:

  https://cdn.jsdelivr.net/gh/kylebarron/deck.gl-extended-layers/assets/colormaps/{colormap_name}.png

  To visualize them, see colormap documentation from rio-tiler.

Band options:

• band_combination: (String) Method of combining bands. Must be one of the following. Default is rgb. Any option other than rgb must provide a colormap texture.

  • rgb: Combines image_r, image_g, and image_b on the GPU in that order. If you pass red, green, and blue bands, a true color image will be rendered. You can alternatively pass other band combinations to create false color images.

  • normalized_difference: Computes the normalized difference of two bands: (x - y) / (x + y). normalized_difference always uses image_r and image_g in that order (as x and y). It then applies the colormap texture to the output. Other bands are ignored.

    To create the Normalized difference vegetation index (NDVI), for example, you would pass the near-infrared band as image_r and the red band as image_g.

  • evi: Computes the Enhanced Vegetation Index (EVI). Layers must be passed as near-infrared, red, and blue as image_r, image_g and image_b, respectively.

  • savi: Computes the Soil Adjusted Vegetation Index (SAVI). Layers must be passed as near-infrared and red as image_r and image_g, respectively.

  • msavi: Computes the Modified Soil Adjusted Vegetation Index (MSAVI). Layers must be passed as near-infrared and red as image_r and image_g, respectively.

• panWeight: (Number). Weight of blue band when pansharpening. Default: 0.2

• usePan: (Boolean) Optionally turn off pansharpening. Useful for false-color RGB combinations. This is automatically off for non-RGB band combinations. If image_pan is not provided, this is ignored.

BitmapLayer options

These options are the same as the normal deck.gl BitmapLayer options.

• bounds
• desaturate
• transparentColor
• tintColor

BandsSimpleMeshLayer

This is a subclass of the SimpleMeshLayer that accepts three or four separate image bands (a fourth band is the panchromatic band, to sharpen other bands). This is designed to have the benefits of the BandsBitmapLayer described above, but used to render 3D terrain on a terrain mesh.

This layer is still undocumented and does not accept all the options described above for the BandsBitmapLayer. Look at the defaultProps in the code to see how to use this.