Hansen Tiles

Hansen Tiles are generated from an EarthEngine asset whose various bands contain the raw Hansen lossyear-data masked by various thresholds of treecover2000. This same asset is used for the Hansen Analysis API (note tests of the API using this image along with derivative ImageCollections can be found here.

This repo contains:

• hansen_ee_processing/js/composite_asset.js: javascript code to produce the most recent version of the Hansen Asset described above
• hansen_ee_processing/python/hansen_tiles.py: python script that generates the hansen tiles (in 2 steps).

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Hansen Composite 18

To re-generate this asset simply run the code. To update future years, simply replace loss asset and rename final output COMPOSITE_IMG_NAME.

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Hansen Tiles

Due to the earthengine limits discussed here tile processing happens in 2 (and a half) steps:

1. Export Tiles for zoom-levels 12-7, and export an earthengine asset for zoom-level 7
2. Export Tiles for zoom-levels 6-2

The code can be run via the command line:

# step 1
$ python hansen_tiles.py {threshold} inside

# step 2 (after the earthengine asset for zoom-level 7 has completed processing)
$ python hansen_tiles.py {threshold} outside

There are various options like using test geometries, versioning, changing the zoom-level used as a break between step 1 and 2, and more.

python|master $ python hansen_tiles.py -h
usage: hansen_tiles.py [-h] [-g GEOM_NAME] [-v VERSION]
                       threshold {inside,outside,zasset} ...

HANSEN COMPOSITE

positional arguments:
  threshold             treecover 2000: one of [10, 15, 20, 25, 30, 50, 75]
  {inside,outside,zasset}
    inside              export the zoomed in z-levels
    outside             export the zoomed out z-levels
    zasset              export z-level to asset

optional arguments:
  -h, --help            show this help message and exit
  -g GEOM_NAME, --geom_name GEOM_NAME
                        geometry name (https://fusiontables.google.com/DataSou
                        rce?docid=13BvM9v1Rzr90Ykf1bzPgbYvbb8kGSvwyqyDwO8NI)
  -v VERSION, --version VERSION
                        version