dem_mask

Identify control surfaces for DEM co-registration

usage: dem_mask [-h] [--toa] [--toa_thresh TOA_THRESH] [--snodas]
                [--snodas_thresh SNODAS_THRESH] [--modscag]
                [--modscag_thresh MODSCAG_THRESH]
                [--bareground_thresh BAREGROUND_THRESH] [--no_icemask]
                [--filter {rock,rock+ice,rock+ice+water,not_forest}]
                [--dilate DILATE]
                dem_fn

Required Arguments

dem_fn

DEM filename

Optional Arguments

--toa=False	Use top-of-atmosphere reflectance values (requires pregenerated “dem_fn_toa.tif”)
--toa_thresh=0.4
	Top-of-atmosphere reflectance threshold (default: 0.4, valid range 0.0-1.0), mask values greater than this value
--snodas=False	Use SNODAS snow depth products
--snodas_thresh=0.2
	SNODAS snow depth threshold (default: 0.2 m), mask values greater than this value
--modscag=False
	Use MODSCAG fractional snow cover products
--modscag_thresh=50
	MODSCAG fractional snow cover percent threshold (default: 50%, valid range 0-100), mask greater than this value
--bareground_thresh=80
	Percent bareground threshold (default: 80%, valid range 0-100), mask greater than this value (only relevant for global bareground data)
--no_icemask=False
	Don’t mask glacier polygons
--filter="rock+ice+water"
	Preserve these LULC pixels (default: “rock+ice+water”) Possible choices: rock, rock+ice, rock+ice+water, not_forest
--dilate	Dilate mask with this many iterations (default: None)

Utility to automate reference surface identification for raster co-registration

Note: Initial run may take a long time to download and process required data (NLCD, global bareground, glacier polygons)

Can control location of these data files with DATADIR environmental variable

export DATADIR=dir

Dependencies: gdal, wget, requests, bs4

demcoreg.dem_mask.get_bareground(datadir=None)

Calls external shell script get_bareground.sh to fetch:

~2010 global bare ground, 30 m

Note: unzipped file size is 64 GB! Original products are uncompressed, and tiles are available globally (including empty data over ocean)

The shell script will compress all downloaded tiles using lossless LZW compression.

http://landcover.usgs.gov/glc/BareGroundDescriptionAndDownloads.php

demcoreg.dem_mask.get_glacier_poly(datadir=None)

Calls external shell script get_glacier_poly.sh to fetch:

Randolph Glacier Inventory (RGI) glacier outline shapefiles

Full RGI database: rgi50.zip is 410 MB

The shell script will unzip and merge regional shp into single global shp

http://www.glims.org/RGI/

demcoreg.dem_mask.get_icemask(ds, datadir=None, glac_shp_fn=None)

Generate glacier polygon raster mask for input Dataset res/extent

demcoreg.dem_mask.get_modis_tile_list(geom)

Helper function to identify MODIS tiles that intersect input geometry

modis_gird.py contains dictionary of tile boundaries (tile name and WKT polygon ring from bbox)

See: https://modis-land.gsfc.nasa.gov/MODLAND_grid.html

demcoreg.dem_mask.get_modscag(dem_dt, outdir=None, tile_list=('h08v04', 'h09v04', 'h10v04', 'h08v05', 'h09v05'), pad_days=7)

Function to fetch and process MODSCAG fractional snow cover products for input datetime

Products are tiled in MODIS sinusoidal projection

example url: https://snow-data.jpl.nasa.gov/modscag-historic/2015/001/MOD09GA.A2015001.h07v03.005.2015006001833.snow_fraction.tif

demcoreg.dem_mask.get_nlcd(datadir=None)

Calls external shell script get_nlcd.sh to fetch:

2011 Land Use Land Cover (nlcd) grids, 30 m

http://www.mrlc.gov/nlcd11_leg.php

demcoreg.dem_mask.get_snodas(dem_dt, outdir=None)

Function to fetch and process SNODAS snow depth products for input datetime

http://nsidc.org/data/docs/noaa/g02158_snodas_snow_cover_model/index.html

1036 is snow depth

filename format: us_ssmv11036tS__T0001TTNATS2015042205HP001.Hdr

demcoreg.dem_mask.getparser()

demcoreg.dem_mask.main()

demcoreg.dem_mask.mask_bareground(ds, minperc=80, mask_glaciers=True)

Generate raster mask for exposed bare ground from global bareground data

demcoreg.dem_mask.mask_nlcd(ds, valid='rock+ice+water', datadir=None, mask_glaciers=True)

Generate raster mask for exposed rock in NLCD data

demcoreg.dem_mask.proc_modscag(fn_list, extent=None, t_srs=None)

Process the MODSCAG products for full date range, create composites and reproject