coincident.io.download.download_ncalm_dem#

coincident.io.download.download_ncalm_dem(aoi, dataset_id, product, output_dir='/tmp')#

Download NCALM (or OpenTopo user-hosted) data from OpenTopography S3 based on a dataset identifier and an AOI. Your dataset identifier will be the ‘name’ column from coincident.search.search(dataset=”ncalm”)

NOTE: NCALM provides both DSMs and DTMs e.g. WA18_Wall/WA18_Wall_be/WALL_GEG_1M.tif vs WA18_Wall/WA18_Wall_hh/WALL_GEF_1M.tif where the be suffix stands for “bare earth” and the hh suffix stands for “highest hits” (or first return) GEG = Grid Elevation (Ground) or the the bare earth elevation grid GEF = Grid Elevation (First return) or the the first return elevation grid

For DEM data, the function lists all available DEM tiles under the dataset prefix, downloads each tile, reprojects it (if necessary) to the AOI’s local UTM CRS, clips it to the AOI, and then saves the clipped DEM as a GeoTIFF file.

Parameters:

  • aoi (geopandas.GeoDataFrame) – Area of interest geometry (assumed to be in EPSG:4326).

  • dataset_id (str or int) – Dataset identifier (e.g., “WA18_Wall” or “OTLAS.072019.6339.1”). This is used as the prefix for S3 object keys.

  • product (str) – ‘dtm’ to download the bare-earth DEM (GEG), ‘dsm’ to download the first-return DEM (GEF).

  • output_dir (str, optional) – Directory to save output files. Defaults to “/tmp”.

Returns:

The function writes the cropped/clipped output files to the specified output directory.

Return type:

None