Output DEM formats: netCDF or GeoTIFF

The geofabrics generated by the LidarDemGenerator, HydrologicalDemGenerator and RoughnessDemGenerator processing classes are stored as netCDF or GeoTIFF files. This page describes their contents.

Although GeoTIFF files are supported as outputs, netCDF files should be used when creating intermediate files used for later stages in the GeoFabrics processing pipelines (e.g. the raw_dem.nc output of the LidarDemGenerator that is often an input to the HydrologicalDemGenerator, or the result_dem.nc output of the HydrologicalDemGenerator that is often an input to the RoughnessDemGenerator.

NetCDF file structure

NetCDF is a flexible file format for accessing and storing array-orientated scientific data. It is also defines a community standard (through CF compliance) for sharing scientific data.

Global attributes

The following standard attributes are included:

And the following custom attribute geofabrics_instruction - A JSON dump of the instruction file used to produce the geofabrics.

Coordinates - x and y

Coordinates used to define the location and coordinate systems associated with the geofabric layers. The x, y define the spatial extents, and the spatial_ref defines the coordinate system in a CF compliant manner.

z or ground elevation layer

The ground elevation as estimated in each pixel.

source_class or source classification layer

The source of the data used to produce an estimate in each pixel. Note is now 'coarse DEM' not 'reference DEM'

zo or roughness length layer

The roughness length (a measure of friction experienced by water as it flows) estimate in each pixel.

GeoTIFF file output

If the output file (e.g. result_dem, result_geofabric) in the instruction file is a .tif then each layer will be saved separately as a GeoTIFF by appending _z, _data_source, _lidar_source and (in the case of the roughness layer existing) _zo to the end of the specified file name.