snap_graph.GeocodingConfig

Terrain-Correction tail parameters shared by every product type.

Usage

snap_graph.GeocodingConfig()

Abstract: inherited by each per-product config, which supplies the graph that precedes the shared Terrain-Correction tail via to_xml.

Parameters

grid_spacing

Output pixel spacing in meters of the target CRS. Must be positive.

dem

DEM used for geocoding. A string selects one of SNAP’s auto-download DEMs; a path (or a string with a file suffix) is passed as an external DEM.

dem_name

Name of an external DEM, written to product metadata and compared before an existing product is skipped. Required when dem is a path, and must not be blank; ignored for SNAP’s built-in DEMs, whose dem value is already their name. Name each DEM differently, such as by its source and version.

img_resampling

Resampling of the image during terrain correction. SNAP’s cubic and sinc kernels are not supported, because they corrupt the pixels next to missing data.

dem_resampling

Resampling of the DEM during terrain correction.

align_to_standard_grid

Snap the output to a fixed global grid, so products from different bursts and dates share pixel boundaries and can be stacked without resampling.

external_dem_nodata

No-data value of an external DEM.

external_dem_apply_egm

Convert an external DEM from EGM96 geoid heights to WGS84 ellipsoidal heights, which is the reference terrain correction requires. SNAP does this automatically for its built-in ACE / Copernicus / SRTM DEMs, all of which are geoid-referenced; this flag is the equivalent for an external one and is ignored unless dem is a path.

Set it True for an orthometric DEM (heights above mean sea level, the usual case for national DEMs) and leave it False only when the DEM already carries ellipsoidal heights. Note this default differs from SNAP’s own, which is True. Leave it False for a DEM returned by s1bursts.prepare_dem_for_snap, which has already been converted to ellipsoidal heights. SNAP only applies EGM96, so preprocess DEMs in other vertical datums such as EGM2008 instead of enabling this option.

replace_zeros_with_nan

Convert SNAP’s zero fill value to NaN, so no-data does not enter later averages as a valid low value.

Attributes

Name	Description
standard_grid_origin	Origin of standard grid: At pixel centers.

standard_grid_origin

Origin of standard grid: At pixel centers.

standard_grid_origin: tuple[float, float]

Methods

Name	Description
to_mermaid()	Mermaid `flowchart LR` diagram source for this config’s graph.
to_xml()	Build the SNAP GPT graph XML for this config.

to_mermaid()

Mermaid flowchart LR diagram source for this config’s graph.

Usage

Source

to_mermaid(*, snap_version=None)

Parameters

snap_version: tuple[int, …] | None = None: SNAP version the graph will run under, as for to_xml. No diagram varies with it, but a config whose options need SNAP 14 cannot build its graph without it.

to_xml()

Build the SNAP GPT graph XML for this config.

Usage

Source

to_xml(*, snap_version=None)

Parameters

snap_version: tuple[int, …] | None = None: SNAP version the graph will run under, from s1bursts.snap_client.snap_version. The backscatter graph does not vary with it; the coherence graph writes only the options that version has (see supports_coherence_options). Defaults to SNAP 13 and earlier.