Products and bands

Every product is a GeoTIFF, described in Python by a small metadata record. The record holds the product’s identity, such as burst, date and type, and FileManager.get_product_path() turns it into the file’s location. This page describes what the files contain.

Burst products

Each burst product is one GeoTIFF, with its bands named in the band descriptions:

Product	Bands	Values
RTC backscatter	`gamma0`, `scattering_area`	`gamma0` in linear power, `scattering_area` without units
GTC backscatter	`beta0`	Linear power
Coherence	`coherence`	Magnitude, 0 to 1, without units

Backscatter is stored as linear power, not decibels, in products and composites alike. Convert with 10 * log10(value) only after averaging, since the mean of decibels is not the decibel of the mean. The scattering_area band describes how much ground each pixel covers. Local resolution weighting explains how composites use it.

Composites

A composite has one band, the quantity of its inputs: gamma-0, beta-0 or coherence, in the same units. Its band description is the polarization, such as VV. The bands of the quality layers are named num_obs and cqm.

With write_qa=True, each quality layer of a composite is written to a file of its own:

The number of observations (QA-NUM) counts the acquisitions that contributed to each pixel.
The composite quality map (QA-CQM) rates how fine the combined detail of each pixel is, without units. Only LRW composites have it.

Local resolution weighting explains both.

Missing values

Pixels without a value are NaN, for example outside the burst. Keep them missing in statistics and plots rather than replacing them with zero. The one exception is the number of observations, an integer layer that marks pixels without data as 0. Both are declared as the file’s no-data value, so src.read(1, masked=True) masks them.

Metadata tags

Each GeoTIFF also has tags that say how to read it and how it was made. They include the units of the stored values, the acquisition dates, every processing setting, such as the DEM, the resampling or whether the topographic phase was removed, and the SNAP and s1bursts versions:

with fm.open(product) as src:
    print(src.descriptions, src.units)
    print(src.tags())

These tags make a file understandable on its own, even when separated from the code that wrote it. A composite records the processing settings of its inputs, which must all match. A resolution-weighted coherence composite records those of its coherence products, not of the RTC products that weight them. Where the CEOS-ARD SAR specification has a term, the tag names use it, so it can be looked up there. s1bursts borrows the vocabulary only and does not claim conformance with the specification.

Filenames

A filename contains only what distinguishes one product from another, in fixed fields separated by _. Each product type has its own pattern:

Product	Filename pattern
SLC burst	`S1_SLC_<orbit><pass>_<burst>_<swath>_<pol>_<date>.zip`
RTC backscatter	`S1_RTC_<orbit><pass>_<burst>_<swath>_<pol>_<date>_<zone>.tif`
GTC backscatter	`S1_GTC_<orbit><pass>_<burst>_<swath>_<pol>_<date>_<zone>.tif`
Coherence	`S1_COH<baseline>_<orbit><pass>_<burst>_<swath>_<pol>_<date1>_<date2>_<zone>.tif`
RTC LRW composite	`S1_RTC_LRW[_<qa>]_<square>_<pol>_<start>_<end>.tif`
Coherence LRW composite	`S1_COH<baseline>_LRW[_<qa>]_<square>_<pol>_<start>_<end>.tif`
RTC or GTC pass composite	`S1_RTC_COMP_<pass>[_QA-NUM]_<square>_<pol>_<start>_<end>.tif`, with `GTC` for GTC
Coherence pass composite	`S1_COH<baseline>_COMP_<pass>[_QA-NUM]_<square>_<pol>_<start>_<end>.tif`

The part in square brackets appears only in the name of a quality layer. The fields are:

Field	Meaning	Example
`<orbit>`	Relative orbit number, three digits	`015`
`<pass>`	Pass direction: `A` ascending, `D` descending	`A`
`<burst>`	ESA burst ID, six digits	`030346`
`<swath>`	Sub-swath	`IW1`
`<pol>`	Polarization	`VV`
`<date>`	Acquisition date, `YYYYMMDD`	`20220801`
`<date1>`, `<date2>`	Dates of the primary and secondary acquisitions of a pair	`20220801`, `20220813`
`<baseline>`	Days between the acquisitions of a pair, two digits	`12`
`<zone>`	UTM zone of the product’s CRS	`32N`
`<square>`	MGRS grid square	`32TLS40`
`<start>`, `<end>`	First and last day of the `time_range`, or of the acquisitions without one	`20250801`, `20250831`
`<qa>`	Quality layer: `QA-NUM` or `QA-CQM`	`QA-CQM`

The RTC product of the Quickstart, burst 30346 in sub-swath IW1 on ascending orbit 15, is named S1_RTC_015A_030346_IW1_VV_20220801_32N.tif, and the number of observations of an LRW composite is named S1_RTC_LRW_QA-NUM_32TLS40_VV_20250801_20250831.tif.

FileManager keeps SLC bursts in s1-slc, burst products in s1-prod and composites in s1-comp, below the directory it is given.

Processing settings are not part of the name. They are recorded in the tags instead, and a rerun compares them before it skips an existing file. See Reprocessing and failures.