SVC / GER SIG

Status: Supported (scoped) · Vendor: Spectra Vista (SVC) / GER · Extensions: .sig

.sig is the ASCII export written by Spectra Vista Corporation (and legacy GER) field spectrometers — HR-1024i, GER 3700 and related VNIR/SWIR instruments. Each file pairs a reference and target acquisition and computes a reflectance channel. nirs4all-formats reads the three spectral columns and promotes the rich SVC acquisition header (instrument, foreoptic, per-detector settings, radiometric factors and overlap policy) into canonical metadata.

Instruments & software

Produced by SVC’s HR-1024i software and by older GER instruments (GER 3700). Both PDA-style and laptop-style headers are handled. The committed corpus covers Acer-PDA, laptop-firmware, GER 3700 PDA and HR-1024i field exports.

File structure

  • A Spectra Vista SIG Data header block of key=value lines (instrument, optic, integration, scan coadds, temp, battery, factors, time, latitude/longitude, gpstime, units, comm, etc.), then a literal data= line.

  • The numeric block follows data=: whitespace-separated rows of four columns — wavelength, reference, target and reflectance.

What nirs4all-formats extracts

  • Signals — three per record: reference, target and reflectance. The reflectance channel carries unit %; reference/target are typed from the units= header (radiance) with unit=null because SVC firmware exposes uncalibrated DN-derived radiance.

  • Axis — a wavelength axis in nm.

  • Metadata — the raw header under metadata.vendor, plus promoted canonical fields: instrument_model/instrument_serial (from HI: <serial> (<model>)), foreoptic (two strings), per-detector Si/InGaAs1/InGaAs2 integration times, coadds and temperatures split into reference/target, battery_voltages_volts, error_codes, memory_slots, source_signal_units (from units), acquisition start/end date and time, GPS latitude/longitude and GPS time, and — parsed from the factors= bracket — radiometric_factors (three floats), overlap_policy (preserve/remove), matching_type and overlap_break_wavelengths_nm.

  • Quality flags — matched_overlap_corrected, overlap_removed, detector_overlap_preserved, resampled_export (from the overlap policy, comm= or a _resamp filename), white_reference (_WR_ filename convention) and declared_bad_fixture (with a matching provenance warning).

Variants & support status

Variant

Status

Notes

Acer-PDA exports (clean / white-reference)

Supported

1024-point spectra; reflectance anchors and acquisition metadata asserted.

Laptop-firmware exports

Supported

Reference/target/reflectance plus detector_overlap_preserved.

Matched-overlap-corrected export

Supported

overlap_break_wavelengths_nm and matching_type parsed.

GER 3700 PDA

Supported

Parsed radiometric_factors and overlap breakpoints.

HR-1024i field / resampled export

Supported

Resampling, overlap removal and the 350–2500 nm / 1 nm axis covered.

HR-1024i firmware ≥ 3.0

Partial

Needs more independent samples beyond the spectrolab / R-FieldSpectra corpora.

Limitations & known gaps

  • Reference/target channels are typed radiance from the units= header but carry unit=null; a redistributable calibrated .sig would let a real spectral-radiance unit be promoted on top of the radiometric_factors triplet.

  • Per-detector spectral ranges (Si/InGaAs1/InGaAs2 split points) are not surfaced; they are implicit in overlap_break_wavelengths_nm only for overlap-removed files.

  • HR-1024i firmware ≥ 3.0 variants and historical GER 1500 files still need independent samples.

Reference readers

Compared full-array against spectrolab (R subprocess) in tests/conformance/; specdal is an additional reference candidate. The promoted metadata surface mirrors what spectrolab/specdal expose (instrument, foreoptic, integration, coadds, temperatures, battery, error codes, factors and overlap policy), so the comparison can stay text-only.

Samples & validation

Fifteen fixtures under samples/svc_ger/ are golden-backed in crates/nirs4all-formats/tests/goldens/ with direct semantic assertions covering the Acer-PDA, laptop, matched-overlap-corrected, two declared-bad, GER 3700 PDA and HR-1024i Barrow variants. Control values include BNL13001_000_moc.sig (overlap_break_wavelengths_nm = [970, 1901], matching_type = "Radiance @ 976 - 1010 / NIR-SWIR On"), serbinsh_gr070214_003.sig (overlap_break_wavelengths_nm = [985, 1906]) and serbinsh_BEO_CakeEater_Pheno_026_resamp.sig (LENS 4(1) foreoptic, 350–2500 nm / 1 nm axis). The conformance suite compares the reflectance signal against spectrolab with a 1e-6 relative tolerance. The probe reports format svc-ger-sig at Confidence::Definite.