Pipeline
Each completed flight line writes visual and machine-readable QA artifacts so correction, harmonization, and export decisions remain inspectable after the run.
Visual QA
The PNG is the fastest way to spot unusual behavior in a flight line without loading the raster products manually. Typical panels summarize:
- reflectance distributions for representative wavelengths
- spatial mask coverage and invalid-pixel structure
- before and after brightness behavior
- BRDF correction diagnostics
- wavelength and target-sensor alignment checks
Use the PNG for quick triage before deciding whether deeper inspection is necessary.
Audit outputs
The PDF expands the visual report into a flight-line-level audit artifact with extended diagnostics, tables, optional per-band summaries, and correction details.
Think of it as the human-readable record you keep with a processing run.
The JSON carries the same run into a machine-readable form for dashboards, automation, and regression checks.
It is the better interface when you need to compare runs systematically.
Common QA JSON categories include:
Bandwise min, max, median, saturated or masked fractions, and cloud, snow, shadow, water, or invalid summaries.
BRDF coefficients, reconstruction error summaries, and brightness differences across correction stages.
Brightness coefficients, spectral alignment checks, and regression-based metrics when that path is active.
Solar and view angles plus terrain summaries that help explain unusual correction behavior.
Interpretation
Values well above 1 can point to correction instability, geometry problems, or DEM issues that deserve review.
Substantial step changes between raw, corrected, and harmonized products usually warrant a closer look at the relevant stage outputs.
These can dominate downstream summaries, especially for difficult illumination conditions or partial-scene coverage.
Unstable BRDF or harmonization coefficients often indicate low-SNR regions or other conditions that reduce correction reliability.
QA outputs are part of the workflow contract, not optional polish. They are meant to preserve transparency when a downstream analysis needs to explain how a product was generated.
The focused stage reports and combined cross-stage synthesis are documented in Stage-by-stage scientific QA. They add explicit PASS, WARN, FAIL, and NOT EVALUATED checks without replacing the existing flightline PNG, JSON, or PDF.
Where to go next