QA Panels & Metrics

<p class="sb-kicker">Pipeline</p>
<h1>QA panels and metrics</h1>
<p class="sb-doc-lead">Each completed flight line writes visual and machine-readable QA artifacts so correction, harmonization, and export decisions remain inspectable after the run.</p>
<div class="sb-doc-grid sb-doc-grid--three">
  <article class="sb-doc-card">
    <h3>QA PNG</h3>
    <p>Fast visual triage for reflectance, masks, brightness shifts, and sensor diagnostics.</p>
  </article>
  <article class="sb-doc-card">
    <h3>QA PDF</h3>
    <p>A longer-form audit record when multi-page reporting is enabled for the workflow.</p>
  </article>
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    <h3>QA JSON</h3>
    <p>Machine-readable metrics and metadata for automation, validation, and reproducible review.</p>
  </article>

<p class="sb-kicker">Visual QA</p> <h2>What the QA PNG is for</h2> <p>The PNG is the fastest way to spot unusual behavior in a flight line without loading the raster products manually. Typical panels summarize:</p> <ul class="sb-doc-list"> <li>reflectance distributions for representative wavelengths</li> <li>spatial mask coverage and invalid-pixel structure</li> <li>before and after brightness behavior</li> <li>BRDF correction diagnostics</li> <li>wavelength and target-sensor alignment checks</li> </ul> <p>Use the PNG for quick triage before deciding whether deeper inspection is necessary.</p>

<p class="sb-kicker">Audit outputs</p> <h2>What the PDF and JSON capture</h2> <div class="sb-doc-grid sb-doc-grid--two"> <article class="sb-doc-card"> <h3>QA PDF</h3> <p>The PDF expands the visual report into a flight-line-level audit artifact with extended diagnostics, tables, optional per-band summaries, and correction details.</p> <p>Think of it as the human-readable record you keep with a processing run.</p> </article> <article class="sb-doc-card"> <h3>QA JSON</h3> <p>The JSON carries the same run into a machine-readable form for dashboards, automation, and regression checks.</p> <p>It is the better interface when you need to compare runs systematically.</p> </article> </div> <p>Common QA JSON categories include:</p> <div class="sb-doc-grid sb-doc-grid--two"> <article class="sb-doc-card"> <h3>Reflectance and masks</h3> <p>Bandwise min, max, median, saturated or masked fractions, and cloud, snow, shadow, water, or invalid summaries.</p> </article> <article class="sb-doc-card"> <h3>Correction diagnostics</h3> <p>BRDF coefficients, reconstruction error summaries, and brightness differences across correction stages.</p> </article> <article class="sb-doc-card"> <h3>Sensor harmonization</h3> <p>Brightness coefficients, spectral alignment checks, and regression-based metrics when that path is active.</p> </article> <article class="sb-doc-card"> <h3>Geometry context</h3> <p>Solar and view angles plus terrain summaries that help explain unusual correction behavior.</p> </article> </div>

<p class="sb-kicker">Interpretation</p> <h2>What to watch for</h2> <div class="sb-doc-grid sb-doc-grid--two"> <article class="sb-doc-card"> <h3>Reflectance above expected bounds</h3> <p>Values well above 1 can point to correction instability, geometry problems, or DEM issues that deserve review.</p> </article> <article class="sb-doc-card"> <h3>Large brightness shifts</h3> <p>Substantial step changes between raw, corrected, and harmonized products usually warrant a closer look at the relevant stage outputs.</p> </article> <article class="sb-doc-card"> <h3>High invalid or shadow fractions</h3> <p>These can dominate downstream summaries, especially for difficult illumination conditions or partial-scene coverage.</p> </article> <article class="sb-doc-card"> <h3>Noisy coefficients</h3> <p>Unstable BRDF or harmonization coefficients often indicate low-SNR regions or other conditions that reduce correction reliability.</p> </article> </div> <p class="sb-doc-note">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.</p>

<p class="sb-kicker">Where to go next</p> <h2>Related pages</h2> <div class="sb-doc-grid sb-doc-grid--three"> <a class="sb-doc-link-card" href="stages/"> <strong>Pipeline stages</strong> <span>See how QA fits into the full ordered workflow.</span> </a> <a class="sb-doc-link-card" href="outputs/"> <strong>Outputs and file structure</strong> <span>Find the flight-line files that sit next to the QA artifacts.</span> </a> <a class="sb-doc-link-card" href="../troubleshooting/"> <strong>Troubleshooting</strong> <span>Use the QA outputs to diagnose common pipeline problems.</span> </a> </div>