Planning authorities increasingly rely on satellite-derived nighttime light data to assess the vitality of historic urban districts facing redevelopment pressure. This paper demonstrates that such measurements systematically misread inward-facing urban fabric — the spatial logic of which was never designed to be legible from above — and that this misreading carries direct consequences for heritage impact assessment. We examine Kond, one of the oldest surviving districts in central Yerevan, Armenia, as a case where satellite nighttime light data structurally underestimates urban activity relative to the surrounding Soviet-era grid fabric. The problem is not one of sensor noise or spatial resolution. Measurement tools calibrated to the outward-facing, glazed, and grid-organised fabric of post-war urban modernism will produce systematically lower readings for inward-facing, opaque, and topologically deep historic fabric — not because such districts are less active, but because they were built to contain rather than project their activity. In planning practice, lower readings become evidence of decline; evidence of decline becomes justification for clearance. The measurement instrument, in this context, is not neutral: it is a technology of misrecognition. Using VIIRS monthly composites (2017–2025), ALOS AW3D30 digital surface model (DSM) data, and OpenStreetMap (OSM) building and road geometries, we show that Kond’s post-2022 NTL normalised index (1.66 relative to 2017–2019 baseline) lags the adjacent Soviet-grid control zone (1.87) and the broader Kentron background (1.51), despite evidence of sustained residential occupation and informal economic activity. We argue this gap is not evidence of decline but of measurement bias: Kond’s Persian-Armenian spatial logic — inward-facing courtyards, enclosed alleys, small opaque building volumes — suppresses light spillage in ways that Soviet-grid commercial fabric, with its large glazed street frontages, does not. OSM morphometric analysis confirms the structural basis of this argument: Kond contains 5,749.0 buildings per km2, a median footprint of 46.0 m2, and 259.9 dead ends per km2, compared with the control zone’s 746.3 buildings per km2 and 348.8 m2 median footprint. ALOS DSM data show Kond occupies a higher and more topographically varied surface (mean 1,019 m a.s.l., elevation range 54 m) than the control zone, reinforcing the spatial isolation that compounds NTL suppression. These findings reframe the problem beyond methodological caution. NTL metrics, uncorrected for morphological structure, do not merely produce imprecise measurements of inward-facing historic districts: they produce measurements biased in a specific direction — toward underestimating activity — and that bias is structurally identical to the spatial logic of the urban fabric whose demolition they are routinely called upon to justify. For Kond, where Government Decision No. 1151-N (2002) established the legal basis for expropriation and where a design competition launched in 2021 awaits its second-stage verdict, the measurement question carries direct planning consequences. The paper concludes by arguing that morphometric evidence — not NTL trajectories alone — should anchor heritage impact assessment for inward-facing pre-Soviet urban fabric, and that the OSM baselines established here constitute a quantitative record of what would be lost if current redevelopment pressure prevails.
Ying Li (Sat,) studied this question.