https://earthtodate.com/learn.html Field notes on large-area Earth observation from EarthToDate. en Tue, 30 Jun 2026 09:00:00 +0000 https://earthtodate.com/learn/sentinel5p-pollution-year-on-year.html https://earthtodate.com/learn/sentinel5p-pollution-year-on-year.html Tue, 30 Jun 2026 09:00:00 +0000 Sentinel-5P measures NO₂, SO₂, CO, CH₄, HCHO and aerosols daily, worldwide. Why the year-on-year delta against a same-period baseline beats a single snapshot for spotting real change. https://earthtodate.com/learn/glof-releasable-discharge-volume.html https://earthtodate.com/learn/glof-releasable-discharge-volume.html Sat, 27 Jun 2026 09:00:00 +0000 Most glacial-lake risk assessments report total lake volume — the wrong number. What determines downstream impact is the volume that would actually discharge if the moraine fails, and that needs a metre-accurate DEM. https://earthtodate.com/learn/pansharpening-misregistration.html https://earthtodate.com/learn/pansharpening-misregistration.html Wed, 24 Jun 2026 09:00:00 +0000 Panchromatic and multispectral bands aren't always co-registered. On off-nadir RPC products the offset varies across the scene, producing colour fringing that a single shift can't remove. A measure-then-align approach. https://earthtodate.com/learn/flood-mapping-terrain-problem.html https://earthtodate.com/learn/flood-mapping-terrain-problem.html Mon, 22 Jun 2026 09:00:00 +0000 Answering 'what floods if water reaches this height' depends entirely on elevation accuracy. Public 30 m DEMs blur out the kerbs, embankments and drainage lines that decide where water actually goes. https://earthtodate.com/learn/land-cover-without-training-data.html https://earthtodate.com/learn/land-cover-without-training-data.html Sat, 20 Jun 2026 09:00:00 +0000 Supervised land-cover classifiers need labels and generalise poorly across geographies. A training-free approach clusters materials by spectrum and reads spatial context, so built-up, roads and cropland emerge as queries against one representation. https://earthtodate.com/learn/dark-ship-detection-ais-sar.html https://earthtodate.com/learn/dark-ship-detection-ais-sar.html Thu, 18 Jun 2026 09:00:00 +0000 AIS tells you who is reporting; SAR shows every hull, day or night, through cloud. The intelligence is in the mismatch — how fusing the two surfaces dark ships and AIS spoofing. https://earthtodate.com/learn/illegal-construction-detection.html https://earthtodate.com/learn/illegal-construction-detection.html Tue, 16 Jun 2026 09:00:00 +0000 Unpermitted construction is small, dispersed and constant. Detecting pixels that are built now but weren't months ago — at national scale — needs a false-positive discipline, not just a classifier. https://earthtodate.com/learn/mining-monitoring-resolution-cadence.html https://earthtodate.com/learn/mining-monitoring-resolution-cadence.html Sun, 14 Jun 2026 09:00:00 +0000 Free mining-detection data exists — but it's Amazon-only, quarterly and 480 m. Why resolution and cadence decide how many sites you actually find, and what typed detection adds for enforcement. https://earthtodate.com/learn/field-anomaly-detection-4m.html https://earthtodate.com/learn/field-anomaly-detection-4m.html Fri, 12 Jun 2026 09:00:00 +0000 A native Sentinel-2 pixel is 100 m²; a problem must dominate it to register. At 4×4 m, divergence from the local trend surfaces disease, pests, weeds and irrigation faults before they cost a season. https://earthtodate.com/learn/worldview3-swir-mineral-mapping.html https://earthtodate.com/learn/worldview3-swir-mineral-mapping.html Wed, 10 Jun 2026 09:00:00 +0000 WorldView-3 retired in December 2025, ending the only sub-5 m shortwave-infrared source for hydrothermal alteration mapping. How enhanced Sentinel-2 fills the gap at 2–4 m — worldwide and without tasking. https://earthtodate.com/learn/basedem-1m-global-elevation.html https://earthtodate.com/learn/basedem-1m-global-elevation.html Mon, 08 Jun 2026 09:00:00 +0000 Public DEMs are 30 m with 5–16 m vertical error; survey LiDAR is episodic and local. A consistent 1 m global DEM changes flood, drainage, drill-targeting and earthworks work. https://earthtodate.com/learn/country-scale-water-leak-detection.html https://earthtodate.com/learn/country-scale-water-leak-detection.html Fri, 05 Jun 2026 09:00:00 +0000 Utilities lose 20–40% of treated water. Tasking-SAR services can't cover a national network affordably. How 2 m soil-moisture indices from Sentinel-2 change the unit economics. https://earthtodate.com/learn/physics-vs-hallucinated-super-resolution.html https://earthtodate.com/learn/physics-vs-hallucinated-super-resolution.html Thu, 28 May 2026 09:00:00 +0000 Generative super-resolution invents plausible detail. For measurement, geolocation and change detection, invented pixels are a liability. What 'enhancement without hallucination' means in practice.