RGB - Alta risoluzione

Ecosystem Servicesv08.00 credits/per_km2

Responsible:Niccolò Calandri

RGB High Resolution — Google Maps

Overview

The RGB High Resolution layer provides very-high-resolution true-color imagery sourced from the Google Maps Platform via the Google Map Tiles API. Resolution ranges from 0.075 m/pixel (zoom level 21) to 2.4 m/pixel (zoom level 16), depending on the configured zoom level and geographic availability.

Unlike Sentinel-2 RGB (10 m), this product enables identification of fine-scale features: individual trees, building footprints, parking lots, garden plots, swimming pools, and other sub-meter features that are invisible at satellite resolution.

Primary use cases:

Visual validation of satellite-derived indices and classifications
Urban feature recognition for built-up area analysis
Stakeholder communication with familiar, high-detail imagery
Fine-scale land cover verification for quality control

Calculation Methodology

Tile-based download pipeline:

Bounding box computation — The analysis area polygon is converted to a bounding box in Web Mercator (EPSG:3857)
Tile grid calculation — The bounding box is divided into 256×256 pixel tiles at the specified zoom level
Tile download — Each tile is requested from the Google Map Tiles API via authenticated HTTPS requests
Mosaic assembly — Downloaded tiles are stitched into a single georeferenced image
Clipping — The mosaic is clipped to the analysis area boundary
Georeferencing — Output GeoTIFF with proper CRS and spatial extent metadata

Resolution by zoom level:

Zoom Level	Approximate Resolution	Typical Use
16	~2.4 m/pixel	Regional overview
17	~1.2 m/pixel	Neighborhood scale
18	~0.6 m/pixel	Street scale
19	~0.3 m/pixel	Building scale
20	~0.15 m/pixel	Sub-building detail
21	~0.075 m/pixel	Maximum detail

Data Sources

Source	Provider	Type	Coverage	Resolution	Update
Google Map Tiles API	Google Maps Platform	RGB tiles	Global (variable)	0.075–2.4 m	Variable

Documentation: Google Map Tiles API

Technical Notes

Resolution and image freshness vary by geographic location; urban areas typically have the highest resolution and most recent imagery
Google Maps imagery is a composite from multiple commercial satellite providers and aerial photography
Imagery dates are not uniformly available and may vary across the extent of a single site
API usage is subject to Google Maps Platform pricing and usage limits
The downloaded tiles are in Web Mercator projection (EPSG:3857), which introduces area distortion at high latitudes

References

Google Maps Platform. "Map Tiles API: Overview". Available at: https://developers.google.com/maps/documentation/tile

Data Sources & References

Sources

WRD_GMTIL_99

Methodology

Le immagini RGB ad alta risoluzione vengono scaricate dalla Google Maps Platform - Dynamic Tiles API, basate su immagini aeree e satellitari commerciali ad altissima risoluzione. La risoluzione varia in base al livello di zoom: zoom 16 = ~2.4 m/pixel (aree urbane estese), zoom 18 = ~0.6 m/pixel (quartieri), zoom 20 = ~0.15 m/pixel (singoli edifici), zoom 21 = ~0.075 m/pixel (dettaglio massimo). Il livello di zoom viene calcolato automaticamente in base all'area del poligono, mantenendo la dimensione dell'immagine finale entro limiti gestibili (~3.2 milioni di pixel). Le tile necessarie vengono identificate usando la libreria mercantile per convertire i bounds geografici in coordinate tile. Il download avviene in parallelo con massimo 10 worker. Le tile scaricate vengono composte (mosaicate) in un'unica immagine usando numpy. L'immagine viene georeferenziata calcolando la trasformazione affine basata sui bounds delle tile in Web Mercator, quindi riproiettata nel sistema di riferimento richiesto. Limitazioni: max ~6000 richieste/minuto, ~15000/giorno, costo ~0.0006 $/richiesta. Le immagini sono utili per validazione di classificazioni automatiche, riconoscimento di feature urbane (edifici, strade), e comunicazione visiva dei risultati.