A GeoTIFF is a TIFF image file that carries embedded georeferencing metadata, so the raster knows where it sits on the Earth, which coordinate reference system it uses, and the ground size of each pixel. It is one of the most widely used formats for elevation models, satellite imagery, and scanned maps in GIS.

Why it matters

Plain TIFFs store pixels but no spatial location. GeoTIFF adds geokeys (CRS, model transformation or tie points, pixel scale) directly inside the file, so a DEM or satellite scene loads into the correct map position automatically, with no sidecar required. Because the standard is open and supported by GDAL, QGIS, ArcGIS, and rasterio, it is a reliable interchange format for raster data.

Concrete details

  • Georeferencing is stored in TIFF tags such as ModelPixelScaleTag, ModelTiepointTag, and the GeoKeyDirectoryTag, which typically encodes the CRS as an EPSG code (for example EPSG:32633).
  • Inspect a file with gdalinfo scene.tif to read its CRS, corner coordinates, pixel size, band count, and NoData value.
  • A .tfw world file plus a .prj can supply georeferencing for a plain TIFF, but a true GeoTIFF needs no sidecars.

Cloud-Optimized GeoTIFF

A Cloud-Optimized GeoTIFF (COG) is a valid GeoTIFF organised with internal tiling and overviews so HTTP range requests can fetch only the needed portion. COGs power efficient cloud and web-map raster access without a tiling server.

Common pitfall

Large GeoTIFFs without internal overviews or compression render slowly and bloat storage. Build overviews (gdaladdo) and use compression (for example COMPRESS=DEFLATE or LZW) when producing deliverables. Also confirm the embedded CRS is correct; an absent or wrong geokey leaves the raster mislocated.

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