Chart Geolocation

Required roles: AIS Charts API — Roles
Base endpoint: https://ais-charts-api.ibosoft.net.tr:2087
Reference documents: ISO 32000-2 (PDF 2.0), geospatial features · OGC GeoTIFF Standard 1.1
Attribution: show ibonav.aero wherever this data is displayed
Data sources:
Last updated: 08 NOV 2026

Many AIP and other charts carry their own georeference: GeoPDF and GeoTIFF files hold the coordinates of the chart inside the file. Such a chart can be placed on a map directly from the file; no separate project or world file is needed.

Which charts can be placed on a map

The file lists of the AIS Charts API mark each chart under aip-charts and other-charts with geolocated:

Value Meaning
true The file carries its own georeference and can be placed on the map
false It cannot: no georeference, not a PDF or TIFF, or a password-protected PDF
null Not determined yet. A new or changed file is listed at once with null and gets true or false within minutes

The value is read from the file itself, so you can decide whether to show a map button without downloading the chart.

Where the georeference is

GeoPDF. A page carries one or more viewports (/VP). A viewport whose measure dictionary has /Subtype /GEO maps the viewport area to the earth: /GPTS holds the geographic corner points as latitude, longitude pairs, /LPTS the matching points in the viewport, and /GCS the coordinate reference system. Older GeoPDFs use the /LGIDict page dictionary instead. A file may have the georeference on any page.

GeoTIFF. The georeference is in the TIFF tags: the GeoKey directory (tag 34735) together with tie points (33922) or a transformation matrix (34264).

Side files such as .tfw or .aux.xml are not used and are not served by the API.

Displaying a chart

  1. List the folder with get-file-index and take the files with geolocated: true.
  2. Download the file with get-file.
  3. Read the georeference as described above and draw the page or image in the chart's coordinate system. GIS software such as QGIS and GDAL opens both formats directly.