IMDF explained: the open format for indoor maps

IMDF, short for Indoor Mapping Data Format, describes the inside of a building as data: levels, units, openings and the things in them. Apple created it for indoor maps in Apple Maps, and it has since been published as an OGC Community Standard. If you are buying an indoor mapping platform, IMDF is the closest thing the industry has to a common language.

What’s inside an IMDF archive

An IMDF dataset is a zip file of GeoJSON files, one per feature type, using WGS 84 coordinates. The core types describe the physical building and what is in it:

• Venue, building and footprint: the site and its structures.
• Level: each floor, with its ordinal (ground is 0, basements are negative).
• Unit: rooms, corridors, stairs, lifts and other spaces, each with a category.
• Opening: doors and other gaps between units.
• Amenity and occupant: things people look for, such as toilets, cash machines and the shops or departments that occupy units.
• Anchor and address: label points and postal addresses.
• Optional types such as section, fixture, kiosk, geofence, detail and relationship add finer detail.

Why it matters

• Portability. A map in IMDF can move between vendors without being redrawn.
• Distribution. Apple Maps and workplace tools such as Microsoft Places accept IMDF, so one dataset can reach several platforms.
• Sharing. GIS teams and first responders can read GeoJSON with standard tools.

What IMDF doesn’t do

IMDF is an exchange format, not a full product. It describes spaces and openings but not a ready-made routing network: a routing engine has to derive the walkable graph from units, openings and traversal relationships. It doesn’t carry styling, live data or analytics, and it says nothing about opening hours beyond what you put in custom properties.

Questions to ask a vendor

• Can I export IMDF on the plan I’m paying for, or only on a higher tier?
• Can I import IMDF from another vendor, or only export it?
• Does the export pass Apple’s IMDF validator without manual fixes?
• What custom properties do you add, and are they documented?

Mapfloors imports and exports IMDF on every plan, alongside GeoJSON, GeoPackage and Shapefile.