IMDF (Indoor Mapping Data Format)

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Introduction

IMDF (Indoor Map Data Format) is an indoor mapping data format developed by Apple to provide indoor navigation and location information services. IMDF is based on the GeoJSON data format and can store information such as building structure, floors, facilities, entrances and exits, passages, POIs (points of interest) in a standardized form. This format is widely used in indoor map systems and applications such as Apple Maps, and plays an important role in GIS (Geographic Information System), facility management and smart city projects.

File Structure

IMDF files use a GeoJSON-based structure and contain the following main elements:

VENUE (venue information): overall information of a building or facility (name, address, category, etc.)
FEATURES (feature data): information that defines each element inside a building

UNIT (unit): polygons representing rooms or areas (such as offices, stores, meeting rooms, etc.)
LEVEL (floor): represents each floor of a building
ANCHOR (anchor point): coordinate information representing important points inside a building
VERTEX (vertex): coordinate point information required for map drawing
ADDRESS (address): address information of a facility
ENTRANCE (entrance): building entrance and exit information
NAVIGATION (navigation): pedestrian path or movement route information
OCCUPANT (tenant information): information about stores or businesses within a facility
KIOSK (information terminal): location of an information center or touch screen panel

RELATIONSHIPS (association information): associations between different objects (for example: a specific floor to which a room belongs, the connection between a room and a passage, etc.)
GEOMETRY (geometric information): coordinate data representing the shape of each object (polygon, line, point)

IMDF’s data structure is hierarchical and can store detailed information from the entire facility (VENUE) → floor (LEVEL) → room (UNIT).

Pros

1. Highly compatible with Apple Maps: IMDF is a format developed by Apple that can be directly imported into Apple Maps for use as indoor maps and can be easily integrated into the Apple ecosystem (iPhone, iPad, Mac).

**2. Based on GeoJSON, easy to process: **Due to the use of the universal JSON format, data parsing and editing are very convenient and can be easily processed by a variety of GIS software and programs.

3. Provide detailed indoor information: It can include detailed information such as building structure, floors, tenants, navigation paths, etc., which is suitable for indoor space management.

4. Lightweight and flexible: The JSON format makes its data volume small, suitable for fast processing on the Web and mobile terminals.

5. Suitable for smart cities and facility management: It can be used for indoor map production in airports, commercial centers, hospitals, office buildings and other places, which helps to establish facility management and navigation systems.

Cons

1. Highly dependent on Apple: IMDF is optimized for Apple Maps and cannot be used directly on Google Maps or other GIS platforms, requiring format conversion.

2. Low standardization: Compared with Shapefile (SHP) or GeoJSON, IMDF is less well-known, has fewer supported GIS tools, and has limited compatibility.

3. Difficult to integrate with outdoor maps: IMDF focuses on indoor mapping and requires additional data conversion when integrated with outdoor maps (road networks, terrain data, etc.).

4. Creating data requires expertise: Correctly creating IMDF files requires familiarity with GeoJSON, GIS knowledge, and following Apple’s guidelines. When the data structure does not meet the requirements, Apple Maps may not display correctly.

Application Scenario

IMDF files can be used in a variety of scenarios that require indoor maps. For example, in facilities such as airports, shopping malls, hospitals, university campuses, office buildings, etc., it can be used to create accurate indoor maps and support navigation systems. In addition, it is suitable for smart city projects and digital twin construction, and can be used for facility management, information guidance systems, and barrier-free access optimization. With Apple Maps, users can intuitively view indoor routes on their iPhone or iPad and reach their destination smoothly.