From CAD to IMDF : A Practical Workflow for Indoor Map Data

Converting CAD drawings into IMDF is more than a file-format change. It requires clean floor plan geometry, reliable space attributes, georeferencing, validation, and a clear understanding of the platform or system that will consume the data.

This article outlines the practical workflow for turning CAD and DWG floor plans into structured indoor map data that can support Microsoft Places, workplace apps, GIS workflows, IWMS/CAFM systems, and long-term space data governance.

Why CAD drawings need conversion

CAD drawings are often the best source material for indoor mapping, but they are rarely ready for IMDF without preparation. CAD files may contain drafting layers, text labels, blocks, hatches, reference files, construction notes, and legacy conventions that made sense for drawing production but do not directly translate into valid indoor map data.

IMDF datasets are delivered as ZIP archives, include a manifest.json file, and organize feature data as homogeneous GeoJSON FeatureCollections in .geojson files. That structure requires clean geometry, stable identifiers, consistent classifications, and a clear mapping between drawing content and IMDF feature types.

CAD Readiness Boundaries

Common CAD readiness issues include open room boundaries, inconsistent layer names, missing room identifiers, retired or conflicting floor names, unclassified areas, and geometry that is not aligned to real-world coordinates.

The CAD to IMDF workflow

1. Define the target use case

The first step is understanding where the IMDF data needs to go. A general IMDF dataset for indoor mapping may not have the same requirements as a Microsoft Places package, an Apple indoor map submission, a custom web map, an internal GIS workflow, or a workplace app.

Luft starts by clarifying the intended output, target platforms, portfolio scale, source systems, and maintenance expectations. This prevents the conversion from producing a technically valid file that does not support the actual business workflow.

2. Inventory the drawing library

The next step is to inventory the available floor plan assets. This includes DWG files, PDFs, Revit or BIM exports, building and floor lists, room schedules, space IDs, occupancy data, booking resources, and any existing IWMS/CAFM exports.

For large portfolios, the inventory is as important as the conversion itself. It shows which buildings are ready, which floors require cleanup, and where missing or outdated source data will create risk.

A drawing inventory helps separate ready floors from floors that need remediation.

3. Clean and standardize the CAD geometry

CAD cleanup prepares the drawing for structured data extraction. This can include normalizing layers, removing obsolete linework, resolving duplicate geometry, confirming closed room or unit boundaries, separating walls from spaces, checking floor outlines, and standardizing text and block usage.

The objective is not to make the drawing look nicer. The objective is to make the drawing machine-readable enough to support reliable feature extraction into IMDF and GeoJSON.

4. Build the attribute model

Indoor map data needs attributes that remain meaningful after conversion. Feature names, categories, addresses, display points, level references, relationships, and stable identifiers all need to be handled consistently. IMDF feature objects include an id member and a feature_type member, and the reference notes that feature IDs must be globally unique and retained across deliveries for the lifetime of the feature

This is where space management experience becomes critical. CAD labels may not be enough. The conversion may need to reconcile room numbers, floor names, department codes, booking resources, BOMA or FICM categories, occupancy records, and system IDs from IWMS, CAFM, HR, or Microsoft 365 sources.

Attribute mapping connects drawing geometry to the operational data that systems depend on

5. Georeference and align the indoor map

Georeferencing places the indoor map in real-world coordinates. This is important for campus maps, multi-building portfolios, GIS workflows, mobile experiences, and any downstream system that expects indoor data to align with outdoor basemaps or building footprints.

Microsoft Places explicitly requires IMDF packages used for floor plans to be georeferenced, and other IMDF use cases also benefit from consistent spatial alignment across buildings and systems

Georeferencing aligns indoor floor plan data to its real-world location.

6. Generate the IMDF package

After geometry, attributes, and alignment are prepared, the data is exported into an IMDF package. A general IMDF delivery is a ZIP archive with manifest.json and .geojson FeatureCollection files

The exact file set depends on the use case. A simple indoor map may require a different level of detail than a venue map with amenities and occupants. A workplace app may need room, desk, and neighborhood data. Microsoft Places has its own package expectations, including required files such as building.geojson, footprint.geojson, level.geojson, and unit.geojson, with section.geojson and fixture.geojson used when sections and furniture need to appear

Microsoft Places IMDF geoJSON structure example.

7. Validate the dataset

Validation checks whether the IMDF package is structurally and semantically usable. It can reveal missing files, invalid feature IDs, geometry problems, relationship errors, empty string values, missing display points, precision problems, or platform-specific issues.

The OGC IMDF reference defines many constraints that affect conversion quality, including ZIP delivery, manifest requirements, GeoJSON FeatureCollections, valid feature types, globally unique feature IDs, string rules, precision guidance, and geometry expectations.

Validation finds issues before the data reaches a map, app, or platform upload.

8. Maintain the indoor map data

IMDF conversion should not end when the first package is delivered. Buildings change, spaces are renovated, departments move, floor names are corrected, booking resources change, and new systems are introduced.

A maintainable workflow defines how future field changes, CAD updates, attribute changes, and platform-specific exports will be handled. This makes IMDF part of the organization’s space data governance process rather than a one-time file conversion.

A repeatable lifecycle keeps IMDF data current after launch.

Common CAD to IMDF issues we help resolve

Many CAD to IMDF projects stall because the source drawing looks complete to a human but is not structured enough for software. Luft helps identify and resolve issues before they become validation errors, rendering problems, or platform upload failures.

• Room or unit boundaries are not closed.
• CAD layers are inconsistent across floors, buildings, or vendors.
• Space labels are missing, or out of date.
• Room numbers do not match IWMS, CAFM, booking, or occupancy systems.
• Floor naming differs between CAD, facilities records, and target platforms.
• Building and floor geometry is not georeferenced.
• CAD blocks, hatches, and annotations are mixed with extractable geometry.
• Display names, categories, and feature relationships are incomplete.
• IMDF feature IDs are not stable across updates.
• A package is technically generated but not suitable for the target system.

Most conversion risks are easier to fix before package generation.

What Luft can deliver

Luft can support the CAD to IMDF workflow at the planning, conversion, validation, and maintenance stages.

What we need to get started

An initial review can usually begin with a representative sample instead of the entire portfolio.

• One or more DWG files.
• A building and floor list.
• Any room, suite, desk, or space ID export.
• Target system or intended use case.
• Any existing GIS, IWMS, CAFM, Microsoft Places, Apple indoor map, or workplace app requirements.

A small sample set can reveal the likely conversion path and risk areas.

FAQ

What is IMDF?
IMDF stands for Indoor Mapping Data Format. It is a data model for indoor locations that supports orientation, navigation, and discovery, and it is designed to represent indoor spaces in a structured, software-readable way.

Is IMDF the same as GeoJSON?
IMDF is based on GeoJSON concepts and conforms to RFC 7946 according to Apple’s IMDF overview, but IMDF adds its own feature types, package structure, rules, and validation expectations for indoor maps

Can a CAD drawing be converted directly into IMDF?
Sometimes a drawing can be used as strong source material, but most CAD files require preparation before conversion. Layers, boundaries, identifiers, floor names, attributes, and georeferencing often need review and cleanup before an IMDF package can be trusted.

What files are in an IMDF package?
A general IMDF package is delivered as a ZIP archive with manifest.json and .geojson FeatureCollection files. Common feature files include building.geojson, footprint.geojson, level.geojson, unit.geojson, section.geojson, and others depending on the use case.

Does IMDF only matter for Microsoft Places?
No. Microsoft Places is one important IMDF use case, but IMDF is a broader indoor mapping format that can support indoor maps, wayfinding, discovery, GIS/BIM workflows, workplace applications, and enterprise location-based experiences

What is different about Microsoft Places IMDF?
Microsoft Places uses IMDF as the input format for floor plans and adds requirements around georeferencing, one package per building, required files, floor SortOrder, map correlation, and PowerShell upload workflows

Can Luft help if the target platform is not Microsoft Places?
Yes. Luft can help prepare CAD drawings for standards-based IMDF and can also review platform-specific requirements for other indoor mapping, GIS, workplace, or facility systems.

Need help preparing CAD drawings for IMDF?

Luft Enterprises helps teams review CAD readiness, map space data, validate IMDF packages, and prepare floor plans for platforms such as Microsoft Places. Visit our CAD to IMDF services page to learn more.