Validating IMDF Datasets

Liz Sanderson
Liz Sanderson
  • Updated

FME Version

  • FME 2018.x


Apple Maps supports indoor mapping, where visitors can plan trips or even navigate around buildings. Maps submitted to be used in Apple Maps must be in the Indoor Mapping Data Format (IMDF).

IMDF files submitted to Apple must follow strict guidelines to ensure data integrity and maximize the usefulness of the data for Apple Maps and other indoor mapping applications. Pre-submission validation ensures that data follows these guidelines, meaning that it can be uploaded to Apple Maps without any issues.

The experts at Safe Software have created two different methods of validating IMDF files to check for errors: an online data validator, and a validation transformer for use in FME.


The online data validator accepts IMDF file uploads. In return, the user receives an email report, indicating any errors and warnings.

The IMDFValidator custom transformer is used in FME workspaces, to validate spatial data before writing it to IMDF. It too provides detailed feedback, so that users can readily understand where problems exist and can more easily correct them.


Validation is typically an iterative process. It's best to start with a small sampling of data, such as a few foundational feature types (venue, building, footprint, address, level) and only a few features per feature type. This way it isn’t necessary to review thousands of repetitive errors. As corrections are made then more features can be added to the evaluation until the whole dataset validates.


Disclaimer: Passing IMDF validation with either the online tool or the custom transformer does not guarantee acceptance from Apple. These are just tools to help your data meet the minimum standards.


Validation Reports

There are two types of messages that you may see in a validation report:

Error|<error message>
Warning|<warning message>

An Error is generally a problem that must be fixed for the IMDF to be accepted by Apple Maps. A Warning is generally an issue that will not prevent acceptance of the data, but will reduce its usefulness to end users.

If a feature does not generate a message, this means it has passed the validation.


Online IMDF Validator

The free online IMDF validation tool offered by Safe Software uses FME Server to generate a validation report for each uploaded IMDF file.

Visit the IMDF Validator free tool webpage and upload your IMDF file in step 1. In step 2, enter your name and email address. In a few minutes, check your inbox for the validation report.

Note: the online report is only available for 7 days, if you require this report for longer, please save the HTML page.


Online IMDF Validator webpage


The validation report provides details about which file was tested, when it was tested, and with what IMDF standard it was tested against.

The report lists all of the features that don’t meet the requirements and shows each issue on a map.

It also provides details about the Feature Type (all features and layers), ID, Category, Level, and Validation Error. Use the Feature Type and ID to determine which feature contains the issue. You may then wish to use FME Desktop to fix the reported problems.

Errors MUST be fixed before submitting IMDF data to Apple. Warnings ought to be addressed, where possible, in order to improve the usefulness of the data, but the presence of warnings should not prevent the submission from going through.

Note: In FME, a Feature Type refers to the source dataset schema or structure. Every format used by FME identifies features through a classification scheme. This classification is known in FME as a feature type.


Validation report with errors.


This example validation report has many errors, with missing Address and Building being major. If the FME workspace demonstrated in the CAD to IMDF article was used to generate this data, the workspace could be modified to provide the correct results.


IMDFValidator Custom Transformer

The IMDFValidator custom transformer is used within an FME workspace. It is useful for checking your data throughout the translation process before it is written to IMDF.


IMDFValidator custom transformer


The IMDFValidator provides a detailed report on the data. Combined with FME Workbench tools such as Run with Feature Caching, it allows the user to look into why each error message occurs, to review all of the attributes, and to inspect the geometry further.

Viewing these example results in the FME Data Inspector, it appears that the building feature type has no attributes at all:


Output of the IMDFValidator viewed in the FME Data inspector


Knowing the cause of the problem helps in revising your FME workspace to produce the correct results.

Note: Given the complexity of the business rules that it models, the IMDFValidator has a significant overhead in a translation. Once a workflow and dataset has been validated, it may be desirable for performance reasons to bypass the IMDFValidator when producing the final output.

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