Using MicroMVDs for exchange requirements

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To guarantee correct BIM data, data exchange requirements need to be specified and audited. A MicroMVD is a collection of sentences that describe auditing requirements, written in plain language understood by both technical and non-technical stakeholders. These sentences are organised into categories, and can be processed by a computer to automatically check whether or not the requirements are satisfied.

This approach builds on the concept in software development called unit testing, specifically behavior driven development. Describing the requirement in simple to understand (but still machine readable) gherkin format makes the intentions clear to designers and makes writing unit tests simple.

BIMTester has implemented use of MicroMVDs for auditing model quality from IFC files. BIMTester is integrated into the BlenderBIM Add-on

Here is an example of a simple MicroMVD, which checks that an IFC4 file is provided with a particular filename.

Feature: Project setup

In order to view the BIM data
As any interested stakeholder
We need an IFC file

Scenario: Receiving a file
 * The IFC file "project.ifc" must be provided
 * IFC data must use the IFC4 schema

This MicroMVD is stored in a simple text file with the .feature file extension. The file name is arbitrary, but may be used to describe what it is auditing. These simple text files can be edited in any text editor, such as Vim, Apple TextEdit, or Microsoft Notepad. No proprietary software is required: anybody can read and write MicroMVDs.

These *.feature files, each containing sentences like the above can be processed by a computer. In the example above, a MicroMVD auditing program will look for a file named "project.ifc" and will check that it is IFC4. The MicroMVD auditing program can then generate a report, which can be used by stakeholers to track whether or not a project is satisfying its requirements.

Unlike other auditing solutions like Solibri or SimpleBIM, MicroMVDs are non-proprietary, do not expire, are free, much lighter, are easy to change and develop, and are cross-platform.

List of MicroMVDs[edit]

Although you are free to write your own MicroMVD specific to your project, a series of MicroMVDs have been published online that address common problems. You can copy and paste these templates into your own *.feature files, and modify it to suite your project.

All MicroMVD can be found in MicroMVD

Auditing BIM data with MicroMVDs[edit]

The BIMTester Quality Auditing panel in the BlenderBIM Add-on
An example audit report from BIMTester

To begin auditing BIM data, you will need an IFC file. Let's imagine you have a file called myfile.ifc.

You will then need to specify your exchange requirements. Follow the steps below:

  1. Create a new text file called my_first_micromvd.feature
  2. Copy a MicroMVD template (e.g. Project setup MicroMVD) into your my_first_micromvd.feature file.
  3. Modify the template based on your project. For example, you may change the sentence * The IFC file "{file}" must be provided to read * The IFC file "myfile.ifc" must be provided. Note that the myfile.ifc has to be in the same directory as your my_first_micromvd.feature file.

Now that you have specified your exchange requirements, you can audit it using a program. One free and open source option is BIMTester, which comes with the BlenderBIM Add-on, or can be run standalone. Here's an example of how to audit it:

  1. Launch Blender with the BlenderBIM Add-on installed.
  2. Open up the BIMTester Quality Auditing panel in the Scene Properties.
  3. Navigate to the directory that you placed your my_first_micromvd.feature file in the Features Directory property.
  4. You will see that it will detect your features file, as well as the exchange scenarios within it. Press the Execute BIMTester button.
  5. Your audit report results will pop up in your browser.

Modifying a MicroMVD[edit]

MicroMVDs are designed to be modified to be specific to your project. You are free to delete lines that don't apply to your project, or add additional lines if you need to audit more things in your project. You can have a single .feature or multiple files for each IFC, depending on how you want to organise your project. Once you have tailored it to your project, it is encouraged to include it in your project contract, so that all stakeholders are crystal clear on exactly what the data exchange requirements are, and how it will be audited.

If you know how to code, you can also define your own sentences. Read more in Developing custom MicroMVDs.