Rail Revitalisation Project
Using 12d Model with Industry Foundation Classes (IFCs) and Revit is quite
advantageous for all Revit users; using this information allows them to have
greater collaboration between the two products.
Previously, in other projects, the challenges GHD faced involved linking 12d
Model drainage network models into Revit (various methods used include 3D CAD,
ExDS .xml Generator, an Excel-based generator), 12d TINs into Revit (limited
information) and Civil data into Revit (various plugins including Dynamo to try
and replicate civil design data such as track slabs for light rail). However,
across a major project, replicating 12d data in Dynamo without a dedicated
resource can be a lengthy process. These methods often involved long and
complicated import processes, and they only had limited information.
Using 12d Model with IFC helped to alleviate some of this. IFCs are the global
standard used to describe, share, and exchange construction and facilities
management information. As a data format, IFC is neutral and non-proprietary
(i.e. not the product of, or favouring, any particular vendor).
GHD’s workflow for using 12d Model with Revit entails exporting an IFC file from
12d Model, editing the IFC file in a text editor, then linking it into Revit.
They use the IFC Express Writer within 12d Model to facilitate this process.
Once they’ve shifted the 12d Model closer to zero for Revit, they open it with a
text editor so as to change the IFCCartesianPoint to 0,0 (the IFCCartesianPoint
is the coordinate used by Revit as its placement point).
This process will stop the data from being distorted and therefore useable by
Revit. This model shift and step of editing the file is not done for other
software like Navisworks.
from 12d Model to Revit, Sean said it’s important to remember to change the
IFCCARTESIANPOINT to ((0.0,0.0,0.0)), making sure the origin in the IFC Express
Writer Dialogue Box matches the Revit Project base point coordinates, and to
ensure the Export Attributes box has been ticked.
Before they bring it into Revit, they set up a few options that allow them to
map certain 12d Model elements and IFC classes to an appropriate object inside
Revit. They achieve this by setting up a template with a pre-defined project
base point which allows them to generate a model in real-world coordinates. They
also set an IFC mapping class, which allows them to map 12d elements to the
correct Revit categories e.g. pipes that come out on an IFC element assembly to
the Pipes category inside Revit, 12d TINs to a Site category inside Revit, and
for anything that’s on a building element proxy, they can choose to map this to
a generic model or something else.
an IFC file into Revit creates a few extra automatic files (IFC files, Revit
files, HTML Log files, and Shared Parameters files, which are used for mapping
attribute data from 12d Model a parameter inside Revit).
Sean demonstrated aspects of these processes, including handy tips for how to
get around some issues that can arise, and how interrogating a model in Revit
allows them to see all the different kinds of data that are coming through from
attributes in 12d
Model. Mapping attributes
and checking calculations are correct is essential to this process.
So what is actually generated when we put an IFC into Revit from 12d Model? All
the element information comes from the 12d Attributes, but it’s a static model
when linking into Revit. By using these programs together, Sean’s team was able
to produce an accurate replication of geometry without having to re-model
through Dynamo. The colours were driven from 12d Model polygon colour mapping,
which was ideal for standardisation. They used a Shaded/Realistic model with
Graphics Display Options – Show Edges = “Off” to make polygon triangulation
disappear (something Sean was able to demonstrate to the audience in his
presentation), and created Linked Views for project consistency.
The string information from 12d Model, according to Sean, was extremely
beneficial as an export – they were able to use IFC generated strings for 3D
pick line modelling, and to colour strings by filter or category using the
parameter information from 12d Model. Strings were used to show edges in 3D
views while “Show Edges” was unticked.
In Plan View, some important steps in GHD’s processes included filtering 12d
strings to show Control Lines and Road Linemarking, using filters to hide the
lower Trimesh models for a cleaner view, and adjusting transparency to view
below the surface. They also used shading techniques to get their Linked View
plans looking consistent across all projects. In Section View, they filtered for
annotation of different elements.
When linking 12d IFCs into Revit, there are automatically generated schedules
for each IFC Class mapped, and schedules are generated as a result of the IFC
Class to Revit Category Mapping template. This allows them to check data
and use it for their own techniques when writing documentation.
As with the trimeshes from 12d Model, the GHD team is able to use the IFCSite
Export function from 12d to generate a Site category family of any TIN. The
ability to export an existing SurveyTIN and SuperTin with Linework for use in
drawings have also proved invaluable, as having cross-sectional display control,
Plan Shaded, Colour Change, contour and linework control, and the ability to
change Mapping of Survey export from ‘Generic Models’ to ‘Lines’ Revit category.
Sean also ran through some of the challenges his team faced in using Revit, such
as not being able to edit elements when linking IFC files, and not being able to
use colour overrides in Plan or 3D, and how upgrading to 12d Model 14 is helping
them to overcome some of these issues. In particular, using IFC 4 in 12d Model
14, the team was able to bring data back into 12d. This method keeps file sizes
smaller, allowing for more complex design. ‘Splitting data into Entity models’
allowed them to separate all the IFC elements into their individual IFC Class
The GHD team was also impressed by their ability to use these processes in their
civil documentation without the need to remodel services – it all came directly
out in their annotated cross sections, with the help of macros in 12d Model.
Overall, the positive impact of being able to use 12d Model in this way, Sean
said, has given GHD the ability to gain accurate and up-to-date information in a
variety of areas, to help them produce even better-detailed design jobs for
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