CATIA, interoperability, revit

Revit to CATIA Interoperability Workflow

Every piece of software has its limitations. The good thing about knowing may different kinds of programs is that you can combine them to achieve anything you want.

In this post, I’ll go over the steps of bringing in an IFC file of a steel truss from Revit into CATIA, which can then be used in other apps, such as xGen.

Importing an IFC File

Clicking on the ‘+’ arrow at the top right corner of the window allows you to import the IFC file. In this case, I already uploaded the file into the 3DDrive, but you can also get the file directly from your computer.

You will know that the IFC file has successfully been imported within the pop-up window.

Also, within the tree, all the geometry is read properly as beams.

Creating a Derived Representation

A derived representation makes a copy of the beam elements and puts them into a new 3D shape. Basically its an extraction process so the elements can be linked elsewhere.

Moreover, an IFC file cannot be directly manipulated or referenced, so this process is necessary.

To start, make sure that the root is selected, which in this case is the Site. Then, hover over the root and the ‘Derived Representation’ button will appear.

In the pop-up window, create a new 3D Shape into which the copied elements will go. You can either drag select the elements you want to copy within the tree or use the auto-select button.

The beam elements now live inside a new 3D shape!

Linking Elements into a New Product

In order to aid in organizing all the parts, the next and final step is to link the derived representation, the 3D shape, into a new product.

This separates the old IFC geometry with the new, usable geometry too.

Firstly, right-click on the new 3D shape and click ‘Share this representation’. This makes the 3D Shape accessible to be inserted into the new Product.

Now make a new product and right-click on it, selecting Insert > Existing 3D Shape.

As you’re prompted to select an existing 3D shape, go to the new 3D shape created and click on it.

After doing this last step, you can rename the product to something more telling of what it is, and so you can open it up in other programs. And don’t forget to save (though this app with remind you before you close out of the app)!

Opening in xGen

You can now drag and drop this new product with the beam elements within another app such as xGen and start working with it!

For this project, I used xGen for some complex steel framing modeling of one part of the truss. I’ll go into more detail in the next post!

CATIA, Component Based Design, Research, xGenerative Design

High Detail Modeling through Component-Based Design

The goal here is to populate a model with a template to create a highly detailed facade. The concept behind this process is called Component-Based Design.

Whereas you might think in a more traditionally-architectural sense in terms of a building being made up of a core, shell, and interiors, this approach focuses on the individual parts which make up the whole.

Hopefully, the prior posts, and this culminating one, shows that it’s very possible to have a workflow in which both design and production can be integrated into a more holistic process.

Creating an Object Type

First, an object type must be created. An object types stores things like the engineering template and user-defined feature, which will be explain later.

When creating new content, search for ‘Covering type’ and select it. And for the product instantiation method, select ‘Adaptive’. This allows the template to adapt per the inputs created.

The template and user-defined feature (UDF) are stored in the Resource Table. Within the table, you will see two rows, one for each resource.

You need to create a UDF in order to instantiate the template. The two resources are linked, with the idea being that the UDF will be a more simplified version of the Template, acting as an anchor for the more detailed product.

Creating a User Defined Feature

Again, the UDF needs to be super simple, so in this case, it will only contain an Axis System that will act as the anchor.

Note that there are two Axis Systems. The first will be referenced in the UDF; the second is a formula-based Axis System that is linked to the first Axis System.

Within the Building Engineering 3D Design app, highlight the first Axis System in the tree and then select the ‘User Defined Feature’ tool. This will automatically link both Axis Systems to a new Knowledge Template for the UDF.

So, an anchor for the UDF is now live. But, now an anchor for the template needs to be created too!

Simply create a new Axis System and use the ‘Define Component’ tool to associate this new axis system as the anchor. Notice that the axis system then becomes published, which means that is now exposed for other processes to use it.

Creating a High LOD Facade Model

Instantiated panels of one side of the skylight facade

In order to truly merge a design with the reality of the physical, the inputs from the design and the inputs of the template need to match. And to reiterate, these inputs are a set of points which define the boundary of the panel and the axis system, which ultimately is a coordinate location of where that panel lives.

To set this up, first the design model modified using xGen must be inserted into the site,which was previously used to test the template.

The main tool to use is ‘Capture Component Specifications’, where the inputs from the design model are linked up with several items, which include:

  • Object type – Click on the search icon and find the Covering object type
  • Part Body – create a new 3D shape where the specifications will live
  • Inputs – Includes axis systems, and three points from the design model
  • Parameters – Used in the template; offset and thickness, in this case

The inputs are associated using a selection pattern; a manual process of selecting the whole list of axis systems within the tree.

Once the selection pattern is processed, the inputs are then associated with a panel.

Note that in the screenshots above, the panels have already been exposed ⁠— its a very easy step from here though!

Back to the concept of level of development, a specific tool called ‘Change Level of Development’ actually populates the template individually.

Again, the UDF is this example is super simple, made up of just the axis system. This is because the simple version of the model lives in Rhino, and only extracted the essential geometrical data with xGen.

You can imagine, however, that the UDF could also contain a simple surface to represent the panels as well.

One of the benefits of this approach is that the panels are organized in a list, each with a unique name, generated automatically. You can then export these details into an Excel sheet or convert this model into IFC and link into a architectural Revit model.

Another benefit is the idea of continuous LOD, which means that I can update the template, adding more details to the panel, and reinstantiate the templates fairly quickly following the steps above, due to the links created between the design model and the template.

In other words, a conceptual design can rapidly become a highly detailed model — the stuff dreams are made of!

See the video above to see the quick change in level of development for yourself! 🙂

CATIA, Research, xGenerative Design

xGen + CATIA – Publishing Geometry

In order to populate the engineering template, we need get the inputs from the design model, which are living within the Rhino model.

This requires importing the Rhino model into xGenerative Design, exporting as a STEP file and then importing this file into a new 3D product.

But before moving on, all surfaces must be assembled, or joined, using the ‘Join’ tool. Otherwise, when you try to use the surfaces in xGen, you will have to import each surface individually. It is much more convienent to have the surfaces in just one list!

Extracting Geometry with xGen

After opening the new product within xGen, you can import the joined surfaces. The current workaround for this is to click on the ‘Join’, and then click any tool, such as translate, which appears in the 3D browser. This automatically creates the connected nodes and simulaneously imports all the surfaces. Now, on to the fun part: deconstruction!

The main nodes used for the importing and extracting of inputs were:

  • Dissassemble – Connecting the ‘Import’ node to this will give you the full list of surfaces
  • Sub Elements – Plug the output from the ‘Disassemble’ node here to get all three vertices of each surface; main inputs for template instantiation
  • Centroid – Use this node with the next one on this list; used as the reference point to get Axis Systems
  • Axis System on Surface – Get Axis Systems for each surface; an main input used for the template instantiation process
  • Publish – Don’t forget to add this to the final outputs! This exposes the main inputs (the three vertices/points and axis systems) for use later down the line
Full graph used to get geometrical data from the imported surfaces
Highlighting of main inputs: 3 points and Axis System

Next, we can start to actually use these inputs and the template created together! How exciting is that?!

CATIA, Component Based Design, Research

High LOD Modeling – Template Instantiation

After creating the base model, the next step is to create a Engineering Template. It’s comparable to an adaptive component family in Revit, but with the main difference being that you can include alot more geometrical information.

Creating an Engineering Template

Clicking on the ‘+’ arrow at the top right corner of the window allows you to create new content. Searching for ‘template’ brings up the Engineering Template icon.

After clicking the icon, a separate tab opens. Click on the ‘Add Reference’ button to link the base model to the template.

The program prompts you to select the components to be added, so you click on the top of the tree, the ‘Glazing_Panel A.1’, which contains all the information needed.

Automatically, this portion of the model gets added. In order to add the other portions of the model, such as the Skeleton, click on that part under ‘Unchanged Components’ and then the arrow. This includes all the parts into the ‘Components to process’ dialogue box.

Next, the inputs created, such as the axis system and three points which make up the edges of the panel, need to be linked. Clicking on the Inputs tab, a small window will pop up. In order to be able to select the inputs, click on the ‘Glazing_Panel A.1’ within the tree. This loads all the available parts that can be selected. Then, clicking on the small right arrow moves the necessary inputs to the ‘Selected objects’ box.

The last step is to link in the ‘Offset’ and ‘Thickness’ parameters, in a similar way as in the last step.

Testing the Template

Within the Building and Civil Assemblies app, create a test building and add some test inputs.

Using the Engineering Template tool, we can then test to see if the base model has been properly constructed. So, if anything looks wonky, this test will show you what needs to be fixed!

The tool prompts you to select the Engineering Template that you want to populate. So, again, click on the main part of the tree, or ‘PLM_Template_Panel A.1’, in this case.

Now, this is the fun part. A new window appears, and asks for the inputs. You can either select them on the tree menu or directly on the 3D viewer. Then, you get a nice little diagram of the different parts and how they interconnect.

And, when you thought it couldn’t get better, you can actually preview the result before instantiating the whole panel. Definitely feels good when you get a idea ahead of time if your model will work after all!

And yes, the moment of truth— it works!!!!!!!!!!

In the next post, I’ll go over how to populate the panel on a real design.

CATIA, Component Based Design, Computational Design, Research

High LOD Glazing Panel Creation

It’s a constant struggle with most modeling programs to create truly high LOD models. And this is especially true if the shape or design being attempted is not rectilinear or a quadrilateral. Fortunately, there some great tools, such as xGenerative Design, Assembly Design, and Building 3D Design to help with this, as well as this super helpful video, which I highly recommend to watch.

The Design

Rhino model imported into xGenerative Design, with each reference surface

I used a design of a skylight done in Rhino; the model had the base surfaces which represent the glazing panels. In order to add more detail to this model, I looked at the detail drawings provided by the client, which gave important info such as the type of glazing, size of panels, and offsets for things like sealants — turns out, the glazing panel is triple pane with 1/2″ offset between panels for the sealant!

Creating the Panel

The glass panel was created using Assembly Design, and the Covering element type contains all the different parts of the panel.

Tree Structure

The panel’s basic structure within Assembly Design

The tree structure is made up of two parts: the Skeleton and Plate. The skeleton contains all the inputs and base geometry required to build up the panel, such as the axis system, points, boundary curve and surface. The ‘Plate’ mostly contains references from the Skeleton, in order to further build up the geometry which makes up the panel.


View of panel, highlighting the inputs which make up the panel

The inputs are crucial in order to create a template, which will be referenced in the overall design later on.

Panel Construction

The Thickened Surface tool, highlighting the linked surface

To create the glass panels, the surface from the Skeleton is copied into the Plate as a link. Then, using the Thicken Surface tool, the first glass panel is created. The rest of the panels are made in the same way, with the offset distances varying depending on its location.

One thing to note is that the ‘Offset’ of the surface is controlled by a formula, which has some associated parameters which can be changed. This isn’t so important as it’s unlikely that the glass panel type, and therefore thickness, will change after the design development phase, but it was a nice exercise in creating a more parametric model.

Plate Construction

View of a Sketch, for the profile for the sweep which represents the sealants

Another parameter that drives the overall shape of the panel is an ‘Offset’, which allows room to add a profile for the sealant. The boundary is constructed using a polyline, created using the input points. The profile is constrained by a point on the polyline, as well as the linked surface.

In the next post, I’ll go over how to create an Engineering Template from this model. Stay tuned!