Using the Revit IFC Export in your own add-on

In September 2011, Autodesk make accessible the Industry Foundation Classes (IFC) exporter for Revit as open source code, licensed through a LGPL v. 2.1 licensing agreement. In 2014, this project evolved to include IFC import as well, and was named “IFC for Revit”.

This source code is available on Source Forge, and everyone can contribute to the part of Revit that deal with IFC.

This source code is now the built-in IFC engine for Revit, and I was told that this engine is also behind the conversion service available through Forge.

When the user clicks on Export to IFC, an even is triggered, and Revit catch this even to run the IFC exporter. This also works when the event is triggered by the Document.Export() used through the Revit API by a third-party add-on, like the one I built last week. This IFC Export engine will then read the Revit model, convert every element into its IFC counterpart, and write the resulting IFC file.

How Revit export to IFC

This IFC engine comes with a special UI, the IFCExporterUI, designed to tap into the capabilities of the open-source IFC exporter to give you more control over the configuration of your export.

There are different add-ons for each Revit version, and each new release of Revit is shipped with the most up-to-date IFC engine available at the time. However, the code for this engine evolve quickly, and you can always download the latest version as an add-on on the Autodesk App Store.

At the time of writing, the landscape looks like this:

Revit Version Built-in IFC Exporter version Latest IFC Exporter version (with the Revit IFC add-on)
2016 Exporter 16.0.490.0 – Default UI Exporter 16.6.0.0 – Alternate UI 16.6.0.0
2017 Exporter 17.0.1081.0 – Alternate UI 17.14.0.0 Exporter 17.4.0.0 – Alternate UI 17.4.0.0
2018 Exporter 18.0.0.420 – Alternate UI 18.0.0.420 Exporter 18.2.0.0 – Alternate UI 18.2.0.0

If you want to know witch version you have, you can check it by opening an IFC file with a text editor and look among the first lines, the FILE_NAME one:

Check you exporter version

I didn’t dig into the subtleties of the different flavors of each Revit version, like R2 and other exotic name, you get the picture.

Last week, I published a Revit add-on to send a model to bimsync. Under the hood, this add-on exports the Revit model to IFC before uploading it to bimsync. As I was building my add-on, I realized that I couldn’t just use the Document.Export() function with whatever IFC export settings Revit could provide me. To be useful, such an add-on must allow the user to set up his own IFC Export configuration.

I look into the code of the IFC Exporter UI to understand how this user interface communicate with the export engine. I found out that you need an IFCExportConfiguration class to use a specific IFC Export configuration. Below is an example of the code needed to export a Revit model to IFC:

//Create an instance of IFCExportOptions
IFCExportOptions IFCOptions = new IFCExportOptions();

//Get an instance of IFCExportConfiguration
IFCExportConfiguration selectedConfig = modelSelection.Configuration;

//Get the current view Id, or -1 if you want to export the entire model
ElementId activeViewId = GenerateActiveViewIdFromDocument(doc);
selectedConfig.ActiveViewId = 
        selectedConfig.UseActiveViewGeometry ? activeViewId.IntegerValue : -1;

//Update the IFCExportOptions
selectedConfig.UpdateOptions(IFCOptions, activeViewId);

string folder = "A path to a folder where you want to save your IFC file";
string name = "the name of your IFC file";

//Export the model to IFC
doc.Export(folder, name, IFCOptions);

You start by creating an instance of the IFCExportOptions found in the Autodesk.Revit.DB namespace. This is standard in all Revit flavors.

Then, you retrieve or create an instance of the IFCExportConfiguration class. This is a class provided by the IFC Export add-on that hold every aspect of your export configuration, from knowing if you want to export the BaseQuanties to the path to the IfcPropertySets mapping files.

You get the Id of the active view and use the UpdateOptions method of IFCExportConfiguration to pass it along with all other properties to the IFCExportOptions.

The IFC Export add-on also provide an IFCExportConfigurationsMap class to get the built-in configurations and store the new ones.

The existing export setups

But where find these IFCExportConfiguration and IFCExportConfigurationMaps classes ?

If the IFC for Revit add-on is installed, you can find these classes in the IFCExporterUIOverride.dll. This dll can be found in your ApplicationPlugins folder, in the IFC plugin install folder (C:\ProgramData\Autodesk\ApplicationPlugins\IFC 2018.bundle\Contents\2018)

Running this on a Revit equipped with the add-on will work nicely, but it will fail miserably when the user doesn’t have the IFC for Revit add-on. In this case, the add-on can’t find the IFCExporterUIOverride.dll containing the IFCExportConfiguration class:

Using IFCExportConfiguration without the add-on

If you have a Revit version with the IFC Exporter UI built in (Revit 2017 or 2018), the IFCExportConfiguration and IFCExportConfigurationMaps classes can be found in the IFCExportUI.dll, located in your Revit installation folder (C:\Program Files\Autodesk\Revit 2018\AddIns\IFCExporterUI). In this case, the features available are the same than our previous case, but are in a different dll.

If you don’t have the IFC Exporter UI at all (Revit 2016 and earlier versions), you must fall back to the basic export options.

In a nutshell, we have to manage these three cases:

Class DLL Revit version
IFCExportConfiguration IFCExporterUIOverride.dll

In C:\ProgramData\Autodesk\ ApplicationPlugins\IFC 2018.bundle\Contents\2018

All Revit version equipped with the IFC for Revit add-on
IFCExportConfiguration IFCExportUI.dll

In C:\Program Files\Autodesk\Revit 2018\AddIns\IFCExporterUI

Revit 2017 and 2018 without the IFC for Revit add-on
IFCExportOptions RevitAPI.dll

In C:\Program Files\Autodesk\Revit 2018

Revit 2016 and earlier without the IFC for Revit add-on

To manage these different cases, I created my own export configuration class, named IFCExportConfigurationCustom. This class handle the configuration of the export and is an interface between my code and the possible IFC export options.

I load in my Visual Studio solution the two dll containing the IFCExportConfiguration class, and using alias, I call a different version of it depending on the installation of the user:

IFCExportUI::BIM.IFC.Export.UI.IFCExportConfiguration
IFCExportUIOverride::BIM.IFC.Export.UI.IFCExportConfiguration

I also handle the vanilla Revit 2016 in my IFCExportConfigurationCustom class, without using any version of the IFCExportConfiguration (which is not available in this version of Revit), using instead the plain old IFCExportOptions built-in into Revit.

By managing the different possibilities of the Revit installation, I am able to make use of the best configuration available to export IFC. I am also able to use directly the Setup configuration interface available in the custom UI, and retrieve these user-defined export setups in my add-on.

Edit IFC Export Setup

If you plan on building your own Revit add-on to upload IFC models to a cloud service, don’t hesitate to look into the source code behind this article, the solution can be found on Github.

By opening the source code of its IFC engine, Autodesk make an underrated effort toward interoperability. Even if it’s obviously not for every Revit user, I think that everyone who rely on the Revit IFC export for its own software should look at this engine to get a full understanding of the possibilities offered by this exporter

 

Revit and bimsync Just Got a Room Together!

This is no mystery that I am a big fan of bimsync. But the lack of integration with Revit make things a bit too time consuming than it should be. To start solving this issue, I created a small Revit plugin to upload your model to bimsync in a single click.

You must first log into your bimsync account. After clicking on login, a browser session will open, and bimsync will ask for your credentials and if you want to allow the Revit plugin to be connected to your account. This will grant the plugin access rights to your bimsync account.

Login into your bimsync account

Login into your bimsync account

Once connected, your credential will be safely stored on your computer so you won’t have to login the next time you open Revit.

You can now upload model to your bimsync account. Select “Upload”, select your bimsync project and model, type in the associated comment, select the IFC settings and click on “Upload”. After a while, depending on your file size, your Revit model will be uploaded to bimsync.

Upload your model to bimsync

Upload your model to bimsync

The Setup drop down allows you to select the IFC Export configuration. You can choose a standard “bimsync” recommended setup, an existing setup, or create a new one.

After the first export, bimsync project and model ids will be saved in your Revit model, so you won’t have to select them again the next time. If you are curious, you can find these ids in your Project Information:

Your Project information

Your Project information

To create your own IFC Export setup, you can use the usual IFC Setup Dialog. Select File -> Export -> IFC to open the “Export IFC” dialog. Select “Modify Setup” to open the “Modify Setup” windows, and click on “New” to create a new configuration. You can now set everything in this new configuration before selecting OK to close the “Modify Setup” windows. You can now safely close the IFC Export dialog without exporting anything, and open again the Upload dialog in the bimsync plugin. Your new configuration will be available in the drop-down.

Edit IFC Export Setup

Edit IFC Export Setup

You can also go directly to your bimsync account from Revit by clicking on “Profile”. This is not very useful, but at least you will be a few clicks nearer to change your profile picture.

Under the hood, the system is quite simple. The plugin will look at your selected IFC Setup and use them to export your Revit model in an IFC file. This file is then zipped and uploaded to bimsync.

Between exporting to IFC, compressing the file and uploading it to bimsync, the entire process can be rather long. Depending on your model size, computing power and Internet bandwidth, the Upload command can take a few minutes to complete. I am thinking on using the Autodesk service Forge to convert Revit model to IFC online, freeing your computer from this tedious task.

You can already download the plugin on the Autodesk App Store.

As usual, the entire source code is available on Github, feel free to use it on your own project. Don’t hesitate to report on any issue you might have with this plugin, there is always a lot of room for improvement.

VR for Revit

I recently get my hand on an HTC Vive headset, and I spend some time exploring various solutions to display a model in this headset.

The HTC Vive headset

There are a handful of solutions, like the Revit Live from Autodesk or Enscape, but I choose to focus on a VR-only solution build by IrisVR, Prospect.

Installing Prospect is pretty straightforward, and you end up with the Prospect application along with the Revit plugin.

I run the Revit plugin, select a 3D view, and export my model to the Prospect application.

Export your Revit model to a VR scene

The resulting virtual visit is saved in my Prospect library. I can also save this scene as an external file, to open it in another computer running Prospect and a Vive headset.

The visit itself is divided in two, a scale model overview and a walkthrough.

In the scale model mode, you can see a small-scale view of the model that you are able to manipulate like any 3D view in your favorite design tool. You can also add sections and move them around. The feeling is close to manipulating an actual physical mockup, as we move it, turn it around and “grab” it to have a closer look.

Section and rotation of the scale model

This scale model mode also works as the entry point to the virtual visit itself, as it allows you to teleport yourself in the building.

Teleport in the model

In the second mode, the visit itself, you can actually walk into the building and look around. The navigation tool is well designed, and you quickly end up teleporting yourself everywhere in the building, walking around like you own the place.

Along with the walkthrough, Prospect provide a few tools for design review, like screenshots and markups. You can draw a few notes in mid-air and take a picture of your annotations for later review.

There is also a nice daylighting simulation tools which helps us feel the light inside the future building.

Daylighting analysis

Daylighting analysis

To enjoy all these features, you will need a Pro subscription, but you can start with the free tiers, which include the ability to create a VR scene from Revit, Rhino and Sketchup.

The overall experience is really interesting, and let us imagine new workflows to validate a design with a colleague or a client. The main drawback, shared by any VR experience, is the lack of interaction with others. Strapped in your headset, you can only see what is inside the scene, and the experience feels rather lonely. However, this is probably the best tool to immerse yourself in the future building and get a sense of the space and light.

Revit plugins updates and new features

As usual during this time of the year, I published the new version of my plugins for Revit.

Align

The big improvement this year is the ability to align any type of elements, annotations or tags. I must thank Deyan Nenov and his large contribution to the source code for this new feature.

From now on, you can select any kind of element and align or distribute them evenly. This feature use the bounding box of the element in the view as a reference.

Align or distribute all elements

The Align command is still view-dependent, so using it in section view or in a plan view will not have the same effect on the overall position of a given element. A word of caution however, the align function can be unreliable in a 3D view.

View-dependent align functions

Of course, you can still use it to align or distribute your tags and annotations, and it even works with viewports:

Align viewports

Along with these improvement, Align now fully support Area tags, and a few bugs have been eliminated. You can now use Align even if on tag without a leader, and multi-leader text are now fully supported, and some selection subtlety have been introduced.

Align tags and texts

I haven’t tested it with all categories, if you find something weird, please let me know, I would be happy to fix it.

You can find this new version on the Autodesk App Store.

Room Finishing

Along with the support for Revit 2018, I corrected an issue where a skirting board was created even if the room was not bound by a wall. From now on, Room Finishing will not create a skirting board along room bounding lines.

Support room with room boundary lines

Room Finishing is also available on the App Store.

Time Stamper

The Time Stamper plugin got a few improvements this year along with the usual bug smashing.

You can now choose between applying your time stamp to every element, or just the one visible in the view. This will give you the ability to filter on which element you want to apply a stamp.

You can also choose to keep or override an existing value, this should help you keep the history of a given element.

A few bugs where corrected, making the creation of the four shared parameters far more reliable. Groups are now supported.

Support for groups

Time Stamper is now available here.

These new versions are now available on the Autodesk App Store. Don’t hesitate to report any issue you might find in them or ask for improvement.

These plugins are open source, you can find the source code here, here and here. Feel free to use it on your own project or contribute to these projects.

Modeling a neighborhood with Flux Site Extractor, GIS data and Revit

Since my last post, I kept on working on urban development. I particularly think about importing GIS data into our usual authoring tools. My experience with Infraworks was interesting, but it is still difficult to use this data in a Revit model.

The most promising resource out there for creating a context in a Revit model is the Flux Site Extractor. You select an area, add some features to extract and send them to a Flux project.

The Flux Site Extractor interface

After retrieving this data in my Flux Site Project, I use the Flux Dynamo nodes to get the topography as a mesh, extract the vertices of this mesh as points and use these points to create a toposurface in Revit.

Creating a toposurface from the Flux Site Extractor

Building profiles and heights came from OpenStreetMap, and aren’t accurate enough to be used for site analysis. But I am using building profiles to draw on a plan view the footprint of every building retreived with Flux. This will help me futher down the road to align my buildings on the toposurface.

Buildings footprints drawn in a plan view

I found more accurate data on the parisian buildings on the APUR Open Data plateform. I download this data as a shapefile containing every building in Paris.

Obviously, this dataset is too large to be imported as it in Revit. I am using QGIS, an open source GIS application, to extract a subset of this file. To do so, I draw a polygon encompassing the few city blocks I want to retrieve and use the “Clip” function to create a new shapefile containing only the selected buildings.

Isolate the propers city blocks

I am using the DynamoGIS package to import this shapefile into Revit. These nodes allow me to read the file and extract the shapes of the buildings.

The most difficult thing here was to include inner boundaries in a building shape. These boundaries are not taken into account by the Surface.ByPatch node. I manage to split the first surface (the largest) using the inner curve. This allow me to create the hollowed surface.

Highlight of inner boundaries

The DynamoGIS include nodes to query any value associated with shapes. I am using them to retrieve building heights in the dataset and extrude my buildings at their proper height.

Since it is GIS data, I am using a nice tip from LandArch to move my geometry near the project base point, and make it usable in Revit.

I am using the FamilyInstance.ByGeometry node from the great Spring nodes of Dimitar Venkov to create the buildings as mass families.

This Dynamo definition create a mass family for every building in the shapefile, extruded up to its actual height. Combined with the toposurface created with Flux, this look like an actual neighborhood, where you can think about massing and site integration directly in Revit.

Site integration of a project

This process still has a few issues. The buildings aren’t adjusted at the toposurface and aligning them with the toposurface created with the Flux Site Extractor involve some manipulations. I still have some work to do on this process to streamline it, and get a more accurate representation of an existing site.

Another view of the project

 

Linking documents to a model

These days, there is a lot of ideas around using a building information model for facilities management. Among these ideas, a recurring theme is to integrate documents, mostly technical sheets, directly into the model.

Aside from the fact that I don’t see how a model build to design, analyse, and coordinate a building could be use directly in facilities management, there is also some non-trivial technical problems to overcome to have any documents properly linked to your model, whether you are using Revit, Navisworks, or an IFC viewer.
Below is a list of these technical problems, and some though on how to solve them.

Adding a link in Revit

Adding a link in Revit is fairly straightforward, you just have to use a “URL” parameter (shared or built in), and type in your link. Since a technical sheet is generally the same for every building element of a given type, it makes more sense to me to add it in a type parameter.

Door Type URL parameter

Door Type URL parameter

As you can see, I type in a relative path to my technical documentation, this allows me to move around the entire “As-built documentation” folder (models and technical sheets in PDF) without breaking the links. I end up with a pretty simple folder structure, with a model at its root, and the technical sheets nicely ordered in one folder per category.

The folder structure

The folder structure

If you click on the small “…” button in Revit, your linked technical document will immediately open in the associate viewer, here, Acrobat Reader.

How to open the linked technical sheet

How to open the linked technical sheet

Adding a link without Revit

Selecting equipment and material is generally done through spreadsheets or building economy software, and by people who could not be proficient with Revit. Therefore, I have searched for solution to do it outside Revit.
The new Flux Scheduler is an application based on Flux, which allows us to create online schedules from data uploaded through the Revit Flux plugin.

The Flux Scheduler

The Flux Scheduler

By using this Flux Scheduler, I could upload my doors on Flux, create a door schedule directly on Flux, use Excel to add the URL link, and upload back these values in Revit

Type the URL in Excel before uploading them in Revit

Type the URL in Excel before uploading them in Revit

Delivering a Navisworks model

Once exported to Navisworks, the “Link” button will display a small link button on every linked object, which open the linked technical sheet.

The link in Navisworks

The link in Navisworks

However, you must keep your Navisworks model in the same location in your “As-Build Documentation” folder structure as your initial Revit model to keep the relative links functional. In our case, we end up with the following folder structure:

The folder structure with a Navisworks model

The folder structure with a Navisworks model

Delivering an IFC model

If you export this Revit model to IFC, and open it in Solibri Model Viewer, you can display the link, but not click on it. However, by writing a “\” before the link in Revit, Solibri Model Viewer recognize it as link and you can open the technical sheet with a click. This could obviously become problematic in Revit, since when you add this “\”, Revit doesn’t recognize the link anymore.

The clickable link in Solibri

The clickable link in Solibri

Tekla BIMSight, on the other hand, couldn’t recognized any of those links as a clickable item.

As you can see, they are many ways to link documents to a model and retrieve them in a viewer, and a few things could go wrong along the way. So, before starting anything, I would recommend to make sure you can link or embedded documents in your deliverables and structure these deliverables accordingly.

Room Finishes Update

I keep on working on my Revit add-ins. After Align, it is now Room Finishes who have been updated to support Revit 2017. Along with this update, I also have integrated some new features.

First of all, Room Finishes now support all kind of units. You just have to type your dimension with its unit symbol, and the plugin will convert it in a floor height or a skirting board height. The plug-in will now also use the default length unit of your model.

interface

I have to thanks Brian Winterscheidt for this update, who was kind enough to contribute to my plug-in on Github, and point me to the Revit unit conversion system available in the API.

The other major update is the ability to join skirting board with their supporting wall. You can now join both geometries automatically. This enable one of the most wanted feature, the ability to cut the skirting board around the door.

Just select “Join geometry” before running the command, and every skirting board will be joined with its host wall.

join

This feature could generate its fair share of warning, so I have remove every related error message. You will now be able to run this command without having to dismiss every warning that come up.

I also add some minor UI improvements, like the ability to resize the window, or sorting wall type names by alphabetical order to be able to quickly find the specific wall type you have created for your skirting board or your floor finish.

Of course, Room Finishes is still open source, the entire code can be found on Github.

This plug-in is already available on the Autodesk App Store. If you like it, don’t hesitate to write a nice comment or add a few stars, it always means so much to me!

Align Tag Update

It is this time of the year again, and I have finally take the time to update Align on the App Store for the new version of Revit.

However, there is more in this than a simple version update, and this new release is packed with improvement, both small and large.

The main change reside in the alignment method. In the previous version of Align Tag, I was using the center point of a given tag as a reference to align tag (either left or right). To improve on the alignment of tags of various sizes, I now use the bounding box of the tag.

AlignSolution

Tags will now properly align themselves along their right or left side, regardless of their size or origin point.

Align

However, if you want something similar to the older version, you can use the new Align Center and Align Midlle commands, which will use the center of the tag as a reference.

This new alignment method is more in line with what can be found on solutions like PowerPoint, or Adobe Illustrator, and will allows you to neatly arrange your tag whatever their size or origin point.

Another important improvement is the long awaited support for Text. You can now align Text along with Tag, using the same command.

While I was at it, I also add support for Keynote tag, Room Tag and Space Tag, basically every tag. The Area Tag is still missing, but can be expected for the next version.

However, this support came at a cost, and I have to drop the support for Revit 2015 and prior. So, if you are still using this version, you will have to keep the old Align plugin.

There is also a handful of small UI improvement that I hope will help you.

Aligned tags are now kept selected after running the command so you can align them in another direction right away.

Your Align commands are also one click closer to you! The interface have been artfully arranged in a new tab to keep every icon directly accessible in the ribbon.

icons1

Under the hood, I have rewrote a large part of the code to support more types of annotation elements, and I hope to be able to use this new framework for more complex manipulations, including in the Arrange Tags function.

Of course, Align Tag is still open source, the entire code can be found on Bitbucket.

This plug-in is already available on the Autodesk App Store. If you like it, don’t hesitate to write a nice comment or add a few stars, it always means so much to me!

Bridge design

One of my colleague is currently working on bridge design with Revit. I have to admit, my first reaction was more like “Revit is not fit for bridge modeling, period”. But after some thought, I found Revit to be a pretty interesting solution to design these kind of infrastructures.

The main issue is that even a simple bridge has a rather complex geometry, with a double-curved alignment and potentially a variable cross section. There is various possibilities to create this kind of geometry in Revit, I will present only one of them here.

This entire article is mostly inspired by the work of Matthias Stark, from Autodesk, and its great AU 2015 class.

The alignment

The first issue we ran into while designing our bridge is the inability for Revit to create a real double-curved, 3D curve.
This is why I create my alignment in Rhino, and use Grasshopper to create a list of X, Y and Z coordinates that define points along my alignment. Another solution is presented by Matthias Stark in his class, where he is using AutoCAD Civil 3D to export the coordinates of the alignment in an Excel spreadsheet.

Once I have all my coordinates in an Excel file, I use a simple definition in Dynamo to create a series of reference points in a Mass family, and use these points to create a curve representing my alignment.

Alignement

I also make sure that units in my Revit mass family are consistent with the unit of my alignment coordinates points.

The cross section

To create the cross section shape of my bridge, I use an adaptive family with a single adaptive point, which will be placed on our alignment.

The keep our cross section properly aligned with our bridge axe, I use the “Orient to” parameter of the adaptive point. By setting it to “Global (z) the Host (xy)”, I make sure than the X and Y axes (Red and Green) will follow my alignment, while the Z axe will stay vertical.

axesI make a few try before getting it right, but I was finally able to properly align my adaptive component with the divided path. Since the X (Red) axis will be tangent to the alignment, I had to draw my cross section in the “Center (Left/Right)” plane of the adaptive family.

adaptiveFamily

Modeling

The rest of the modeling is pretty straightforward. After placing the first adaptive component on a divided path based on our alignment, just select Repeat to place one on every division point, then decompose the Repeat pattern and create a form.

repeat

form

To create the cavity inside the bridge deck, I use the same divided path to place two cavity profiles (right and left) and create two void forms to cut into the bridge deck.

voidForms

Section View

The main issue with this mass family is around dimensions. If you try to add dimensions directly on the Mass family in a section view, these dimensions will be anchored on the wrong point.

firstSection

To be able to create section view anyway, I am using the adaptive component loaded in the Mass family. I make it visible in the project and draw a detail line along one of them. This detail line allows me to draw a section view perfectly aligned with my adaptive component

sectionView

Since my section is perfectly aligned with my profile, it appears in the view and can be used as a reference for the dimensions. I temporary hide my mass family, place the necessary dimensions and show again the mass.

With this workaround, I was able to create a simple section view, with the proper dimensions.

section

Matthias Stark also present in his class an entire detailing process using Dynamo, and that I still have to explore this part. But his approach to bridge modeling allows me to create a great first draft, and I will keep on digging this solution.

Measuring ceiling heights

I recently have to measure the actual headroom of every room in an architectural model, and copy this value in a room parameter.

Instead of checking manually every room, I create a small Dynamo definition, based on the most underrated node in Dynamo, Raybounce.

The Raybounce.ByOriginDirection is basically a laser rangefinder for Dynamo. It works with an origin point and a direction, and give in return the first intersecting element, along with the point of intersection. It is pretty powerful, and its uses range from basic measurements to advanced Line Of Sight Analysis.

UsingRaybounce

Using DynamoMEP, I retrieve every room in the model, and create a grid of points in each of them. These points are arbitrary spaced 50 cm apart, and serve as origin points for my Raybounce node.

RetriveRooms

Furthermore, in order to avoid that my laser beams hit the floor, I move my origin points 1 cm above the floor level.

MoveOriginPoints

The Raybounce.ByOriginDirection use these points, a Z vector as a direction and a 3D view. Since only elements visible in this view will be detected, I hide doors and stairs to remove interferences with these elements.

RayBounce

Along with the intersection point, the Raybounce.ByOriginDirection return the origin point that I filter out with a boolean mask.

FilterPoints

Points

I also make use of the List.Map node to perform any kind of operation (Flatten, Sort …) on the sublist containing the points while keeping them grouped by lists corresponding to the original rooms.

ListMap

I finally calculate the headroom height, and retrieve the shortest one for each room. I pass this value to the Limit Offset parameter of the corresponding room.

CalculateHeadRoom

Initially, every room’s Limit Offset is 2m.

Before

After running the Dynamo script, every Limit Offset is updated to reflect the actual minimum headroom in each room. Since we have a sloped roof, the minimum headroom is not necessarily the ceiling, but can be the lower part of the roof.

After

Using the Raybounce node can be quite challenging, especially when it comes to sorting the resulting points, but it is totally worth the effort. You will find here the Dynamo definition, feel free to use it for your own project.

This was also the occasion for me to update DynamoMEP for Dynamo 1.0, and add a Grid function to create a nice array of point in a Room or a Space. As usual, you will find these updates in the Dynamo Package Manager.