Sandbox:TutorialArchBIM


 * Vilanova Artigas
 * pictures by Pedro Kok
 * Barão de Jaceguaí, 1151 - Campo Belo, São Paulo-SP (Google) With 30 images

Goal of this document
Update original Arch Tutorial by Yorik van Havre.

The purpose was to seriously try to learn some Freecad Work flows, after playing with it at various points in time for at least the last 5 years.

Reflect version 0.17 / 0.18 of Freecad Use a BIM workflow

Currently this document is WORK in Progress

Images
All Images not already on wiki are named and uploaded to File:at2_*

Introduction
This tutorial aims at giving you the basics to work with the Arch Workbench. I will try to make it simple enough so you don't need any previous experience with FreeCAD, but having some experience with 3D or BIM applications will be useful. In any case, you should be prepared to look for yourself for further information about how FreeCAD works on the FreeCAD documentation wiki. The Getting started page is a must read, if you have no previous experience with FreeCAD. Also check our tutorials section, and on youtube you will also find a lot more of FreeCAD tutorials.

The purpose of the Arch Workbench is to offer a complete BIM workflow inside FreeCAD. As it is still under development, don't expect to find here the same tools and level of completion as grown-up commercial alternatives such as Revit or ArchiCAD, but on the other hand, FreeCAD being used in a much bigger scope than these applications, the Arch Workbench greatly benefits from the other disciplines FreeCAD caters to, and offers some features rarely seen in traditional BIM applications.

Here are, for example, a couple of interesting features of FreeCAD's Arch Workbench that you'll hardly find in other BIM apps:


 * Architectural objects are always solids. From FreeCAD's strong mechanical background, we learned the importance of always working with solid objects. This ensures a much more error-free workflow, and very reliable boolean operations. Since cutting through 3D objects with a 2D plane, in order to extract sections, is also a boolean operation, you can immediately see the importance of this point.


 * Architectural objects can always have any shape. No restrictions. Walls don't need to be vertical, slabs don't need to look like slabs. Any solid object can always become any architectural object. Very complex things, usually hard to define in other BIM applications, like a floor slab curving up and becoming a wall (yes Zaha Hadid, it's you we're talking about), present no particular problem at all in FreeCAD.


 * The whole power of FreeCAD is at your fingertips. You can design architectural objects with any other tool of FreeCAD, such as the PartDesign Workbench, and when they are ready, convert them to architectural objects. They will still retain their full modeling history, and continue being totally editable. The Arch Workbench also inherits much of the Draft Workbench functionality, such as snapping and working planes.


 * The Arch Workbench is very mesh-friendly. You can easily design an architectural model in a mesh-based application such as Blender or SketchUp and import it in FreeCAD. If you took care of the quality of your model and its objects are manifold solid shapes, turning them into architectural objects only requires the press of a button.

At the time of writing, the Arch Workbench, as the rest of FreeCAD, suffers some limitations. Most are being worked on, and will disappear in the future.


 * FreeCAD is no 2D application. It is made for 3D. There is a reasonable set of tools for drawing and editing 2D objects with the Draft Workbench and Sketcher Workbench, but it is not made for handling very large (and sometimes badly drawn) 2D CAD files. You can usually successfully import 2D files, but don't expect very high performance if you want to keep working on them in 2D. You have been warned.


 * No materials support. FreeCAD will have a complete Material system, able to define very complex materials, with all the goodies you can expect (custom properties, material families, rendering and visual aspect properties, etc), and the Arch Workbench will of course use it when it is ready.


 * Very preliminary IFC support. You can already import IFC files, quite reliably, provided IfcOpenShell is installed on your system, but exporting is still not officially supported. This is worked on both by the FreeCAD and IfcOpenShell developers, and in the future we can expect full-powered IFC support.


 * Most Arch tools are still in development. That means that automatic "wizard" tools that create complex geometry automatically, such as Arch Roof or Arch Stairs can only produce certain types of objects, and other tools that have presets, such as Arch Structure or Arch Window only have a couple of basic presets. This will of course grow over time.


 * Relations between objects in FreeCAD are still not officially available. These, for example the relation between a window and its host wall, are currently implemented in the Arch Workbench with temporary (and therefore somewhat limited) methods. Many new possibilities will arise when this feature will be fully available.


 * Units are being implemented in FreeCAD, which will allow you to work with any unit you wish (even imperial units, you guys from the USA can be eternally grateful for this to Jürgen, FreeCAD's godfather and dictator). But at the moment the implementation is not complete, and the Arch workbench still doesn't support them. You must consider it "unit-less". This tutorial uses millimeters as units.

Typical workflows
In this tutorial we focus on a BIM oriented approach of using FreeCad. We will use mostly three workbenches: Arch Workbench and BIM, of course, but also Draft, whose tools are all included in Arch, so there is no need to switch workbenches, and Sketcher. Conveniently, can create a custom toolbar in your Arch workbench, with Tools → Customize, and add the tools from the sketcher that you use often.

Preparation
Instead of creating a project from scratch, let's take an example project to model, it will save us time. This wonderful house by the famous architect Vilanova Artigas (see a series of pictures by Pedro Kok), because it is close to where Yorik lives. It is simple, it's a wonderful example of the amazing modernist architecture of São Paulo. Drawings in dwg format are easily available. We will use the 2D DWG drawings obtained from the link above (you need to register on the above site to download, but it's free, or grab directly a dxf version here) as a base to build our model. So the first thing you'll want to do is to download the file, unzip it, and open the DWG file inside with a dwg application such as DraftSight. Alternatively, you can convert it to DXF with a free utility such as the Teigha File Converter. If you have the Teigha converter installed (and its path set in the Arch preferences settings), FreeCAD is also able to import DWG files directly. But since these files can sometimes be of bad quality and very heavy, it's usually better to open it first with a 2D CAD application and do some cleaning. Here, all the detail drawings are removed, all the title-blocks and page layouts. A "clean" ("purge" in AutoCAD slang) to remove all unused entities, reorganized the sections at a logical location in relation to the plan view, and moved everything to the (0,0) point. After that, our file can be opened quite efficiently in FreeCAD. Check the different options available in Edit → Preferences →



This is how the file looks after being opened in FreeCAD. Changed the thickness of the walls (the contents of the "muros" group), and flipped a couple of doors that were imported with wrong X scale, with the Draft Scale tool:

Preparing dwg / dxf Alternative text
For editing and exporting to dxf there are various free tools available. Found that of the free tools out there, [DraftSight by Dassault] worked fine. Most files when importing are in Meters. Scale by 1000 (same scale on all axis), either in FC or other system. To Isolate the various views, I found most effective was deleting all but the one I was seeking, and doing a SaveAs, with dxf as extension. This was repeated for all views.

Next, import the various views to Freecad.

Tip It is a good idea to import or save the various views into separate FCStd files. This keeps the files smaller and quicker to work with. Naming of files is Your choice, but it is a good idea to use a naming convention.

FIXME

Need place to upload attached files

''For dxf files, they are placed in a directory named ./ref/dxf below the project directory. If You want to skip this step, the imported dxf files can be found here.''

Plan View
Start with importing and placing the Plan View.



Your imported geometry will now turn up as a bunch of edges. It is a good idea to organize these into a Group. The Group can be created before importing, or You can select all the imported edges and ‘drag/drop’ them into the Group.



Now, do the same for all the other views. Next In this document, we will place the various view at their location, elevation and rotation, according to our ArchAxisSystem. Before Rotating and placing the various views, we need to do some planning.

Tip

FIXME needs Checking

FreeCad dxf import treats everything as Edges or Shapes, This is generally ok for lines. Bad for circles. No easy way to find Center.

Planning
As a minimum

A defined project zero / origin – with local x,y,z coordinates 0,0,0 shall be defined and used throughout the project.

Tip

For further planning of File structure jump to the IFC section of this document

In this project we will follow Axis system of downloaded original Drawings.



Defining the project origin at intersection of Axis 01 & D. By our convention this equals SouthWest corner of model. Observe that the axis pass through the center of walls.

When modeling any Architectural model, You will most certainly want to split into separate files. By the way, partial IFC files seem to be the trend at the moment. Mainly split by discipline. The split can be by discipline or other. It is good practice to have a common origin and orientation across these models (files). This makes it easy to copy paste groups between files as needed. It also provides a good basis for several people to work on the project as needed.

Tip

For reference we have made the assumption that global Y-axis equals North.

Defining the Arch Axis System
We now want to make an ArchAxisSystem for reference when modeling our building. The result will look something like this:



To find the data for making the ArchAxisSystem study the Plan View of the imported dwg. This will show You Axis and Dimensions.



Alternatively measure between the various axis in Freecad. This can be done in several ways, using the part workbench Measure linear, Tape Measure works fine for this.



By Studying original dxf files.



When measuring distance between axis 10 and 11, we find Delta X = 3.6246 Index 11 above, has been adjusted since if possible, we like to work with ‘round’ figures.

Arch axis X
Now, let’s make the Axis along global X: The Freecad Command is Arch Axis



Image shows Data and labels Used.

Arch Y-Axis


Image shows Data and labels Used.

Tip

Observe the 270deg rotation and offset of placement to get labels to get desired layout.

Combining to Axis System
Arch AxisSystem is used to combine the x and y Arch Axis into an Arch Axis system.

Tip If You save Your AxisSystem to a file, without any other geometry, it does not seem to open as the first file. FreeCad simply Crashes. However, not such a big deal, because if You open another file containing geometry first, then You are able to open the file containing only the AxisSystem without any problem. Strange??

Placing and rotating 2d Views
In order to place 2d views in 3d, we need to prepare some helper objects. In FreeCad we have several ways we can set-up, store and name Working Planes. We can name these and store them by using a WorkingPlaneProxy object.



You should end up with something looking like this

Tip

By placing and rotating the imported 2d view, You will have a good way of checking their consistency.

Walls
Walls can be:
 * Inner / Outer, Structural / Non Structural
 * Walls should contain openings for doors, windows, or other

Like most Arch objects, walls can be built upon a big variety of other objects: lines, wires (polylines), sketches, faces or solid (or even on nothing at all, in which case they are defined by height, width and length). The resulting geometry of the wall depends on that base geometry, and the properties you fill in, such as width and height. As you might guess, a wall based on a line will use that line as its alignment line, while a wall based on a face will use that face as its base footprint, and a wall based on a solid will simply adopt the shape of that solid. This allows about any shape imaginable to become a wall.

There are different possible strategies to build walls in FreeCAD. One might want to build a complete "floor plan" with the sketcher, and build one, big, wall object from it. This technique works, but you can only give one thickness for all the walls of the project. Or, you can build each piece of wall from separate line segments. Or, this is what we will do here, a mix of both: We will build a couple of wires on top of the imported plan, one for each type of wall:

Tip

Have found the KISS principle (Keep It Simple & Stupid) is a good approach.


 * Using lines as a base for walls works fine.
 * They are easy to move and change.
 * When editing the line defining a wall, the wall will update
 * At a later stage You can always join them as needed.

FIXME

So how to organize? Believe the main differing factor is Structural / Non Structural Next Level Inner / Outer

Curtain Walls are always Non Structural

Floors
Generally defined as Slabs

Doors
Inner or outer

Windows
Inner or Outer

IFC and BIM
Building Information Modelling (BIM) is a very broad term that describes the process of creating a digital model of a building.

Planning BEP ( BIM Execution Plan) All BIM projects should have a BEP ( BIM Execution Plan) As a minimum Origin point, northing, and elevation One of the simplest yet most critical aspects of good project coordination is the establishment of a common or shared base point for all BIM data to follow. It is also essential to have a common site base point as the data is used through the life-cycle of the building. IFC Links Planning and Standards by U.S. General Services Administration IFC4 - is it ready yet?

IFC round tripping Aim is to also test round tripping, exporting IFC from FreeCAD and importing same file for comparison. Abbreviations BEP | BIM Execution Plan References & Links

Tip Icon Downloaded

Document Draft Snippets This is where we have temporarily stored snippets of text, that maybe should be placed somewhere in the document

BIM requirements by stakeholders UK Government In the UK, the Government Construction Strategy published in May 2011, stated that the '...government will require fully collaborative 3D BIM (with all project and asset information, documentation and data being electronic) as a minimum by 2016'. This represents a minimum requirement for Level 2 BIM on centrally-procured public projects.

Customizing Arch WorkBench
This is an example "customized" Arch workbench:



In this tutorial, we will model the house in 3D, based on the 2D drawings we will download from the net, and extract from it 2D documents, such as plans, elevations and sections.