Tutorial Módulo de Arquitectura
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El objetivo de este tutorial es ofrecer los aspectos básicos del Módulo de arquitectura. Trataré de hacerlo lo más simple posible para que resulte útil a aquellos que no tengan experiencia previa con FreeCAD pero sí posean cierta experiencia con programas de 3D o aplicaciones BIM. En cualquier caso, hay que estar preparados para buscar más información acerca de cómo funciona FreeCAD en la Wiki de documentación de FreeCAD. Para quienes no posean experiencia previa en Freecad la página Getting started/es es esencial, así como también puede ser interesante visitar la sección de tutoriales y los tutoriales publicados en: esta página de youtube
El objetivo del Módulo de arquitectura es ofrecer un flujo de trabajo completo de BIM dentro de FreeCAD. Dado que todavía está en desarrollo, no es de esperar que tenga las mismas herramientas y nivel de acabado que alternativas comerciales maduras como Revit o ArchiCAD, sin embargo dado el mayor alcance de FreeCAD respecto a estas aplicaciones, el Módulo de arquitectura se beneficia enormemente de las otras disciplinas a las que se orienta FreeCAD y a la vez ofrece características que son raras de ver en aplicaciones BIM tradicionales.
Estos son unos ejemplos de características del Módulo de arquitectura que difícilmente pueden encontrarse en otras aplicaciones BIM:
- Los objetos arquitectónicos son siempre sólidos. Dado que los órigenes de FreeCAD están en la mecánica, hemos aprendido la importancia de trabajar siempre con sólidos. De este modo se asegura un flujo de trabajo más libre de errores ya que se basa en las operaciones booleanas. Dado que el hecho de cortar objetos 3D con un plano 2D para obtener secciones es también una operación booleana, la importancia de trabajar con sólidos salta a la vista.
- Los objetos arquitectónicos pueden tener cualquier forma. Sin restricciones. Los muros no tienen por qué ser verticales, los forjados no tienen que parecer forjados. Cualquier sólido siempre puede convertirse en un objeto arquitectónico. Los objetos muy complejos normalmente son difíciles de definir en otras herramientas BIM, como el caso de forjados que se curvan y se convierten en muros (sí, Zaha Hadid, estamos hablando de ti) no tienen ninguna dificultad añadida en FreeCAD.
- Toda la potencia de FreeCAD en tus dedos. Puede diseñarse cualquier objeto arquitectónico con cualquier herramienta de FreeCAD, como el PartDesign Workbench/es, y una vez listos convertirlos en objetos arquitectónicos. Una vez transformados seguirán conservando todo el histórico de modelado y seguirán siendo totalmente editables. El módulo de arquitectura también hereda gran parte de las funcionalidades del Draft Module/es, como el snapping y los planos de trabajo.
- El Módulo de arquitectura es "mesh-friendly": puede diseñarse un modelo arquitectónico en una aplicación basada en mallas como Blender or SketchUp e importarlo en FreeCAD. En caso de que se haya modelado correctamente y teniendo en cuenta que los objetos sean formas manifold, convertirlas en objetos arquitectónicos puede hacerse con un solo clic.
En el momento de escribir este tutorial, Módulo de arquitectura, al igual que el resto de FreeCAD, tiene ciertas limitaciones. Se está trabajando en la mayoría de ellas, con lo cual desaparecerán en el futuro. Algunas de las limitaciones a tener en cuenta son:
- FreeCAD no es una aplicación 2D, sino que está pensada para trabajar en 3D. A pesar de ello, hay numerosas herramientas para dibujar y editar objetos en 2D con el Módulo de bocetado y el Sketcher Module/es.Sin embargo hay que tener en cuenta que no está pensado para manejar archivos de CAD en 2D demasiado complejos (y no siempre bien dibujados). Pueden importarse archivos en 2D, pero no puede esperarse un gran rendimiento en caso de querer seguir trabajando en 2D. Estáis advertidos.
- No hay soporte para materiales. FreeCAD tendrá un sistema completo para Materiales, capaz de definir materiales complejos con todas las características que pueden esperarse (propiedades personalizadas, familias de materiales, renderizado...) y el Módulo de arquitectura lo usará cuando esté listo.
- Soporte muy básico para IFC. Aunque pueden importarse ficheros IFC con bastante fidelidad (siempre que se tenga instalado IfcOpenShell en el sistema), la exportación todavía no está soportada de forma oficial. Se está trabajando en ello tanto por parte de los desarrolladores de FreeCAD como de IfcOpenShell y es de esperar que en el futuro exista soporte completo para IFC.
- La mayoría de herramientas está todavía en desarrollo. Esto significa que los asistentes automáticos para crear geometría compleja de forma automática, tales como Cubiertas o escaleras únicamente pueden producir ciertos tipos de objetos, mientras que los que asistentes que utilizan conjuntos predefinidos (Como el caso de Estructuras or Ventanas) apenas cuentan con unos pocos modelos predefinidos. Con el tiempo el número de modelos predefinidos irá aumentando.
- FreeCAD todavía no incorpora Relaciones entre objetos, con lo cual relaciones como las que existen entre una ventana y el muro al que pertenece están implementadas utilizando el Módulo de arquitectura de forma temporal y presenta ciertas limitaciones. En el momento en que las relaciones estén implementadas habrá muchas nuevas posibilidades.
- Todavía se están implementando el uso de Unidades que permitirán trabajar en cualquier unidad (incluidas las medidas imperiales -gente de EEUUAA podéis estar eternamente agradecidos a Jürgen, el padrino y dictador de FreeCAD). Sin embargo, su implementación no es completa todavía y el módulo de arquitectura todavía no las soporta. Deberá considerarse que el modelo sea adimensional.
Este tutorial se ha escrito usando la version 0.14 de FreeCAD. Es necesario tener esta versión o superiores para poder seguir las instrucciones, ya que versiones anteriores pueden no tener todas las herramientas u opciones necesarias.
Flujos de trabajo típicos
El Módulo de arquitectura está pensado principalmente para dos tipos de flujos de trabajo:
- Construir el modelo con una aplicación más rápida basada en mallas como Blender o SketchUp y luego importarlo en FreeCAD para extraer vistas de planos y secciones. Modelar completamente en FreeCAD puede ser una tarea ardua y lenta, dado que FreeCAD es una herramienta de modelado de precisión. Por este motivo este flujo de trabajo tiene ciertas ventajas que describí en este this artículo en mi blog (en inglés). Si estás acostumbrado a modelar con precisión y correctamente (de forma límpia, sin mallas non-manifold), este flujo de trabajo te proporcionará el mismo rendimiento y precisión que el otro.
- Construir el modelo directamente en FreeCAD. Esto es lo que veremos en este tutorial. Mayormente utilizaremos tres módulos: Arquitectura, por supuesto, y también Draft (cuyas herramientas están todas incluídas en el módulo de arquitectura y por tanto no será necesario estar cambiando de módulos contínuamente) y Sketcher. Para mayor conveniencia puedes crear una barra de herramientas personalizada dentro de tu módulo de arquitectura a través del menú Herramientas → Personalizar y añadir las herramientas del sketcher que uses más a menudo. Este es mi módulo de arquitectura personalizado:
En este tutorial modelaremos la casa en 3D basándonos en planos 2D que habremos descargado previamenet de la red y luego extraeremos documentación en 2D tal como plantas, alzados y secciones.
En lugar de crear el proyecto desde cero nos basaremos en un ejemplo concreto para ahorrar tiempo. Elegí esta vivienda del famoso arquitecto brasileño Vilanova Artigas (ver la galería de fotografías de Leonardo Finotti) porque está próxima a donde vivo, es sencilla, es un ejemplo perfecto de la arquitectura moderna de São Paulo y es fácil encontrar planos en dwg.
Utilizaremos los DWG en 2D que pueden obtenerse de | este enlace (es necesario el registro para poder descargar los archivos, pero es gratuito) como base para construir nuestro modelo. Lo primero que haremos será descargar el archivo, descomprimirlo y abrir el DWG que contiene mediante una aplicación que permita abrir estos formatos como DraftSight. Opcionalmente puede convertirse el DWG a formato DXF mediante una utilidad gratuita como ODA File Converter. FreeCAD también puede puede importar archivos DWG directamente, para lo cual es necesario tener ODA Converter instalado y haber añadido la ruta hacia el programa dentro de las preferencias de FreeCAD. Sin embargo, dado que este tipo de archivos habitualmente son de mala calidad y muy pesados, suele ser recomendable abrirlos primero con una aplicación de CAD 2D para hacer una limpieza y preparación previas.
El siguiente paso es eliminar todos los detalles del dibujo, todos los titulos y presentaciones y hacer "limpieza" de todas las entidades sin utilizar (el comando "_purge" en argot de AutoCAD) y reorganizar las secciones en la posición lógica en relación a la planta y finalmente mover todo al orígen de coordenadas. Después de todos estos pasos el archivo puede ser abierto de forma bastante eficiente en FreeCAD. Comprueba las distintas opciones disponibles en el menú Edit → Preferences → Draft → Import/Export ya que pueden afectar la forma y rapidez en la que se importen los archivos DXF/DWG.
Este es el aspecto que tiene el archivo tras ser abierto en FreeCAD. También modifiqué el espesor de los muros e hice unas simetrías en un par de puertas que se importaron con la escala X incorrecta utilizando la herramienta Draft Scale/es
El importador DXF (que también se encarga de los archivos DWG, pues en el fondo éstos se convierten primero a DXF) agrupa los objetos importados a través de las capas. En FreeCAD no existen capas, sino grupos. Los grupos ofrecen una forma similar de organizar los objetos de un archivo, pero no tienen propiedades específicas que se apliquen a sus contenidos, tal y como ocurre con las capas de AutoCAD, sin embargo un grupo puede contenerse dentro de otro grupo, lo cual es bastante útil. Lo primero que deberemos hacer es crear un nuevo grupo, para lo cual deberemos hacer clic derecho en el icono de documento de la vista de árbol, añadir un grupo, hacer clic derecho de nuevo y renombrarlo como "planos base 2D" y arrastrar y soltar todos los objetos importados dentro de él.
Construyendo los muros
Como la mayoría de objetos del Módulo de arquitectura, los muros pueden contruirse sobre una gran variedad de otros objetos: líneas, contornos (polilíneas), croquis, caras o sólidos (o incluso ninguno en absoluto, en cuyo caso se definnen a través de su altura, anchura y longitud). La geometría resultante de los muros depende de la geometría base y de las propiedades especificadas, como anchura y altura. Como habrás podido deducir, un muro basado en una línea usará esta como alineación, mientras que si usamos una cara, ésta será su huella base y un muro basado en un sólido símplemente adoptará la forma de ese sólido. Esto implica que cualquier forma imaginable puede convertirse en un muro.
Pueden utilizarse varias estrategias distintas para construir muros en FreeCAD. Una opción podría ser construir una planta completa con el croquizador y construir un solo objeto de tipo muro a partir de él. Otra opción puede ser construir cada segmento de muro a partir de distintos segmentos de líneas. O, tal y como haremos en este tutorial, una mezcla de ambos métodos: construiremos un par de contornos sobre la planta importada, uno para cada tipo de muro:
Tal y como puede verse, he dibujado en rojo las líneas que se convertirán en muros de hormigón (una búsqueda de fotografíasde la casa puede ayudarte a determinar los distintos tipos de muros), los verdes son muros de ladrillo exteriores, y los azules serán los tabiques interiores. Las líneas atraviesan también las puertas, ya que éstas se insertaran sobre los muros más tarde y se crearán los huecos de forma automática. Los muros pueden alinearse a la izquierda, derecha o centro de la línea base, así que no importa demasiado en qué lugar se dibuje la línea base. He tratado de evitar las intersecciones siempre que ha sido posible, ya que el modelo será más limpio de esta forma, pero ya nos ocuparemos de las intersecciones más tarde.
Cuando hayamos hecho esto, es recomendable agrupar todas estas líneas en un nuevo grupo. Tras ello deberemos seleccionar las líneas una a una o varias a la vez y hacer clic en la herramienta Muro para construir un muro a partir de cada una de ellas. Tras hacer esto y corregir los espesores (los muros exteriores tienen un ancho de 25cm y los tabiques son de 15cm) y alineaciones, tendremos nuestros muros listos.
Podríamos haber construido nuestros muros desde cero. Si presionamos el botón Muro sin haber seleccionado ningún objeto, podremos hacer clic en dos puntos de la pantalla para dibujar un muro. Sin embargo, lo que hace a nivel interno la herramienta es en realidad dibujar una línea y construir un muro sobre ella. Es por eso que he considerado más didáctico mostrar cómo funcionan las cosas.
¿Te has fijado en que he tratado de no intersecar ningún muro? Hacerlo nos ahorrará mucho tiempo más tarde, por ejemplo si exportamos nuestro trabajo a otras aplicaciones. Solo existe una intersección, ya que fui demasiado perezoso para dibujar dos segmentos pequeños, así que dibujé una sola polilínea intersecando otra. Eso es algo que debería arreglarse. Afortunadamente todos los objetos arquitectónicos tienen una característica muy interesante: pueden añadirse unos a otros. Al hacerlo, las geometrías se unifican pero siguen siendo editables de forma independiente. Para añadir uno de nuestros muros intersecados a otro basta con seleccionar uno y hacer CTRL+ selección del otro y hacer clic en la herramienta Añadir:
On the left are the two intersecting walls, on the right the result after adding one to the other.
Something is important to consider already. As you can see, in FreeCAD, everything is parametric: Our new "united" wall is made from two walls, each based on a baseline. When you expand them in the tree view, you can see all that chain of dependencies. As you can imagine, this little game can quickly become very complex. Furthermore, if you already know how to work with the sketcher, you might have wanted to draw the baselines with constrained sketches. This whole complexity has a cost: it raises exponentially the number of calculations that FreeCAD has to perform to keep your model geometry up to date. So, think about it, don't add unnecessary complexity when you don't need it. Keep a good balance between simple and complex objects, and keep these for the cases where you really need them.
For example, I could have drawn all my baselines above without caring about what crosses what, and fix things with the Arch Add tool later. But I would have raised much the complexity of my model, for no gain at all. Better make them correct right from the start, and keeping them as very simple pieces of geometry.
Now that our walls are okay, we need to raise their height, until they intersect the roof. Then, since the wall object still cannot be cut automatically by roofs (this will happen some day, though), we will build a "dummy" object, that follows the shape of the roof, to be subtracted from our walls.
First, by looking at our 2D drawings, we can see that the highest point of the roof is 5.6m above the ground. So let's give all our walls a height of 6m, so we make sure they will be cut by our dummy roof volume. Why 6m and not 5.6m? You may ask. Well, if you already worked with boolean operations (additions, subtractions, intersections), you must already know that these operations usually don't like much "face-on-face" situations. They prefer clearly, frankly intersecting objects. So by doing this, we keep on the safe side.
To raise the height of our walls, simply select all of them (don't forget the one we added to the other) in the tree view, and change the value of their "height" property.
Before making our roof and cutting the walls, let's make the remaining objects that will need to be cut: The walls of the above studio, and the columns. The walls of the studio are made the same way as we did, on the superior floor plan, but they will be raised up to level 2.6m. So we will give them the needed height so their top is at 6m too, that is, 3.4m. Once this is done, let's move our walls up by 2.6m: Select them both, put yourself in frontal view (View → Standard Views → Front), press the Draft Move button, select a first point, then enter 0, 2.6, 0 as coordinates, and press enter. Your objects now have jumped 2.6m high:
The Draft objects, and most Arch objects too, obey to a Draft system called working planes. This system defines a 2D plane where next operations will take place. If you don't specify any, that working plane adapts itself to the current view. This is why we switched to frontal view, and you see that we indicated a movement in X of 0 and in Y of 2.6. We could also have forced the working plane to stay on the ground, by using the Draft SelectPlane tool. Then, we would have entered a movement of X of 0, Y of 0 and Z of 2.6.
Now let's move our walls horizontally, to their correct location. Since we have points to snap to, this is easier: Select both walls, press the Draft Move tool, and move them from one point to the other:
Finally, I changed the color of some walls to a brick-like color (so it's easier to differentiate), and made a small correction: Some walls don't go up to the roof, but stop at a height of 2.60m. I corrected the height of those walls.
Raising the structure
Now, since we'll have to cut our walls with a subtraction volume, we might as well see if there aren't other objects that will need to be cut that way. There are, some of the columns. This is a good opportunity to introduce a second arch object: the Arch Structure. Structure objects behave more or less like walls, but they aren't made to follow a baseline. Rather, they prefer to work from a profile, that gets extruded (along a profile line or not). Any flat object can be a profile for a structure, with only one requirement: they must form a closed shape.
For our columns, we will use another strategy than with the walls. Instead of "drawing" on top of the 2D plans, we will directly use objects from it: the circles that represent the columns in the plan view. In theory, we could just select one of them, and press the Arch Structure button. However, if we do that, we produce an "empty" structural object. This is because you can never be too sure at how well objects were drawn in the DWG file, and often they are not closed shapes. So, before turning them into actual columns, let's turn them into faces, by using the Draft Upgrade tool twice on them. The first time to convert them into closed wires (polylines), the second time to convert those wires into faces. That second step is not mandatory, but, if you have a face, you are 100% sure that it is closed (otherwise a face cannot be made).
After we have converted all our columns to faces, we can use the Arch Structure tool on them, and adjust the height (some have 6m, other only 2.25m height):
On the image above, you can see two columns that are still as they were in the DWG file, two that were upgraded to faces, and two that were turned into structural objects, and their height set to 6m and 2.25m.
Note that those different Arch objects (walls, structures, and all the others we'll discover) all share a lot of things between them (for example all can be added one to another, like we already saw with walls, and any of them can be converted to another). So it's more a matter of taste, we could have made our columns with the wall tool too, and converted them if needed. In fact, some of our walls are concrete walls, we might want to convert them to structures later.
Now it is time to build our subtraction volume. The easiest way will be to draw its profile on top of the section view. Then, we will rotate it and place it at its correct position. See why I placed the sections and elevations like that before beginning? It will be very handy for drawing stuff there, then moving it to its correct position on the model.
Let's draw a volume, bigger than the roof, that will be subtracted from our walls. To do that, I drew two lines on top of the base of the roof, then extended them a bit further with the Draft Trimex tool. Then, I drew a wire, snapping on these lines, and going well above our 6 meters. I also drew a blue line on the ground level (0.00), that will be our rotation axis.
Now is the tricky part: We will use the Draft Rotate tool to rotate our profile 90 degrees up, in the right position to be extruded. To do that, we must first change the working plane to the YZ plane. Once this is done, the rotation will happen in that plane. But if we do like we did a bit earlier, and set our view to side view, it will be hard to see and select our profile, and to know where is the basepoint around which it must rotate, right? Then we must set the working plane manually: Press the Draft SelectPlane button (it is in the "tasks" tab of the tree view), and set it to YZ (which is the "side" plane). Once you set the working plane manually, like that, it won't change depending on your view. You can now rotate your view until you have a good view of all the things you must select. To switch the working plane back to "automatic" mode later, press the Draft SelectPlane button again and set it to "None".
Now the rotation will be easy to do: Select the profile, press the Draft Rotate button, click on a point of the blue line, enter 0 as start angle, and 90 as rotation:
Now all we need to do it to move the profile a bit closer to the model (set the working plane to XY if needed), and extrude it. This can be done either with the Part Extrude tool, or Draft Trimex, which also has the special hidden power to extrude faces. Make sure your extrusion is larger than all the walls it will be subtracted from, to avoid face-on-face situations:
Now, here comes into action the contrary of the Arch Add tool: Arch Remove. As you might have guessed, it also makes an object a child of another, but its shape is subtracted from the host object, instead of being united. So now things are simple: Select the volume to subtract (I renamed it as "Roof volume to subtract" in the tree view so it is easy to spot), CTRL + select a wall, and press the Arch Remove button. You'll see that, after the subtraction happened, the volume to subtract disappeared from both the 3D view and the tree view. That is because it has been marked as child of the wall, and "swallowed" by that wall. Select the wall, expand it in the tree view, there is our volume.
Now, select the volume in the tree vieew, CTRL + select the next wall, press Arch Remove. Repeat for the next walls until you have everything properly cut:
Arch objects that support such additions and subtractions (all of them except the "visual" helper objects such as the axes) keep track of such objects by having two properties, respectively "Additions" and "Subtractions", that contain a list of links to other objects to be subtracted or added. A same object can be in the lists of several other objects, as it is the case of our subtraction volume here. Each of the fathers will want to swallow it in the tree view, though, so it will usually "live" in the last one. But you can always edit those lists for any object, by double-clicking it in the tree view, which in FreeCAD enters edit mode. Pressing the escape key exits edit mode.
Making the roofs
Now, all we have to do to complete the structure, is to make the roof and the smaller inner slabs. Again, the easiest way is to draw their profiles on top of the section, with the Draft Wire tool. Here I drew 3 profiles on top of each other (I moved them apart in the image below so you see better). The green one will be used for the lateral borders of the roof slab, then the blue one for the side parts, and the red ones for the central part, that sits above the bathroom block:
Then, we must repeat the rotation operation above, to rotate the objects in a vertical position, then move them at their correct places, and copy some of them that will need to be extruded twice, with the Draft Move tool, with the ALT key pressed, which creates copies instead of moving the current object. I also added two more profiles for the side walls of the bathroom opening.
After that, we can see some problems arising: two of the columns on the right are too short (they should go up to the roof), and there is a gap between the slab and the walls of the studio on the far right (the 2.60 level symbol on the section view was obviously wrong). Thanks to the parametric objects, all this is very easy to solve: For the columns, just change their height to 6m, fish your roof subtraction volume from the tree view, and subtract it to the columns. For the walls, it's even easier: move them a bit down. Since the subtraction volume remains at the same place, the wall geometry will adapt automatically.
Now one last thing must be fixed, there is a small slab in the bathroom, that intersects some walls. Let's fix that by creating a new subtraction volume, and subtract it from those walls. Another feature of the Draft Trimex tool, that we use to extrude stuff, is that it can also extrude one single face of an existing object. This creates a new, separate object, so there is no risk to "harm" the other object. So we can select the base face of the small slab (look at it from beneath the model, you'll see it), then press the Draft Trimex button, and extrude it up to well above the roofs. Then, subtract it from the two inner bathroom walls with the Arch Remove tool:
Floors, stairs and chimney
Now, our structure is complete, we just have a couple of smaller objects to do.
Let's start with the chimney. Now you already know how it works, right? Draw a couple of closed wires, move them up at their correct height with the Draft Move tool, extrude them with the Draft Trimex tool, turn the bigger one into a structure, and subtract the smaller ones. Notice how the chimney tube wasn't drawn on the plan view, but I found its position by dragging blue lines from the section views.
The floors are not well represented in the base drawings. When looking at the sections, you cannot know where and how thick the floor slabs are. So I will suppose that the walls are sitting on top of foundation blocks, at level 0.00, and that there are floor slabs, also sitting on those blocks, 15cm thick. So the floor slabs don't run under the walls, but around them. We could do that by creating a big rectangular slab then subtracting the walls, but remember, subtraction operations cost us. Better do it in smaller pieces, it will be "cheaper" in terms of calculation, and also if we do it intelligently, room by room, these will also be useful to calculate floor areas later:
Once the wires are drawn, just turn them into structures, and give them a height of 0.15:
Now the stairs. Meet the next of the Arch tools, the Arch Stairs. This tool is still in a very early stage of development, at the time I'm writing, so don't expect too much of it. But it is already pretty useful to make simple, straight stairs. One concept is important to know, the stairs tool is thought to build stairs from a flat floor up to a wall. In other words, when viewed from the top, the stairs object occupies exactly the space that it occupies on the plan view, so the last riser is not drawn (but it is of course taken into account when calculating heights).
In this case, I preferred to build the stairs on the section view, because we'll need many measurements that are easier to get from that view. Here, I drew a couple of red guidelines, then two blue lines that will be the base of our two pieces of stairs, and two green closed wires, that will form the missing parts. Now select the first blue line, press the Arch Stairs tool, set the number of steps to 5, the height to 0.875, the width to 1.30, the structure type to "massive" and the structure thickness to 0.12. Repeat for the other piece.
Then, extrude both green wires by 1.30, and rotate and move them to the right position:
On the elevation view, draw (then rotate) the border:
Then move everything into place:
Don't forget also to cut the column that crosses the stairs, because in BIM it's always bad to have intersecting objects. We are building like in the real world, remember, where solid objects cannot intersect. Here, I didn't want to subtract the column directly from the stairs (otherwise the column object would be swallowed by the stairs object in the tree view, and I didn't like that), so I took the face on which the column was built, and extruded it again. This new extrusion was then subtracted from the stairs.
Right! All the hard work is now done, let's go on with the very hard work!
Doors and windows
Arch Windows are pretty complex objects. They are used to make all kinds of "inserted" objects, such as windows or doors. Yes, in FreeCAD, doors are just a special kind of window. In real life too, if you think of it, no? The Arch Window tool can still be a bit hard to use today, but consider this as a tradeoff, as it was built for maximum power. Almost any kind of window your imagination can produce can be done with it. But as the tool will gain more presets, this situation will certainly become better in the future.
The Arch Window object works like this: It is based on a 2D layout, any 2D object, but preferably a sketch, that contains closed wires (polylines). These wires define the different parts of the window: outer frames, inner frames, glass panels, solid panels, etc. The window objects then has a property that stores what to do with each of these wires: extrude it, place it at a certain offset, etc. Finally, a window can be inserted into a host object such as a wall or structure, and it will automatically create a hole in it. That hole will be calculated by extruding the biggest wire found in the 2D layout.
There are two ways to create such objects in FreeCAD: By using a preset, or drawing the window layout from scratch. We'll look at both methods here. But remember that the preset method does nothing else than creating the layout object and defining the necessary extrusions for you.
When pressing the Arch Window tool with no object selected, you are invited either to pick a 2D layout, or to use one of the presets. Let's use the "Simple Door" preset to place the main entrance door of our model. Give it a width of 1m, a height of 2.45m, a W1 size of 0.15m, and leave the other parameters to 0.05m. Then click the lower left corner of the wall, and your new door is created:
You will notice that your new door won't appear in the tree view. That is because, by snapping to a wall, we indicated that wall as its host object. Consequently, it has been "swallowed" by the wall. But a right click on it → Go to selection will find it in the tree.
In this case, as our window is not inserted in any wall (the opening was there already), we might as well detach our window from its host wall. This is done by double-clicking the host wall in the tree view to enter its edit mode. There, you will see the window in its "Subtractions" group. Simply select the window there, press the "remove element" button, then "OK". Our window has now been removed from its host wall, and lies at the bottom of the tree view.
We have a second door, exactly the same as this one, a bit on the left. Instead of creating a new door from scratch, we have two ways to make a copy of the previous one: By using the Draft Move tool, with the ALT key pressed, which, as you already know, copies an object instead of moving it. Or, even better, we can use the Draft Clone tool. The clone tool produces a "clone" of a selected object, that you can move around, but that retains the shape of the original object. If the original object changes, the clone changes too.
Organizing your model
Now would be a good time to do a bit of housecleaning. Since we already have two windows, it is a good moment to do some cleaning in the tree view: Create a new group, rename it to "windows", and drop the 2 windows in it. I also recommend you to separate other elements that way, such as the walls and structures. Since you can also create groups inside groups, you can organize further, for example by placing all elements that form the roof into a separate group, so it is easy to turn on and off (turning a group visible or invisible does the same with all objects inside).
The Arch Workbench has some additional tools to organize your model: the Arch Site, Arch Building and Arch Floor. Those 3 objects are based on the standard FreeCAD group, so they behave exactly like groups, but they have a couple of additional properties. For example, floors have the ability to set and manage the height of the contained walls and structure, and when they are moved, all their contents are moved too.
But here, since we have only one building with only one (and a half) floor, there is no real need to use such objects, so let's stick with simple groups.
Now, let's get back to work. Turn off the roof group, so we can see better inside, and switch the Display Mode of the floor objects to Wireframe (or use the Draft ToggleDisplayMode tool) so we can still snap to them, but we can see the plan view underneath. But you can also turn off the floors completely, then place your doors at level 0, then raise them of 15cm with the Draft Move tool.
Let's place the interior doors. Use the "Simple Door" preset again, make doors of 1.00m and 0.70m wide x 2.10m high, with W1 size of 0.1m. Make sure you snap to the correct wall when you place them, so they automatically create a hole in that wall. If it is hard to place them correctly, you can place them at an easier location, at the corner of the wall, for example, then move them. The "hole" will move together.
If by mistake you hosted a window in the wrong wall, it is easy to fix: Remove the window from the "Subtraction" group of the host wall in edit mode, as we saw above, then add it to the "Subtraction" group of the correct wall, by the same method, or, simply, using the Arch Remove tool.
A little work later, all our doors are there:
After a closer look at the elevation view, I now detected another error: The top of the brick walls is not as 2.60m, but 17.5cm lower, that is, 2.425m. Fortunately, windows based on presets have a facility: You can alter their general dimensions (width and height) from their properties. So let's change their height to 2.425 - 0.15, that is, 2.275. The second window, as it is a clone of the first one, will adapt too. This is basically where the true magic of parametric design appears.
Now we can look at the really interesting stuff: How to design your own custom windows.
Creating custom windows
As I explained above, Arch Window objects are created from 2D layouts, made of closed elements (wires (polylines), circles, rectangles, anything). Since Draft objects cannot hold more than one of these elements, the preferred tool to draw window layouts is the Sketcher. Unfortunately, with the sketcher, it is not possible to snap to external objects like with the Draft workbench, which would be useful here, since our elevations are drawn already. Fortunately, a tool exists to convert Draft objects to a sketch: The Draft To Sketch tool.
So, let's start by building our first window layout. I drew it on the elevation, using several rectangles: One for the outer line, and 4 for the inner lines. I stopped before the door, because, remember, our door already has a frame there:
Then, select all the rectangles, and press the Draft To Sketch button (and delete the rectangles, because this tool doesn't delete the original objects, in case something goes wrong). Then, with the new sketch selected, press the Arch Window tool:
The tool will detect that the layout has one outer wire and several inner wires, and automatically proposes you a default configuration: One frame, made by subtracting the inner wires from the outer one, extruded by 1m. Let's change that, by entering the window's edit mode, by double-clicking on it in the tree view:
You will see a "Default" component, that has been created automatically by the Window tool, that uses the 5 wires (always subtracting the other ones from the biggest one), and has an extrusion value of 1. Let's change its extrusion value to 0.1, to match what we used in the doors.
Then, let's add 4 new glass panels, each using a single wire, and give them an extrusion of 0.01, and an offset of 0.05, so they are placed at the middle of the frame. This will be how your window looks like when you are finished:
I suppose now you must have understood the power of this system: Any combination of frames and panels of any shape is possible. If you can draw it in 2D, it can exist as a full valid 3D object.
Now, let's draw the other pieces, then we'll move everything into place together. But first. we'll need to do some corrections to the base 2D drawing, because some lines are clearly missing, where the windows meet the stairs. We can fix that by offsetting the stairs line by 2.5cm with the Draft Offset tool (with ALT pressed of course, to copy our lines instead of moving them). Now we can draw our layout, with wires, then convert them to a sketch, then making a window of it.
After doing that a couple of times (I made it in 4 separate pieces, but it's up to you to decide), we have our facade complete:
Now, as before, it's just a matter of rotating the pieces, and moving them to their correct position:
Last missing piece, there is a segment of wall that didn't appear on the plan view, that we need to add. We have several options for that, I chose to draw a line on the ground plane, then move it up to the correct height, then create a wall from it. Then, we also need to fish up our roof subtraction volume (it must have stayed in the last column), then subtract it. Now this side of the building is ready:
Ready? Not quite. Look at the image above, we did our doors with a 5cm frame, remember (it was the default from the preset). But the other windows have 2.5cm frames. This needs to be fixed.
We already saw how to build and update window components, via the window's edit mode, but we can also edit the underlying sketch. Preset windows are not different than custom windows, the Arch Window tool only created the underlying sketch fo you. Select our door object (the original, not the copy, remember, we made a clone), and expand it in the tree view. There is our sketch. Double-click it to enter edit mode.
the Sketcher Workbench is an extremely powerful tool. It doesn't have some of the Draft conveniences, such as snapping or working planes, but it has many other advantages. In FreeCAD you will frequently use one or another depending on the need. The most important feature of the sketcher is constraints. Constraints allow you to automatically fix the position of some elements relative to others. For example, you can force a segment to always be vertical, or to always be at a certain distance to another.
When we edit our door sketch, we can see that it is made on a fully constrained sketch:
Now all we need to do is edit the 5cm distances between the outer line and the inner line, by double-clicking them, and changing their value to 2.5cm (Remember, the units are still not fully functional at the time I'm writing this). After clicking the "OK" button, our door (and its clone) have been updated.
Working without 2D support
Until now our work has been relatively easy, because we had the underlying 2D drawings to base our work upon. But now, we must do the opposite facade and the glass atrium, and things are getting more complicated: The opposite facade drawing has a lot of wrong things, doesn't represent the atrium at all, and we have simply no drawing for the inner walls of the atrium. So we will need to invent a couple of things ourselves. Be sure to have a look at reference pictures to figure out how things are made. Or do it as you wish!
One thing we can already do: duplicate the complicated stairs window with the Draft Move tool, because it is equal on both sides:
Note that here, I preferred to duplicate with the Draft Move tool instead of using a clone, because the clone currently doesn't support different colors inside objects. The difference is that the clone is a copy of the final shape of the original object, while if you copy an object, you create a new object and give it all the same properties as the original one (therefore, also its base sketch and its window components definition, which are both stored as properties).
Now we must attack the parts that are not drawn anywhere. Let's start with the glass wall between the sitting room and the atrium. It'll be easier to draw it on the elevation view, because we'll get the correct height of the roof. Once you are in plan view, you can rotate the view from the menu View → Standard Views → Rotate left or right, until you get a comfortable view to work, like this:
Note how on the image above, I made a line from the model to the left section, to get the exact width of the window. Then, I reproduced that width on the elevation view and divided it into 4 pieces. Then I built one main window piece, plus 4 additional windows for the sliding doors. The sketcher sometimes has difficulties with overlapping wires, that's why I preferred to keep them separated like this:
After the necessary rotations, everything clicks perfectly into place:
We still need some corner piece there. A little useful trick with the Draft SelectPlane tool, if you have a face selected when you press the button, the working plane matches this face (at least its position, and if the face is rectangular, it also tries to match its axes). This is useful to draw 2D objects directly on the model, such as here, we can draw a rectangle to be extruded directly at its correct position:
Then let's do the two remaining pieces. One is easy, it is a copy of what's on the other side, so we can simply use the 2D drawing:
The other one is a bit tricky, by looking at the pictures, we see that it has many vertical divisions, like the stairs windows. By chance (or very good design from Vilanova Artigas), the width of our window, of 4.50m, is exactly the same as the stairs window, so we can use the exact same division: 15 pieces of 30cm. Here I used the Draft Array tool to copy over the two lines 15 times,and drew rectangles on top of them:
Once this is done, we can create our window with the same method we already know. Another small useful trick, in case you haven't found it yourself already: When editing a window, if you change the name of a component, it actually creates a duplicate of it. So to create the 15 inner glass panels, instead of clicking 15 times the "add" button and fill 15 times the data, you can just keep editing one, and change its name and wire, it will create a copy each time.
After the window is rotated and moved into place, the atrium is complete:
Edits and fixes
Now when we look at our back elevation, and compare it with the plan, we see that there are some differences that need to be fixed. Namely, the bedroom windows are smaller than I first thought, and we'll need to add some more walls. In order to do that properly, some floors need to be cut:
We have of course several ways to do that, making a subtraction volume would be an easy way, but it would add unnecessary complexity to the model. Better to edit the base wire of each floors. This is where the Draft Edit mode comes into action. By expanding these floors in the tree view, then making their base wire visible, we can then double-click them to enter edit mode. There, we can move their points, or add or remove points. With this,editing our floor plates becomes easy.
After some more sweat (the person who made those drawings obviously became pretty lazy when did this last elevation, much is drawn wrong), we finally have our complete house:
Note the chimney tube, which is made from a circle I used to make a hole in the chimney block, that I extruded, then converted into a tube with the Part Offset tool.
Sometimes an object you made can have problems. For example, the object it was based onto has been deleted, and the object can therefore not recalculate its shape. These are usually shown to you by a little red sign on their icon, and/or a warning in the output window. There is no generic recipe to fix these problems, because they can have many origins. But, the easiest way to solve them is often to delete them, and, if you didn't delete their base objects, recreate them.
Now, after all the hard work we passed through to build this model, comes the reward: What can we do with it? Basically, this is the big advantage of working with BIM, all our traditional architectural needs, such as 2d drawings (plans, sections, etc), renderings, and calculations (bills of quantities, etc) can all be extracted from the model. And, even better, regenerated every time the model changes. I'll show you here how to obtain these different documents.
Before starting to export stuff, one consideration is interesting to do: As you saw, our model is becoming increasingly complex, with a lot of relationships between objects. This can make subsequent calculation operations, such as cutting through the model, heavy. One quick way to magically "simplify" drastically your model, is to remove all of this complexity, by exporting it to the STEP format. That format will preserve all your geometry, but will discard all the relationships and parametric constructions, keeping only the final shape. When reimporting that STEP file into FreeCAD, you will get a model that has no relationship, and a much smaller file size. Think of it as an "output" file, that you can regenerate anytime from your "master" file:
Exporting to IFC and other applications
One of the very fundamental things you need when working with BIM is to be able to import and export IFC files. This is still a work in progress in FreeCAD. IFC format is already supported, and importing IFC files into FreeCAD is already pretty reliable. Exporting is still experimental, though, and has currently many limitations. However, things are bettering and we should get proper IFC export very soon.
IFC export requires very little setup, once the necessary software libraries are installed. You only need to recreate the building structure, which is needed in all IFC files, by adding an Arch Building to your file, then an Arch Floor, then moving all the groups of objects that compose your model in it. Make sure you leave your construction geometry (all the 2D stuff we've been drawing) out of it to avoid making your IFC file unnecessarily heavy.
Another thing to set, is to check the "Role" property of structural elements. Since IFC has no "generic" structural element, like FreeCAD, we need to assign them roles (column, beam, etc...) so the exporter knows what element to create in the IFC file.
In this case, we need our whole architectural system, so the IFC exporter can know if an object must be exported as a wall or a column, so we are using our "master" model, not our "output" model.
Once this is done, simply select your building object, and choose the "Industry Foundation Classes" format. Exporting to non-BIM applications, such as Sketchup is also easy, you have several export formats at your disposal, such as Collada, STEP, IGES ou OBJ.
FreeCAD also features a rendering module, the Raytracing Workbench. That workbench currently supports two render engines, PovRay and LuxRender. Since FreeCAD is not designed for image rendering, the features that the Raytracing workbench offer to you are somewhat limited. The best course of action when you want to do proper rendering, is to export your model to a mesh-based format such as OBJ or STL, and open it in an application more suited to rendering, such as blender. The image below has been rendered with blender's cycles engine:
But, for a quick rendering, the Raytracing workbench can already do a good job, with the advantage of being very easy to setup, thanks to its templates system. This is a rendering of our model fully made within FreeCAD, with the Luxrender engine, using the "indoor" template.
The Raytracing workbench still offers you very limited control over materials, but lighting and environments are defined in templates, so they can be fully customized.
Certainly the most important use of BIM is to produce 2D drawings automatically. This is done in FreeCAD with the Arch SectionPlane tool. This tool allows you to place a section plane object in the 3D view, that you can orient to produce plans, sections and elevations. Section planes must know what objects they must consider, so once you have created one, you must add objects to it with the Arch Add tool. You can add individual objects, or, more conveniently, a group, a floor or a whole building. This allows you to easily change the scope of a certain section plane later, by adding or removing objects to/from that group. Any change to these objects gets reflected in the views produced by the section plane.
The section plane automatically produces cut views of the objects it intersects. In other words, to produce views instead of sections, you just need to place the section plane outside of your objects.
The section planes can produce two different outputs: shape objects, that live in the same document as your 3D model, or drawing views, that are made to use on a drawing sheet produced by the Drawing workbench. Each of these behave differently, and has its own advantages.
This output is produced by using the Draft Shape2DView tool with a section plane selected. You produce a 2D view of the model directly in the 3D space, like on the image above. The main advantage here is that you can work on them using the Draft tools (or any other standard tool of FreeCAD), so you can add texts, dimensions, symbols, etc:
On the image above, two Shape2D views have been produced for each section, one showing everything, the other showing only the cut lines. This allows us to give it a different line weight, and turn hatching on. Then, dimensions, texts and symbols have been added, and a couple of DXF blocks have been imported to represent the furniture. These views are then easy to export to DXF or DWG, and open in your favorite 2D CAD application, such as LibreCAD or DraftSight, where you can work further on them:
Note that some features are still not supported by the DXF/DWG exporter so the result in your 2D application might differ a bit. For example, in the image above, I had to redo the hatching, and correct the position of some dimension texts. If you place your objects in different groups in FreeCAD, these become layers in your 2D CAD application.
The other kind of output that can be produced from section planes is a Drawing view. These are produced by using the Draft Drawing tool with a section plane selected. This method has one big limitation compared to the previous one: you have limited possibilities to edit the results, and at the moment, things like dimensioning or hatching are still not natively supported.
On the other hand, the final output being easier to manipulate, and the graphical possibilities of the SVG format being huge, in the future, undoubtedly this will be the preferred method. At the moment, though, you'll get better results using the previous one.
On the image above, the geometry is the direct output of the section plane, but some other Draft objects have been added, such as dimensions and hatched polygons, and another view object with same scale and offset values has been produced from them with the Draft Drawing tool. In the future, such operations will be done directly on the Drawing page, leaving your model totally clean.
This is another very important task to be performed on BIM models. In FreeCAD, things look good right from the start, since the OpenCasCade kernel of FreeCAD already takes care of calculating lengths, areas and volumes for all the shapes it produces. Since all Arch objects are solids, you are always guaranteed to be able to obtain a volume from them.
There is a brand-new workbench in FreeCAD, the Spreadsheet Workbench, that is the perfect tool for collecting such information about our model. It can count objects of a certain name or a certain type, or display a specific properties of those objects. The spreadsheet workbench features two objects: The spreadsheet object is a simple spreadsheet container, that you can edit, and place values inside the cells, but has no automation. The cell controller, on the other hand, is an object that you must insert in a spreadsheet, that controls a series of cells of its host spreadsheet, filling them according to what you specify. This, provided that you organized your model well, allows you to easily retrieve individual values:
Note that the spreadsheet workbench is still very new, and like everything very new, still contains many bugs and limitations. But for simple summaries like this, it already works well. The resulting spreadsheet can then be exported to a CSV file, which can be imported in any spreadsheet application.
The survey mode
Another way to survey your model and extract values, is to use the Arch Survey mode. In this mode, you can click on points, edges, faces or double-click to select whole objects, and you get altitude, length, area or volume values, shown on the model, printed on the FreeCAD output window, and copied to the clipboard, so you can easily pick and paste values in another opened application
I hope this gives you a good overview of the available tools, be sure to refer to the Arch Workbench and Draft Workbench documentation for more (there are more tools that I didn't mention here), and, more generally, to the rest of the FreeCAD documentation. Pay a visit to the forum too, many problems can usually be solved there in no time, and follow my blog for news about he Arch workbench development.
The file created during this tutorial can be found here