Arch tutorial/it

Introduzione
Questo tutorial è guida pratica che mira a fornire le basi per lavorare con l'ambiente Architettura. Cercherò di renderla abbastanza semplice, in modo che non serva alcuna precedente esperienza con FreeCAD, è comunque utile avere almeno una discreta esperienza con il 3D o con le applicazioni BIM. In ogni caso, si deve essere disposti a cercare in proprio, nel wiki della documentazione di FreeCAD, ulteriori informazioni su come funziona FreeCAD. Chi non ha mai provato FreeCAD deve prima leggere la pagina Per iniziare. È utile consultare anche la nostra sezione dedicata ai tutorial e ricordare che su youtube si trovano molte altre guide sull'uso di FreeCAD.

Lo scopo dell'ambiente Arch è quello di offrire un flusso completo di lavoro BIM all'interno di FreeCAD. Poiché è ancora in fase di sviluppo, non aspettatevi di trovare gli stessi strumenti e il grado di perfezionamento delle evolute alternative commerciali come Revit o ArchiCAD, ma d'altra parte FreeCAD è utilizzato in un ambito molto più vasto di quanto lo siano queste applicazioni e l'ambiente Arch trae grossi benefici dalle altre discipline a cui FreeCAD si rivolge, e offre alcune caratteristiche viste raramente nelle applicazioni BIM tradizionali.

Ecco, come esempio, alcuni caratteristiche interessanti dell'ambiente Arch di FreeCAD che è difficile trovare in altre applicazioni BIM:


 * Gli oggetti architettonici sono sempre dei solidi. Dal forte retroterra meccanico di FreeCAD abbiamo appreso l'importanza di lavorare sempre con degli oggetti solidi. Questo assicura un flusso di lavoro con meno possibilità di errori, e le operazioni booleane sono molto affidabili. Dato che tagliare degli oggetti 3D con un piano 2D, per estrarre le sezioni, è anche un'operazione booleana, è possibile intuire immediatamente l'importanza di questo punto.


 * Gli oggetti architettonici possono sempre avere qualsiasi forma. Non c'è nessuna restrizione. I muri non devono necessariamente essere verticali, le solette non hanno bisogno di apparire come solette. Ogni oggetto solido può sempre diventare qualsiasi oggetto architettonico. Cose molto complesse, di solito difficili da definire in altre applicazioni BIM, come una soletta curva che cresce diventando un muro (sì, è proprio di Zaha Hadid che stiamo parlando), in FreeCAD non presentano nessun problema particolare.


 * Tutta la potenza di FreeCAD è a portata di mano. È possibile progettare gli oggetti architettonici con qualsiasi altro strumento di FreeCAD, ad esempio con quelli di PartDesign, e poi, quando sono pronti, convertirli in oggetti architettonici. Essi conservano sempre l'intero storico della loro modellazione, e continuano ad essere completamente modificabili. L'ambiente Arch eredita anche gran parte delle funzionalità dell'ambiente Draft, quali lo snap e i piani di lavoro.


 * L'ambiente Arch è molto mesh-friendly. Si può facilmente progettare un modello architettonico con un'applicazione basata su mesh, ad esempio Blender o SketchUp, e poi importarlo in FreeCAD. Se la qualità del modello è stata curata e i suoi oggetti sono forme solide non-manifold, per trasformarlo in oggetto architettonico basta premere un tasto.

In questo momento, però, l'ambiente Arch, come il resto di FreeCAD, soffre di alcune limitazioni. Sulla maggior parte si sta lavorando e in futuro spariranno.


 * FreeCAD non è una applicazione 2D. È pensato e sviluppato per il 3D. Mette a disposizione un discreto insieme di strumenti per il disegno e la modifica di oggetti 2D negli ambienti Draft e Sketcher, ma non è fatto per gestire grandi (e talvolta mal disegnati) file di CAD 2D. Di solito è possibile importare correttamente i file 2D, ma non aspettatevi prestazioni elevate se intendete continuare a lavorare su di essi in 2D. Siete stati avvertiti.


 * Per ora non c'è nessun supporto di materiali. FreeCAD avrà presto un sistema completo di Materiali, in grado di definire dei materiali molto complessi, con tutte le chicche che ci si può aspettare (proprietà personalizzate, famiglie dei materiali, il rendering e le proprietà aspetto visivo, ecc), e ovviamente appena sarà pronto l'ambiente Arch lo utilizzerà.


 * Supporto molto preliminare di IFC. È già possibile importare i file IFC, in modo abbastanza affidabile, a condizione che IfcOpenShell sia installato sul sistema, ma l'esportazione non è ancora supportata ufficialmente. Su questo stanno lavorando sia gli sviluppatori di FreeCAD che di IfcOpenShell, e ci si può aspettare in futuro il completo supporto di IFC.


 * La maggior parte degli strumenti di Arch sono ancora in sviluppo. Ciò significa che gli strumenti automatici "wizard", quelli che creano automaticamente delle geometrie complesse, quali Tetto o Scala possono produrre solo alcuni tipi di oggetti, e che altri strumenti che hanno delle impostazioni predefinite, quali Struttura o Finestra, per ora hanno solo un paio di preimpostazioni di base. Ovviamente cresceranno nel tempo.


 * Le Relazioni tra gli oggetti non sono ancora ufficialmente disponibili. Attualmente, per esempio, la relazione tra una finestra e la sua parete ospitante, sono implementate nell'ambiente Arch con metodi temporanei e quindi un po' limitati. Quando questa funzione sarà completamente disponibile saranno presenti molte nuove possibilità.


 * In FreeCAD è già stato implementato il Sistema di Unità di misura che permetterà di lavorare con qualsiasi unità desiderata (anche con le unità di misura imperiali, e di questo chi proveniene dagli Stati Uniti può essere eternamente grato a Jürgen, il padrino e dittatore di FreeCAD). Al momento, però l'attuazione non è completa, e l'ambiente Arch non lo supporta ancora. È necessario considere Arch come "unit-less", cioè adimensionale.

Flussi di lavoro tipici
L'ambiente Arch è fatto principalmente per due tipi di flussi di lavoro:


 * Costruire il modello con una applicazione più veloce, basata su mesh come Blender o SketchUp, e importarlo in FreeCAD per estrarre i piani e le viste delle sezioni. FreeCAD è stato pensato per la modellazione di precisione, ad un livello molto più elevato di quello che di solito serve per la modellazione architettonica, costruire i modelli direttamente in FreeCAD può essere faticoso e lento. Per tale motivo, questo flusso di lavoro presenta grandi vantaggi. Nel mio blog ho descritto il procedimento in questo articolo. Se il modello è curato, corretto e preciso (pulito, solido, mesh non-manifold), questo flusso di lavoro dà le stesse prestazioni e lo stesso livello di precisione dell'altro.


 * Costruire il modello direttamente in FreeCAD. Questo è il procedimento che voglio mostrare in questo tutorial. Useremo principalmente tre ambienti di lavoro: naturalmente Arch, ma anche Draft, i cui strumenti sono tutti inclusi in Arch e quindi non c'è bisogno di cambiare ambiente, e Sketcher. Per comodità, come faccio di solito, si può creare una barra degli strumenti personalizzata per il proprio ambiente Arch, con Strumenti -> Personalizza, e aggiungervi gli strumenti di Sketcher che si usano spesso. Questo è il mio ambiente Arch modificato "su misura":



In questo tutorial, modelleremo la casa in 3D, sulla base di disegni 2D scaricati dalla rete e estrarremo dal modello i documenti 2D, quali piante, prospetti e sezioni.

Preparazione
Per modellare, invece di creare un progetto da zero, prendiamo un progetto di esempio che ci farà risparmiare tempo. Ho scelto questa splendida casa del famoso architetto Vilanova Artigas (vedere una serie di immagini di Pedro Kok), perché è vicino a dove vivo io, è semplice, è un meraviglioso esempio di splendida architettura moderna di São Paulo (è anche in vendita se si dispone di "pochi" Reals da spendere), e i disegni dwg sono facilmente disponibili.

Useremo i disegni 2D DWG ottenuti dal link indicato sopra (per scaricare è necessario registrarsi, ma è gratis) come base per costruire il nostro modello. Quindi la prima cosa da fare è scaricare il file DWG, scompattarlo e aprirlo all'interno di un'applicazione dwg quale DraftSight. In alternativa, è possibile convertirlo in DXF con una utility free come Teigha File Converter. Se avete Teigha converter installato (e il suo percorso è definito nelle impostazioni delle preferenze di Arch), FreeCAD è anche in grado di importare direttamente i file DWG. Ma siccome questi file possono a volte essere di cattiva qualità e molto pesanti, di solito è meglio aprirli prima con un'applicazione CAD 2D e fare un po' di pulizia.

In questo caso, ho rimosso tutti i disegni dei dettagli, tutti i cartigli e i layout di pagina, ha fatto una "pulizia" ("purga" in gergo AutoCAD) per rimuovere tutte le entità non utilizzate, riorganizzato le sezioni alla posizione logica in relazione alla vista in pianta, e spostato tutto al punto (0,0). Dopo di che, il file può essere aperto molto efficiente in FreeCAD. Controllare le diverse opzioni disponibili in Modifica -> Prefereze -> Draft -> Import/Export che possono influenzare il modo e la velocità di importazione dei file DXF/DWG.

Ecco come appare il file dopo essere stato aperto in FreeCAD. Con lo strumento Scala ho cambiato anche lo spessore delle pareti (i contenuti del gruppo "muros"), e girato un paio di porte che sono state importate con scala X sbagliata:



L'importatore DXF (che si occupa anche del file DWG, siccome quando si importano file DWG, essi sono semplicemente convertiti prima in DXF ), raggruppa gli oggetti importati dai layer. Non ci sono layer in FreeCAD, ma ci sono i gruppi. I gruppi offrono un modo simile per organizzare gli oggetti dei file, ma non hanno delle proprietà specifiche, come i layer di AutoCAD, che applicano al loro contenuto. Ma possono essere posizionati all'interno di altri gruppi, il che è molto comodo. La prima cosa che potremmo voler fare qui, è quello di creare un nuovo gruppo in vista albero, fare clic destro sull'icona del documento, aggiungere un gruppo, fare clic destro su di esso per rinominarlo "base 2D plans", e trascinarvi dentro tutti gli altri oggetti.

Costruire i muri
Come la maggior parte degli oggetti Arch, i muri possono essere costruiti su una grande varietà di altri oggetti: linee, contorni (polilinee), schizzi, facce o solidi (o anche su nulla, nel qual caso essi sono definiti da altezza, larghezza e lunghezza). La geometria risultante della parete dipende da quella geometria di base, e dalle proprietà definite, come la larghezza e l'altezza. Come si può immaginare, un muro basato su una linea usa questa linea come sua linea di allineamento, mentre un muro basato su una faccia usa tale faccia come sua impronta di base, e un muro basato su un solido adotta semplicemente la forma di tale solido. Questo permette a qualsiasi forma immaginabile di diventare un muro.

In FreeCAD sono possibili diverse strategie per costruire un muro. Si potrebbe voler costruire un intero "piano" con sketcher, e poi su di esso costruire un solo, grande, oggetto muro. Questa tecnica funziona, ma si può assegnare un solo spessore per tutte le pareti del progetto. In alternativa, è possibile costruire ogni parte di muro basati su segmenti di linea distinti. Oppure, con un mix di entrambi, e questo è quello che faremo qui. Costruiremo un paio di polilinee sopra il piano importato, una per ogni tipo di muro:



Come potete vedere, ho disegnato in rosso le linee che diventeranno muri di cemento (una ricerca di immagini della casa può aiutare a distinguere i diversi tipi di muro), quelli verdi sono i muri di mattoni esterni, e quelli blu diventeranno le pareti interne. Ho fatto passare le linee attraverso le porte, perché le porte saranno inserite nelle pareti più avanti, e creeranno automaticamente le loro aperture. Le pareti possono anche essere allineate a sinistra, a destra o centralmente sulla loro base, quindi non importa da che parte si disegna la linea di base. Ho anche cercato di evitare intersezioni per quanto ho potuto, perché in questo modo il nostro modello sarà più pulito. Ci occuperemo delle intersezioni più avanti.

Quando questo è fatto, mettere tutte quelle linee in un nuovo gruppo, se si desidera, selezionare ogni riga uno per uno, e premere lo strumento Muro per costruire un muro da ciascuna linea. È anche possibile selezionare contemporaneamente più linee. Dopo aver fatto questo, e aver corretto le larghezze (i muri esterni sono di 25 centimetri e quelli interni sono di 15 centimetri) e alcuni allineamenti, i muri sono pronti:



Avremmo anche potuto costruire i muri partendo da zero. Se si preme il pulsante Muro con nessun oggetto selezionato, si possono scegliere due punti sullo schermo per disegnare un muro. Ma in realtà, lo strumento parete disegna comunque una linea e poi vi costruisce sopra un muro. Ho ritenuto il procedimento proposto più didattico per spiegare come funzionano le cose.

Avete notato che ho avuto grande cura di non incrociare i muri? Questo ci permetterà di evitare dei mal di testa in seguito, per esempio se esportiamo il nostro lavoro in altre applicazioni, che potrebbero non gradire le intersezioni. Ho solo una intersezione, dove ero troppo pigro per disegnare due piccoli segmenti e ho disegnato una lunga polilinea che ne incrocia un'altra. Questo deve essere corretto. Fortunatamente, tutti gli oggetti Arch hanno una grande caratteristica: è ​​possibile aggiungerli uno all'altro. Facendo questo si uniscono le loro geometrie, ma rimangono ancora modificabili in modo indipendente. Per aggiungere uno dei muri che che si incrociano all'altro muro, basta selezionare uno, CTRL + selezionare l'altro, e premere lo strumento Aggiungi:



Sulla sinistra si sono i due muri che si intersecano, sulla destra il risultato dopo aver aggiunto uno all'altro

Ad esempio, avrei potuto disegnare tutte le mie linee di base di cui sopra, senza preoccuparmi di cosa attraversavano e poi sistemarle con lo strumento Aggiungi. Ma avrei elevato molto la complessità del mio modello, senza nessun vantaggio. Meglio farle corrette fin dall'inizio, e tenerle come pezzi molto semplici di geometria.

Ora che i muri sono sistemati, dobbiamo incrementare la loro altezza, fino a quando intersecano il tetto. Poi, dal momento che l'oggetto muro ancora non può essere troncato automaticamente dalla copertura (questo però accadrà in futuro), costruiremo un oggetto "fittizio", che segue la forma del tetto, da sottrarre dai muri.

In primo luogo, guardando nei disegni 2D, possiamo vedere che il punto più alto del tetto è 5,6m dal suolo. Quindi cerchiamo di dare a tutti i muri un'altezza di 6m, in modo da essere certi che saranno tagliati dal nostro volume tetto "fittizio". Si può chiedere: perché 6m e non 5.6m?. Beh, se avete già lavorato con le operazioni booleane (addizioni, sottrazioni, intersezioni), dovreste già sapere che queste operazioni di solito non gradiscono molto le situazioni "face-to-face". Esse preferiscono decisanente gli oggetti intersecati. Così, facendo in questo modo, continuiamo sul sicuro.

Per aumentare l'altezza dei muri, basta selezionarli tutti nella vista ad albero, senza dimenticare quello che abbiamo aggiunto all'altro, e modificare il valore della loro proprietà "height".

Prima di creare il tetto e di tagliare le pareti, costruiamo i rimanenti oggetti che dovranno essere tagliati: le pareti dello studio superiore, e le colonne. Le pareti dello studio sono create nello stesso modo di prima, sul piano piano superiore, ma sono alte 2,6 m. Quindi a loro assegneremo l'altezza necessaria, non 6m che è troppo, ma 3,4 m. Una volta fatto questo, spostiamo in alto le pareti di 2,6 m: Selezionarle entrambe, mettersi in vista frontale (Visualizza -> Viste Standard -> Front), premere il pulsante Sposta, selezionare il primo punto, poi immettere 0, 2.6, 0 come coordinate, e premere Invio. Gli oggetti ora sono spostati in alto di 2.6m:



Ora spostiamo i muri in orizzontale, nella loro posizione corretta. Dato che abbiamo dei punti di snap, questo è più facile: Selezionare entrambi i muri, premere lo strumento Sposta, e spostarli da un punto all'altro:



Infine, ho cambiato il colore di alcuni muri in un colore simil-mattone (così è più facile differenziarli), e fatto una piccola correzione. Siccome alcuni muri non vanno fino al tetto, ma si fermano ad una altezza di 2.60m, ho corretto la loro altezza.

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, their 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.

Subtractions
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 or 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:



Remember that for both Arch Add and Arch Remove, the order you select the objects is important. The host is always the last one, like in "Remove X from Y" or "Add X to Y"

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 actual object. I also added two more profiles for the side walls of the bathroom opening.



When everything is in place, it's just a matter of using the Draft Trimex tool to extrude, then convert them to Arch Structure objects.



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 continues 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.

The chimney
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
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:



The stairs
Now the stairs. Met 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.

Using presets
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.

So all we need to do now is select the door, press the Draft Clone tool, then move the clone to its correct position with the Draft Move tool.

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.

Editing windows
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.

Output
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.

Preparations
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.

Rendering
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.

2D drawings
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.

Shape views

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.

Drawing views

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.

Quantities extraction
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.

Using spreadsheets

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



Conclusion
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