VIZ Day 5/6 – AEC Object Modeling and Gabled Roofs
AEC objects are parametric objects that have editable component parameters and work together as a system. Windows and doors automatically penetrate walls as long as everything remains AEC, and are editable within the wall. We will look at some of the objects and methodologies for using this system, as well as ways of predictably creating segmentation in an object such as a gabled roof.
1) Begin with a simple drawing in AutoCAD outlining the perimeter walls and the roof plan. Any interior partitions should be drawn with a different color or different layer.
a. It’s just going to be faster and easier to draw this sort of thing in AutoCAD, and moving from one program to another is a more than useful ability. It’s a very important fact of life in modeling and visualization.
b. In the image above, the floor plan, roof plan, and interior partition walls are drawn as they would be placed on top of one another and colored differently. For clarity, I have broken them out individually.
2) Save the drawing as a DWG, Import the plans into Viz, and separate entities by color.
a. Import an AutoCAD DWG drawing directly into Viz by going to File – Import. The default options besides the options highlighted in the image are usually sufficient.
3) From this point, you can begin by turning off the roof lines and the interior partitions. We will begin the model using the AEC walls.
a. Select Create – Geometry – AEC Extended – Walls. Set the width and the height of the walls to be created and the justification of the wall.
i. The justification of the wall determines how the parametric wall object is derived from the spline. AEC Wall objects are spline based, meaning that for all intents and purposes editing on these objects is done as if editing a spline. i.e. snaps will most often be 2D rather than 3D, for instance. The wall object is created to the left, right, or center of that originating line.
ii. If the walls should be set on top of the foundation slab, then you need to set the justification so that the wall is created to the interior of the spline. I used Left justification to do this.
b. Using the Keyboard Entry rollout, select the Pick Spline option and select your perimeter walls.
i. The perimeter walls should be a polyline. If this is not a closed shape, you may have issues using the Pick Spline option (such as the corners not completing). You can go into the sub-object mode Vertex on the spline and weld vertices if the object happens to still be open after the import.
c. There are three sub-object modes of the AEC wall. Vertex primarily deals with the lengths of wall segments, and vertices can be added to the wall segments in this mode. Segment primarily deals with the height and width of each individual wall segment, and additional segments can be added or removed in this mode. Profile deals with the shape of the wall segments in the elevation of the segment. We will explore the Profile sub-object mode in more detail shortly.
4) Extrude the spline using a negative number to create the floor slab.
5) Create doors in the model using the AEC Door function. Create – Geometry – Doors – Pivot Door.
a. Before you actually begin drawing the doors, isolate the walls by first selecting the wall object, then clicking ALT & Q at the same time, or using Tools – Isolate Selection.
b. Turn on 3D Snaps, and in the tool options (right-clicking the snaps button) ensure that edge / segment snap and edge / segment snap only is activated.
c. In the perspective viewport, create the door by snapping to the wall edges. Click and drag the width while snapping to the outer segment of the wall, single-click the depth by snapping to the opposite side of the same wall, then single-click the height by snapping to the base of the wall.
i. Once the door is drawn, you can modify the height and the width of the door. The reason you snap to the wall in this way is to ensure the door “links” to the wall object and creates its own opening.
d. Play with the parameters of the door once it has been snapped into place in the wall. You can create quite a few styles from these parameters in real-time.
e. The door can now be copied into other wall segments. Snap the door while shift-transforming to ensure that the door stays inside the walls.
6) Windows work the same way that doors do. Create – Geometry – Windows – Fixed Window
a. Windows can also be copied and propagated around the building. Use the copy clone to change the window parameters to be unique, and use the instance clone to make exact duplicates of the window that will update with any changes of its clones.
7) Let’s go ahead and build the roof for our model. This does not use AEC functions, but uses spline and box modeling techniques. Overall, we are going to create a series of closed splines, attach them all together, extrude them for thickness, then edit the vertices of the extrusion to achieve the hip and gable roof.
a. In the display panel, unhide all, select the roof plan splines, then hide everything else.
b. We are going to trace these splines so that we have a single closed spline for each facet of the roof. For clarity, begin by moving the splines imported from AutoCAD about 12’ from the ground plane.
i. Using 2.5D snaps in the top view, trace around each polygonal facet in the roof plan, closing each spline.
c. Once all of the facets have been traced, attach all of the closed spline facets together to create a single editable spline object. (Geometry Rollout in the Modify panel with any of the closed splines selected - attach)
d. Use the Extrude modifier on the newly created closed spline object. Turn on Edged Faces mode (right-click on the context sensitive area in the upper-left hand corner of the viewport window – edged faces) to see the segmentation in the extruded object.
e. Place an Edit Poly modifier on the object. You can now access all of the sub-object modes – specifically the Vertex sub-object mode of the Edit Poly modifier.
f. Fence-select each stack of vertices that are to be moved in the positive Z axis so they can be moved at one time. Use the Move transform on these vertices to pull them up (you can use the transform type-in to move them a specific height).
g. In Polygon sub-object mode, select all of the polygons and clear the smoothing groups (Polygon Properties rollout – Clear All button)
h. Move the roof to the desired height.
8) Now we will modify the AEC walls to meet the roof profile.
a. In Profile sub-object mode, select one of the segments where the peak occurs in a gable. A grid will be placed on the surface of the wall segment. Set the height of the gable and click on the Create Gable button.
b. For profiles that need to be shaped, but Gable isn’t appropriate, use the Insert button to add and place vertices in the profile. If possible, click and drag using insert to place the points where you need them before releasing the button. Transforming the points after creation can be tricky.
c. A known bug in the program relates to “Real World Scale”. If you do not see the profile update, go back to the Wall level in the modify panel and then check and un-check the “real world scale” button.
9) If you want to create windows that aren’t available in the AEC Window options, you can Boolean holes into the AEC objects to provide those specialty windows. You must, however, do this step last and collapse the stack beforehand in order to retain the object’s progress up to this point.
a. First collapse the stack or convert the walls to an editable poly object. This will retain all holes, profiles, and other edits that have been done to this point.
i. Keep in mind that no other AEC windows or doors can be added once the object has been collapsed.
b. Do the Boolean operations as necessary on the object. Remember to retain any shapes that you might need to create mullions, frames, and other necessities.
10) Build in the interior partitions and continue adding detail.
