S206E057 – Spring 2021

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Copyright ©2021, Chiu-Shui Chan. All Rights Reserved. This lecture concentrates on the 3D solid modeling and editing Solid Modeling Method 1: Extrude 2D to 3D to make a curved façade or solid In this method, 2D drawings should be done first. Line drawings are covered in the last lecture. For drawing curves, Handle Curve, Control Point Curve, Sketch and Curve: Interpolate Points, are popular tools used to draw curves. Among them, Interpolate Points is the best drawing tool (my favorite one). These curves could be modified by moving the control points (select curves first, click F10 to turn the control points on and F11 function key to turn them off). Steps:

• Select the curve > Surface Creation > Extrude Curve Straight (or Surface menu > Extrude Curve > Straight, or type Extrudecrv), then the curves will be extruded to meshes. If turn the Solid option (inside the functional selections) on, then a solid mesh will be created to make the entire mess.

• This method extrudes open or closed lines to surfaces (or solids). • By turning the control points on, there are handle and angle handle that could be used to change the size and

rotation angle. The extruded surfaces could be edited by cut and trim functions. Solid Modeling Methods 2: Creating solid objects by solid creation tools of sphere, cone, box etc… This is a simple concept of using primitives as basis for modeling. In Rhino, a solid is an object that has no naked edges, and its outer surfaces are completely joined. On the other hand, solid is an accurate mathematical description of a volume. Thus, solids in Rhino are multiple NURBS surfaces joined into one primitive. Primitives are basic geometric shapes like a cube, sphere, cylinder and pyramid. All operations concerning creating and editing solids could be found in the menu Solid.

1. Solid menu > Cone, pyramid, box, sphere to construct 3D solid forms, or 2. Use cone, pyramid, box and sphere tools inside the “Solid Tools” to create 3D objects as well, or 3. Use “Solid Creation Tool” to generate forms.

Solid Modeling Methods 3: Creating surfaces with operational options of loft, revolve, Sweep 1 Rail and Sweep 2 Rail, Revolve and Rail Revolve options.

• More of this group will be covered later in Lecture 5. Today’s lecture is to provide sequential information on the methods of generating 3D solid objects.

Solid Modeling Method 4: Creating Objects Using Boolean Commands: To create an object in Rhino, click on one of the Solids from the Solid Creation tool pallet.

This box is defined by two points and a height. Height Two base points Note: use multiple windows to create your box. Define the base point in either the top or the perspective view, then activate ortho at the bottom of the modeling window, and then extrude the box in either front or side view. Or simply click two points to define the base and move the mouse up to define the height.

S206E057 -- Lecture 4, 5/11/2021, Rhino Interface – an overview

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Creating complex objects in Rhino is easy to do using the Boolean operations. Simply build the object you want to cut and place it in the correct location relative to the object you want to keep.

Object to cut (Shown highlighted) Object to keep Deselect all objects, and click on Solid, then Difference. Note: in this same menu you have Union and Intersection as well. Select the Difference from solid, or the menu item of Solid, then Difference. Click on the object you want to keep, first. Hit return, or right click. Then click on the object or objects to want to cut from with. Hit return or right click again. If the DeleteInput option is changed to yes, then the cylinder will be erased at the final form. Cut object

Second example of mechanical components:

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Method 5: Adjusting Surface/model by Editing Ctl Points Along with normal objects, you can adjust “blobs”. Start with a sphere. Click on the solids menu > Sphere > Center, Radius. Click in the screen and draw a sphere.

You can now move the control points that define the sphere by clicking on the Edit points on tool. With the sphere selected, click on this tool to turn on point editing (or select the sphere, then hit F10 or F11 function keys). Now in plan or front view select a series of points. Then click and drag the points stretching out the sphere. Note: This will not work with rectangular solids, but will work with spheres and surface. Control points on, and select one point or a row of points. Selected points moved and sphere is deformed.

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Or use window selection to select the entire row and column, and move. This method will make the entire side shape smooth. This process can be applied to almost any NURBs surface.

Rendered Sphere.

In this 5th example, Control Points were used to control the geometry of shapes. More control points in a shape would give better control of their form changes to generate smoother results. In Rhino, control points were organized as 3 by 3 matrix and more points could be added to a curve or surface by “InsertControlPoint” function. Likewise, this sphere example could add extra control points, which will turn the object into a polysurface. For most of polysurfaces, control points will not be able to be seen and used for the geometric modifications. For instance, results of Boolean objects are polysurfaces which can’t see the control points. Or after adding control points to the surfaces, these points disappear as well. Thus, their control points cannot be accessed by F10 key, but only can be seen by the following function: Solid > Solid Edit Tool > Turn on Points (or Solid Tools > Turn on Solid Control Points) tool to make the points visible and selectable. From moving the points along x or y axes, the geometries will be modified. See images on next page. The sphere is still a primitive object which has 3x3 matrix of control points, whereas the Boolean objects on the left has just control points occurred at the juncture of different surfaces. Those are the shared edges, and seams which could be selected, moved, rotated, or 2D scaled. On the other hand, more control points will make the model more complex, which is not a good idea. It is because that a good model should always be simpler. That means creating a surface from the fewest number of curves, and control points. When dealing with NRUBS and curves, simpler is always better. Therefore, you have to find a balance between the complexity and the number of control points. Method six: Transform solids by Gumball Widget

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Gumball displays the gumball widget on a selected object facilitating move, scale, and rotate transformation around the gumball origin. We could also select a group of object and click gumball to work on the transformation of the selected group of objects. See the following images. Three mechanisms available, these are move arrows, rotation arcs, and scale handles along x, y and z axis. On the side, there is an axes plane indicator that signifies the active plane. The properties of the gumball could be modified or customized through right click on the gumball box > Settings. Details of the use of gumball could be found in the Vimeo video: https://vimeo.com/84954262.

Footnote:

• The first (2D to 3D), second (3D primitives), and fourth (Boolean) methods relate to the construction of solid forms that have clear shapes and a good plan of composition.

• The third (Loft) and fifth (Control points) methods relate to the creation of organic forms that do not have clear (or precise) final form, or the final form might not be that easy to mentally visualize. In fact, the fifth method is used more on editing the form and the sixth one is for transformation purposes.

• This lecture provides enough concepts on the categories of 3D solid generation and editing. Next lecture, we will concentrate on architecture modeling and organic form generation afterwards.

Alternate method for architectural modeling – A building project example:

In lecture 3, there was the method of putting a drawing on the background for modeling the building site. Another method of loading a picture to Rhino is to use the “picture” function to insert an image in the surface representation. Drawing images could be put on the floor plan view or, elevation view as graphic reference for modeling.

Then apply the “scale” function to make the picture image as a full-scale image for modeling. (The scale method was

explained in Lecture 3.) The resulting effects shown below had all the drawing pictures carefully moved and aligned precisely in the model space. We could apply the same method to work on the building model.

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Here is the resulting model.

Here is the image of details done in the project.

The Grasshopper used to create the building.