|Learning Objectives||A general review of all orthographic projection techniques (with an emphasis on 2-point perspective projection, 'cause that's so hard) will be buttressed by a pinup of Project A. Computer drafting in 2d will be briefly introduced anticipating our transition into digital drawing.|
|Uses Tool(s)||Rhinoceros , Rhinoceros for OSX , Drafting Board , Plotters and Printers|
Intro to 2d Drafting in Rhino
Interfacing with Rhino
Rhino presents a fairly intuitive user interface, consisting of the familiar menus, toolbars, viewports, and command line found in many CAD packages.
- The Mouse
- The easiest way to interact with Rhino is via the mouse - which is used to interact with toolbars and to spatially navigate
- The Command Line
- The fastest way to interact with Rhino is via keyboard commands. A working knowledge of rhino's command aliases is essential to improving your workflow.
- As we're drawing in 2d for this session, we'll only be using a single viewport.
- Object Selection
- Rhino is not a visual thinker, and insists that the world is made of discrete objects. As such, you have to be very specific about the objects you want to interact with. Most operations may be performed via noun-verb or verb-noun constructions.
- Object Snaps
- Drawings can get pretty complicated, requiring a higher level of precision than our fat human hands are capable of. Where would we be without object snaps?
- Ortho and Smart Track
- Drawings are all about relationships, and Rhino provides us with a variety of techniques to ensure accurate registration between objects.
- Rhino allows you to model in a variety of units - setting up your drawing properly will help you to avoid confusion later down the road.
Basic Objects in Rhino
The world of rhino is essentially a collection of discrete objects, which belong to a limited set of object types, some of which are described below. Rhino describes itself as a "NURBS Modeler", and was originally developed to facilitate drawing a specific type of curves and surfaces that no other software at the time could handle. Since then, it has developed into a much more generalizable tool, but echos of this origin remain.
The properties of any individual object in Rhino may be displayed by using the object properties dialog .
Many of these objects may be created via a number of different methods. For example, a circle may be created by defining a center and a radius, or by defining three points on which the circle lies. Sometimes, these alternative methods may be found by right-clicking on a toolbar button or by exploring the options displayed in the command window . Other times, objects may be created as a result of operations performed on existing geometry . It's impossible to discuss every possible scenario here, so be sure to explore!
As is the case in all vector-based representations , the most basic element in the world of Rhino is the point . In contrast with hand-drafting, in which the construction line is the foundational element, the effective use of reference points is the hallmark of the expert CAD draftsperson.
Revealing it's bias as a NURBS modeler, Rhino prefers to see every kind of linear entity as a "curve"... even straight lines! It's important to understand that all curves are defined by an underlying set of points called control points , which may be revealed and manipulated through various methods.
One important note: all curves have an inherent 'direction', which may be displayed and edited. This will not likely have any impact when drafting in 2d, but will become very important when modelling in 3d.
- Totally straightforward. Get it?
- May be created by joining lines together, or by creating straight-line connections between multiple points.
- Rational Curves
- Circles, arcs, ellipses, and conics retain a special status in Rhino... until they are manipulated in any way.
- NURBS Curves
- The preferred element type in Rhino facilitates the creation of smooth curves with ease. Mastery and control of these deceptively simple objects is another matter. A general rule of thumb when composing with NURBS: the simpler the better.
- Not truly distinct from polylines, we may see polycurves as simply a collection of curves.
Higher Level Objects
- Collecting heterogeneous objects in a group is a useful organizational tool, but don't confuse a grouped set of lines with a joined set of lines. Exploding a group has the same effect as Ungrouping a group.
- Blocks are an essential construct when working with repetitive elements in a drawing that may require frequent revision or iteration. Effectively working with blocks is an important skill, especially when developing a drawing or model in concert with others.
2d Operations in Rhino
Rhino provides the obligatory set of transformational operations one would expect from a CAD package. Most of the commands listed below feature a copy option, which allows for the duplication of existing objects.
- Translates an object from one place to another. Check out the use last distance and use last point options here for producing arrays of objects easily.
- Turns an object around an axis. When modeling in 3d, the three-dimensional version of this command becomes essential.
- Changes the size of an object.
- Flips objects about an axis.
- Rarely useful in architectural applications, with the notable exception of producing isometric drawings .
- When used in conjunction with reference points, this is a great command for quickly aligning objects.
- Allows for the production of rectangular and polar arrays of objects.
Additionally, there is a set of basic operations unique to modeling in a NURBS environment:
- All-purpose command for breaking stuff apart. Using it recursively on the same set of objects may produce different results - for example, explode preformed on a group containing polycurves will first dissolve the group, and then break apart the polycurves into their constitute curves.
- All-purpose command for putting stuff together. Curves may be joined into polycurves, even when their ends don't quite meet (resulting in a modification of both curves).
- Breaks up objects along cutting planes, lines, or points.
Beyond the basic informational operations listed above, there are a number of operations one may perform on existing geometry in Rhino, which result in the creation of new objects.
- An all-purpose intersection command that, when used on exclusively 2d curves, will generate the complete set of points that result from their intersection.
- Projecting Points & Closest Points
- Not to be confused with the project' command, which is for 3d curves and surfaces, we may project points onto curves in 2d by finding the "closest point" via the ClosestPt command.
- Produces a division of a curve by segment length or by equal divisions. Understanding curve seams, start points, and directions is essential for this operation.
- Curve Boolean
- The best command you've never heard of. Creates new closed-polygon regions from a heterogeneous collection of closed or open curves, and optionally combines neighboring regions seamlessly. Great for cleaning up sections of poorly modeled solids.
- Control Point & Knot Editing
- A range of tools exist for editing control points, adjusting tangencies, and placing "knots". A handlebar editor allows for Adobe Illustrator-like interactions.
Demonstration: Essential Methods in Rhino
- Splitting, Trimming and Dividing Curves
- Working with construction lines via splitting, trimming, and dividing is a method of 2d drafting that mimics hand drafting, and provides an easy entry point for beginners.
- Joining and Closing Curves, Defining Polygonal Regions
- Ensuring that curves are closed, joined, in oriented in the correct direction helps produce cleaner 2d drawings, and is a good habit to adopt anticipating our move into 3d modelling. Defining closed regions via the curve boolean command is a great way to produce clean hatch regions.
- Working with Blocks
- When drafting architectural plans and sections, blocks can be a handy way to work with repeating elements.
- Exporting 2d Lines
- Getting stuff out of Rhino and into other programs, Adobe Illustrator in particular, is easy to do badly and important to do well.
- Tracing Raster Images
- Placing a background bitmap allows us to trace scanned drawings (or images downloaded off the internet).
Demonstration: 2-Point Perspective in Rhino
Here we will demonstrate 2-point perspective using the office method in Rhino 2d.
Related Workflows and Methods
- Tracing 2d Drawings in Rhino
- Demonstrates bringing raster artwork into Rhino, and producing 2d drawings with this artwork as a guide.
- Drawing Plans with Appropriate Detail and Scale
- Shows the basics of creating an orthographic drawing using Rhino 2d, emphasizing the importance of layer organization, using proper lineweights and recognizing representational standards.
- Working with the Construction Plane
- Not exactly relevant to working in 2d Rhino, but a great precursor to moving to 3d.