Week 1 - June 27th - 2D DRAWING AND ORTHOGRAPHIC PROJECTION

124a 2014 Summer

Course 124a
Date 2014/06/27
Learning Objectives We will go over the course syllabus and objectives, and introduce 2D drawing and orthographic projection. We will look at a range of drawing methods and techniques that demonstrate how measured information can be graphically communicated, focusing on plan, section, and elevation.
Agenda
  • Go over syllabus
    • Look at Studiomaven
    • Look at Piazza
    • Look at Box
  • Lecture: 2D Drawing and Orthographic Projection
    • plan
    • section
    • elevation
  • 2D drawing workshop
Uses Tool(s) Rhinoceros

Architectural Graphic Projection

Architectural drawing is as old as the discipline itself. By some accounts, it was the formalization of architectural drawings that established architecture as a discipline distinct from the building trades. For the vast majority of its history, architectural drawing has relied heavily on techniques of graphical projection in general (understood as protocols by which images of three-dimensional objects are projected onto a planar surface), and orthographic projection in particular.

Here, we present a broad overview of architectural drawings , organized by the type of graphic projection each employs. Note in the diagram below the changing relationship between the object depicted, the image (projection) plane, and the projection rays. While these terms are often used very casually in practice, here are some helpful distinctions:

Distinctions Among Parallel Projections

Orthographic projections
Projection rays are parallel to one another, and perpendicular to both the image plane and a dominant plane of the object depicted.
Axonometric projections
Projection rays are parallel to one another, and perpendicular to the image plane - but in no specific relationship to any dominant plane of the object depicted.
Oblique projections
Projection rays are parallel to one another - but non-parallel with the image plane and in no specific relationship to any dominant plane of the object depicted.

Parallel vs Perspective Projections

Parallel projections
Projection rays are parallel to one another. Includes all drawing types listed above.
Perspective projections
Projection rays are converge at a "station point" representing the disembodied eye of a viewer. Includes 1, 2, 3, and 4 point perspectives.

Graphic Projection Systems.jpg

Sectional Drawings

A parallel projection drawing may be considered a "sectional" if the projection plane is positioned such that it intersects the object of interest. In architecture, sectional drawings are further categorized as either "plans" or "sections" by their relationship to the plane of the ground.

Damien Hirst, Mother and Child Divided 1993

Architectural Plans

An architectural plan is a sectional drawing wherein the cut plane is positioned parallel with the ground. In most plans, the cut plane lies at a standard distance (typically 4') above the ground (a "ground plan") or above an occupiable floor (a "floor plan"). While following all the conventions of a typically architectural plan, a "site plan" isn't technically a sectional drawing at all, as the projection plane does not intersect any objects.

Plans are the most widely used graphic device in architecture. They can reveal the interrelation between the interior spaces of a design, how an occupant is able to navigate these spaces, and the relationship between a building and its surrounding context.

Architectural Sections

An architectural section is a sectional drawing wherein the projection plane is positioned intersecting the objects or space of interest, and is not parallel with the plane of the ground. Sections are most often perpendicular with the ground (vertical), but this is not a defining characteristic.

Sections are extraordinarily useful in architectural design, and can reveal the interior composition of wall systems, the interrelation of adjacent spaces, and the relationship between a building and its surrounding context.

Architectural Elevations

At first blush, an architectural elevation does not seem like a sectional drawing at all, as the projection plane does not intersect any objects of interest. Seen another way, we may define an elevation as an architectural section in which the projection plane is positioned near to, but not intersecting the objects or space of interest. Section or non-section: in either case, architectural elevations are useful for describing the exterior composition of a building, and the way in which it sits on a site or in relation to neighboring buildings.

An elevation is essentially a view of a building seen from one side as a flat representation of one fa├žade and is the most common view used to show the external appearance of a building. Each elevation is labelled in relation to the compass direction it faces; for example, the north elevation of a building is the side that most closely faces north. Since many buildings are not simply rectangular in plan, a typical elevation may show all the parts of the building that are seen from a particular direction.

Line Weights, Styles, and Types

Look at our tool part on line weights to review the conventions and the importance of line quality to drawing legibility, or refer to the images below.

Drawing Process

Working from Measurements

You'll need to determine your drawing scale based upon your subject and the size of the media you are presenting on by taking the boundaries of your subject and determining how they will best fit on the page. Once the scale has been determined, use your architect's scale to draw rather than constantly converting measurements - you'll save time and have fewer errors.

Drawing in Layers

Drawing Layout.jpg

Drawing in layers is an important part of the drawing process because it allows for greater control over the final product. By starting with construction lines and soft pencil lines and gradually moving towards hard-lined drawings, architects are able to edit their drawings along the way without ruining the quality of the drawing set. Soft lines in light weights are easy to erase and recreate, but hard-lined drawings drawn with heavy weights and pressures are much more difficult to manipulate.

Begin by establishing the major guidelines of structure and/or envelope with a hard lead and soft pressure. These easily removed lines will help you frame your drawing on the page or determine if a different scale is necessary early on. From there, you'll proceed up the lineweight hierarchy, first using the light lineweight to draw everything, from action lines to fill patters to furniture to structure; then to a medium lineweight, now only drawing the detailing and structure; and finally to the heaviest of your lineweights, drawing only the cut parts of your structure and envelope. Drafting Process.jpg

Rhino - 2D

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.
Viewports
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.
Units
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!

Points

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.

Curves

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.

Lines
Totally straightforward. Get it?
Polylines
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.
Polycurves
Not truly distinct from polylines, we may see polycurves as simply a collection of curves.

Higher Level Objects

Groups
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
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

Basic Operations

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.

Move
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.
Rotate
Turns an object around an axis. When modeling in 3d, the three-dimensional version of this command becomes essential.
Scale
Changes the size of an object.
Mirror
Flips objects about an axis.
Shear
Rarely useful in architectural applications, with the notable exception of producing isometric drawings .
Orient
When used in conjunction with reference points, this is a great command for quickly aligning objects.
Array
Allows for the production of rectangular and polar arrays of objects.
Project
Takes any 2D object and projects it onto that which is behind it, specific to the viewport you are using
Project to C-Plane
Projects any 2D object flat onto the C-Plane. Helpful when you want to align things up to the same plane.


Additionally, there is a set of basic operations unique to modeling in a NURBS environment:

Explode
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.
Join
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).
Split
Breaks up objects along cutting planes, lines, or points.

Advanced Operations

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.

Intersect
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.
Divide
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).

Additional Resources


Plan Drawings

Elevation Drawings

Section Drawings