IAT 106 Terminology

Sketches

We use sketches to communicate to ourselves and others

Orthographic projection

2D Plane, projective view is parallel with perspective projection (At infinity).

(Standard means of graphically representing objects)

Multiview method

Splitting orthographic projections into 3 segments (Usually top, front and side)

Bounding rectangle

A frame used to capture the correct aspect ratio of a 3D Object

Hidden Line

Image on your right

Visible Line

Image on your right

Centre Line

------------------- - -------------------

Dimension and Extension Lines

Image on your right

Phantom line

Represents objects in motion (ie where it was before moving)

Cutting Plane Line

Indicates the location of imaginary cut made to reveal interiors.

Construction Line

(not to be mistaken with visible line, it's slightly lighter.)

Line Hierarchy

Visible > Hidden / Cutting Edge / Section Plane > Center > Break > Dimension/ Extension > Section

Dimensioning

Used to specificy size, location and tolerance (?)

Dimensioning Circles

An arc with more then 1/2 the circle is labeled with the diameter sign

An arc with less then 1/2 the circle is labeled with "r"

Relative Dimensioning

objects locations and dimensions are based off the prior object, originating off inconsistent baselines, this makes the entire structure far more prone to error. There is NO baseline

Coordinate dimensioning

Objects dimensions are scaled and measured from a singular shared point which they all originate from. More accurate, avoids tolerance build up

Infinity Planar View

Viewing an object at a "perfect" parallel.

Projection plane

"Glass wall" we view objects from

Projection

Intersection between projectors and projection plane (the object)

Intersection point

point where lines intersect and connect an object to form its unique shape. (ie. where 2 perpendicular lines may meet)

Perspective Projection

Utilizing a finite viewpoint (Projectors are not parallel) (Looking at an object at an angle)

Forms a realistic view of the object

Parallel Projection

A viewpoint that is infinite. Used to view multigraphic and orthographic planes

Natural View

An object in its natural orientation (ie a car is drawn on its wheels, a person on their legs)

Edge

The intersection of two surfaces

True Length

Parallel to the plane of projection in a Multiview projection.

Oblique Surface

not parallel to any plane of projection (CC)

Inclined Surface

Slanted surface that can be viewed fully in at least one viewpoint. (BB)

Principle Surface

Can be viewed in at least 2 viewpoints. (DD)

Viewpoint

Where the observer stands in relation to the projection plane and the object

Projectors

"Lines" of sight (Indicate if the object is being viewed from infinity or not)

Sketched Features (OnShape)

Shape features have sketches and based on sketches
Sketched features are built from 2D Sketches

Operation Features (OnShape)

Do not utilize sketches
Applied directly to work piece by sketching edges or faces

Isometric projections

True representation of the isometric view of an object
obtained by rotating the object 45 degrees about a vertical axis, then tiling it forward by 35.6 degrees.

(Isometric axes meet at A, B and form equal angles of 120 degrees in the isometric view)

Number of views of the projection are?

Infinite.

Isometric axes positions

Regular Isometric

Reverse Isometric (Basically turn the isometric view inverse)

Isometric Lines

Lines parallel to a "leg" of the isometric axes

Non Isometric Lines

Oblique, or inclined. They are not parallel to a "leg" of the isometric axes

Isometric plane

Any plane parallel to the isometric surfaces formed by 2 adjacent isometric axes.

Glass Box Method

Split an object into 6 views (as if it was encased in a glass box) --> Unfold for Multiview

Pictorial views

Enables use to show several faces of an object at once.

Also represents an object in 3 dimensions.

(Used in technical docs, sales literature, maintenance manuals, architectural drawings)

Axonometric views

Parallel to line of sight, perpendicular to picture

Sorted into Trimetric/Dimetric/Isometric (Names are self explanatory)

Oblique --> Parallel to line of sight

Perspective --> 3 Dimensional, vanishing points only front face, outlines are parallel.

Parallel Projection Technique

Creates a pictorial drawing of an object by rotating the object on an axes relative to a projection or picture plane.

Isometric Axes

Projection of angles now make 120 degrees with each other.

Oblique Lines

Lines that aren't parallel or perpendicular, but rather, slanted.

MITRE Line

Diagonal Line in Multiview drawings

Perspective Drawing

the most realistic form of sketching 3D objects.
Best way to mimic the human eye

a mathematical system for creating the illusion of space and distance on a flat surface

Convergence point

When lines run parallel to teach other away from the viewer, they appear to converge at one point into the distance

Tracing rays

rays of light from an object to a point

pinhole

The pinhole represents the eye in perspective drawings.

Horizon Line

The plane that's on our eye level.

Vanishing point

A point in the horizon where the convergence point is located, and objects seem to "disappear".

Ground point

The point on which the object rests

Station point

represents the eye position of the observer

Picture Plane

A plane on which object is projected and where lines of sight from object form an outline of it.

The position of the picture plane determines the size of the projected object.

If the picture plane is in front of the object, the object appears smaller.

If the picture plane is in front of the object, the object appears larger.

Ground Line relation with horizon line

This determines the type of perspective view used.

Birds eye view
Human eye view
Ground eye view
Worms eye view

Types of perspective drawings

There are three types based on the number of vanishing points needed to capture the three primary directions

one-point perspective
two-point perspective
three-point perspective

one-point perspective

all lines converge at one point

horizontal and vertical lines are parallel to the projection plane

two-point perspective

2 convergence points

Occurs when only one principle direction is parallel to the projection plane.

three-point perspective

Lines appear to convergance at three vanishing point. Either to the sides of the picture plane, or at the top/bottom of the page.

No line is parallel to projection plane

Auxiliary View

A means of projecting "true proportions of an object." Used to draw oblique and inclined edges, which cannot be accurately show in Multiview.

Auxiliary views are perpendicular to the face for which you seek a true shape view

It is an orthographic view that is not one of the six standard projection (top right left bottom ect.)

Principle face

appears as a polygon in one view and edges in the other two views

Inclined face

appears as a polygon in two views and an edge in the other view

Oblique face

appears as a polygon in all three views

Principal edge

appears as an edge in one view

Inclined edge

appears as an edge in 2 views

Oblique edge

appears as an edge in all 3 views

Foreshortened

When an inclined surface is depicted as shorted then it's "true length" in a Multiview drawing.

Secondary Auxiliary view

Projected plane from a primary auxiliary view

Tertiary auxiliary view

projected plane from a secondary or another tertiary auxiliary view.

Partial Auxiliary View

Easier to draw and understand, focuses on just one segment of a plane

Cross sections

Using a cutting plane line, an object is subsequently split.

This is used to depict complex interiors and clarify objects shapes.

The cutting plane line MUST face the direction opposite of the cut. (If you have cut the left side of an object, the cutting plane must point to the right).

Convientional Break

same principle as a cross section, utilized to shorten an object so that it may fit in a drawing and allow proper scaling.

If there's a really long pole in your design, consider using a conventional break to shorten it so that your drawing will be easier to view in regards to the rest of it.

Degrees of Freedom

Refers to an objects ability to move along the (x, y, z) and rotational axis

The number of axis's an object can move around is proportional to the number of degrees of freedom it will possess. EG an object that can move on the x and y axis transitionally, but is unable to rotate has "2 degrees of freedom."

Fastened Mates (On shape function)

A tool used in assembly to manipulate degrees of freedom an object may possess. (ie: restricting an object to just moving on the x dimension.)

ambigious

When a Multiview doesn't have enough views to fully describe the object. (from 2 to 6 views)

Radius constraints when dimensioning

Should only be applied when you are dimensioning less then half a circle

Principle Orthographic views

Camera can be anywhere, infinite number of views .... refer to slides

Size relationship

Cross reference dimensions in Multiview's to avoid re iterating pre-existing dimensions, make sure that said dimensions align

Perspective view

The observer is at a finite distance from the object

Pictorial Display

Refers to when you can see multiple perspectives? Iterations? Of the object. Its a perspective display (I think?)

Three important elements of spacial thinking

Concepts of space (relationship of measurement)

Tools of representation (how we communicate structure, operation, object function)

Process of reasoning (how an operation operates)

Descriptive function

capture, preserve, and convey the properties of the relations among objects

Analytic function

understanding of the structure of objects

inferential function

generate answers pertaining to the evolution and function of objects

Datum line

base line for coordinate/relative dimensioning

tolerance

the amount a measurement can vary before it messes up the design

Baseline

????

wireframe

edges+ vertices (ambigious)

Surface models

edges and vertices and faces

Solid Models

3D models of a computer

Three purposes of spatial thinking

Descriptive function

Analytic function

Inferential function

Tolerance

The deviation of an objects dimensions from its original form with each new iteration, or addition. Prevalent in relative dimensioning.

Projection relations - Oblique

The object is parallel to the projection plane, however the projection rays/lines are angled

Projection relations - Orthographic

Object in relation to projection plane is perpendicular, projection rays are perpendicular.

Projection relations - Isometric

Object in relation to projection plane is angled, however, projection rays are perpendicular

Pictorial Projection

Refers to any projection in which several faces of the object are shown at once (encapsulates Multiview I guess, axonometric, oblique)

Surface Labelling

Labeling pictorial views

Vertex Labeling

Labeling according to orthographic views or Multiview's

3D Modeling technique - CAD Modeling

Modeling with the help of a software such as ONshape or SOlidworks

3D Modeling technique - Features based modeling

Using one sketch, then using on shape operations on it to create the desired object.