Week 8: Graphical communication Flashcards
Communication definition
The transmission of information from one person to another by speech (sound or visual, e.g sign language), writing or signs
Graphic communication definition
The use of a picture to convey information to somebody else
Writing is a form of communication using
Symbols
Symbols have many purposes, most of which can be distilled down into three overarching categories
To identify, To describe, To creat value
Symbols began as _______, which became simpler and in some languages, developed into letters which were a much simpler form
Pictographs
Reason behind the creation of symbols
Simplified depiction of a concept, usually requires context to understand
Skeuomorphism
Interface objects that mimic their real world counterparts in how they appear and/or how the user can interact with them (such as save button that is depicted as floppy disk)
Spatial literacy definition
- The ability to think clearly and express ideas relating to the form, position and orientation of objects in three-dimensional space
Technical drawing definition
A specialised graphic language that represents the mental processes of design brought to reality in a tangible form, and as an accurate message in communication
All technical drawings must
Convey precisely, without ambiguity, the message intended, and leave no room for misinterpretation, or at worst, an inaccurate conclusion
The author of a drawing must
Have a clear conception of the object of interest to be able to make a clear drawing
Engineering drawings are different from
Cadastral and topographic drawings
Types of projections
Perspective (central), Orthographic (parralel), Axonometric, Oblique
Projection definition
The method of representing a 3D object in a 2D space
Orthographic projection definition
A form of parallel projection where the view direction is orthogonal (perpendicular) to the projection plane
Engineering drawings are typically comprised of multi-view orthographic projections
Top/bottom, right side/left side, front/back
Orthographic projection is a form of
Graphical communication
Orthographic projection was developed for the purpose of
Communicating information about physical objects (part of a universal system of drawings)
In simple terms Orthographic drawings are
Views (front, side, top, etc) of an object
Third angle and first angle projections are
Modern orthographic projection that are defined by a reference system of two viewing planes, Horizontal (ground) and Vertical (backdrop)
Horizontal and vertical planes partition 3D space into 4 quadrants which were labelled
I, II, III, IV
Third angle multi-view orthographic projections place the object in quadrant
III, i.e below the H plane and behind the V plane, the planes are transparent and each view is pulled on to the plane closest to it
First angle multi-view orthographic projections place the object in quadrant
I, i.e above the H plane and in front of the V plane, the planes are opaque and each view is pushed through the object onto the plane furthest from it
All 6 external views are not always needed to describe an object, and certain views are selected to avoid
Hidden details and unnecessary repetition of detail (simplicity + clarity)
It is usually sufficient to only show 3 views to fully describe an object. These are
Top, Front, Right (side)
The archaelogical artifact that is the first account of cadastral surveying
Si427 - from Babylonian field
Contains plan view with dimensions and created to document the subdivision of a property
In addition to the drawing, there are other non-drawing elements that provide information on the plan to help the viewer understand the plan content
- Titleblock
- Dimensions
Title blocks should contain
- Name of drafter
- Name of company
- Overall drawing title
- Scale
- Date
- Sheet #
- Job #
- Notes
Title block dimensions change based on
The size of the paper
Engineering drawings have two primary functions
- To allow the designer to visualize the design while it is being calculated
- To allow the builder to construct the design once the drawing is completed
A contractor should never have to
Scale off from an engineering drawing to determine a dimension
Heights, widths, thicknesses, diameters, distances, etc all need to be
Conveyed clearly and with no ambiguity
Most dimensioning problems can be solved by applying a few simple rules:
- Dimensions need to be easily read, print clearly, and place well outside the outline of the most appropriate view wherever possible
- Always include the minimum number of dimensions necessary
- Don’t confuse the issue by repeating dimensions already shown in another view
- Follow the same rules for dimension heights as for lettering heights
The method of representing a 3d object in a 2D space is a form of
Parallel projection, where the view direction is orthogonal (perpendicular) to the projection plane
3rd angle orthographic projection is composed of
Front (elevation), top (plan) and right (elevation) views
3rd angle orthographic projection should have equal spacing between views which represents
The projection planes
In 3rd angle orthographic projections, hidden elements are represented with
Dashed lines
3D parallel projections are either
Axonometric or Oblique
Axonometric projections are
Isometric, where all axis are scaled the same
For oblique projections
- The axes in the front face, typically X and Z are scaled the same
- The receding axis, typically Y at a 45 degree angle is scaled differently to account for it being further away
There are two different ways to depict a deciding Y scale
- Cabinet / reduced scale
- Cavalier / true scale
Oblique drawings use
A true orthographic view for one face (the frontal face) of the object
Which face is typically drawn on the front of the oblique box
- Longest face
- The exception to this rule is when the most complex shaped side is drawn on the front as opposed to the longest face
It is quite common to draw the receding axis at a _____ degree angle to the horizontal
45
If lines parallel to the receding axis are drawn at true scale length, then the drawing is called a
Cavaller drawing
If receding lines are drawn at some fraction of the true scale length (e.g 1/2) the drawing is called
Cabinet drawing
To minimise distortion in oblique drawings, receding lines are usually drawn between
1/2 and 3/4 full size
An axonometric projection is an
Orthographic projection upon a plane oblique to the three principal planes.
When this plane makes equal angles with the principal planes, an isometric projection results
An axonometric projection uses a ____ degree angle set square for the receding lines. and ______ for the vertical lines
30 degrees, verticals
On axonometric projections, the three principal planes are thus represented by
Lines drawn with equal included angles (120 degree) hence the name isometric (greek for same measure)
In axonometric drawings, true dimensions can only be laid off on lines parallel to
One of the three principal axes
In axonometric drawings lines on the object that lie in other planes must be derived from
Their intersection with those planes
In axonometric drawing, circles in the principal planes appear as ellipses with radii laid off at true length along each of the two axes within the plane.
Circles not in the principal planes must
First be plotted on the principal plane and then transferred to the proper position
In axonometric drawing, it is typical to draw
An irregularly shaped object by first drawing a rectangular box that encloses it, locating the intersections of the objects lines on the bix and the completing the object drawing.
