Lecture 2 Flashcards
What are some qualities of 3rd angle projection
- Views are parallel to each other
- Views are perpendicular to each other
- The top is drawn from above
- Left view is drawn from left
- Right view is drawn from right
- Rear view is extreme right or left
- Views can be drawn elsewhere provided it is noted
How does a parallel projection plane appear?
Rectangular plane in one plane but as an edge in adjacent plane
How does an inclined plane appear?
True length (TL) in one plane and foreshortened in adjacent planes
How does a curved plane appear?
True profile in one plane and as edge(line) in adjecent plane
How does an oblique surface appear?
As an incline in all three planes
What are the three types of pictorial drawings?
- Axonometric (isometric)
- Oblique
- Perspective
What does a isometric drawing allow you to see?
A three-dimensional without the distortions created by perspective
In isometric drawings do parallel lines converge?
Parallel lines in actuality do not converge, and represent the object’s real proportions and spatial relationships.
What are isometric drawings most useful for?
Technical drawings
Isometric projection is a from of?
Graphically projection, more specifically axonometric projection
What is the angle of isometric drawings for the x, y and z axis?
120 degrees
How can isometric projection be visualized?
Considering the view of a cubical room from an upper corner looking towards the opposite lower corner.
What does the term isometric mean?
It comes from the Greek for equal measure. Which reflects that the scale along each axis of the projection is the same.
What is a problem with isometric projection?
Because the lines representing each dimension are parallel on the page, objects do not appear larger or smaller as they extend closer to the viewer
All lines parallel to isometric axis is what?
Isometric lines
What are isometric lines foreshortened to?
81/100
Are non-isometric lines foreshortened?
They may or may not be foreshortened
Are projections of parallel lines parallel?
Yes
True or False
All measurements can only be marked on isometric lines?
True
What is a oblique projection?
A simple type of graphical projection used for producing pictorial, two-dimensional image of three-dimensional objects
What type of projection is oblique projection
Parallel
What does oblique projection and orthographic projection have in common?
They are both parallel projection. Parallel lines of the source object produce parallel lines in the projected image.
Why are oblique pictorial drawings unsuitable for working drawings?
The angles displayed among the axes, as well as foreshortening factors (scale) are arbitrary. The resulting distortions make the technique unsuitable for working drawings
How do you create a true shape image for a oblique pictorial?
Aligning one plane of image parallel to the plane of projection
What angle is cabinet projection drawn at?
45 degrees
Cavalier drawings receding axis is drawn at what?
30 degrees and 60 degrees
What is the role of projection drawing for engineers?
To communicate to others how objects appear
What four terms are useful in describing perspective drawings?
- Picture plan- the surface of the pictorial
- Horizon line- divides the sky and the land or the sea if outdoors, It is at eye level and changes with elevation
- Viewing point and direction of view- the location of the eyes relative to the object
- Vanishing point- the point in which parallel lines converge as they recede into the distance
In perspective drawing an object can be represented using how many point perspectives?
One, two or three point perspectives
When is one point perspective useful?
When an object is viewed straight on so that its front view lies in the picture plane
