Engineering Technical Drawing Unit

perspective projection

* realistic
* size changes w/ distance
* lose deph values
* distance & angles not preserved

parallel projection

* good for exact measurements
* parallel lines remian parallel
* size & shape preserved
* less realistic
* angles not always preserved

orthographic

projectors perpendicular to view plane

one point perspective

two point perspective

three point perspective

vanishing point

point on the horizontal in a perspective drawing where the lines converge & disappear

isometric

* equal measure
* all sides connect in a corner
* all angles are equal
* captures 3D info on a gird in which height, depth, & width are drawn to scale

multiview

view of plane parallel to principle planes; 2 or more views

construction line

lightly drawn & used as guides

object line

visible lines that are thick & dark & take precedence over other lines

hidden line

lines used to show interior detail that owuld not be seen from outside the part & are depicted by a dotted line

center line

* thin lines of alternated long & short dashes indicating an axis of symmetry
* important in orthographic sketches & drawings

full section

cutting plane passes fully through the object

half section

cutting plane passes halfway through an object, exposign the interior half (3/4 is left)