Perspective Practices, Continued
Inclined lines
and planes
Lines and planes inclined toward or away from the picture plane have
vanishing points similar to horizontal vanishing points. When constructing
perspective drawings from plan and elevation views, locating the vanishing
points for the inclined lines involves further preliminary projection.
To find the vanishing points of inclined lines in two-point perspective, use
this table:
Step
1
Action
Place the picture plane, horizon line, and ground line as done
previously in the mechanical construction of perspective drawings.
2
the vertical lines AB and CD through the horizontal
vanishing points (VPR and VPL). The vanishing points for
inclined lines and surfaces will fall
these lines. Note that
when you view an object, all inclined planes should project to the
right. which means that all their vanishing points fall to the right of
vertical line CD (figure 5-19, view A).
3
Using the line from the station point to where it intersects the
picture plane (SPY), construct angle a equal to the angle made by
the inclined plane 1234 and the picture plane in the elevation view.
this line beyond line CD (figure 5-19, view
4
5
Construct a perpendicular to this line intersecting CD at Y.
Using a compass or dividers, lay off this perpendicular distance on
CD from the right vanishing point. This is VPRl for the inclined
plane 1234.
6
Proceed with this method for the remaining inclined planes to
obtain VPR2 and VPR3 (figure 5-19, view C).
7
Finish and darken the object outline.
You can find the perspectives of inclined lines without finding the vanishing
points by finding the perspectives of the end points and joining them. You
can determine the perspective of any point by finding the perspectives of any
two lines intersecting at the point.
Continued on next page
5-25
