A three-point perspective is used to describe the illusion of 3-D space in buildings seen from above (or below). In addition to the two vanishing points we’ve already discussed — one for each wall on the right and left — there is the third point to describe how the vertical lines of the walls recede in space.
If you look down at a building from above, for example, the third vanishing point is placed below the ground. If you stand on the ground and look up at a tall building, the third vanishing point is high in space.
The biggest difference in three-point perspective is that there are three vanishing points (VPs). Two are along the horizon, just like two-point, but the third VP is located either above the horizon (at the zenith) or below the horizon (the nadir), depending on the area you intend to draw.
Remember that in basic one-point perspective, lines are either vertical, horizontal or recede toward the vanishing point. In two-point, lines are either horizontal or recede toward one of the two vanishing points. In three-point perspective all lines recede toward one of the three vanishing points.
The three vanishing points make up a triangle, with the viewer’s center of vision roughly in the middle.
To draw a simple shape in three-point perspective, start just as you would in rwo-point perspective, with a horizon line and two vanishing points as close to the edge of your page as possible. Only this time, rather than in the middle, place the horizon line close to the top of your page if the viewer will be looking down, or the bottom of your page if the viewer will be looking up.
Then, as far from the horizon as possible, place a third vanishing point. It can fall anywhere between the horizon vanishing points, though closer to the middle is better for our purposes.
Then, draw lines connecting the three VPs.
To begin, draw a line anywhere you’d like within the triangle toward VP3. It doesn’t have to be vertical. You can make this line any length as well. It can end before it reaches VP3 so long as it will end up there if extended.
Draw lines from both ends of this line toward both of the horizon VPs, just as you would in a two-point perspective drawing.
To determine where your shape ends in space, draw lines from VP3 through both sets of lines receding toward the two horizon VPs.
Draw lines from the back corners toward the opposite horizon VPs and you’ve completed a simple shape in three-point perspective. You can erase any construction lines as needed.
From there, it’s easy to explore making more complicated shapes, so long as you remember that all lines should recede toward one of the three VPs.
Assignment: Create a 3 pt perspective drawing that includes:
- five building – only two over horizon line
- one+ skywalk
- one sunken garden (on roof of a building) with garden or pool area
- three “walls with grid of windows” (not solid glass walls – they must have “building material” in-between windows). One “wall” must have “inset” windows (windows with sills)
- two additional small sets of windows throughout, as needed
- one “wall of balconies” with railing and “fencing”
- four doorways – two garage door entries, two “people” doorways,
- two canopy covering doorway opening
- shaded
http://www.craftsy.com/blog/2013/08/three-point-perspective/?_ct=rbew&_ctp=186215
