Week 5
Alberti
SKETCHLAB SKETCHLAB NOTES
5 PERSPECTIVE PRECISION AND PROPORTION
FOR MR RONNIE TURNBULL
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SKETCHLAB Week 5
BEFORE THE RENAISSANCE
Examples of early attempts to convey
perspective
PERSPECTIVE DRAWING IS The art of drawing
solid objects on a two-dimensional surface so as to
give the right impression of their height, width, depth,
and position in relation to each other when viewed
from a particular point.
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BRUNELLECHI’S BREAKTHROUGH
Before artists began to understand the geometry behind the
illusion of perspective they tried many different devices for
implying distance. These includes reducing the size of distant
objects using angles and stacking things heirarchically. In the
15 th century however the architect Brunelleschi made a
discovery which revolutionised art and the way we see and
represent the word.
This is plagarised from the internet:
An introduction to Filippo Brunelleschi's experiment regarding
linear perspective, c. 1420, in front of the Baptistry in Florence
http://www.artbabble.org/video/ngadc/empire-eye-magic-illusion-trinitymasaccio-part-2
http://www.artbabble.org/topic/series/empire-eye-magic-illusion
http://smarthistory.khanacademy.org/Brunelleschi.html
Brunelleschi and the Rediscovery of Linear
Perspective
Before looking at painting in the Early Renaissance, we need to
learn about the discovery or rediscovery of linear perspective
sometime close to 1420 by Filippo Brunelleschi (rediscovery,
because the ancient Greeks and Romans may have understood
linear perspective too, but if so, knowledge of it was lost during
the Middle Ages). Linear perspective is a way of creating a
convincing, perfect illusion of space on a flat or two-
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SKETCHLAB Week 5
HEADING
dimensional surface. Nearly every Renaissance artist wanted
linear perspective—a way of creating an accurate illusion of space
that could match the new naturalism then being applied to
human figure.
http://www.math.sunysb.edu/~tony/whatsnew/column/
alberti-0102/java/PIERO2.HTM
When Brunelleschi (re)discovered linear prespective circa 1420,
Florentine painters and sculptors became obsessed with it,
especially after detailed instructions were published in a painting
manual written by a fellow Florentine, Leon Battista Alberti, in
1435. John Berger, an art historian, notes that the convention of
perspective fits within Renaissance Humanism because "it
structured all images of reality to address a single spectator who,
unlike God, could only be in one place at a time." In other words,
linear perspective eliminates the multiple viewpoints that we see
in medieval art, and creates an illusion of space from a single,
fixed viewpoint. This suggests a renewed focus on the individual
viewer, and we know that individualism is an important part of
the Humanism of the Renaissance.
Diagram of the main elements of linear perspective—horizon
line, vanishing point, and orthogonals.
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Giotto very nearly got it but used perspective in ione dimension only. Massachio
however a few years later mastered the art of constructing the illusion of depth
based on geometry
Massachio
Giotto
EXAMPLES OF EARLY PERSPECTIVE
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Early Applications of Linear
Perspective
Representing the Body
What renaissance artists had clearly achieved through the careful
observation of nature, including studies of anatomical dissections,
was the means to recreate the 3-dimensional physical reality of
the human form on 2-dimensional surfaces. In part, the key to
this achievement lay in understanding the underlying, hidden
structure of the human body which then enabled the artist to
produce realistic representations of what he saw on the flat
surface of a wall (in the case of frescoes) or on a wooden panel or
paper (in the case of drawings).
Artists in the early 15th century had learned to portray the human
form with faithful accuracy through careful observation and
anatomical dissection, and in 1420 Brunelleschi's experiment
provided a correspondingly accurate representation of physical
space. Antonio Manetti, Brunelleschi's biographer, writing a
century later, describes the experiment based on careful
mathematical calculation.
Perspective and Architecture
It seems reasonable that Brunelleschi devised the method of
perspective for architectural purposes—he is said by Manetti to
have made a ground plan for the Church of Santo Spirito in
Florence (1434-82) on the basis of which he produced a
perspective drawing to show his clients how it would look after it
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was built. We can compare this
drawing with a modern photo of
the actual church. This video clip
allows you to crossfade back and
forth between the original
perspective drawing and the
modern photograph. It is clear how
effective the new technique of
mathematical perspective was in
depicting spatial reality.
Masaccio, Holy Trinity, 1427,
fresco (Santa Maria Novella,
Florence)
The Body in Space
But this was just the beginning.
Ten years later, the painter
Masaccio applied the new method
of mathematical perspective even
more spectacularly—in the fresco The Holy Trinity, where the
barrel vaulted ceiling is incredible in its complex, mathematical
use of perspective.
Here lines overlay Masaccio's actual geometric framework to
make clear the structure of the perspective itself.
From the geometry it is actually possible to work backwards to
accurately measure and reconstruct the full 3-dimensional space
that Masaccio depicts, illustrating exactly, Brunelleschi's interest
in being able to translate schemata directly between two and
three-dimensional spaces. It was not long before a decisive step
was taken by Leon Battista Alberti, who published a treatise on
perspective, Della Pitture (or On Painting), in 1435. Once
Alberti's treatise was published, knowledge of perspective no
longer had to be passed on by word of mouth. For some it
became a matter of consuming artistic, even philosophical
interest.
Text by Dr. Joseph Dauben
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HOW DO WE DO IT?
Draw a light horizontal line as a guide to the
horizon at your eye level
Unless the faces of buildings are co-planar they will
have different vanishing points.
Using a viewfinder establish a cone of vision not
more that 60 degrees
Look to see where line appear to converge in the
distance. Where they intersect with your horizon you
have your vanishing points. Many of these will be off
your paper. Note the ones that are on your paper.
Add a few vertical lines to denote the edges of
buildings. Use the edge of your paper to steady your
hand.
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OBJECTS: ALIGNING TO A VANISHING POINT
Any objects/buildings with faces
which are parellel ( on the same
plane) will have horizontals which
converge at the same VP.
All lines on the same plane to any face will converge at
the same VP.
http://www.youtube.com/watch?v=AW42zyqJ1sI
http://www.youtube.com/watch?v=2GpQMxcHOEU
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DIVIDING FACADES
Establish the outline of the building/objects you are drawing
with just the minimum of lines
Then draw a X shape from one corner to the other of your
facade
This establishes the mid point its clearly not the geometric
centre
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MEASURING DIVISIONS
Then do the same again in each of the two halves-this
subdivides your facade into four- you can usually do the
rest by eye just keep the ratio between any adjacent area
the same.
This ratio changes as the angle of the wall or plane is more
acute to the viewer.
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LOOKING FOR RELATIONSHIP
A viewfinder made of stiff card is very useful both for
choosing a view to draw and for assessing angles. Best to
make a couple with slightly different proportions and mark
thirds along top and bottom. Put your focal point near one
of the intersections of these thirds and the horizon line
close to one of the vertical ones.
Look for geometric shapes within your view. Especially
squares. These are an invaluable aid to getting things in
the right place on paper. See example below.
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PERSPECTIVE DRAWINGS
Use a pencil or pen to help asses
the angles of roofs, road etc Hold
it up align it with the angle you
want to denote then drop it down
to your drawing. Its easy then to
judge if something is badly out of
alignment.
Similarly use a horizontal or
vertical pencil to check for
alignment.
Hockney
And you can use use the length
of the pencil to check relative
lengths, holding it at arms length
and sliding the thumb up and
down as a gauge.
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ELLIPSES
These are points
where ellipse is at a
tangent to the square
First draw a bounding square in
perspective. Draw a cross shape
and then a horizontal and vertical
to find where the edges of the
ellipse will be. The ellipse will
always be tangential to the
square at these points. Add
some dots half way between the
diamond shape and the corners
of the square. The ellipse will
pass through these too. The
ellipse in perspective is far from
symmetric.
Note a common mistake its too flattened here
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DISCOVERING GEOMETRY STRUCTURE AND PATTERN
Most complex forms can be simplified to a
combination of the following
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AND DON’T FORGET TO ENJOY IT
Finally keep it all in:
•
Proportion: How things
fit together, big and small,
nearby and distant.
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