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	       CS 99D - Perspective lecture #1, January 11, 2001

				  Marc Levoy
			      Stanford University
				   (c) 2001

		      (with corrections, March 14, 2003)

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	   *** The invention of illusionistic art by the Greeks ***

Naturalism first appeared in sculpture:

	600 BC	Archaic Greek statuary
		-> Typical Kouros ("youth"), a genre of life-size marble,
		   Gardner, p. 125
			o like Egyptian statuary
			o featues are more symbols than real anatomy
			o symmetric
			o static

	530 BC	Archaic Greek statuary
		-> The kouros named "Kroisos,
		   Gardner, p. 126
			o more realistic modeling of face, abdomen, knees
			o a real body, not a symbol of a body

	480 BC	Classical Greek statuary
		-> The Kritian Boy, a later Kouros statue,
		   Gardner, p. 142
			o contrapposto ("counterbalance")

	450 BC	Classical Greek statuary
		-> Warrier from Riace (at Diocletian Baths in Rome),
		   Gardner, p. 143
			o contrapposto ("counterbalance")
			o still at rest

	450 BC	Myron's discus-thrower
		-> Gardner, p. 145
			o roman marble copy of bronze original
			o dynamic - this figure is in motion


By the way, among the statues we scanned / wanted to scan in the
Stanford Digital Michelangelo Project were:

	1504 AD	Michelangelo's David
		-> Scala, p. 20
			o later example of contrapposto

	100 AD	Laocoon, Roman copy of Hellanistic original,
		w 2nd son added (at right)
		-> Gardner, p. 182
			o later example of dynamics


This naturalism in sculpture demanded a response in painting:

	540 BC	Early classical
		-> Vase in the black-figured style
		   Gombrich SoA, p. 80
			o Achilles and Ajax playing draughts
			o still mainly in egyptian style
			o but chest seen in profile

	500 BC	Early high classical
		-> Vase in the red-figured style
		   Gombrich SoA, p. 81
			o the warrier's leave-taking
			o foreshortening of foot


*Why* did the Greeks invent illusionistic art ("mimesis")?
	o detailed narratives - Homer as eyewitness, more details than Bible

		"dreams for those who are awake" - in Gombrich, A&I, p. 127

	o visual realism - Pygmalion myth
		- Bullfinch's mythology (Holme's illustrated edition), p. 88

	o visual illusion - scenery for Greek theater (= narrative visualized)

	o Plato observering nature, although the Egyptians did this too

		"How does a man stand?  (posture)

		"To ask [this] might have struck an Egyptian artist as it would
		strike us if someone inquired the age or mood of the king on
		the chessboard." - Gombrich, p. 134

		o Egyptian art was schematic
		-> Gardner, fowling scene, p. 90

What was "given up" in adopting naturalism?
	o fixed icon - reliable translation from form to meaning
	o completeness (due to occlusion)
		-> Catlin, Little Bear (1838),
		   Gombrich A&I, p. 269

	o Plato hated naturalism in art, the then "modern art":

		"Does a couch differ from itself according to how you view it
		from the side or the front or in any other way?"  The same
		magnitude...viewed from near or far does not appear equal.  And
		the same things appear bent and straight to those who view them
		in water and out owing to similar errors of vision...  And so
		scene-painting in its exploitation of this weakness of our
		nature falls nothing short of witchcraft..."
			- Plato, the Laws (360 BC), in Gombrich A&I, p. 126

	  He considered perspective an unfortunate weakness of vision.
	  He preferred drawing the object schematically.

We believe that Greeks also used light and shade, aerial perspective, etc., but
these would be difficult to achieve given their vase-painting methods, and
almost no paintings survive.  Here is a quick summary of the state-of-the-art
at the height of the Roman Empire:

	50 BC	"Second style" of Roman painting
		-> Wall painting from villa near Pompeii,
		   Gardner, p. 212
			o one-point perspective
			o decreasing spacing
			o circles as ellipses
			o aerial perspective

	70 AD	"Fourth style" of Roman painting
		-> Wall painting, Herculaneum
		   Gardner, p. 217
			o shading
			o shadows
			o highlights
			o transparency
			o refraction

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			    *** The middle ages ***

The disappearance of naturalism:

	504 AD	Early Christian
		-> Mosaic, Saint'Apollinare Nuovo, Ravenna,
		   Gardner, p. 273
			o narrative overtakes naturalism
			o depth, shading, shadows, background disappearing

	547	Early Byzantine
		-> Mosaic, San Vitale, Ravenna (a Byzantine city since 493),
		   Gardner, p. 295
			o naturalism completely gone
			o gold background
			o halo is from ancient Persia = descended from the Sun


Sidelight: oblique projections:

	~350 BC	-> Apulian (Greek) vase,
		   Dubery and Willats, p. 32
			o oblique

	1300-20	-> The Numbering of the People, St. Saviour in Chora, Istanbul,
		   Dubery and Willats, p. 35
			o oblique
			o inconsistent

	~1420	-> Giovanni de Paolo's The Birth of St. John the Baptist,
		   Dubery and Willats, p. 53
			o pseudo-perspective pavimento
			o reduction of transversal spacing using a ratio
			o oblique but converging furniture

	1565	-> Mughal miniature
		   Dubery and Willats, p. 25
			o vertical oblique

	1914	-> Juan Gris's Breakfast,
		   Dubery and Willats, p. 112
			o modern usage of vertical oblique


The reappearance of naturalism:

	1308-11	Late medieval (Italo-Byzantine, a.k.a. "maniera greca")
		-> Duccio's Virgin and Child Enthroned with Saints,
		   Maesta Alterpiece, Siena,
		   Gardner, p. 632
			o during Siena's heyday
			o sizes of figures depend on importance
			o faces are individualized and softened
			o naturalistic details reappearing

	1305	Renaissance art is usually dated to Giotto
		-> Giotto's Faith, Arena Chapel, Padua,
		   Gombrich SoA, p. 200
			o reintroduction of light and shadow
			o realistic pose
			o breaking out of the frame, intruding into your space,
			requiring that he successfully delineate that space

		-> Giotto's The Mourning of Christ, Arena Chapel,
		   Gombrich SoA, p. 203, and detail on next page
			o reintroduction of foreshortening
			o dynamic poses
			o composition that reflects the unfolding drama


The rediscovery of antiquity:

	1428-32	-> Donatello's David, Bargello, Florence
		   Gardner, p. 688
			o classical theme
			o reintroduction of classical nude, contrapposto
			o David "marvels" at his accomplishment, self-awareness

	1419-24	-> Brunelleschi's Ospedale degli Innocenti
		   (Foundling Hospital), Florence
		   Gardner, p. 691
			o reintroduction of classical architecture
			o 20 years until anyone copied his move
			o restrained (delicate), rational (modular)


The general conditions at the start of the Renaissance:

	o crusades -> trade
	o Florence - wool trade
	o Venice - spice (and dye) trades, we'll come back to this under color
	o rebirth of learning -> universities (Bologna = ~1088)
	o artisan, not yet "artiste"
	o guild/workshop/apprentice system
	o mathematics:
		o arithmetic - for bankers
		o physics (natural philosophy) - for astrologers
		o geometry - for craftsmen

	1420-36	-> Brunelleschi's dome, Florence,
		   Gombrich SoA, p. 225
			o challenges:
				o largest span in the world at the time
				o too big for centering
				o no room for external buttresses
			o principal features:
				o ogival shape + lantern
				o double shell
				o chained dome
				o no centering
			o technical virtuosity
			o blending of artist and scientist
			o beginnings of artist / scientist as hero

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		       *** Definition of perspective ***

Definitions of "perspective":

	Common assumptions:
		1.  Light leaving an object travels in straight lines
		2.  These lines converge to a point (more or less) at the eye
		o Both can be verified from simple observation

	"Natural perspective":
		3a. More distant objects subtend smaller visual angles
			-> drawing from Euclid (3c BC), in Kemp, fig 31, p. 27

	"Linear (artificial) perspective":
		3b. A perspective image is formed by the intersection of these
		    lines with a "picture plane" (the surface of the painting)
			-> drawing from Piero (1474), Kemp, fig. 32, p. 28

	Warning: Leonardo uses different definitions:
		o his natural = my linear
		o his accidental = linear not viewed from intended viewpoint

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	*** The invention of linear perspective in the Renaissance ***

1413	Brunelleschi's panels of the Baptistery and Pza. Signoria,
	   -> Kemp, p. 12 and Alison Cole's Perspective (DK book), p. 12,
	      see also Dubery and Willats for various conjectures and drawings
	About the baptistery panel:
		o peephole forces you to observe panel from correct viewpoint
		o assumes mirror held parallel to panel at the correct distance
		o mirrored background would, if you stood at correct
		  real station point in the doorway of the cathedral,
		  superimpose the real Baptistry, showing any errors

1435	Alberti's Della Pittura ("On painting")
		o originally in Latin ("de pictura")
		o dedicated to Brunelleschi
		o specialized for one-point perspective of pavimento

		-> Giovanni de Paolo's The Birth of St. John the Baptist,
		   Dubery and Willats, p. 53, ~1420
			o pseudo-perspective pavimento
			o reduction of transversal spacing using a ratio
			o oblique but converging furniture

		-> Explanation in Cole, p. 13, top

		-> Justification for convergence of orthogonals is brilliantly
		   demonstrated in 3D in a drawing in Vignola's Le Due regole
		   (1583), in Kemp, fig. 151, p. 80

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