look bigger than it really is. When a skybox is used, the level is
enclosed in a cuboid; and the sky, distant mountains, distant buildings,
and other unreachable objects are projected onto the cube's faces
(using a technique called
), thus creating the illusion of distant three-dimensional surroundings. A
instead of a cube.
graphics is computationally expensive, specifically in real-time games,
and poses multiple limits. Levels have to be processed at tremendous
speeds, making it difficult to render vast skyscapes in real-time.
Additionally, realtime graphics generally have
with limited bit-depth which puts a limit on the amount of detail that can be rendered at a distance.
To compensate for these problems, games often employ skyboxes.
Traditionally, these are simple cubes with up to 6 different textures
placed on the faces. By careful alignment, a viewer in the exact middle
of the skybox will perceive the illusion of a real 3D world around it,
made up of those 6 faces.
As a viewer moves through a 3D scene, it is common for the skybox to
remain stationary with respect to the viewer. This technique gives the
skybox the illusion of being very far away since other objects in the
scene appear to move, while the skybox does not. This imitates real
life, where distant objects such as clouds, stars and even mountains
appear to be stationary when the viewpoint is displaced by relatively
small distances. Effectively, everything in a skybox will always appear
to be infinitely distant from the viewer. This consequence of skyboxes
dictates that designers should be careful not to carelessly include
images of discrete objects in the textures of a skybox since the viewer
may be able to perceive the inconsistencies of those objects' sizes as
the scene is traversed.
including photographs, hand-drawn images, or pre-rendered 3D geometry.
Usually, these textures are created and aligned in 6 directions, with
viewing angles of 90 degrees (which covers up the 6 faces of the cube).
From Wikipedia, the free encyclopedia
A traveller puts his head under the edge of the firmament in the original (1888) printing of the Flammarion engraving.
The
Flammarion engraving is a
wood engraving by an unknown artist, so named because its first documented appearance is in
Camille Flammarion's
1888 book
L'atmosphère: météorologie populaire ("The Atmosphere: Popular Meteorology").
[1] The engraving has often, but erroneously, been referred to as a
woodcut. It has been used to represent a supposedly medieval cosmology, including a
flat earth bounded by a solid and opaque sky, or
firmament, and also as a metaphorical illustration of either the
scientific or the
mystical quests for knowledge.
Description
The engraving depicts a man, clothed in a long robe and carrying a
staff, who kneels down and passes his head, shoulders, and right arm
through a gap between the starry sky and the earth, discovering a
marvellous realm of circling clouds, fires and suns beyond the heavens.
One of the elements of the cosmic machinery bears a strong resemblance
to traditional pictorial representations of the "
wheel in the middle of a wheel" described in the visions of the Hebrew
prophet Ezekiel.
The caption that accompanies the engraving in Flammarion's book reads
A missionary of the Middle Ages tells that he had found the point where the sky and the Earth touch...
[1]
This image refers to the text on the facing page (p. 163), which also
clarifies Flammarion's intent in using it as an illustration:
Whether the sky be clear or cloudy, it always seems to us to have
the shape of an elliptic arch; far from having the form of a circular
arch, it always seems flattened and depressed above our heads, and
gradually to become farther removed toward the horizon. Our ancestors
imagined that this blue vault was really what the eye would lead them to
believe it to be; but, as
Voltaire
remarks, this is about as reasonable as if a silk-worm took his web for
the limits of the universe. The Greek astronomers represented it as
formed of a solid crystal substance; and so recently as
Copernicus, a large number of astronomers thought it was as solid as plate-glass. The Latin poets placed the divinities of
Olympus
and the stately mythological court upon this vault, above the planets
and the fixed stars. Previous to the knowledge that the earth was moving
in space, and that space is everywhere, theologians had installed the
Trinity in the
empyrean, the glorified body of Jesus, that of the Virgin Mary, the
angelic hierarchy,
the saints, and all the heavenly host.... A naïve missionary of the
Middle Ages even tells us that, in one of his voyages in search of the
terrestrial paradise,
he reached the horizon where the earth and the heavens met, and that he
discovered a certain point where they were not joined together, and
where, by stooping his shoulders, he passed under the roof of the
heavens...
[2]
It must be pointed out that this paragraph had already appeared,
without the accompanying engraving, in an earlier edition of the text published under the title of
L'atmosphère: description des grands phénomènes de la Nature ("The Atmosphere: Description of the Great Phenomena of Nature," 1872).
[3]
Yet the correspondence between the text and the illustration is so
close that one would appear to be based on the other. Had Flammarion
known of the engraving in 1872, it seems unlikely that he would have
left it out of that year's edition, which was already heavily
illustrated. The more probable conclusion therefore is that Flammarion
commissioned the engraving specifically to illustrate this particular
text, though this has not been ascertained conclusively.
Literary sources
The idea of the contact of a solid sky with the earth is one that repeatedly appears in Flammarion's earlier works. In his
Les mondes imaginaires et les mondes réels
("The Imaginary Worlds and the Real Worlds," 1864), he cites a legend
of a Christian saint, Macarius the Roman, which he dates to the 6th
century. This legend includes the story of three monks (Theophilus,
Sergius, and Hyginus) who "wished to discover the point where the sky
and the earth touch"
[4] (in Latin:
ubi cœlum terræ se conjungit).
[5] After recounting the legend
[6]
he remarks that "the preceding monks hoped to go to heaven without
leaving the earth, to find 'the place where the sky and the earth
touch,' and open the mysterious gateway which separates this world from
the other. Such is the cosmographical notion of the universe; it is
always the terrestrial valley crowned by the canopy of the heavens."
In the legend of St. Macarius, the monks do not in fact find the place where earth and sky touch. In
Les mondes imaginaires Flammarion recounts another story:
This fact reminds us of the tale which Le Vayer recounts in his
Letters. It appears that an
anchorite,
probably a relative of the Desert Fathers of the East, boasted of
having been as far as the end of the world, and of having been obliged
to stoop his shoulders, on account of the joining of the sky and of the earth in that distant place.
[7]
Flammarion also mentioned the same citation, in nearly the same words, in his
Histoire du Ciel ("History of the Sky"):
"I have in my library," interrupted the deputy, "a very curious
work: Levayer's letters. I recall having read there of a good anchorite
who bragged of having been 'to the ends of the earth,' and of having
been obliged to stoop his shoulders, because of the union of the sky and
of the earth at this extremity."
[8]
The
Letters referred to are a series of short essays by
François de La Mothe Le Vayer. In letter 89, Le Vayer, after referring to
Strabo's scornful opinion of the explorer
Pytheas, who had mentioned a region in the far north where land, sea, and air seemed to mingle in a single gelatinous substance, adds:
That good anchorite, who boasted of having been as far as the end
of the world, said likewise, that he had been obliged to stoop low, on
account of the joining of the sky and earth in that distant region.
[9]
Le Vayer does not specify who this "anchorite" was, or provide any
further details about the story or its sources. Le Vayer's hint was
expanded upon by Pierre Estève in his
Histoire generale et particuliere de l'astronomie
("General and Particular History of Astronomy," 1755), where he
interprets Le Vayer's statement (without credit) as a claim that Pytheas
"had arrived at a corner of the sky, and was obliged to stoop down in
order not to touch it."
[10]
The combination of the story of St. Macarius with Le Vayer's remark
seems to be due to Flammarion himself. It also appears in his
Les terres du ciel ("The Lands of the Sky"):
With respect to the bounds (of the Earth)... some monks of the
tenth century of our era, bolder than the rest, say that, in making a
voyage in search of the terrestrial paradise, they had found the point
where the heaven and earth touch, and had even been obliged to lower
their shoulders!
[11]
Pictorial sources
In 1957,
astronomer Ernst Zinner claimed that the image dated to the
German Renaissance, but he was unable to find any version published earlier than 1906.
[12]
Further investigation, however, revealed that the work was a composite
of images characteristic of different historical periods, and that it
had been made with a
burin, a tool used for
wood engraving only since the late 18th century. The image was traced to Flammarion's book by
Arthur Beer, an astrophysicist and historian of German science at
Cambridge and, independently, by
Bruno Weber, the curator of rare books at the
Zürich central library.
[13]
Flammarion had been apprenticed at the age of twelve to an engraver in
Paris
and it is believed that many of the illustrations for his books were
engraved from his own drawings, probably under his supervision.
Therefore it is plausible that Flammarion himself created the image,
though the evidence for this remains circumstantial. Like most other
illustrations in Flammarion's books, the engraving carries no
attribution. Although sometimes referred to as a forgery or a hoax,
Flammarion does not characterize the engraving as a medieval or
renaissance woodcut, and the mistaken interpretation of the engraving as
an older work did not occur until after Flammarion's death. The
decorative border surrounding the engraving is distinctly non-medieval
and it was only by cropping it that the confusion about the historical
origins of the image became possible.
According to Bruno Weber and to astronomer
Joseph Ashbrook,
[14] the depiction of a spherical heavenly vault separating the earth from an outer realm is similar to the first illustration in
Sebastian Münster's
Cosmographia of 1544,
[15] a book which Flammarion, an ardent bibliophile and book collector, might have owned.
Later uses and interpretations
The image was used as an illustration in
C. G. Jung's
Flying Saucers: A Modern Myth of Things Seen in the Skies (1959), and in
The Mathematical Experience (1981) by
Philip J. Davis and
Reuben Hersh. It served as the cover illustration for
Daniel J. Boorstin's
The Discoverers (1983), a bestselling account of the
history of science, for Richard Sorabji's
Matter, Space & Motion: Theories in Antiquity and Their Sequel (1988),
Stephan Hoeller's
Gnosticism: New Light on the Ancient Tradition of Inner Knowing (2002), and more recently for
William T. Vollmann's
Uncentering the Earth: Copernicus and On the Revolutions of the Heavenly Spheres (2006).
Donovan's 1973 LP,
Cosmic Wheels, had a copy in its inner sleeve.
Some commentators have claimed that Flammarion produced the image to
propagandize the myth that medieval Europeans widely believed the
Earth to be flat.
[16]
In his book, however, Flammarion never discusses the issue of the shape
of the Earth. His text suggests that the image is simply a fanciful
illustration of the false view of the sky as an opaque barrier.
See also
References
- ^ a b Flammarion, Camille (1888). L'atmosphère: météorologie populaire. Paris. p. 163.. The text is also available here.
- ^ Flammarion, Camille (1873). The Atmosphere. New York. p. 103.
- ^ Flammarion, Camille (1872). L'atmosphère: description des grands phénomènes de la Nature. Paris. p. 138.
- ^ Flammarion, Camille (1865). Les mondes imaginaires et les mondes réels. Paris. p. 246.
- ^ De Vitis Patrum Liber Primus. Paris. 1860. p. 415.
- ^ The legend of St. Macarius may be read in English translation at Vitae Patrum.
- ^ Flammarion, Camille (1865). Les mondes imaginaires et les mondes réels. Paris. p. 328.
- ^ Flammarion, Camille (1872). Histoire du Ciel. Paris. p. 299.
- ^ de La Mothe Le Vayer, François (1662). Oeuvres de François de La Mothe Le Vayer, Volume 3. Paris. p. 777.
- ^ Estève, Pierre (1755). Histoire generale et particuliere de l'astronomie. Paris. p. 242.
- ^ Flammarion, Camille (1884). Les terres du ciel. Paris. p. 395.
- ^ Ernst Zinner, in Börsenblatt für den Deutschen Buchhandel, Frankfurt, 18 March 1957.
- ^ Bruno Weber, in Gutenberg-Jahrbuch, pp. 381-407 (1973).
- ^ Joseph Ashbrook, "Astronomical Scrapbook: About an Astronomical Woodcut," Sky & Telescope, 53 (5), pp. 356-407, May 1977.
- ^ The image is shown here
- ^ See, e.g., here, and here
External links
