1081
etching, photoetching; photoglyphy and photoglyptic
engraving.
Luis Nadeau
See also: Heliogravure; Photogravure; and Talbot,
William Henry Fox.
Further Reading
Bull, A.J., “The pioneer work of Fox Talbot,” Penrose Annual,
vol. 37 (1935):. 63–64.
Denison, Herbert, A Treatise on Photogravure in Intaglio by the
Talbot-Klic Process, London, Iliffe & Son, 1895, reprinted by
The Visual Studies Workshop, Rochester, 1974.
Morrish, David, and MacCallum, Marlene, Copper Plate Pho-
togravure: Demystifying the Process, Boston, Focal Press,
2003.
Schaaf, Larry J. (project dir.), “The Correspondence of William
Henry Fox Talbot,” the University of Glasgow web site.
Stannard, William John, The Art-Exemplar. A Guide to Dis-
tinguish One Species of Print From Another with Pictorial
Examples and Written Descriptions of Every Known Style of
Illustration..., 77–82, 1859..
Talbot, C.H., “Some account of Fox Talbot’s process of photo-
graphic engraving,” Penrose Annual, vol. 8 (1902–1903):.
9–16.
Talbot, H.F., “Photographic engraving,” Journal of the Photo-
graphic Society,. vol. 1 (1853):. 42–44.
PHOTOGRAMMETRY
Photogrammetry, the art of making measurements from
images, synthesizes the science of mathematics and the
technology of photography. The development of pho-
tography in the 19th century, which is the embodiment
of projective geometry, led to widespread development
of photogrammetry for topographic and architectural
measurement by the end of the century.
The mathematical basis of photogrammetry is pro-
jective geometry; initial work in this area was done by
Lambert (1728–1777), with Poncelet’s 1822 treatise
providing a broad basis for later development. Projec-
tive geometry is a generalization of standard Euclidean
geometry, with the basic axiom being that parallel lines
meet in a point. This describes the properties of central
perspective, in that parallel lines imaged by a lens appear
to meet at the vanishing point.
Given this mathematical basis, mapping was fi rst
attempted using freehand perspective drawings from
multiple viewpoints. In 1846, Aimé Laussedat (1819–
1904), a captain in the French Army, experimented
with freehand perspective drawings for mapping of the
Pyrenees. Discovering the limited accuracy and detail
from using freehand drawings, he experimented with
the camera lucida. The camera lucida used a four-sided
prism to project a view of the scene onto the drawing
paper, where it could be traced by the operator. After
several improvements to the device and the develop-
ment of graphical techniques to produce the fi nal map,
Laussedat produced drawings of the façade of l’Hotel
des Invalides in 1849 and a topographic map of the
fort du Vincennes in 1850. He named this technique
iconometrie.
The development of photography at this time pro-
vided another method of generating perspective views,
although Laussedat realized that existing cameras would
not be suitable for mapping purposes due to their nar-
row fi elds of view and lack of calibrated orientation.
He therefore commissioned the Paris instrument maker
Brunner to construct a camera to his specifi cations in- The camera had a 50cm focal length lens and used
glass plates with a 27 × 33 cm format. The internal cam-
era geometry was established by fi ducial marks exposed
on the plates, which allowed the reconstruction of the
position of the plate relative to the principal point (inter-
section of the optical axis with the image plane). The fi rst
topographic map was produced in 1861 depicting the
village of Buc and covering approximately 200 hectares.
This and other successful mapping demonstrations led
to the establishment of a French military mapping unit
using Laussedat’s equipment and techniques.
Albrecht Meydenbaur, a German architect, realized
the potential of photography for documenting and
measuring buildings. Understanding the limitations
of the cameras of the time, he designed his own cam-
era which combined stable imaging geometry with
a measuring circle from a surveying instrument. His
phototheodolite was tripod-mounted and had a wide
angle lens with a 105° fi eld of view and a 25cm focal
length, imaging onto a 30 × 30 cm and later 40 × 40
cm format glass plate. Leveling screws maintained the
image plane in a vertical position, thereby simplifying
the graphical reduction of the data. Later versions were
designed to be collapsible, to ease transportation, and
with a lens which could be vertically shifted to better
record buildings.
Meydenbaur’s initial experiments were performed
in 1867 in Freyburg-on-Unstrut, where he photogram-
metrically documented the town church and topography.
In a paper describing this work he introduced the term
“photogrammetrie.” While military applications were
unsuccessful, the detailed metric information derived
from his photographs proved valuable for architectural
documentation. His work led to the formation of the
Royal Prussian Photogrammetric Institute, whose goal
was the photogrammetric documentation of German
cultural monuments and which still holds a large archive
of Meydenbaur’s photographs.
Ignazio Porro (1801–1875), an Italian surveyor and
instrument maker, developed a panoramic camera for
mapping in 1858. By mechanically scanning a narrow
fi eld-of-view lens he obtained a wide fi eld of view
without the accompanying lens distortion. However,
data reduction from the panoramic imagery could not