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John Adolphus Flemer.

An elementary treatise on phototopographic methods and instruments, including a concise review of executed phototopographic surveys and of publicatins on this subject online

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zer Bauzeitung, Hefte n u. 12, 1896.



24 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.



VI. Photographic Surveying in Italy.

The extensive mountainous regions of Italy are peculiarly
well adapted for the application of photography to their topo-
graphic surveys and we find that phototopography for several
decades past has been practiced in that country with marked
success.

Prof. Porro spent much time, labor, and energy towards
perfecting the methods and instruments to apply photography
to tachymetry and to topography. The results of his investi-
gations, which date back to the year 1853, were published under
the title " Applicatione della Fotografia alia Geodesia " (Sal-
dini, Milano, 1855).

Prof. Porro's instruments, which were supplied with sen-
sitized plates of spherical shape (" Fotografia sf erica "), have
been preserved by Salmairaghi, Director of the Polytechnic
Institute in Milan, Prof. Porro having been a member of the
faculty of this institution.

With Porro's death further investigations and experiments
in phototopography ceased in Italy until the year 1875, when
Michele Manzi, an officer of the Military Geographic Institute
of Italy, utilized some photographs of views, taken in the Abruzzi
Mountains with an ordinary camera, to supplement the topo-
graphic details of his plane-table survey of the Gran Sasso
group. This attempt gave such gratifying results that the
same officer in the following year made a special and more prac-
tical application of photography in the topographic survey
of Mont Cenis, particularly of the region about the Bart
Glacier.

In 1878 Gen. Ferrero, Chief of the Geodetic Department
of the Military Geographic Institute, pointed out to the Direc-
tory that the resumption of practical tests and experimental
surveys in phototopography were very desirable, in view of the
advances which had been made in the photographic methods



PHOTOGRAPHIC SURVEYING IN ITALY. 25

recently. Phototopography had been suspended in deference
to the claims of several members of the Institute that photo-
graphic data were too unreliable for topographic purposes, par-
ticularly for large scale maps.

In the same year (1878) L. P. Paganini, Engineer Geographer
of the Institute, was instructed to proceed to Apua and resume
phototopographic survey work, with a view toward ascertaining
whether phototopographic surveys would be economical and
more expedient, now that such decided advances had been made
in both the manufacture of photographic lenses and in the photo-
chemical process.

The practical results of Paganini's investigations and experi-
mental surveys during the period from 1878 to 1879 were so
satisfactory that, in 1880, he was directed to begin a systematic
phototopographic survey of the area bounded by the valleys
of the Oreo, the Valsoana, the Cogne, and the Valsavaranche,
comprising an area of about 390 square miles. The survey
of this mountain complex was finished by Paganini in 1885.
In 1884, however, the phototheodolite of the Institute had been
replaced by an improved instrument of superior qualities, made
by Galileo in Florence after plans and specifications submitted
by Paganini and incorporating improvements suggested by the
experience gained in the field.

This phototheodolite, model of 1884, has been fully described
by Paganini in " La Fototopografia in Italia," Rivista Marit-
tima, Fasc. VI e VII, 1889; also in Rivista di Topografia e
Catasto, Nos. 8, 9, e 10, 1889. A German translation, by
A. Schepp, of L. P. Paganini's " La Fototopografia in Italia "
may be found in the Zeitschrift fuer Vermessung, Nos. 3 and
12, 1891, and No. 3, 1892. A translated extract from Paga-
nini's article has been published in Appendix No. 3, in the
Superintendent's Report of the U. S. Coast and Geodetic Sur-
vey for 1893.

Paganini's excellent results effectively established the effi-
ciency of phototopography for alpine topography and fully



26 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.

solved the technical side of the problem. Owing to the untiring
efforts of the officers of the Military Geographic Institute toward
improving phototopographic methods and instruments, the sur-
veying camera has been adopted as an auxiliary instrument
to the plane table, the combined use of both instruments in
the new topographic survey of Italy having produced the best
results.

The latest improvements to Paganini's camera-theodolite were
first described in a report to the First Geographic Congress in
Italy. A German extract from that report by Fenner may
be found in the Zeitschrift fuer Vermessung, 1893.

The principal departure from the older model (1884) consists
in abolishing the excentrically mounted telescope and converting
' the camera itself into a centrally mounted telescope by replacing
the ground-glass plate of the camera with an opaque plate having a
Ramsden eyepiece in its center whenever observations with the
telescope are to be made. This new model (1890), having all the
details of a theodolite with vertical circle, may be used, when-
ever the necessity arises, for making angular measurements,
in the same way as with an engineer's transit, simply by exchang-
ing the ground glass for the plate with eyepiece, as just men-
tioned.

This instrument, together with the "photographic azimuth
apparatus " designed for hydrographic surveys, has been described
by Paganini in " Nuovi Appunti di Fototopografia; Applicationi
della Fotogrammetria all' Idrografia, seguiti alia Nota; La
Fototopografia in Italia." Publicata nella Rivista Marittima,
Roma, E. C. Forzani, 1894.

When the Military Geographic Institute, in 1891, sent some
map specimens and phototopographic instruments to the Ninth
Geographic Congress in Vienna, in illustration of the Italian
phototopographic methods, Col. Robert von Sterneck wrote
to the Institute, in the name of the Committee on Awards,
that the Italian phototopographic exhibit undoubtedly deserved
the first prize. Franz Hafferl, Engineer of Austrian Railways,



PHOTOGRAPHIC SURVEYING IN SPAIN. 27

wrote: " Votre exposition photogrammetrique est sans comparison
la meilleure. Toutes les autres ne sont que des essais plus ou
moins manques de construction d'appareils phototopographiques
et des constructions de cartes d'une petite entendue." Dr. S.
Finsterwalder (Professor of Mathematics and Photogrammetry in
Munich, Bavaria), Vincenz Pollack (Engineer in Chief of the
Austrian railroad system), and Col. Otto Krifka (of the Geographic
Institute in Vienna) also made commendable reference to the
Italian exhibit.

Other publications having reference to the phototopographic
work in Italy, besides those already referred to in the preceding
paragraphs, may be cited as follows :

GIUSEPPE BERTELLI. "Noteed Appunti di Topografia-Fotografia." Rivista
Militare Italiana, Feb., 1884.

Capt. CARLO MARSELLI. "La Foto-topografia applicata alia Construzione
della Carta Alpine." Bolletino del Club Alpino Italiano, XXIV, No. 57
1890.

GIACOMO BUONOME. "La Foto-topografia in Africa." Bolletino della
Societa Africana, I e II, 1890.

Prof. INNOCENZO GOLFARELLI. "Bolletino della Societa Fotografica Ital-
iana." Firenze, April and May, 1890.

L. BENNATI. "La Fotografia nelle sue Applicazione militare." Rivista
d'Artiglieria et Genio, II, 1892.

Col. A. LAUSSEDAT. "Iconometrie et Metrophotographie Notice sur 1'His-
toire des Applications de la Perspective a la Topographic et a la Carto-
graphic." Paris, Photographe, Sept. et Oct., 1891.

Dr. S. FINSTERWALDER. "Die Photogrammetrie in den Italienischen Hoch-
Alpen." Mittheilungen des deutschen und oesterreichischen Alpen-
Vereins, No. i, 1890.

Wochenschrift des Oester. Ing. u. Archit. Vereins, Nos. 21 and 22, 1890.



VII. Photographic Surveying in Spain.

Although an early interest was manifested in photography
applied to surveying in Spain, little has been accomplished in
the practical 1 application of photogrammetric methods until quite
recently.



28 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.

The Madrid Academy of Sciences, in 1862, offered a prize for
the best treatise in answer to the query, What is the best process
or method for applying photography to the plotting of maps and
plans ? Of the answers received the memoir, submitted by Capt.
A. Laussedat in 1863, was awarded the prize. This memorandum
was accompained by the plan of the village Buc, near Versailles,
plotted on 1:1000 scale, together with eight photographic views
on which the topography of this plan was based.

In the following year Lieut. -Col. Don Pedro de Zea was com-
missioned to study the French methods and instruments used in
photographic surveying. Lieut.-Col. P. de Zea examined Capt.
Laussedat's phototopographic camera (made by Brunrrer, Paris),
Capt. Chevallier's "planchette photographique," Sutton's "pano-
ramic camera " (made by Thos. Ross, London), etc., collating
and describing the results of his investigations in :

DON PEDRO DE ZEA. "Las Applicaciones de la Fotografia al Service militar."
Madrid, 1863.

Don Juan Pie y Allue, Mining Engineer, published a phamplet
on phototopography, in 1896, in which a specimen survey that he
had made in the province of Almeria, plotted on 1:1000 scale,
was included :

DON JUAN PIE Y ALLUE. " Fotogrametria 6 Topografia fotografica." Enrique
Teodoro. Madrid, 1896.

A very complete and general work on phototopographic
methods, instruments, and executed surveys, including experi-
mental survey specimens made in Spain, has been published by
Messrs. C. de Iriarte and L. Navarro, in 1899:

CIRIACO DE IRIARTE y LEANDRO NAVARRO. " Topografia fotografica 6 sea
Applicacion de la Fotografia al Levantamiento de Pianos." Raoul
Peant. Madrid, 1899.



PHOTOGRAPHIC SURVEYING IN CANADA AND IN ALASKA. 2Q



VIII. Photographic Surveying in the Dominion of Canada and

in Alaska.

Capt. E. Deville, Surveyor-General of Dominion Lands, inau-
gurated extensive phototopographic surveys in Canada, which
from their inception, in 1888, were marked with great success.
These surveys were carried out under the auspices of the Canadian
Department of the Interior in the vicinity of the Canadian Pacific
R.R. in the Rocky Mountains. A special triangulation had been
made and a single photographic surveying party of four men
(under J. J. MacArthur) covered an average area of 500 square
miles per annum until 1892. The winter months of each year
were spent in Ottawa with plotting the photographic data col-
lated in the preceding season (under the direction of Capt. Deville)
on a scale of i : 20000.

At the World's Columbian Exposition in Chicago, 1893, a
phototopographic map of a part of the Rocky Mountain Park,
comprising a dozen sheets of about sixty square miles each,
published on a i : 40000 scale, formed one of the most interesting
exhibits of the government of the Dominion of Canada. The
topography on each sheet was obtained, on an average, from six-
teen stations, giving from seventy to one hundred and twenty
panorama views. Six complete panoramas were taken, on an
average, from stations situated within the limits of the topography
mapped on each sheet and the development of the terrene was
controlled by about ten additional camera stations falling outside
of the actual sheet margin and furnishing ten additional partial
panoramas.

From fifteen to twenty points per square mile were plotted
iconometrically, and whenever possible such points were checked
by means of vertical and horizontal angles, observed from the
several camera stations, for locating (instrumentally) a series
of so-called' reference points. These fifteen to twenty points
form the control per square mile of topography, all intervening



30 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.

details and topographic features being sketched, after a careful
study of the panorama views, in a similar manner as the plane-
tabler would sketch such details, under a careful and critical
study of the surrounding terrene. The published map, scale
i : 40000, shows horizontal contours of one hundred feet vertical
interval. The average cost of this survey was about seven
dollars and one half per square mile.

The atmospheric conditions of this sparsely settled region,
between the 5ist and the 52d degree northern latitude, are notori-
ously unfavorable for executing the field work of the ordinary
topographic surveying methods, and the periods of reasonably
clear weather at best are of short duration. The field season
lasts about three months July, August, and September and
even during that short period the observers have to contend with
fogs, rain, dense smoke caused by forest fires, and snow-storms
(in the higher altitudes). These conditions being well known,
Capt. Deville's suggestion, to give the phototopographic method
a practical trial for the survey of the Rocky Mountain region,
was endorsed by the Canadian Government. The good results
obtained in the first season showed that the economical and
rapid solution of this difficult problem would not have been
possible without the aid of photography.

The remarkably good results that were obtained in the photo-
topographic survey of the Rocky Mountain regions are in a
great measure due to the ability of the field observers adapting
themselves readily to the new methods, but the credit for the
inception of the work, devising new methods, and a compact and
serviceable topographic surveying camera suiting the prevailing
conditions of the country, and for the general excellence of the
results that were obtained, primarily belongs to Capt. E. Deville,
Surveyor- General of Dominion Lands and author of an excellent
manual on " Photographic Surveying," published by the Cana-
dian Government at Ottawa in 1889. This edition, of about
fifty copies, was lithographed in the Survey's office, having
been prepared for the use of the Dominion land surveyors



PHOTOGRAPHIC SURVEYING IN CANADA AND IN ALASKA. 31

employed under the Department of the Interior for making
the phototopographic surveys.

The Rocky Mountain work was suspended when the ques-
tion arose of making a topographic reconnaissance of S.E. Alaska
for the delimitation of the boundary line between S.E. Alaska
and British Columbia. This topographic reconnaissance work
in Alaska gave the phototopographers of Canada (who for these
new duties were placed under the direction of Dr. W. F. King,
Alaskan Boundary Commissioner to H. M.) another opportu-
nity to demonstrate the superiority of this method above all
other surveying methods for delineating the topography of a
country peculiarly rich in climatic and topographic difficulties.

During the summer months (middle of May to end of August)
of 1893-94 and to a smaller extent in 1895, this method was
used for surveying the topography of S.E. Alaska. Each sea-
son's work was plotted in Ottawa in the following winter on
i : 80000 scale with horizontal contours of 250 feet vertical intervaL

The number of phototopographers prior to 1893 was com-
paratively small in Canada. Seven of the Dominion land sur-
veyors were given a practical course in phototopography, under
J. J. MacArthur, in the suburbs of Ottawa, to familiarize them
with the methods and instruments devised by Capt. Deville. In
May, 1893, these surveyors were placed in charge of the Cana-
dian phototopographic parties, each chief having assigned him
one assistant (also a D. L. S.), from four to five general helpers,
or packers, and one cook. The survey being jointly made by-
both the Canadian and the American Governments, six of the
Canadian parties were joined by one U. S. Coast and Geodetic
Survey officer with an additional packer for each American.

During the summer season of 1893 these parties experienced
an average of but twenty days favorable for carrying on the work
in the mountains, and the Canadian expert phototopographer
(J. J. MacArthur) occupied about seventeen camera stations
during that period. He exposed 108 plates, which controlled
an area of about 1 1 50 square miles. The other parties, in charge



32 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.

of less experienced observers, averaged from ,450 to 500 square
miles each during the first season.

The season of 1894 proved more favorable for the work in
Alaska than the preceding one, both on account of better weather
(averaging about forty days suitable for work in the mountains)
and because the observers were now more experienced in the
rountine and requirements of this class of work. Mr. J. J.
MacArthur covered an area of about 1900 square miles, having
occupied twenty-four mountain peaks and exposed 275 plates
during this season, while the other six parties averaged noo
square miles each.

These results, however, should not be placed in the same
class with the phototopographic survey of the Rocky Mountain
Park, as the result aimed at in Alaska was only a topographic
reconnaissance, based on a narrow coast triangulation which
also extended inland along the more prominent inlets and rivers.
This triangulation had been made by the U. S. Coast and Geodetic
Survey to control the usual strip of coastal topography and to
form the basis for the hydrographic surveys of the navigable
waters of S.E. Alaska.

The members of the Coast and Geodetic Survey, who had
been attached to Canadian parties in 1893, became familiar
with the practical operations and applications of the photo-
topographic surveying method, and, in 1894, Dr. T. C. Menden-
hall, Superintendent Coast and Geodetic Survey and American
Boundary Commissioner, had a surveying camera used in con-
junction with the plane table for the topographic reconnaissance
at the Head of Lynn Canal, Alaska, by which means the area
covered with the plane table alone was doubled by the sub-
sequent iconometric plotting in the office from ninety negatives.

The same surveying camera was used by the Coast and
Geodetic Survey parties in Alaska in 1895 (Portland Canal) and
again in 1897 (Pribilof Islands), under Gen. W. W. Duffield,
Superintendent U. S. C. and G. S. and American Boundary
Commissioner.



PHOTOGRAPHIC SURVEYING IN CANADA AND IN ALASKA. 33

Photography has also been applied recently to surveys made
for the solution of questions of irrigation in those regions of the
British N.W. Territories where the rainfall is insufficient for
agricultural purposes.

Capt. Deville's first edition of his book on photographic
surveying having been too limited to supply a general demand
he yielded to the pressing demand for an English manual on
this subject by revising and reissuing his book. The valuable
contents of this work, including the elements of descriptive
geometry and perspective, fully justify the expectations that
were connected with its appearance.



LITERATURE (ENGLISH).

BRIDGES-LEE. "Phototheodolite," 2d edition. L. Casella, Maker to the

Admiralty, Ordnance, etc. London, E.C.
R. STRACHY and G. M. WHTPPLE, Supt. "Cloud Photography conducted

under the Meteorological Council at Kew Observatory." Proc. of the

Royal Soc. of London, Vol. 49, 1891.

C. W. VERNER. "Notes on Military Topography." Allen. London, 1891^
STANLEY. "Photographic Surveying." San. Eng., 1892, p. 71.
Col. A. LAUSSEDAT. "Topographical Reconnaissances with the Aid of

Photography." Phot. Times Almanac, 1895.
B. J. EDWARDS. "Color Screens for Use with Isochromatic Plates and

Films." Phot. Times Almanac, 1895.
ALBERT CLEAVES. "Some Scientific Applications of Photography." Phot.

Times Almanac, 1895.
OTTO J. KLOTZ. "Experimental Application of the Phototopographical

Method of Surveying to the Baird Glacier, Alaska." The University of

Chicago Press, 1895.

The Canadian phototopographic methods have been de-
scribed in the following publications:

Capt. E. DEVLLLE. "Photographic Surveying, including the Elements of
Descriptive Geometry and Perspective." Ottawa, Government Printing
Bureau > 1895.

OTTO J. KLOTZ. " Photogrammetrische Arbeiten in Canada." Zeitschr. des
Oester. Ing. u. Archit. Vereins, 1894, pp. 233-234.



34 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.

Col. A. LAUSSEDAT. "Sur le Progres de PArt de lever les Plans a PAide
de la Photographic, en Europe et en Amerique." Comptes rendus de
PAcademie des Sciences, 1893.

Col. A. LAUSSEDAT. "Reconnaissance faite a PAide de la Photographic, pour
la Delimitation de la Frontiere entre P Alaska et la Colombie Britamque."
Comptes rendus de PAcademie des Sciences. Paris, 1894.

Report of the Superintendent U. S. Coast and Geodetic Survey for 1897,
Appendix No. 10, " Phototopographic Methods and Instruments."
Washington, D. C.



CHAPTER II.
THE ELEMENTS OF PERSPECTIVE (CENTRAL PROJECTION).

PHOTOGRAMMETRY being the inverse of perspective it may
not be out of place here to review, at least in a summary manner,
the principal laws of monocular vision, as they are identical
in a great measure with the laws which form the foundation
of perspective. J. H. Lambert (1728 to 1777) apparently was
the first to lay down rules for finding the point of view of a per-
spective and to determine the dimensions of objects represented
in perspective.

I. Visual Seeing.

The eye in order to see an object must receive visual rays
from every illuminated point of the object. It is a well-known
fact that the retina of the eye receives an inverted image of every
sighted object, and yet we all know that objects are seen hi
their natural positions, without requiring a mental transposition
of the inverted image into the erect position. The explanation
for this may be found in the so-called " law of visible direction,"
which, according to LeConte, may be stated thus: "The impres-
sion on the retina of the eye produced by a ray of light enter-
ing the eye is referred from the^eye along the ray- line back again
into space whence it emanated, and therefore back to its source
or proper place."

Every luminous impact which the retina receives by a light
ray passing through the nodal point of the lens into the eye
is immediately and intuitively referred outward, along the same

35



36 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.

path which the entering ray traversed, to the true place which
the luminous point occupies in space. In other words, objects
sighted as such in space are always the results of " outward
projections " from the images on the retina through the nodal
point of the eye as center.

II. Central Projection.

If we project from a fixed center say from the nodal point
of the eye the " visible " parts of an object upon a plane inter-
posed between the eye and the object, the outlines of such pro-
jection will produce the same impression on the retina of the
eye as the outlines of the natural object, provided, of course,
that one eye only was used and at the same time that the rays
which emanated from the different points of the pictured object
could be made of the same kind (of the same intensity and color)
as those coming from the corresponding points of the object
itself. The view of such a perspective would then produce sen-
sibly the same impression on the eye of the observer as the object
in nature.

Of the different perspectives capable of being represented
on a plane surface we are interested here mainly in the so-called
monocular or focal and linear or mathematical perspectives,
both outgrowths of descriptive geometry and consisting in the
application of the rules of projection in general and those of
orthogonal projection in particular.

III. Photographic Perspectives.

The iconometrical problem to be solved in phototopography
may be stated in the following general terms. From a given
perspective (central projection) of a body, projected from a
fixed center (point of view, nodal point) upon a (vertical) pic-
ture plane, we are to construct the horizontal orthogonal pro-
jection of that body.



PHOTOGRAPHIC PERSPECTIVES. 37

With reference to Fig. i, Plate I, we may say the perspective
a, b, c, d, e in the vertical picture plane VV is the central pro-
jection of the object A, B, C, D, E in space from the nodal
point O as center or point of view.

Any one object will produce in a given picture plane but one
perspective image from the same point as center. A point B
of the object is pictured but once, in b, b being that point in the
picture plane VV where the visual or projecting ray of the point B
penetrates the plane VV.

Of the numerous methods by means of which perspective
views may be constructed we shall refer only to those which
have reference to iconometric plotting. To elucidate the close
connection between the three elements that control or define
the central projection or perspective, viz., object, picture plane,



Online LibraryJohn Adolphus FlemerAn elementary treatise on phototopographic methods and instruments, including a concise review of executed phototopographic surveys and of publicatins on this subject → online text (page 4 of 33)