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

. (page 1 of 33)
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 1 of 33)
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Topographical Engineer






Copyright, 1906





LIGHT-RAYS, in addition to their heating and illuminating
qualities, have a chemical or so-called " actinic " power, char-
acterized by a general tendency to decompose certain chemical
compounds, some of which, for that very reason, being utilized
in photography.

The term photography, composed of two Greek words
phos, or phota, and grapho, means light-drawing or sun-
picture, and a photograph may be denned as a picture pro-
duced by the actinic action of light- rays (emanating from the
object to be pictured) upon a surface chemically prepared for
this particular purpose.

Although the origin of photography may be ascribed to the
alchemists of the sixteenth century, who had observed that chlo-
ride of silver becomes blackened when subjected sufficiently
long to the action of light- rays, still, photography as we know
that art to-day is not so very old.

In 1777 the Swedish chemist Scheele discovered that the
intensity of the actinic power of light-rays changed with the
quality of the light, inasmuch as argentic chloride would turn
black quicker when exposed to the rays of the violet end of the
solar spectrum.

Wedgewood and Davy probably produced the first " sun-
pictures " obtained by the action of light- rays upon surfaces



sensitized with nitrate of silver. Their pictures, however, were
not permanent they were not " fixed."

Joseph Nicephore Niepce produced the first permanent sun-
pictures in 1814 by a process known under the name of heliog-
raphy, and in 1824 Daguerre commenced his researches and
experiments which eventually (after Niepce and Daguerre had
formed a copartnership in 1829) kd to the perfection of the
so-called " daguerreotype."

In 1839, while alluding to the details of the daguerreotype
process before the Chamber of Deputies, in Paris, Arago declared :
. . . " Nous pourrions, par exemple, parler de quelques idees
qu'on a eu sur les moyens rapides d'investigation, que le topo-
graphe pourra emprunter a la photographic." . . .

Gay Lussac expressed himself in a similar manner when
he had occasion to refer to the possibilities in adapting photog-
raphy to topographical surveys. At about the same period, or
possibly a little earlier, Fox Talbot read a paper on photogenic
drawings before the Royal Society in London, describing his
method for obtaining silhouettes, or shadowgraphs, of objects
on paper that first had been treated with a solution of common
table salt, then dried and immersed in a solution of nitrate of
silver. The salt absorbed by the paper converts a part of the
nitrate of silver deposit into chloride of silver, some of the silver
nitrate remaining unaffected in the paper. Talbot fixed these
silhouettes on the paper by treating the outline pictures with a
solution of bromide of potassium.

In 1841 Talbot had perfected his method to reproduce objects
in general, and his method thereafter became known as the
Calotype or Talbotype.

In 1851 Scott Archer introduced the so-called " wet collo-
dion process," which remained in general use during the fol-
lowing twenty-five years. The wet collodion process required
the plates to be coated immediately before use, first with collo-
dion iodide and again with the sensitizing silver bath, and imme-
diately after exposure they had to be developed and fixed. For


outdoor photography a dark-tent or a dark-room wagon had to
be provided and the necessary chemicals had to be carried along
in the field, together with the camera, plates, and plate-holders.
The old photographic cameras, moreover, were unwieldy and
cumbersome, and to apply photography on exploring expeditions
and travels generally required such an increase in baggage,
not to mention the need of special expert knowledge in photo-
graphic chemistry, that amateur photography was practically
unknown during the period when the wet-plate process flourished.

All these difficulties, restricting the practice of photography
to professionals, were overcome when, in 1871, Dr. Maddox
discovered the so-called " dry-plate process " and published the
details of his " gelatine-emulsion dry-plate coating " for photo-
graphic plates.

Dr. Maddox had succeeded in preparing an emulsion of
bromide of silver in gelatine, with which plates could be coated
and dried in the dark-room until the film had become quite
hard, such plates remaining sensitive to the action of light-rays
long after the sensitized film had been applied. The present
general popularity of photography and its extensive application
in various branches of the sciences as well as in the arts dates
from Dr. Maddox's invention, which, in 1873, was improved by

Collodion has now been entirely replaced by gelatine for all
outdoor work and gelatino- bromide dry-plates are manufactured
in large quantities and in such variety as to answer all demands
and requirements of the different applications of photography
of the present day.

The method of photographic surveying as developed by
Col. A. Laussedat, who in his first experimental work used the
" camera clara," now became more widely known and Lausse-
dat's methods found practical application in several countries,
where they now receive a general recognition as valuable adjuncts
to the instrumental topographic methods.

Notwithstanding the recent rise in favor of photography,


applied to the sciences in general and to topographic surveys in
particular, we still meet with many surveyors who seriously
question the practical value and general accuracy of photographic
surveys, either from misconception of their guiding principles,
from defective results so often obtained from a mere mechanical
application of phototopographic rules and methods, or more fre-
quently still, from extreme conservatism.

Others, again, may have failed to become interested in photo-
graphic surveying, believing that a thorough familiarity with
the theories and laws of optics, photochemistry, descriptive
geometry, perspective and general cartography are essentials
without which no practical knowledge and understanding of
photographic surveying may be obtained.

It should, of course, be admitted that such knowledge will
enable the student to master phototopography in a rapid and
easy manner, giving him an unquestioned advantage in, and an
enlarged field for, the practical application of photography to
surveying, or in teaching photogrammetric methods to others,
yet the fundamental principles underlying these methods are so
simple that it is believed any topographer (with the knowledge
that he should have as such) may readily acquire enough of the
theory to become fully able to apply photography quite success-
fully to practical surveying, especially if he is familiar with the
methods of the plane table.

This treatise has been written primarily with a view towards
overcoming some of the existing prejudices against photographic
surveying, and if it aids to demonstrate that this branch of
surveying may rightly be assigned a legitimate place in the cur-
riculum of every modern topographer, filling as it does a par-
ticular gap in the general series of topographic methods here-
tofore recognized, its existence will be justified.

In the following pages reference will be made chiefly to
those photogrammetric methods which find application to topo-
graphic surveys, although the same principles are also used when
applying photography to:


Geological Surveys, made for the study of volcanic eruptions
and their effects; for the study of recurrent changes in sand-
dunes caused by winds blowing from certain directions at regu-
lar intervals; for noting changes in glaciers (glacial motion or
variation), based upon the comparison of glacier maps and
photographs obtained at stated time intervals from identical and
fixed camera stations, etc.

Meteorological Observations, for the study of the higher air-
currents and cloud altitudes, based upon iconometric cloud
charts obtained from photographic plates exposed at two or
more stations (simultaneously) at stated time intervals; for the
study of the paths of lightning, their lengths, forms, etc.

Hydrographic Surveys, for the location of rocks, buoys, cur-
rent floats, etc. ; for the study of fluvial currents, riparian changes
due to corrasion, erosion, shoaling, or silting, etc.; for obtaining
coast views from points marked on the charts to serve for future
determinations of the positions of vessels that may sight the
land from the same locality in regions where fogs prevail; for
preliminary surveys of coastal belts while conducting a hydro-
graphic survey of the coast, harbors, etc.

Engineering Works, for estimating the amount of work accom-
plished at any date, based on photographic records showing .the
status of the work at specified dates, excavations, cuts, fills, struc-
tural buildings, etc.; for preliminary surveys to be used for the
location of roads, irrigation dams, canals, etc.

Architectural Surveys, for constructing the ground plans and
elevations of old buildings from their photographs; for purposes
of renovation, remodeling, publication, etc.

Military and Secret Surveys, for establishing the positions of
the enemy's forces; for locating fortifications; for establishing
range lines for artillery use; for obtaining topographic recon-
naissance maps, etc.

This treatise will indicate, in a general way, how photography
may be applied to topography by describing the simple processes
and methods, particularly those of a graphic character, that will


suffice to direct beginners in their practical application, leaving
it to experience and subsequent special study to determine the
measure of success, the more so as several excellent works on
this subject have been published recently in the English, French,
German, Spanish, and Italian languages.

Preference should be given to the graphic solution of icono-
metric problems, inasmuch as topographic maps are primarily
graphical records of instrumental measurements made in the
field for locating the principal points of the terrene. Artificial
details and topographic features are largely sketched, or inter-
polated, when using the ordinary topographic surveying methods,
whereas this sketching may be reduced to a minimum when
applying photogrammetric methods by determining an increased
number of points that control the characteristic horizontal and
vertical changes in the terrene, which, in this case, are located
graphically upon the chart by means of iconometric transfers
from the photographic perspectives of the landscape.

The main control for a phototopographic survey should,
of course, be of trigonometric origin and the coordinates of the
triangulation points should be computed with a degree of accu-
racy commensurate with the degree of precision attained in the
field observations.

The writer, having consulted all available publications on
phototopographic methods and instruments in use, gladly acknowl-
edges his indebtedness for valuable information on this subject
to Col. A. Laussedat, Director of the Conservatoire des Arts
et Metiers, Paris; Capt. E. Deville, Surveyor-general of Dominion
Lands, Ottawa, Canada; Dr. W. F. King, Alaskan Boundary
Commissioner to H. M., Ottawa; SignoreL. P. Paganini, Engineer
Geographer of the Military Geographical Institute of Italy;
Dr. R. Doergens, Prof, of Geodesy, Royal Technical High School,
Charlottenburg, Prussia, and particularly to the following pub-
lications :

" La Fototopografia in Italia," L. P. Paganini, Ri vista Marit-
tima, 1889;


" Nuovi Appunti di Fototopografia," L. P. Paganini, Riv.
Marittima, 1894;

" Zeitschrift fuer Vermessungswesen," Stuttgart;

" Zeitschrift fuer Instrumentenkunde " ;

" Lehrbuch der Praktischen Photographic," Dr. A. Miethe;

"Anthony's Photographic Journal";

" Die Photographische Messkunst," Prof. F. Schiffner,
Halle a./S., 1892;

" Die Anwendung der Photographic in der Practischen Mess-
kunst," E. Dolezal, Halle a./S., W. Knapp, 1896;

"Die Stereo- Photogrammetrie," Maj. von Huebl, Mitth.
des k. u. k. Militaer-Geographischen Inst., XII, 1903;

"Photographic Surveying," E. Deville, Ottawa, 1895;

" Photogrammetrie und Internationale Wolkenmessung," Dr.
C. Koppe, Braunschweig, 1896;

" Comptes Rendues de F Academic des Sciences," Paris;

" Annales de FObservatoire Meteorologique du Mont Blanc,"
J. Vallot, Paris, 1896;

" Recherches sur les Instruments, les Methodes et le Dessin
Topographiques," Col. A. Laussedat, Paris, 1898.






I. Photographic Surveying in France 5

Literature (French) 9

II Photographic Surveying in Germany 12

III. Photographic Surveying in Austria 15

Literature (German and Austrian) 16

IV. Photographic Surveying in Sweden 21

Literature (Swedish) 22

V. Photographic Surveying in Switzerland 23

VI. Photographic Surveying in Italy 25

VII. Photographic Surveying in Spain 27

VIII. Photographic Surveying in the Dominion of Canada and in Alaska . 29

Literature (English) 33



I. Visual Seeing 35

II. Central Projection 36

III. Photographic Perspectives 36






I. Diameter of the Pin-hole 42

II. Length of Exposure 43

III. Focal Lengths of Pin-hole Cameras 44

IV. Determination of the Values of the Pin-hole-camera Constants. . . 44



I. Orienting the Picture Traces on the Plotting-sheet 47

A. Iconometric Plotting when using a Surveying Camera only . 49

B. Plotting the Picture Traces when using a Camera or Photo-

theodolite 49

II. Arithmetical Determination of the Principal and of the Horizon

Line on the Photographic Perspectives. . . 51

A. Determination of the Principal Point and Distance Line of

the Photographic Perspective 51

B. Determination of the Position of the Horizon Line on the

Perspective 5

III. Graphic Method for Determining the Positions of the Principal

and Horizon Lines on the Perspectives 54

IV. The "Five-point Problem" (by Prof. F. Steiner), or Locating

the Plotted Position of the Camera Station by means of the
Perspective when Five Triangulation Points are Pictured on
the Same Photographic Perspective 55

A. Determination of the Principal Point and Distance Line .... 55

B. Simplified Construction for Locating the Plotted Position

of the Camera Station by Means of the " Five -point
Problem " 56

C. Application of the "Five-point Problem" to the Special Case,

where the Five Points range themselves into a Triangle

on the Working-sheet 57

D. To Find the Elevation of the Camera Horizon for a Station

that has been Located by Means of the "Five-point
Problem" 58



V. The "Three-point Problem" 59

A. Mechanical Solution of the "Three-point Problem" (using a

Three -arm Protractor or Station-pointer) 60

B. Graphic Solution of the "Three-point Problem" 60

1. Using the so-called "Two-circle Method" 60

2. Using the Method of Bohnenberger and Bessel 61

VI. The Orientation of Picture Traces, Based on Instrumental Measure-
ments Made in the Field 62

VII. Relations between Two Perspectives of the Same Object, Viewed

from Different Stations. (Prof. Guido Hauck's Method) . . 62

A. "Kernel Points" and "Kernel Planes" 64

B. Use of the "Perspective Axis" (Line of Intersection) of Two

Picture Planes that show Identical Objects Viewed from

Different Stations 66

VIII. To Plot a Figure, Situated in a Horizontal Plane, on the Ground

Plan by Means of its Perspective 68

IX. To Draw the Horizontal Projection of a Plane Figure on the Ground
Plan by Means of the so-called "Method of Squares," if its
Perspective in Vertical Plane and the Elements of the Per-
spective are given 72

X. The "Vanishing Scale" 74



A. To Plot the Picture Trace of an Inclined Plate 78

B. Plotting the Lines of Direction to Points Pictured on an Inclined

Photographic Plate 79

C. Determination of the Altitudes of Points Pictured on an Inclined

Plate 80

D. Applications of Prof. Guido Hauck's Method So



I. Analytical or Arithmetical Phototopographic Methods 83

A. Method of Prof W. Jordan 83

B. Method of Dr. G. Le Bon. . 86



G. Method of L. P. Paganini (Italian Method) 88

1. Determ 'nation of the Focal Length of the Photographic

Perspective 88

a. When the Reference Point is Bisected by the Prin-

cipal Line of the Perspective 88

Example No. i 89

b. The Image of the Reference Point falls to either

Side o' the Principal Line of the Photographic

Perspective 90

Example No. 2 91

Example No. 3. 92

2. Orientation of the Picture Traces 92

3. Determination of the Elevations of Pictured Terrene

Points 95

Example No. 4 .' . 95

(a) Computation of the Focal Length (/) 98

(/?) Computation of the Abscissae for Plotting
Lines of Horizontal Directions to Pictured
Points of the Terrene and for Checking

the Position of the Principal Point 98

(f) Computation of the O dinates of Pictured
Terrene Points of Known Elevations to
Check the Position of the Horizon Line on

the Negative 98

(8) Orienting a Panorama 99

4. Checking the Verticality of an Exposed Plate 100

Example No. 5 102

5. Application of Franz HafferPs Method for Finding the

Focal Length of, a Photographic Perspective from

the Abscissae of Two Pictured Terrene Points .... 107

Example No. 6 108

Example No. 7 1 1 1

6. Supplement 113

a. Forms Showing Arrangements of Field Records for

Panorama Views 113

b. Form used for Recording the Elevations of Second-

ary Points of the Panorama Views 115

D. General Arithmetical Method for Finding the Plotted Posi-

tions of Terrene Points when Pictured on Vertically Ex-
posed Picture Planes 115

E. General Arithmetical Method for Finding the Plptted Posi-



tions of Terrene Points when Pictured on Inclined

Picture Planes 117

F. General Arithmetical Determination of the Elements of a

Photographic Perspective 119

Graphical Iconometrical Plotting Methods 121

A. Col. A. Laussedat's Method (French Method) 121

i. Orientation of the Picture Traces on the Plotting-sheet. 124
. 2. Locating Points on the Plotting-sheet that have been

Identified on Several Photographs 124

3. The Iconometric Determination of Elevations of Pic-

tured Terrene Points 125

4. Drawing the Plan Including Horizontal Contours 126

B. Method of Dr. A. Meydenbaur (German Method) 128

1. Determination of the Focal-length Value for the Photo-

graphic Perspective 128

2. Orientation of the Picture Traces on the Plotting-sheet. 130

3. Locating Points, Identified on Several Photographs, on

the Plotting-sbeet 131

4. The Iconometric Determination of Elevations of Pic-

tured Terrene Points 132

C. Capt. E. Deville's Method (Canadian Method) 132

1. General Remarks on the Field-work 132

2. General Remarks on the Iconometric Plotting of the'

Survey 135

3. Orienting the Picture Traces on the Working-plan 137

4. The Identification of Pictured Points in Photographs

Representing Identical Points of the Terrene 138

5. Application of Prof. G. Hauck's Method for the Iden-

tification of Terrene Points Pictured on Several
Photographs 139

6. Plotting Pictured Terrene Points as Intersections of Lines

of Horizontal Directions. Iconometric Plotting of
Terrene Points in General. ("Horizontal Inter-
sections") 140

7. Iconometric Plotting of Pictured Terrene Points by so-'

called " Vertical Intersections " 142

8. Iconometric Determination of the Elevations of Pic-

tured Terrene Points 145

9. Iconometric Determination of the Elevations of Pic-

tured Terrene Points by Means of the so-called
"Scale of Heights " '. 147



10. The Use of the so-called "Photograph Board" 148

11. Iconometric Plotting of the Trace of a Figure's Plane. . 149

12. Iconometric Contouring 151

13. The Use of the so-called "Photograph Protractor".. . . 154

D. Method of Commandant V. Legros for Locating the Horizon

Line of a Vertically Exposed Plate 156

E. Prof. S. Finsteiwalder's Method for the Iconometric Plotting

of Horizontal Contours 157



A. The Refractive Index 159

B. Refraction of Light-rays 160

C. The Optical Lens 161

D. Optical Distortion 163

E. Nodal Points and Nodal Planes of a Lens 165

F. Principal Foci and Focal Planes of a Lens 168

G. The Focal Length of a Lens 169

H. The Biconvex or Positive Lens 170

I. Conjugate Foci and Conjugate Planes 171

K. To Find the Image of any Luminous Point for the Biconvex Lens. . 172

L. The Biconcave or Negative Lens 173

M. To Find the Image of a Luminous Point for a Biconcave Lens 174

N. Lens Combinations 1 74

O. Diaphragms or Lens Stops 1 76

P. Rapidity of a Lens 1 76

Q. Length of Exposure 177

R. Distortion Produced by Diaphragms 177

S. Chromatic Aberration of Light-rays 178



General Requirements to be Fulfilled by a Topographic Surveying-
camera 183

I. Ordinary Cameras (with Extension Bellows) Converted into Sur-
veying-cameras 184

II. Special Surveying-cameras with Constant Focal Lengths 185

A. Dr. A. Meydenbaur's New Small Magazine Camera 185


B. Capt. E. Deville's Surveying-camera (New Model) 186

1. Determination of the Focal Length, the Horizon Line,

and the Principal Line . . . . : 189

2. Adjustment of Camera Spirit-levels 192

3. Use of the Instruments Comprised in the Canadian

Phototopographic Outfit 193

C. The U. S. Coast and Geodetic Survey Phototopographic

Cameras 196

D. L. P. Paganini's New Phototopographic Instrument for

Reconaissance Surveys on Scales of 1:50000 and

i : 100,000 (Model of 1897) 200

1. The Phototopographic Camera Proper 201

2. The Horizontal Graduated Circle 203

3. The Azimuth Compass 203

4. The Tripod 204

5. Adjustments and Use of the Instruments 204

III. Surveying-cameras Combined with Geodetic Instruments. (Pho-

totheodolites, Phototachymeters, Photographic Plane Tables,
etc.) . 209

A. L. P. Paganini's Photogrammetric Instrument (Model of

1884) 211

Constant Focal Lengths of the Italian Cameras 215

B. L. P. Paganini's New Photo theodolite (Model of 1894) .... 219

C. L. P. Paganini's Photographic Azimuth Compass (Photo-

graphic "Azimutale r ). . 223

D. Photogrammetric Theodolite of Prof. S. Finsterwalder 227

E. Phototheodolite for Precise Work, by O. Ney 231

F. Phototheodolite of Dr. C. Koppe 234

G. Dr. C. Koppe 's New Instrument and Method for Observing

Horizontal and Vertical Angles Directly on the Photo-
graphic Negative 236

H. Phototheodolite Devised by V. Polkck; Manufactured by

R. Lechner in Vienna, Austria 241

I. Phototheodolite Devised by Pollack and Hafferl 242

K. R. Lechner's Photogrammeter 243

L. Phototheodolite of Col. A. Laussedat (New Model) 244

M. Phototheodolite of Starke and Kammerer 245

N. Capt. von Huebl's Plane-table Photogrammeter 250

O. Phototheodolite ("Phototacheometre") Devised by J. and

H. Vallot 253

P. Phototheodolite Designed by J. Bridges-Lee 262





I. The Photographic P!ane Table Devised by A. Chevallier 270

II. The Rockwood-Shallenberger Panoramic Camera 271

III. R. Moessard's Topographic Cylindrograph 271



I. Graphic Protractor (of L. P. Paganini) 275

II. L. P. Paganini's Graphic Sector ("Settore Grafico") 278

III. L. P. Paganini's Graphic Hypsometer ("Squadro Grafico") 284

IV. The Centro-linead as Used by Capt. E. Deville 290

A. To Set the Arms / and V of the Centro-linead if the Direc-

tion to the Vanishing Point be given by a Line in the
Ground Plan 293

B. To Set the Arms of the Centro-linead if the given Line

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 1 of 33)