This report represents the state-or-the-art for photographic intelligence in April 1944 as understood by the Army Air Forces/Navy photographic intelligence effort in the Washington, DC, area. It gives data needed by photo interpreters and service members working with photographic intelligence. It includes mathematical, technical, and organizational data and aids for identification of various types of installations, structures, ships, aircraft, and fighting vehicles.
This report is listed in WorldCat under Accession Number: OCLC: 61437289.
RADIAL LINE PLOT
SINGLE OBLIQUE PHOTO
TRI· METROGON PHOTOGRAPHY & MAPPING
METHOD OF MAKING BASE MAP FROM AN OBLIQU

Bolin, Robert L, Depositor

English

UNL | Libraries

University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
DOD Military Intelligence U.S. Department of Defense
3-1944
Photographic Interpretation Handbook, United
States Forces: Section 11 Plotting from Photos
Robert L. Bolin Depositor
University of Nebraska-Lincoln, rbolin2@unl.edu
Follow this and additional works at: http://digitalcommons.unl.edu/dodmilintel
This Article is brought to you for free and open access by the U.S. Department of Defense at DigitalCommons@University of Nebraska - Lincoln. It has
been accepted for inclusion in DOD Military Intelligence by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln.
Bolin, Robert L. Depositor, "Photographic Interpretation Handbook, United States Forces: Section 11 Plotting from Photos" (1944).
DOD Military Intelligence. 14.
http://digitalcommons.unl.edu/dodmilintel/14
SECTION 11 PLOTTING 
11.01-11.99 
r 
t 
t 
l 
l 
1 
l 
l 
l 
l 
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PLOTTING RESTRICTED 
RADIAL LINE PLOT ICONT.I 
r·----------, 
3a 
3b 
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~.---------------------------------____ __.J 
4a. 
4b. 
3a. 
3b. 
Begin the preliminary radial plot. (All lines shown in 3a, 3b, 4a , 
4b, to be drawn on the cellulose sheet in red, using a pencil). 
Preliminary radial plot extended. 
'kx >K % * 
~-----J----
~ 
1 
~ 
V) 
~ 
1 ?f- 2 3 15 6" V) 4 0 , oj 
~ D~i ~ ~ 
* * 
~ 
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L ___________________ ..l 
4a 
'kx~ )1( /K 
* 
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U) 
~ ~ 9 13 ~ 4' 5 "6 7 8 10 11 12 14 ~ 1 B )/:G '5 ~ 
*' *' * 
~ 
* 
of 
* 
l ~ 
* 
D~,* >K '" ;{ eX>K ;t( (J 
4b 
Preliminary radial plot extended. 
Freliminary radial plot concluded. Now draw polyconic projection to 
the average scale of the flight. (The projection lines and the scale 
to be left in pencil. see Plate 7.) All ground control signsls 
are plotted and marked with a small red circle (about ~ inch 
diameter), using red cellulose ink. (This sheet is the MASTER SHEET.) 
11.02 RESTRICTED 
r 1-
f ,= 
-... 
r - r-
[ ,: 
~ 
P - f-
-..... 
,-
f ,: 
[ I: 
r ,: 
r 
r I: 
[I: 
[,: 
[ I : 
-
,-
,.-
,-
,.-
\~ .. 
RESTRICTED PLOTTING 
RADIAL LINE PLOT ICONT.I 
- - --., 
- -~- - - ;--:;: 
23l-----l A --/--,---: +-------\ :,"\\", I '-" ;,,-': ~ 0 
5b 
, 
-------- : 1--&8- : 
23'-7-- A'>.,-----.j-//--:-, --+---1 
, , 
, , 
: -.--~--+-- : I~--:: 2 I 
:1,.-')'8 : 
22"---------'--+-----1 22'!-+-' ---+--+--t---J 
. , ~ , 
------, 
:0.-: c ~ i 1...---1---1 -
1I'2~IL·I-8'----IL7'------',6c:-' --' 
-
\, II( ) 
23'f----- ~ __ I-~:'z.,j{' ~. --+'----'--.;...' -+---
, 
, 
------~- ~:3---jo--lOB t:. : ~ 
-, 
, 
22'1------+-':.---+---+-+----1 ~ '/ '~, "i ::>t!, '" ~ DO !--~---- ----------: I 
1I'21'L----IL1'---~16c:;-' ----+.15':-------' 11'18' 
23' A --'-+---+--+-+----1 
3 .-
1 08 
22' L---l.l-------+-..;....~ 
: Q 
"\: ~ 
---~ ~ 
~ 
II" 21~1 L'I-8'----ILT---~16c:;-'------' 
5a~ Start the controlled plot Extend the picture control between, and 
adj scent, to the located ground control. 
5b. Picture control plot extended. 
-""- ' -- "~---- : 
o B -2 ---l---3~- ---- k>-'---~ 6 1\ 
22'1--------+------+---+, -+--------H---Q--j 
')K k i DP\':l ':~\ ~ 
L _______________ l_i ~ 
6a 
II' 21'L ___ ..L ___ -,l::-:-___ l:-;-___ ~;__---.-J 
71'18' 17' 16' 15' 14' 
22'1--------+------+----+-----+----1 
6b 
~llf "~ D'~~~~ 
"[f!1":' A~ 'ii, I' / ;", l' 
11'21' L--_..L ___ -1 ____ -L.-___ ....L-;--__ _ 
71'18' 17' 16' 15' 
6a. Picture control plot extended to the nearest ground control point. 
(All lines shown in Sa, 5b, 6~ are drawn on the master sheet in red, 
using ~ pencil.) 
6b. Adjustment of the picture control plot. 
RESTRICTED 11.03 
, 
p 
,II 
~ll 
fUI 
JHI 
III 
f~l 
, 
r 
, 
[ 
, 
, 
, 
, 
[ 
:[ 
1 
PLOTTING RESTRICTED 
RADIAL LINE PLOT (CONT.I 
7 
11'18' IT 16' 15' 14' 13' 12' II' 71'10' 
11"27',:.-----,------,-----,-----,------.----,-----,------.11"27' 
Z4'f-----+------+-----+-----+-------t------j------+-------l24' 
o o o o 
o o OA 0 (0 0 0 0 ( 
23"f-------t---1".J----+-------t-----+------+-------j-----t::----- 23' 
~F 
08 o 4 
o 
6 
o 
8 o 10 
o 
II 
o 
12 
o 
13 o 
14 
22'I-___ -j ____ -+ ____ + ____ + ____ +-____ ~----PG----22' 
o o 0 C 
o o o D o 
o o o 
O[ o o o 
II'ZI~IL·I-8,.-' -----'17------'.-16,.-' ----ISL '------'14-c'-----'-13-:-' -----:1':c2'--:---~11-,-' ----7~1·116'2t' 
7, The completed control plot. The radial intersections are marked with 
a small blue circle (about ~ inch diameter), using blue cellulose 
ink, the principal points of all photographs are marked with a 
small red circle (about 1/16 inch diameter), using red cellulose 
ink. All points marked. on reverse side of master sheet. The pro-
jection lines on the master sheet are inked (black cellulose ink) 
and the scale is inked (red cellulose ink). 
TRACING DETAIL FROM PHOTOS TO WORK SHEET 
PROCEDURE: 
1. Select additional points to control planimetric detail (detail 
points). Such points may be along shore line, outlying rocks, drainage 
lines, buildings and other critical points necessary for tracing detail. 
2. Transfer these detail points to each succeeding and preceding print. 
(~ green circles) 
3. Place photo under work sheet and orient it according to center 
point and intersections of picture control points on work sheet. Then 
get radial intersection of detail points hy same method as picture 
control intersections were obtained. (~ green circles) 
4. Place each pair of photographs under stereoscope and outline ground 
detail desired by drawing on photographs. 
5. Place photograph under work sheet in its proper orientation. 
n. When tr8cing detail, move detail point of intersection oT" sheet ex-
actly over the corresponding detail point on the photograph, keeping 
in line with the principal point. Then trace the detail arounri this 
detail point and gradually move the work sheet so that when tracing 
arrives at the next detAil point, the detail point on the work sheet IS 
exactly over the same detail point on the photograph. This movement 
from point to point, should be from the principal point, in or out, as 
the case may be. 
11.04 RESTRICTED 
RESTRICTED PLOTTING 
CONSTRUCTION OF CANADIAN GRID 
SINGLE OBLIQUE PHOTO 
Three conditions are required: 
1. Precise focal length 
2. Flying height 
3. Visible horizon 
PROCEDURE: 
I Establish true horizon. 
TRUE HORIZON H 
APPAR NT HORIZON HI 
e TRUE ANGLE OF TILT 
D = DIP ANGLE 
II 
r-~~~--~~--------4-
P 
P principal point 
A - altitude 
9 - True angle of tilt 
Gapparent tilt + dip angle) 
HI - Apparent horizon 
H 
- f'rue. hor i zan 
D 
- Dip angle 
tan of apparent tilt PHI measured on photo in inches 
focal length in inches 
Dip angle in minutes = .98 altitude in feet 
Distance PH is found from formula 
PH = f tan 9 
Line PH is perpendicular to the apparent horizon. 
Draw a line thru H parallel to the apparent horizon. 
Erect a construction line AA' parallel to the trllP horizon 
thru point Gi(Diagram on following page). 
HG in inches = Altitude X Scale 
cos 9 
Scale Scale of grid 
Example: Scale - 1" on grid 
Altitude - 5,000 
Tilt 30 0 
5000 1 " HG x-
8nn 660' 
660' on ground 
9.99 " 
Point G is plotted along a line thru P. The construction line 
AA' parallel to the true horizon is drawn thru G. 
TILT 
RESTRICTED 
11.05 
flJ 
~I 
JII 
III 
III 
Jll 
,II 
III 
III 
r 
r 
r 
J 
iJ 
J 
:f 
I 
:1 
1 
!( 
!:( 
II 
III 
II 
II 
:1 
: il I 
I' 
,ii 
PLOTTING RESTRICTED 
SINGLE OBLIQUE PHOTO (CONT.) 
CONSTRUCTION OF CANADIAN GRID (CONTo) 
TRUE HORIZON 
A 
III 
IV 
Layoff along AA' equal space units(previously determined as 
the scale of the grid)originating spaces at point G. Draw 
meridians connecting these points and point H. 
The vanishing points for a system of parallel lines that make 
an angle of 45 0 on the ground with the meridian lines is lo-
cated on the true horizon at a distance HX or HX1 from point 
H. 
HX or HX1= __ f_ 
cos '0 
Plot X and Xl an~ draw llones thru P from X and Xl ttO {j cu lng 
across the meridian lines. 
V The points where the diagonals cross the meridian lines will 
give the proper spacing for the horizontal lines. 
METHOD OF MAKING BASE MAP FROM AN OBLIQUE 
Four conditions are required: 
I 
11.06 
1-
2. 
3. 
4. 
Precise focal length 
Flying heighth 
Visible horizon 
Comparatively flat terrain 
Establish true horizon. 
e = Apparent tilt + dip angle 
(Same as Canadian grid) 
RESTRICTED 
-
L ••• 
L 111-
:L 
L 
L ... 
:L .... 
."'. 
.... 
... 
1 'I'" 
... 
iL ..... 
.". 
1 
!l 
RESTRICTED PLOTTING 
SINGLE OBLIQUE PHOTO 
CONSTRUCTION OF CANADIAN GRID 
Three conditions are required: 
1. Precise focal length 
2. Flying height 
3. Visible horizon 
PROCEDURE: 
I Establish true horizon. 
TRUE HORIZON H e TRUE ANGLE OF TILT 
APPAR NT HORIZON H' D = DIP ANGLE 
II 
P 
P - principal point 
A - altitude 
G - True angle 
(+app a r en t 
of tilt 
tilt + dip angle) 
HI - Apparent horizon 
H - flrue. hor i zon 
D - Dip angle 
tan of apparent tilt = PHI measured on photo in inches 
focal length in inches 
Dip angle in minutes = .98 altitude in feet 
Distance PH is found from formula 
PH = f tan 9 
Line PH is perpendicular to the apparent horizon • 
Draw a line thru H parallel to the apparent horizon. 
Erect a construction line AA' parallel to the trllP hnrizon 
thru point Gj(Diagram on following page). 
HG in'inches = Altitude X Scale 
cos 9 
Sca 1 e Scale of grid 
Exampl e: Scale - 1" on grid = 
Altitude - 5,000 
Tilt - 30 0 
660' on ground 
5000 1 " 
HG x- 9.99 " 
81)/'i 660' 
Point G is plotted along a line thru P. The construction line 
AA' parallel to the true horizon is drawn thru G. 
TILT 
RESTRICTED 11.05 
fi, i, I 
:1 I 
,II 
JI! 
JII 
Jil 
JII 
~Il 
,11 
I' 
II fl ~ 
Ii, 
II 
Il 
Il 
IiI I' 
" 
Iii 
1:1 
PLOTTING RESTRICTED 
SINGLE OBLIQUE PHOTO (CONT.I 
CONSTRUCTION OF CANADIAN GRID (CONT,) 
TRUE HORIZON 
A------------------~--~+--+~~~-+--~~-+~~4-~~~~-\--~--~~--------------A' 
III 
IV 
Layoff along AA' equal space units(previously determined as 
the scale of the grid)originating spaces at point G. Draw 
meridians connecting these points and point H. 
The vanishing points for a system of parallel lines that make 
an angle of 45 0 on the ground with the meridian lines is lo-
cated on the true horizon at a distance HX or HX 1 from point 
H. 
HX or HXI:=t __ f_ 
cos '0 
plot X and Xl and draw lines thru P from X and Xl cutting 
across the meridian lines. 
V The points where the diagonals cross the meridian lines will 
give the proper spacing for the horizontal lines. 
METHOD OF MAKING BASE MAP FROM AN OBLIQUE 
Four conditions are required: 
I 
11.06 
1. Precise focal length 
2. Flying heighth 
3. Visible horizon 
4. Comparatively flat terrain 
Establish true horizon. 
e == Apparent tilt + dip angle 
(Same as Canadian grid) 
RESTRICTED 
~ I ~ 
I II J 
I I J 
[ I J 
t I J 
C I J 
C I ] 
[ I J 
[I~ 
[ I · 
Ie II • 
I[ I • 
I[ I ~' 
I 
Ie I • 
Ie 
I[ 's.-
I[ 
tC ijlL 
Il ~ 
Il 'foI1.-
RESTRICTED PLOTTING r 
SINGLE OBLIQUE PHOTO (CONT.I 
METHOD OF MAKING BASE MAP FROM AN OBLIQUE (CONT.) 
II 
NOTE: 
Draw perpendicular (principal line) from true horizon passing 
through principal point. 
Procedure involved in I and II is the same as that for Canadian 
grid. 
III Determine isocenter. 
IV 
V 
VI 
Distance HI Focal len~h in inches 
cos 9 
Erect a construction line (isoline) parallel to the true horizon 
passing through the isocenter. This construction line gives a 
scale equal to that of ~ vertical photograph of same focal length 
and same altitude. 
Draw rays through image points selected as control from the per-
spective center H. Project these rays through the image point 
to the isoline and at this intersection erect a line parallel to 
the principal line. 
Then, from the isocenter draw rays through the image points, and 
points where these rays intersect the parallels erected from the 
isoline are the rectified positions in a horizontal plane. 
B' 
D' 
PRINCIPAL LINE 
A' 
f--'.o--___________ -M' __ +-+--__ .f--I-->.--.:.:TR:.::U:::E,.:.HORIZON 
ISOLINE 
RESTRICTED 11.07 
p 
Iii 
1111 
I: I 
1'1 
f 
r 
I' 
I 
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l 
l 
l 
I 
I 
I; 
l 
I 
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1. 
l. 
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'I L 
l(, 
j, 
PLOTTING RESTRICTED 
TRI· METROGON 
TRI· METROGON PHOTOGRAPHY & MAPPING 
In trimetrogon photography an assembly of three cameras is used. 
One camera is directed vertically downward and two are mounted at an 
angle of 30· from horizontal and perpendicular to the line of flight. 
The two oblique cameras are so placed that they photograph both the 
horizon and a small area covered by the vertical camera. All cameras 
are exposed simultaneously, so that the area from horizon to horizon, 
perpendicular to the line of flight, is covered by the three photo-
graphs. 
For mapping large areas at a small scale (1:1,000,000 to 1:250,000) 
trimetrogon photography has the following advantages: 
11.08 
1. The distance between flight lines can be much greater than 
in single lens photography (about 25 miles apart at 20,000 feet.) 
2. Flight lines need not be flown as accurately as in single lens 
photography. 
3. Less ground control needed. 
4. More economical for mapping large areas (less film, fewer 
flying hours.) 
RESTRICTED 
[ 1 
-
.-
-
[ I .--
[ 1 
-
.--
[ 
[ 1 
, I 
[ I 
[I 
[ 1 
[ 
RESTRICTED PLOTTING 
SINGLE OBLIQUE PHOTO (CONT.I 
METHOD OF MAKING BASE MAP FROM AN OBLIQUE ICONT.) 
II Draw perpendicular (principal line) from true horizon passing 
through principal point. 
NOTE: Procedure involved in I and II is the same as that for Canadian 
grid. 
III Determine isocenter. 
Distance HI Focal length in inches 
cos 9 
IV Erect a construction line (isoline) parallel to the true horizon 
passing through the isocenter. This construction line gives a 
scale equal to that of ~ vertical photograph of same focal length 
and same altitude. 
V Draw rays through image points selected as control from the per-
spective center H. Project these rays through the image point 
to the isoline and at this intersection erect a line parallel to 
the principal line. 
VI Then, from the isocenter draw rays through the image points, and 
points where these rays intersect the parallels erected from the 
isoline are the rectified positions in a horizontal plane. 
B' 
D' 
PRINCIPAL LINE 
,TRUE HORIZON 
ISOLINE 
RESTRICTED 11.07 
~I 
~I 
~" 
I~I 
'Ill 
fill 
lU 
PLOTTING RESTRICTED 
TR I . M ETROGON 
TRI· METROGON PHOTOGRAPHY & MAPPING 
In trimetrogon photography an assembly of three cameras is used. 
One camera is directed vertically downward and two are mounted at an 
angle of 30· from horizontal and perpendicular to the line of flight. 
The two oblique cameras are so placed that they photograph both the 
horizon and a small area covered by the 
are exposed simultaneously, so that the 
perpendicular to the line of flight, is 
graphs. 
vertical camera. All cameras 
area from horizon to horizon, 
covered by the three photo-
For mapping large areas at a small scale (1: 1,000,000 to 1:250,000) 
trimetrogon photography has the following advantages: 
11.08 
1. The distance between flight lines can be much greater than 
in single lens photography (about 25 miles apart at 20,000 feet.) 
2. Flight lines need not be flown as accurately as in single lens 
phot og r aphy. 
3. Less ground control needed. 
4. More economical for mapping large areas (less film, fewer 
flying hours.) 
RESTRICTED 


Photographic Interpretation Handbook, United States Forces: Section 11 Plotting from Photos

DigitalCommons@University of Nebraska

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnDOD Military Intelligence U.S. Department of Defense3-1944Photographic Interpretation Handbook, UnitedStates Forces: Section 11 Plotting from PhotosRobert L. Bolin DepositorUniversity of Nebraska-Lincoln, rbolin2@unl.eduFollow this and additional works at: http://digitalcommons.unl.edu/dodmilintelThis Article is brought to you for free and open access by the U.S. Department of Defense at DigitalCommons@University of Nebraska - Lincoln. It hasbeen accepted for inclusion in DOD Military Intelligence by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln.Bolin, Robert L. Depositor, "Photographic Interpretation Handbook, United States Forces: Section 11 Plotting from Photos" (1944).DOD Military Intelligence. 14.http://digitalcommons.unl.edu/dodmilintel/14SECTION 11 PLOTTING 11.01-11.99 r t t l l 1 l l l l L PLOTTING RESTRICTED RADIAL LINE PLOT ICONT.I r·----------, 3a 3b ,---- - --- ---- --- ----, !'J.v ¥ ! :T\AW /, ";: : / \ / : , , ~: 1" , r ~\~ _______ J ~----- -y-------: Y1" /: , , , , 0-:::: : 1 """"-B- I 4 I : : l:~ , '" ' '-'\ ' L _________________ ...I r--------------___ _ ,-------- -- -- --. ----, '{ X ~ I\A :1 A , , , ~:0--;;;:. j 2 3 ---: 1 B: ~ : , , : : .--- - --._---- -- -----"> ~ t ':/: :1'\ ~ /': , , : ~--L----s---- : 1 ~ :4 : , ' i* 'i \ ~[ L _________________ .J ~.---------------------------------____ __.J 4a. 4b. 3a. 3b. Begin the preliminary radial plot. (All lines shown in 3a, 3b, 4a , 4b, to be drawn on the cellulose sheet in red, using a pencil). Preliminary radial plot extended. 'kx >K % * ~-----J----~ 1 ~ V) ~ 1 ?f- 2 3 15 6" V) 4 0 , oj ~ D~i ~ ~ * * ~ ~ {' eX)/( (J L ___________________ ..l 4a 'kx~ )1( /K * ::K )K )/( /K )/( )K >K t ~ ~ X! ~ ~ U) ~ ~ 9 13 ~ 4' 5 "6 7 8 10 11 12 14 ~ 1 B )/:G '5 ~ *' *' * ~ * of * l ~ * D~,* >K '" ;{ eX>K ;t( (J 4b Preliminary radial plot extended. Freliminary radial plot concluded. Now draw polyconic projection to the average scale of the flight. (The projection lines and the scale to be left in pencil. see Plate 7.) All ground control signsls are plotted and marked with a small red circle (about ~ inch diameter), using red cellulose ink. (This sheet is the MASTER SHEET.) 11.02 RESTRICTED r 1-f ,= -... r - r-[ ,: ~ P - f--..... ,-f ,: [ I: r ,: r r I: [I: [,: [ I : -,-,.-,-,.-\~ .. RESTRICTED PLOTTING RADIAL LINE PLOT ICONT.I - - --., - -~- - - ;--:;: 23l-----l A --/--,---: +-------\ :,"\\", I '-" ;,,-': ~ 0 5b , -------- : 1--&8- : 23'-7-- A'>.,-----.j-//--:-, --+---1 , , , , : -.--~--+-- : I~--:: 2 I :1,.-')'8 : 22"---------'--+-----1 22'!-+-' ---+--+--t---J . , ~ , ------, :0.-: c ~ i 1...---1---1 -1I'2~IL·I-8'----IL7'------',6c:-' --' -\, II( ) 23'f----- ~ __ I-~:'z.,j{' ~. --+'----'--.;...' -+---, , ------~- ~:3---jo--lOB t:. : ~ -, , 22'1------+-':.---+---+-+----1 ~ '/ '~, "i ::>t!, '" ~ DO !--~---- ----------: I 1I'21'L----IL1'---~16c:;-' ----+.15':-------' 11'18' 23' A --'-+---+--+-+----1 3 .-1 08 22' L---l.l-------+-..;....~ : Q "\: ~ ---~ ~ ~ II" 21~1 L'I-8'----ILT---~16c:;-'------' 5a~ Start the controlled plot Extend the picture control between, and adj scent, to the located ground control. 5b. Picture control plot extended. -""- ' -- "~---- : o B -2 ---l---3~- ---- k>-'---~ 6 1\ 22'1--------+------+---+, -+--------H---Q--j ')K k i DP\':l ':~\ ~ L _______________ l_i ~ 6a II' 21'L ___ ..L ___ -,l::-:-___ l:-;-___ ~;__---.-J 71'18' 17' 16' 15' 14' 22'1--------+------+----+-----+----1 6b ~llf "~ D'~~~~ "[f!1":' A~ 'ii, I' / ;", l' 11'21' L--_..L ___ -1 ____ -L.-___ ....L-;--__ _ 71'18' 17' 16' 15' 6a. Picture control plot extended to the nearest ground control point. (All lines shown in Sa, 5b, 6~ are drawn on the master sheet in red, using ~ pencil.) 6b. Adjustment of the picture control plot. RESTRICTED 11.03 , p ,II ~ll fUI JHI III f~l , r , [ , , , , [ :[ 1 PLOTTING RESTRICTED RADIAL LINE PLOT (CONT.I 7 11'18' IT 16' 15' 14' 13' 12' II' 71'10' 11"27',:.-----,------,-----,-----,------.----,-----,------.11"27' Z4'f-----+------+-----+-----+-------t------j------+-------l24' o o o o o o OA 0 (0 0 0 0 ( 23"f-------t---1".J----+-------t-----+------+-------j-----t::----- 23' ~F 08 o 4 o 6 o 8 o 10 o II o 12 o 13 o 14 22'I-___ -j ____ -+ ____ + ____ + ____ +-____ ~----PG----22' o o 0 C o o o D o o o o O[ o o o II'ZI~IL·I-8,.-' -----'17------'.-16,.-' ----ISL '------'14-c'-----'-13-:-' -----:1':c2'--:---~11-,-' ----7~1·116'2t' 7, The completed control plot. The radial intersections are marked with a small blue circle (about ~ inch diameter), using blue cellulose ink, the principal points of all photographs are marked with a small red circle (about 1/16 inch diameter), using red cellulose ink. All points marked. on reverse side of master sheet. The pro-jection lines on the master sheet are inked (black cellulose ink) and the scale is inked (red cellulose ink). TRACING DETAIL FROM PHOTOS TO WORK SHEET PROCEDURE: 1. Select additional points to control planimetric detail (detail points). Such points may be along shore line, outlying rocks, drainage lines, buildings and other critical points necessary for tracing detail. 2. Transfer these detail points to each succeeding and preceding print. (~ green circles) 3. Place photo under work sheet and orient it according to center point and intersections of picture control points on work sheet. Then get radial intersection of detail points hy same method as picture control intersections were obtained. (~ green circles) 4. Place each pair of photographs under stereoscope and outline ground detail desired by drawing on photographs. 5. Place photograph under work sheet in its proper orientation. n. When tr8cing detail, move detail point of intersection oT" sheet ex-actly over the corresponding detail point on the photograph, keeping in line with the principal point. Then trace the detail arounri this detail point and gradually move the work sheet so that when tracing arrives at the next detAil point, the detail point on the work sheet IS exactly over the same detail point on the photograph. This movement from point to point, should be from the principal point, in or out, as the case may be. 11.04 RESTRICTED RESTRICTED PLOTTING CONSTRUCTION OF CANADIAN GRID SINGLE OBLIQUE PHOTO Three conditions are required: 1. Precise focal length 2. Flying height 3. Visible horizon PROCEDURE: I Establish true horizon. TRUE HORIZON H APPAR NT HORIZON HI e TRUE ANGLE OF TILT D = DIP ANGLE II r-~~~--~~--------4-P P principal point A - altitude 9 - True angle of tilt Gapparent tilt + dip angle) HI - Apparent horizon H - f'rue. hor i zan D - Dip angle tan of apparent tilt PHI measured on photo in inches focal length in inches Dip angle in minutes = .98 altitude in feet Distance PH is found from formula PH = f tan 9 Line PH is perpendicular to the apparent horizon. Draw a line thru H parallel to the apparent horizon. Erect a construction line AA' parallel to the trllP horizon thru point Gi(Diagram on following page). HG in inches = Altitude X Scale cos 9 Scale Scale of grid Example: Scale - 1" on grid Altitude - 5,000 Tilt 30 0 5000 1 " HG x-8nn 660' 660' on ground 9.99 " Point G is plotted along a line thru P. The construction line AA' parallel to the true horizon is drawn thru G. TILT RESTRICTED 11.05 flJ ~I JII III III Jll ,II III III r r r J iJ J :f I :1 1 !( !:( II III II II :1 : il I I' ,ii PLOTTING RESTRICTED SINGLE OBLIQUE PHOTO (CONT.) CONSTRUCTION OF CANADIAN GRID (CONTo) TRUE HORIZON A III IV Layoff along AA' equal space units(previously determined as the scale of the grid)originating spaces at point G. Draw meridians connecting these points and point H. The vanishing points for a system of parallel lines that make an angle of 45 0 on the ground with the meridian lines is lo-cated on the true horizon at a distance HX or HX1 from point H. HX or HX1= __ f_ cos '0 Plot X and Xl an~ draw llones thru P from X and Xl ttO {j cu lng across the meridian lines. V The points where the diagonals cross the meridian lines will give the proper spacing for the horizontal lines. METHOD OF MAKING BASE MAP FROM AN OBLIQUE Four conditions are required: I 11.06 1-2. 3. 4. Precise focal length Flying heighth Visible horizon Comparatively flat terrain Establish true horizon. e = Apparent tilt + dip angle (Same as Canadian grid) RESTRICTED -L ••• L 111-:L L L ... :L .... ."'. .... ... 1 'I'" ... iL ..... .". 1 !l RESTRICTED PLOTTING SINGLE OBLIQUE PHOTO CONSTRUCTION OF CANADIAN GRID Three conditions are required: 1. Precise focal length 2. Flying height 3. Visible horizon PROCEDURE: I Establish true horizon. TRUE HORIZON H e TRUE ANGLE OF TILT APPAR NT HORIZON H' D = DIP ANGLE II P P - principal point A - altitude G - True angle (+app a r en t of tilt tilt + dip angle) HI - Apparent horizon H - flrue. hor i zon D - Dip angle tan of apparent tilt = PHI measured on photo in inches focal length in inches Dip angle in minutes = .98 altitude in feet Distance PH is found from formula PH = f tan 9 Line PH is perpendicular to the apparent horizon • Draw a line thru H parallel to the apparent horizon. Erect a construction line AA' parallel to the trllP hnrizon thru point Gj(Diagram on following page). HG in'inches = Altitude X Scale cos 9 Sca 1 e Scale of grid Exampl e: Scale - 1" on grid = Altitude - 5,000 Tilt - 30 0 660' on ground 5000 1 " HG x- 9.99 " 81)/'i 660' Point G is plotted along a line thru P. The construction line AA' parallel to the true horizon is drawn thru G. TILT RESTRICTED 11.05 fi, i, I :1 I ,II JI! JII Jil JII ~Il ,11 I' II fl ~ Ii, II Il Il IiI I' " Iii 1:1 PLOTTING RESTRICTED SINGLE OBLIQUE PHOTO (CONT.I CONSTRUCTION OF CANADIAN GRID (CONT,) TRUE HORIZON A------------------~--~+--+~~~-+--~~-+~~4-~~~~-\--~--~~--------------A' III IV Layoff along AA' equal space units(previously determined as the scale of the grid)originating spaces at point G. Draw meridians connecting these points and point H. The vanishing points for a system of parallel lines that make an angle of 45 0 on the ground with the meridian lines is lo-cated on the true horizon at a distance HX or HX 1 from point H. HX or HXI:=t __ f_ cos '0 plot X and Xl and draw lines thru P from X and Xl cutting across the meridian lines. V The points where the diagonals cross the meridian lines will give the proper spacing for the horizontal lines. METHOD OF MAKING BASE MAP FROM AN OBLIQUE Four conditions are required: I 11.06 1. Precise focal length 2. Flying heighth 3. Visible horizon 4. Comparatively flat terrain Establish true horizon. e == Apparent tilt + dip angle (Same as Canadian grid) RESTRICTED ~ I ~ I II J I I J [ I J t I J C I J C I ] [ I J [I~ [ I · Ie II • I[ I • I[ I ~' I Ie I • Ie I[ 's.-I[ tC ijlL Il ~ Il 'foI1.-RESTRICTED PLOTTING r SINGLE OBLIQUE PHOTO (CONT.I METHOD OF MAKING BASE MAP FROM AN OBLIQUE (CONT.) II NOTE: Draw perpendicular (principal line) from true horizon passing through principal point. Procedure involved in I and II is the same as that for Canadian grid. III Determine isocenter. IV V VI Distance HI Focal len~h in inches cos 9 Erect a construction line (isoline) parallel to the true horizon passing through the isocenter. This construction line gives a scale equal to that of ~ vertical photograph of same focal length and same altitude. Draw rays through image points selected as control from the per-spective center H. Project these rays through the image point to the isoline and at this intersection erect a line parallel to the principal line. Then, from the isocenter draw rays through the image points, and points where these rays intersect the parallels erected from the isoline are the rectified positions in a horizontal plane. B' D' PRINCIPAL LINE A' f--'.o--___________ -M' __ +-+--__ .f--I-->.--.:.:TR:.::U:::E,.:.HORIZON ISOLINE RESTRICTED 11.07 p Iii 1111 I: I 1'1 f r I' I l l l l I I I; l I l :1 1. l. l l L L l L 'I L l(, j, PLOTTING RESTRICTED TRI· METROGON TRI· METROGON PHOTOGRAPHY & MAPPING In trimetrogon photography an assembly of three cameras is used. One camera is directed vertically downward and two are mounted at an angle of 30· from horizontal and perpendicular to the line of flight. The two oblique cameras are so placed that they photograph both the horizon and a small area covered by the vertical camera. All cameras are exposed simultaneously, so that the area from horizon to horizon, perpendicular to the line of flight, is covered by the three photo-graphs. For mapping large areas at a small scale (1:1,000,000 to 1:250,000) trimetrogon photography has the following advantages: 11.08 1. The distance between flight lines can be much greater than in single lens photography (about 25 miles apart at 20,000 feet.) 2. Flight lines need not be flown as accurately as in single lens photography. 3. Less ground control needed. 4. More economical for mapping large areas (less film, fewer flying hours.) RESTRICTED [ 1 -.--[ I .--[ 1 -.--[ [ 1 , I [ I [I [ 1 [ RESTRICTED PLOTTING SINGLE OBLIQUE PHOTO (CONT.I METHOD OF MAKING BASE MAP FROM AN OBLIQUE ICONT.) II Draw perpendicular (principal line) from true horizon passing through principal point. NOTE: Procedure involved in I and II is the same as that for Canadian grid. III Determine isocenter. Distance HI Focal length in inches cos 9 IV Erect a construction line (isoline) parallel to the true horizon passing through the isocenter. This construction line gives a scale equal to that of ~ vertical photograph of same focal length and same altitude. V Draw rays through image points selected as control from the per-spective center H. Project these rays through the image point to the isoline and at this intersection erect a line parallel to the principal line. VI Then, from the isocenter draw rays through the image points, and points where these rays intersect the parallels erected from the isoline are the rectified positions in a horizontal plane. B' D' PRINCIPAL LINE ,TRUE HORIZON ISOLINE RESTRICTED 11.07 ~I ~I ~" I~I 'Ill fill lU PLOTTING RESTRICTED TR I . M ETROGON TRI· METROGON PHOTOGRAPHY & MAPPING In trimetrogon photography an assembly of three cameras is used. One camera is directed vertically downward and two are mounted at an angle of 30· from horizontal and perpendicular to the line of flight. The two oblique cameras are so placed that they photograph both the horizon and a small area covered by the are exposed simultaneously, so that the perpendicular to the line of flight, is graphs. vertical camera. All cameras area from horizon to horizon, covered by the three photo-For mapping large areas at a small scale (1: 1,000,000 to 1:250,000) trimetrogon photography has the following advantages: 11.08 1. The distance between flight lines can be much greater than in single lens photography (about 25 miles apart at 20,000 feet.) 2. Flight lines need not be flown as accurately as in single lens phot og r aphy. 3. Less ground control needed. 4. More economical for mapping large areas (less film, fewer flying hours.) RESTRICTED 

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Photographic Interpretation Handbook, United States Forces: Section 11 Plotting from Photos

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