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FACTORS THAT INFLUENCE 

THE QUALITY OF SATELLITE PHOTOGRAPHY 

September 1973 

Prepared by: R. J. Kohler 

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Unauthonzad Disclosure SvbJHI to 

Criminal Sanctions. 

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TABLE OF CONTENTS 

1.0 INTRODUCTION 

2. 0 THE EFFECT OF LAUNCH TIME ON IMAGE QUALITY . 2.1 Spectral Reflections 

2.2 Shadowless Acquisitions 

2.3 Optimizing Shadows for Mensuration 

2.4 Position in Latitude of the Terminator 

2.5 Minimization of Required Camera Exposure 

Changes 

2.6 Summary 

· ·page 

2 

2 

3 

7 

8 

10 

13 

13 

3.0 THE INTERACTION OF THE CAMERA AND THE ACQUISITION 17 

CONDITIONS 

3.1 GAMBIT CUBED 21 

3.2 

3.3 

3.4 

3.5 

3.1.1 Exposure Time and Smear 21 

3.1.2 Camera Performance 21 

3.1.3 The Impact of Contrast on Achieved 25 

Resolution 

HEXAGON 

3.2.1 Exposure Time and Smear 

3.2.2 Camera Performance 

3.2.5 The 'Impact of Contrast on Resolution 

Effect of Target Type, Illumination and 

Time of Year 

3.3.1 Target Type and Illumination 

3.3.2 Contrast and Time of Year 

The Relationships between Photographic Image Quality and PI Suitability 

3.4.1 GAMBIT CUBED 

3.4.1.1 Exposure Time 

3.4.1.2 Time of Year 

3.4.1.3 Target Dependency 

3.4.2 HEXAGON 

3.4.2.1 

3.4.2.2 

3.4.2.3 

Summary 

Exposure Time 

Achieved Mission Performance 

Effect of Specular Reflections 

and Shadowless Acquisitions 

on Quality 

30 

30 

30 

34 

38 

38 

42 

44 

44 

44 

46 

47 

47 

47 

48 

58 

4.0 EFFECTS OF THE REPRODUCTION PROCESS 

4.1 Tone Transfer 

59 

63 

63 

4.2 Resolution Transfer 65 

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LIST OF TABLES 

Page 

2-1 Optimum Launch Time to Minimize Specular 7 

Reflections 

2-2 Optimum Launch Times for Best Image Quality 18 

(96,3° Inclination) 

2-3 Optimum Launch Times for Best Image Quality 19 

(GAMBIT at 110° Inclination) 

3-1 HEXAGON Mission Resolving Power Data from VEM 48 

3-2 Summary of All Weather PI Suitability Ratings 49 

3-3 Mission Ranking, Best to Worst, for Several 51 

Factors 

3-4 Area Weighted GRD Summary for Typical Intelli- 52 

gence Targets 

3-5 Area Weighted GRD Summary for 2:1 Contrast 53 

3-6 Summary of HEXAGON Mission Performance 56 

3-7 Summary of PI Suitability Ratings from Stereo, 55 

Clear and Complete Coverage of OAK Targets 

4-1 Resolution Losses in Reproduction 66 

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HEXAGON GAMBIT 

LIST OF FIGURES 

Page 

2-1 Geometry Resulting in Severe Specular Reflection 4 

2-2 Latitude and Scan Angle of Specular Reflections 5 

as Functions of Time of Year and Launch Time 

(Forward Look, 10° Pitch, Descending Pass) 

2-3 Latitude and Scan Angle of Specular Reflections 6 

as Functions of Time of Year and Launch Time 

(Aft Look, 10° Pitch, Descending Pass) 

2-4 Geometry Associated with Full Front Lighting 9 

(Shadowless Acquisitions) 

2-5 Optimum Launch Time to Maximize Shadow Detail for 11 

Mensuration 

2-6 Latitude at Which 0° Solar Altitude Occurs for 12 

96.3° Inclination 

2-7 Exposure Change as Function of Launch Time for 14 

Specified Latitude Ranges (Summer Solstice) 

2-8 Exposure Change as Function of Launch Time for 15 

Specified Latitude Range (Winter Solstice) 

2-9 Exposure Change as Function of Launch Time for 16 

Specified Latitude Ranges (Equinoxes) 

2-10 Example of Orbit Inclinations to Optimize Image 20 

Quality 

3-1 Typical Exposure vs. Solar Altitude Curve for 22 

GAMBIT CUBED 

3-2 GAMBIT CUBED Estimated Mean Smear for 4342 and Up 23 

3-3 Mean Expected GAMBIT CUBED Ground Resolved Dis- 24 

tance (GRD) for Constant 2:1 Contrast 

3-4 Mean Expected GAMBIT CUBED Ground Resolved Dis- 26 

tance (GRD) for Typical Intelligence Targets 

riEXAGON Gf\MillT. 

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HEXAGON GAMBIT • 

LIST OF FIGURES (CONTINUED) 

Page 

3-5 Mean Expected GAMBIT CUBED Ground Resolved 27 

Distance (GRD) for Typical Intelligence Targets 

3-6 GAMBIT CUBED Resolution for Various Conditions of 29 

Solar Altitude, Contrast and Roll Angle 

3-7 Typical HEXAGON Exposure Time vs. Solar Altitude 31 

3-8 Typical HEXAGON Smear vs. Solar Altitude 32 

3-9 Mean Expected HEXAGON Ground Resolved Distance 33 

(GRD) for Constant 2:1 Contrast 

3-10 Mean Expected HEXAGON Ground Resolved Distance (GRD) 35 

for Typical Intelligence Targets (Nadir) 

3-11 Mean Expected HEXAGON Ground Resolved Distance (GRD) 36 

for Typical Intelligence Targets (45° Scan Angle) 

3-12 HEXAGON Resolution for Various Conditions of 37 

Solar Altitude, Contrast and Scan Angle (Two 

Sigma Low Values) 

3 13 Relative GRD for Various Types of Target Illumi- 40 

nation for Summer Acquisition 

3-14 Relative GRD for Various Types of Target Illumi- 41 

nation for Winter Acquisition 

3-15 HEXAGON Ground Resolved Distance (GRD) vs. Scan 43 

Angle for Specific Target Categories 

3-16 Scene Brightness Range Data for Urban/Industrial 45 

Scenes for 1200- and 4300-Series Missions 

3-17 Grand Area Weighted Average (GAWA) Resolution vs. 54 

OAK Targets Rated Good under All Weather Conditions 

3-18 Mean GRD (ft) within +30° of Scan vs. OAK Targets 54 

Rated Good under Clear Weather Conditions 

3-19 Example of Effects of Front Lighting 60 

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H GON GAMBIT 

LIST OF FIGURES (CONTINUED) 

Page 

3-ZO Example of Effects of Front Lighting on Intelli- 61 

gence Target 

4-1 Density Distribution of Urban Areas 65 

4-2 Density Distribution of Industrial Target Area 66 

with Snow Surround 

AG MBIT 

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1.0 INTRODUCTION 

...... -- ..ri&,1'#-~rfrl'.i.ffiJl'l'• P'lll,11-r 

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I UI Ut..VUI. I nwa I 

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The factors that influence the quality of a photographic 

image produced by a satellite reconnaissance system are many. 

Not only are these factors numerous but often their interactions 

are complicated and difficult to analyze. It is the purpose of 

this rep~rt to discuss the major influences on image quality 

and, to the extent practical, illustrate how these factors 

relate to each other. 

The discussion will include an analysis of the effect of 

launch time on image quality, the effect of the camera acquisition conditions on image quality, the influence of contrast on 

resolution and how these factors relate to image suitability 

from a photointerpreter point of view. Lastly, the effect of 

the duplication process on quality will be briefly discussed. 

The report will not discuss the numerous camera design 

factors (focus, smear, thermal effects, etc.) that influence 

image quality since that is not its purpose. Indeed, given that 

the camera has no significant problems and is performing reasonably in accordance with its design, other factors are considerably more significant than the camera in determining the 

image quality the PI will see. 

2.0 THE EFFECT OF LAUNCH TIME ON IMAGE QUALITY 

This section treats a number of photographic quality parameters as they are affected by launch time. It does not consider problems such as time synchronization of the photographic 

vehicle with a meteorologic satellite, or vehicle thermodynamic problems. The discussion assumes all such problems are solvable. 

It does consider, however, the optimum launch times from a 

photographic viewpoint. In this regard, the section considers 

the following factors: 

a. mitigation of the effects of spectral reflections 

b. the avoidance of sun-camera geometry resulting 

in shadowless target acquisitions 

c. optimization of shadow lengths for mensuration 

d. the position of the terminator in terms of latitude. 

BYE-108499-73 

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e. the minimization of camera exposure change in the 

north latitude, descending pass portion of the orbit. 

For most of the discussion, several assumptions were made concerning the orbit. The orbital inclination was assumed to be 

96.3°. The launch time and the time of accessing 35°N latitude 

during a revolution are taken to be identical*. As such, most 

of the details are applicable to HEXAGON and GAMBIT CUBED if 

flown at this inclination. There is a summary chart, however, 

that illustrates the proper launch time for 110° inclinations, 

the current GAMBIT CUBED orbit. All times mentioned in the 

report are apparent solar times (true sun time). In addition, 

the discussion pertains to the northern latitudes only, because 

that is where the vast majority of intelligence photography is 

taken. 

2.1 Spectral Reflections 

Specular reflections can occur when the acquisition conditions are near those illustrated in Figure 2-1. Specular reflections produce a severe blooming of the imagery and, when 

they occur, can severely impair the utility of the imagery for 

interpretation. Fortunately, whether or not a specular reflection will occur, given the acquisition conditions of Figure 2-1, 

is also dependent on the nature of the target. Water or wet 

soil, for example, always produce specular reflections. 

During the period 23 March to 21 September, specular reflections can be a problem, particularly with regard to forwardlooking acquisitions (descending pass). Figures 2-2 and 2-3 

indicate the position in latitude and scan (roll) angle of the 

most intense specular reflections. Degradation usually extends 

approximately +5° in latitude and +7° in scan about the indi 

cated values. -

* That is, the launch times discussed herein are the true sun 

time at 35°N latitude at the time of launch and not the actual 

time at VAFB. This was done to avoid the problems of the 

difference between local time and true sun time, which is the 

important factor. This way of expressing launch time, however, 

does not deviate from the local time at VAFB by more than seven 

minutes. 

HEXAGON GAt181T 

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FIGURE 2-1 

Geometry Resulting in Severe Specular Reflection 

Zo= Zs 

I 

I 

AZIMUTH 

ANGLE 

180° 

· BETWEEN 

THE PLANES 

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BYE~l08499-73 

Page 4 

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23 JUN 

50 15 MAY --- 29 JUL 

15 AUG 

28 APR 

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15 OCT 

0 15 FEB 

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LATITUDE AND SCAN ANGLE OF SPECULAR REFLECTIONS 

AS FUNCTIONS OF TIME OF YEAR AND LAUNCH TIME 

(Forward look, lOQ pitch, descending pass) 

-POSITION IN LATITUDE (NORTH) 

•--- POSITION IN SCAN 

SCAN Ai."l'GLE (EAST) 

I 

\ 

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-5L----~----L----L-----1..-----L----l..-----L.---~::----:-:~-----' 

0800 0830 0900 0930 1000, 1030 1100 1130 1200 

LAU:NCH TIME 

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15 MAY\ 

29JUL 

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23 MAR 

O 21 SEP 

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FIGURE 2-3 

LATITUDE AND SCAN ANGLE OF SPECULAR REFLECTIONS 

AS FUNCTIONS OF TIME OF YEAR AIDLAUNCH TIME 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

(Aft look, 10° pitch, descending pass) 

\ 

\ 

\ 

\ 

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--- POSITION IN LATITUDE (NORTH) 

----- POSITION rn SCAN 

0 SCAN ANGLE (EAST) 

~ 

_5 ___ .....,,_ _______ '----......L.---..J----li.._,---..&.----'----"----......I 0800 0830 0900 0930 1000 1030 1200 

LAUNCH TIME 

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The position of the specular reflections in latitude is 

governed mainly by the· solar declination and secondarily by 

launch time. The position in scan (or roll) is governed by 

launch time. Around the time of th~ summer solstice, a very 

early launch is desirable in that it locates the specular 

reflections far out in scan (roll) angle. Table 2-1 illustrates 

the launch ti1nes required to minimize the effects of specular 

reflection. 

TABLE 2-1 

Optimum Launch Times to Minimize 

Specular Reflections 

Month Time 

September thru March There is no problem during these 

months because the solar declination is minus. 

April 8 :35 

May 8: 15 

June 8:00 

July 8: 10 

August 8:30 

The criteria applied in this table are to put the majority 

of specular reflections below 20°N latitude and that above 20°N 

the specular reflection must fall at a scan (roll) angle of 

45° or greater. 

2.2 Shadowless Acquisitions 

Associated geometrically with the problem of specular reflections is the problem of shadowless target acquisitions; 

that is to say, when the camera geometry is such that the optical 

axis has the same altitude and azimuth angles as the sun. This 

HEXAGO~J Gf,rJBIT ~---RUFF 

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is illustrated in Figure 2-4. The result of such acquisitions 

is to produce imagery that has no shadows and, hence, greatly 

reduced contrast. Such imagery looks dimensionless and, in the 

worst cases, image detail is actually lost. In the latter case, 

stereo viewing can also be significantly impaired. The graphs 

(Figures 2-2 and 2-3) for the location of specular reflections 

hold equally well for this problem except that the geometry is 

reversed. To determine the position of shadowless geometry 

for the aft look, use the forward look graph and read the positive scan (roll) angle as being west instead of east. It 

follows from this discussion that if a launch time is selected 

which minimizes specular reflections, then the shadowless acquisition problem is reduced also. 

Akin to the shadowless acquisition problem is that of 

taking pictures at very high solar altitudes, While geometrically the problem is not the same, the practical effect is. 

When the sun is at very high solar altitudes, there are, of 

course, no shadows; and again the image contrast is very poor. 

2.3 Optimizing Shadows for Mensuration 

The optimum solar altitude for shadow mensuration is 45°. 

As the solar altitude decreases from 45°, errors in measurement 

arise due to uncertainties regarding the elevation of the surface that the shadow is projected upon. Additionally, as the 

solar altitude decreases from 20°, the contrast between the 

shadow and the background is lowered substantially and the edges 

of the shadows become increasingly difficult to ascertain. As 

the solar altitude increases from 45°, errors in measurement 

arise due to the shortening dimension of the shadows. 

Approaching the problem of optimum laumch time with regard 

to shadow mensuration, the question arises as to which latitudes 

are considered important. Three northern latitude groups are 

considered here: 

a. 0-80° - this latitude range is considered to contain most targets of significant intelligence interest. 

b. 20-60° - this latitude range is considered to 

contain the majority of important intelligence targets. 

c. 50° - targets at latitudes ranging around this 

latitude are generally considered to be the most important. 

BYE-108499-73 

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FIGURE 2-4 

Geometry Associated with Full Front Lighting 

(Shadowless Acquisitions) 

OBSERVER STATIONED AT 

AZIMJTH ANO/OR ALTITUDE 

ANGLES DIFFERENT FROM 

THE SUN'S, SEES ·sHAOOWS 

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GOU GAMBIT 

The solar altitudes were computed from each group for 

launch times between 0800 and 1200 local sun time for ten dates 

during the year. For groups a and b, the solar altitudes for 

every 10° of latitude were averaged. No weighting was given 

with regard to latitude, since the decrease in area with increasing north latitude is offset somewhat by the increase in 

the number of targets. For each date, a launch time was 

selected for which the deviation for 45° solar altitude was the 

least for all three groups, although some judgment was used to 

bias the least deviation in favor of the latitudes around 50°N. 

Figure 2-5 illustrates the optimum launch time versus date to 

optimize this factor. It should be noted that optimization of 

launch time to attain a solar altitude of approximately 45° at 

50°N can only be made between approximately 21 March and 23 September due to the fact that the solar altitude simply does not 

get high enough in the winter. When the 45° optimization was 

impossible, the launch time was selected which resulted in the 

highest possible solar altitude for latitudes around 50°N. 

2.4 Position in Latitude of the Terminator 

It is desirable to launch the vehicle such that the terminator crossing is at the highest attainable north latitude, 

since 0° solar altitude represents a quality trade off point 

beneath which a higher speed film is required to record the 

highest possible ground resolution. This consideration is of 

particular importance around the time of the winter solstice, 

and it becomes insignificant between approximately 7 March and 

6 October, when the highest latitude of the terminator is above 

the highest latitude attained with a 96.3° orbital inclination. 

Figure 2-6 illustrates the launch times at various dates 

in the year which will result in the optimum positioning of the 

terminator with regard to latitude. The curve marked "highest 

latitude line" relates the date and attendant solar declination 

to the appropriate launch time. The 0800 launch time for a 

solar declination of -5.5° was set by judgment and is not the 

calculated value. 

Due to various other factors discussed in the report, it 

is obvious that some of the very early launch times recommended 

on Figure 2-6 (i.e. 0830 on 1 March) are undesirable. However, 

any launch time between the "highest latitude line" and approximately noon would be acceptable since the reduction in latitude 

at which 0° solar altitude occurs for a later launch affects 

only the extremely high latitudes. This is due to the fact that 

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FIGURE 2-5 

Optimum Launch Time to Maximize 

Shadow Detail for Mensuration 

11 :301-----...,g,---

11:00 

10:30 

08!30 ( *) LT < 9: 30 ~ SA '5._ 4 5 AT 50 N. L. 

08:00--------------------------------....... ---- JAN MAR APR MAY JUN JUL AUG 

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FIGURE 2-6 

LATITUDE AT WHICH 0° SOLAR ALTITUDE OCCURS FOR 96.3° INCLINATION 

0800 0830 

HtGHEST 

WINTER SOLSTICE LATITUDE 

-..... """-· - ~-~"_,...-.!51)_ - - - - _ 1 _ - LINE 7 JAN 

-

_ _...-------,----- 87. 5° -

6 DEC 

22 JAN --- 21 NOV 

1 FEB --~--->----:;;;~-------- 72. 5° 11 NOV 

9 FEB ----"'---------:7:....-.---------- 750 3 KOV 

17 FEB __,,__-----:;7----------'I>----~ ., 26 OCT 

77.5 

0900 0930 1000 

LAUNCH TIME 

24 FEB 

19 OCT 

80" 1 !v!AR 

12 OCT 

7 M1\R 

82. 5" 6 OCT 

NOTE: Curves are plotted values of latitude in degrees. 

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HEXAGON GAMBIT 9 

proceeding north in latitude, the sun's hour angle is increasingly less of a factor in determining the solar altitude, the 

solar declination becoming the dictating influence. 

2.5 Minimization of Required Camera Exposure Changes 

An additional advantage is achieved by keeping the solar 

altitude close to some given value throughout the latitude range 

of interest. This advantage is that the variation in camera 

exposure time is held to a minimum. Thus, a fail-safe provision 

can be built in during mission planning. At the times of the 

summer and winter solstices, the launch times required to minimize camera exposure changes are essentially those required to 

obtain shadow record optimization and are illustrated in Figures 

2-7 and 2-8. The latitude range of 0° to 80° is not considered 

at the time of the winter solstice since exposure compensation 

is impossible due to large negative values of solar altitude 

which occur at high north latitudes. At the times of the equinoxes, minimization of camera exposure change can be accomplished 

only at the expense of considerably lowering the average solar 

altitude. Figure 2-9 illustrates this dilemma. No great change 

in camera exposure range with variations in launch time is 

incurred, howe~er, for the critical latitude range of 20°N to 

60°N. The solar altitude required to maximize quality is discussed in Section 3.0. The exposure minimization factor is 

more important with HEXAGON than GAMBIT, because HEXAGON contains a fail-safe slit. That is, if the main slit and shutter 

mechanism fails, a mechanical device puts in one slit so that 

photography can still be taken. Minimizing the required exposure range will maximize the quality produced in this situation. 

2.6 Summary 

Several factors associated with the launch time of the 

mission can affect the quality of the resultant imagery produced. While the factors discussed are not necessarily of 

equal importance, they all yield essentially the same answer: 

launch late in the winter and early in the summer. The spring 

and fall are problem areas relative to the sun synchronous 

inclination because the solar declination is changing so 

rapidly that no single launch time is optimum. This is discussed in more detail below. 

HEXAGON GAMBIT 

TOP ~EC1\ET RUFF 

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FIGURE 2-7 

EXPOSURE CHANGE AS FUNCTION OF LAUNCH TIME 

FOR SPECIFIED LATITUDE RANGES 

(Summer Solstice) 

O"N - 80°N 

1. 0 "-----'----~-L-------J-------'-----'------' 

1200 1100 1000 

LAUNCH TIME 

0900 

\

~rv ~ c'l.nl.\ G 1H UHJ 1C.I\, .UUfi ·t1LtU! 

TflP ~~n:r:·~1' m!FF 

Approved for Release: 2023/04/03 C05140951 

0800 0700 

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Pag·e 14 

HANDLE VIA 

BYEMAN-TALr:NT-:(t.:YHOLt 

CONTROL $";' . . . , • . .,.,:; ' .. Y 
I Ui' XH·H~ I rlflit= 

Approved for Release: 2023/04/03 C05140951 

HtXAli~:J GAMBIT 

FIGURE 2-8 

EXPOSURE CHANGE AS FUNCTION OF LAUNCH TIME 

FOR A SPECIFIED LATITUDE RANGE 

'l. o.-

6.6 

6.2 

5.8 

4.. 2 

3.8 -

3.4 

(Winter Solstice} I 

I 

I 

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LAUNCH TlME 

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Page 15 

I-IANDLE VIA 

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CONTROL SYsn::Ms JOINTLY 
4.4 

4.0 

3.0 

2.0 

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Approved for Release: 2023/04/03 C05140951 

• VI "I.UH'-I HUI I -

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FIGURE 2-9 

EXPOSURE CHANGE AS FUNCTION OF LAUNCH TIME 

FOR SPECIFIED LATITUDE RANGES 

o... ..... --

1200 

(Equinoxes) 

-- O"N- 80"N 

--- 20"N - 60"N 

0 EXPOSURE CHANGE 

X AVERAGE SOLAR ALTITUDE 

-"G 

---- e._ 

---o-_ 

---o 

1100 1000 0900 0800 

LAUNCH TIME 

HE GON GAMBJT 

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tltA/UiUfJ jJ.1Mol I • 

The optimum launch times, then, to maximize photographic 

image quality are shown in Tables 2-2 and 2-3 for the two 

inclinations currently employed. These tables list one other 

factor not discussed above, and that is the launch time required 

to produce a solar altitude of 30° at 50°N latitude. As will 

be discussed in Section 3.0, a solar altitude of 30° is sufficient 

to maximize camera performance. The times in Tables 2-2 and 

2-3 are the minimum launch times. Times later than those indicated (except for the winter months) will produce higher solar 

altitudes at S0°N latitude. 

As was mentioned above, the spring and fall are difficult 

to optimize for sun synchronous inclinations. This can be 

solved, however, by employing non-sun-synchronous orbits. 

Figure 2-10 illustrates two specific inclinations that could 

be employed to provide optimum acquisition conditions in the 

spring (92.9°) and fall (99.9°). These inclinations are 

superimposed on top of the shadow men~uration curve because it 

is generally representative of all the factors considered. 

3.0 THE INTERACTION OF THE CAMERA AND THE ACQUISITION CONDITIONS 

The previous section discussed the effects of launch time 

on quality, irrespective of the performance level of the camera 

itself. Later it will be shown that much of the conclusions 

possible from the previous discussion can be practically implemented. There are, however, other factors that need to be considered in the process of understanding the image quality to be 

achieved with any given system at any given point in time. This 

section attempts to bring together some of the key factors as 

they apply to the GAMBIT and HEXAGON systems; namely, 

a. exposure time and smear 

b. contrast 

c. haze and time of year 

d. target illumination and target reflectance 

HEXAGG~J GAt13rT 

IOP ~(GRif RUFf 

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Approved for Release: 2023/04/03 C05140951 

TABLE 2-2 

Optimum Launch Times for Best Image Quality 

(96.3° Inclination) 

SHADOW 

MENSURATION 

11:30 11:30 11:20 10:05 9:10 8:45 8:55 9:30 10:35 11:30 11:30 11:30 

SPECULAR NP 

REFLECTION/FRONT 

LIGHT I NG 

NP NP 8:35 8:15 8:00 8:10 8:30 NP 

HIGHEST LATITUDE 11:·15 10:25l<a=illl!!llm~ll!llmi:IIIIP NO PROBLEM ~::.m11111~CZ11111.-i 

LINE . 

NP NP NP 

9:35 11:05 11:15 

MINIMUM EXPOSURE 11:30 11:30 11:00 9:45 8:30 9:00 8:30 8:00 10:30 11t30 11:30 11:30 

CHANGE 

(20° TO 60° N.L.) 

MIN. RESOLUTION ~11:45 11:45 9:30 8:15 7:30 7:06 7:12 7:54 9:00 11:06 11:45 11:45 

CHANGE FOR 

HEXAGON 

(50° N.L.) 

MIN. RESOLUTION ~11:45 9:45 8:09 7:09 6:24 6:06 6:12 6:48 7:45 9:00 11:00 11:45 

CHANGE FOR 

GAMBIT 

(50° N.L.) 

NOTES: A. (NP) No problem 

B. Min. resolution change times are the times required 

to maintain a solar altitude of 30° at 50°N latitude. 

These times are only accurate for March through October. 

During November-February the time is that required BYE-108499-73 

to produce the highest possible solar altitude Page 18 

at 50°N latitude. 

Approved for Release: 2023/04/03 C05140951 
Approved for Release: 2023/04/03 C05140951 

TABLE 2-3 

Optimum Launch Times for Best Image Quality 

(GAMBIT at 110° Inclination) 

SHADOW 

MENSURATION 

11:30 11:30 11:30 10:40 8:45 8:30 8:35 9:30 11:15 11:30 11:30 11:30 

SPECULAR NP 

REFLECTION/FRONT 

LIGHT ING 

NP NP 9:05 8:15 8:15 8:20 9:05 NP NP 

HIGHEST LATITUDE 9:40 9: 30 l@~~:mliilll:~~NO PROBLEM~IIUl!1l'.C~:lml:il'J!II~•> 

LINE 

NP NP 

9:10 9:45 

MINIMUM EXPOSURE 12:00 12:00 12:00 9:45 9:30 10:00 9:30 9:00 10:45 12:00 12:00 12:00 

CHANGE 

(20° TO 60° N.L.) 

MIN. RESOLUTION~l2:00 12:001 9:00 7:45 7:00 6:30 6:45 7:25 8:25 10:00 12:00 12:00 

CHANGE FOR 

GAMBIT 

I (50° N.L.) 

NOTES: A. (NP) No problem. 

B. Min. resolution change times are the times required 

to maintain a solar altitude of 30° at 50°N latitude. 

These times are only accurate between March and October. 

During November-February the time is that required BYE-108499-73 

to produce the highest possible solar altitude Page 19 

at 50°N latitude. 

Approved for Release: 2023/04/03 C05140951 
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OCT NOV DEC 

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1 ur u~vhLI nurr 

HE GOU GAMBIT 

3.1 GAMBIT CUBED 

3.1.1 Exposure Time and Smear 

All satellite camera systems produce smear of one kind 

or another. Image motion compensation (IMC) can only easily 

compensate for smear perfectly at zero degree field and on a 

line along the major axis of film travel. The amount of smear 

in a picture, however, is primarily a function of the exposure 

time, the longer the exposure time the greater the smear. The 

exposure time required is, of course, a function of the solar 

altitude and the resultant brightness of the scene in question. 

Figure 3-1 shows the typical exposure time required for GAMBIT 

CUBED as a function of solar altitude. This graph illustrates 

that exposure time does not change very much above a solar altitude of 20-30°. The mean smear that would be expected, then, 

as a function of solar altitude is shown in Figure 3-2. This 

figure is for the worst direction (cross-track) smear. In any 

event, the graph shows that at solar altitudes above about 20° 

the smear can be expected to be less than two microns 50% of the 

time. 

3.1.2 Camera Performance 

The effect of the required exposure time and the resultant smear on the resolution produced can be computed. Figure 

3-3 illustrates the mean expected GRD for GAMBIT CUBED as a 

function of solar altitude for nadir and 30° roll angle. Here 

the effects of the smear are clearly seen. Below solar altitudes of 20°, the resolutiol drons o £ drastically. In the case 

of nadir, t~rom lat 20° solar altitude 

to a GRD of L______Jat 5° solar altitude. This is a loss 

in GRD of 65%, due solely to the increasing smear resultant 

from the longer exposure times. At higher solar altitudes, 

however, the reverse situation is true. While, as the solar 

altitude increases the resolution also increases, the change 

is not nearly so dramatic ~bl 1 e 

1

20° solar altitude produces 

a mean GRD at nadir of goinr to 50° solar altitude 

only improves this figure to~----~ an improvement in GRD 

of only 7%. Clearly, from a pure camera performance point of 

view, as long as the acquisition solar altitude is 20° or 

greater, there will be no significant change in resolution. As 

shown in Figure 3-3, these conclusions are applicable to a 30° 

roll angle as well. 

BYE-108499-73 

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FIGURE 3-1 

TYPICAL EXPOSURE VS. SOLAR ALTITUDE CURVE 

FOR GAMBIT CUBED 

10 20 30 40 

Solar Altitude (Degrees) 

50 60 70 

BYE-108499-73 

Page 22 

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FIGURE 3-3 

MEAN EXPECTED GAMBIT CUBED 

GROUND RESOLVED DISTANCE (GRD) 

FOR CONSTANT 2:1 CONTRAST 

{OQF = 0.82, 73 NM ALTITUDE) 

HEXAGON GAMBIT 

rnn ~f P.1tFT nru:,; Approved for Release: 2023/04/03 C05140951 

BYE-108499-73 

Page 24 

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BYEMAN-TALENT-KEYHOLE 

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Approved for Release: 2023/04/03 C05140951 - .._."' .,,._.....,.. 111 ••" 111i;.~111 I 

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3.1.3 The Impact of Contrast on Achieved Resolution 

The previous section (3.1.2) discussed the impact of 

smear on achieved camera resolution. Figure 3-3 was plotted 

for a constant contrast value of 2:1. This is appropriate since 

the analysis was aimed at evaluating only the effects of smear, 

optics and roll angle on photographic image quality. However, 

when attempting to evaluate performance to be expected in a real 

sense (i.e. ground resolution of intelligence targets), the contrast must be considered. Real intelligence targets (as seen 

by the camera) are usually not 2:1 in contrast. In addition, 

because the camera angle to the sun (CATS) angle is changing 

as a function of solar altitude, the amount of haze back scatter 

changes;and, hence, the contrast of a given target will change 

as a function of solar altitude as well. As will be discussed 

in more detail later, haze is also a function of time of year, 

the summer time being worse (haziest) and the winter time best 

(clearest). 

Figures 3-4 and 3-5, then, present the mean expected 

GRD for GAMBIT CUBED as a function of solar altitude for typical 

intelligence targets. For reference, the constant 2:1 contrast 

performance estimates are included on the graphs. Figures 3-4 

and 3 5 illustrate the following: 

GRD of! _ __ jthe typical intelligence target plot 

a Wh:r::s t~e 2:1 c?ntra:t plo~ indicates a best 

shows ac_____,b~e-s~~-a-t~can practically be expected at nadir 

0£ 

b. Both Figures 3-4 and 3-5 illustrate that (for 

the same solar altitude) December produces better GRD's 

than June. This is to be expected because of the clearer 

weather conditions. It does not consider, however, the 

impact of more pictures being acquired at lower solar 

altitudes in December. This will be discussed later. 

Nor does it consider that prevailing snow and weather 

may obscure significant amounts of the ground scene in 

December. 

c. Whereas Figure 3-3 illustrated that above 20° 

solar altitude no significant improvements in performance 

could be expected, Figures 3-4 and 3-5 do not totally 

agree. Since contrast and smear are both influencing 

the results presented in Figures 3-4 and 3-5, it should 

be expected that slightly different conclusions would be 

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BYE-108499-73 

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TOP ., rr 

pproved for Release: 2023/04/03 C05140951 Bir· r.lllUKC. .:>-'t 

MEAN EXPECTED GAMBIT CUBED 

GROUND RESOLVED DISTANCE (GRD) 

FOR TYPICAL INTELLIGENCE TARGETS 

(73 NM ALTITUDE) 

HtXAGO:J ·t?~MBIT 

Tl?D ~~P..JT DHJ:'t 

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BYE-108499-73 

Page 26 

HANDLE VIA 

BYEMAN-TALENT-KEYHOLE. 

CONTROL SYST"'~~,:; .!OINT1.Y 
MEAN EXPECTED GAMBIT CUBED 

GROUND RESOLVED DISTANCE (GRD) 

FOR TYPICAL INTELLIGENCE TARGETS 

(73 NM ALTITUDE} 

HE G n; J GP.w1B lT 

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BYE-108499-73 

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CONTROL SYST!::MS JO!NTLY 
·rriri rrrnrr nurt 

Approved for Release: 2023/04/03 C05140951 

HE • 

reached. For nadir in either June or December, the 20° 

solar altitude is still acceptable. For 30° roll, however, the ground resolution of typical intelligence targets is dropping off more sharply with solar altitude 

than it does for the 2:1 contrast case. In the 30° roll 

case, a solar altitude of 25-30° is needed before no 

significant change in resolution is noted. 

The above discussion considered, however, only the average seasonal haze conditions that exist for the two months as a function of solar altitude. In any event, it can be seen for 

Figures 3-4 and 3-5 that the average GRD produced by the GAMBIT 

CUBED ctmera ;for lypical intelligence targets] can vary from a 

best of to a low of nearly 20 inches, depending solely 

on the 1me o year, roll angle and solar altitude. 

Haze tends to be akin to exposure time in its effect. 

That is, there is a range of relatively clear haze conditions 

that do notchange performance very much. However, as haze gets 

worse than average, performance drops off more rapidly. 

Figure 3-6 illustrates the point. This figure presents 

the mean GRD that would be expected for GAMBIT CUBED under a 

vari.ety of .haze conditions, two solar altitudes, nadir and 30° 

roll. There are several interesting observations that can be 

made from the graph: 

a. As noted above, as the haze levels get better 

(clearer) than average, there is no significant improvement in GRD, with the possible exception of the 30° roll 

case at 10° solar altitude. 

b. The significant losses in resolution occur as 

the haze condition worsens from the average level. In 

addition, whereas a GRD of~----~is predicted at 

nadir (30° solar altitude) for the average haze conditions r v ry heavy haze, this is reduced to a best 

ofL_ ___ ~ __ j---'~~~, 30° roll, 10° solar altitude case, 

the GRD of~---~-~ nder average haze conditions 

decreases to 17.5 inches for the very heavy haze condition. 

c. The important observation, however, is that as 

the acquisition conditions worsen (i.e. lower solar altitude, higher roll angle, etc.), the effect of haze on 

contrast becomes increasingly severe;and, hence, the 

LIE Grt?~ Gn "'BJT ~ 

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BYE-108499-73 

Page 28 

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Approved for Release: 2023/04/03 C05140951 

FIGURE 3-6 

GAMBIT CUBED RESOLUTION FOR VARIOUS CONDITIONS 

Atmospheric Transmission at 550 n.m. 

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::r.:.. 

---- 0:, ---1 
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App~o~e.9 for_R~le~se: 2023/04/03 C05140951 

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resultant ground resolution becomes increasingly degraded. 

3.2 HEXAGON 

The factors that influence the image quality of the HEXAGON 

camera are very similar to those that influence that of the 

GAMBIT CUBED camera. These effects are discussed in the following paragraphs. 

3.2.1 Exposure Time and Smear 

The influence of the smear produced by the HEXAGON camera 

is much the same as that with the GAMBIT CUBED. HEXAGON, however, because it is a panoramic camera the optics of which 

rotate about its major axis, must move the film (in the crosstrack direction) much faster* than need GAMBIT CUBED. This 

results in a slightly larger smear budget for HEXAGON**. While 

the budgeted smear rates for HEXAGON are nominally twice those 

of GAMBIT CUBED, it can stand more smear since it has a faster 

lens _(f/3.S for HEXAGON vs. f/4.0 Jor GAMBIT) and hence can 

employ shorter exposure times. The nominal required exposure 

times for HEXAGON (for both filters) are shown in Figure 3-7. 

Figure 3-8, then, shows the mean smear that is expected with 

HEXAGON as a function of solar altitude. In this case, the 

expected smear does not get below two microns until approximately 

25° solar altitude. 

3.2.2 Camera Performance 

As was done for GAMBIT CUBED, the effect of the required 

exposure time and the resultant smear can be computed. Figure 

3-9 illustrates the mean expected GRD for HEXAGON as a function 

of solar altitude for nadir and 45° of scan. Again, the effects 

of smear are clearly seen. Below a solar altitude of 20°, the 

resolution drops off rapidly. In the case of nadir, the GRD 

*Up to a maximum of 204 in/sec. 

**The HEXAGON mean expected smear spec is .OS in/sec both intrack and cross-track. This equat~s to 1.3 microns/msec. 

The comparable rate for GAMBIT is 0.52 microns/msec. 

HE GON GAMBIT 

TOO C:t_r.RFf RHF~ 

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CONTROL S'f!.:iT'i::MS JOINTLY 
C05140951 

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FIGURE 3-9 

MEAN EXPECTED HEXAGON 

GROUND RESOLVED DISTANCE (GRD) 

FOR CONSTANT 2:1 CONTRAST 

(89.3 NM ALTITUDE} 

. , - f' ~-: 

t. •. ·;r:-:-·. 

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Solar Altitude (Degrees) 

HEXAGON GAMBJT 

r'DP SECRET RUFF 

40 

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50 

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Approved for Release: 2023/04/03 C05140951 

IUI \,i'i..Ul\b.l IIIUII 

goes from 1.9 feet at 20° solar altitude to a GRD of 2.8 feet 

at 5° solar altitude, a loss in resolution of 50%. At high 

solar altitudes, however, the reverse is true. While the solar 

altitude increases, there is almost no change in predicted 

mean GRD, going from 1.9 feet at 20° solar altitude to 1.8 feet 

at 50° solar altitude. These observations are generally applicable to the 45° scan angle case, except the solar altitude of 

no significant improvement appears to be about 30°. 

3.2.3 The Impact of Contrast on Resolution 

As with the GAMBIT discussion, the previous section (3.2.2) 

was limited to evaluating the effects of sun angle, exposure 

time, smear and scan angle on quality. HEXAGON performance as 

well is affected by contrast effects; and when considering the 

GRD to be produced for real intelligence targets at various 

times, the contrast effects must be considered. As pointed out 

in Section 3.1.3, real intelligence targets are not usually of 

2:1 contrast (at the camera aperture), and haze effects (and 

hence contrast) change as a function of solar altitude and time 

of year. 

Figures 3~10 and 3-11 present the mean expected GRD for 

HEXAGON, as a function of solar altitude, for typical intelligence targets instead of the constant 2:1 contrast discussed 

above. The following observations can be made: 

a. Whereas the 2:1 contrast plot indicates a best 

GRD of 1.8 feet, the typical intelligence target plot 

(3-10) shows a best of 2.9 feet for the same solar altitude condition (30°). The 45° scan angle comparisons 

are 3.2 feet (2:1 contrast) vs. 4.9 feet (15 December 

plot) for the typical intelligence target. These comparisons are also for 30° solar altitude. 

b. Again, both Figures 3-10 and 3-11 predict better 

GRD's for the same solar altitude in December than in 

June. As with GAMBIT CUBED, this is due to the better 

haze conditions, and hence contrast, in December versus 

June. 

c. Figures 3-10 and 3-11 show performance improving 

more dramatically above 30° solar altitude than did 

Figure 3-9. This is particularly true for the 45° scan 

angle case. 

HE GOf~ Gt1MBfT 

"f0') ,:'f\r,-,~· nurr or .. it rd, i Nnrr 

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HANDLE VrA 

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Approved for Release: 2023/04/03 C05140951 

HE GON GAMBIT • 

FIGURE 3-10 

· MEAN EXPECTED HEXAGON 

GROUND RESOLVED DISTANCE (GRD) 

FOR TYPICAL INTELLIGENCE TARGETS 

(89.3 NM ALTITUDE) 

10 20 30 40 

Solar Altitude (Degrees) 

HE GON ~AMBIT 

~~ RUFF 

Approved for Release: 2023/01/03 C05140951 

50 60 

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FIGURE 3-11 

MEAN EXPECTED HEXAGON 

GROUND RESOLVED DISTANCE (GRD) 

FOR TYPICAL INTELLIGENCE TARGETS 

(89.3 NM ALTITUDE) 

10 20 30 40 

Solar Altitude (Degrees) 

6011 G:lMBIT 

TOP St f~QCT r1111:,: Approved for Release: 2023/04/03 C05140951 

50 60 

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As before, the above discussion relative to the effects of contrast considers only the "typical" intelligence target and 

average seasonal haze conditions. The influence of different 

specific targets will be discussed later. The effects of other 

than average haze are shown on Figure 3-12*. This figure illustrates, as well, that average-to-clear haze conditions do not 

affect resolution that significantly. As haze conditions worsen, 

however, the effect on resolution becomes more severe, the 

severity increasing in its effect with lower sun angle and 

higher scan angle. 

3.3 Effect of Target Type, Illumination and Time of Year 

The previous sections (3.1 and 3.2) discussed image quality 

in a somewhat theoretical sense since they were based on analysis 

using models of camera performance and the atmosphere. In these 

previous discussions, it was assumed that the target was a horizontal one, on a horizontal plane and illuminated by daylight. 

Real intelligence targets are often not horizontal in nature nor 

are they necessarily illuminated by daylight. This section 

attempts to discuss in more detail the effects on photographic 

image quality of the target itself, its illumination conditions 

a-Rd the time of yea-r the picture is taken. 

3.3.l Target Type and Illumination 

There are numerous combinations of camera/target/sun 

(CATS) angle and target illumination that will cause variations 

in the amount of energy at the image plane. Even if the spectral reflectance of the target is identical under all conditions of illumination, the effective contrast at the image 

plane differs in each situation. For example, a target of 

interest might be found in shadow, in partial shadow; or the 

target could be a vertical object that is front-lighted or backlighted. It is the purpose of this section to give the reader 

insight as to how relative GRD may vary when a single target 

having a maximum and minimum reflectance of 33 and 7 percent 

*It should be noted that the GRD values in Figure 3-12 are two 

sigma low estimates. The previous plots presented the mean 

expected GRD. 

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respectively (a CORN tri-bar target) is illuminated under 

various conditions and is acquired from various scan (roll) 

angles. 

Figure 3-13* gives relative GRD as a function of scan 

angle for a June 23 acquisition using a forward-looking camera 

(at 10° pitch) to photograph various targets under a variety 

of combinations of illumination and target orientation. The 

relative GRD values include dnly the effect of atmospheric 

haze, target illumination an target orientation. Effects of 

slant range and other geometric considerations are excluded. 

In Figure 3-13, the greatest loss in relative GRD occurs 

when the target is either horizontal or vertical but under 

shadow conditions. The case for a vertical target in shadow 

improves, however, when acquired in December. This is the 

result of a lesser effect of haze combined with look angle conditions and illumination conditions which are improved in the 

December acquisition for vertical targets. Figure 3-14 shows 

the results of the prediction of GRD for a December 23 acquisition. The characteristic U-shaped curve is found on every 

illumination and object orientation condition. 

The two figures illustrate the very significant influence 

the illumination conditions have on the resultant GRD, irrespective of the performance level of the camera itself. In the 

summer, the GRD produced at nadir for a specific horizontal target can vary by a factor of nearly one foot (say 2.5 feet to 

3.5 feet) based strictly on whether or not the target is 

illuminated by daylight or is in cloud shadow. This observation most likely has more practical consequences with the 

GAMBIT system since it is more target-oriented than is HEXAGON. 

For the same set of conditions (nadir, horizontal object), the GAMBIT GRD also will vary by nearly one foot (say 

12 inches to 24 inches) based solely on whether or not the 

object is in daylight or cloud shadow. If the target is in 

object shadow (equipment in shadow of building, for example), 

then the losses at nadir are on the order of two feet. That 

is, for a GAMBIT CUBED system operating at a nominal 12-inch 

*The calculations that resulted in Figures 3-13 and 3-14 were 

done specifically for HEXAGON. They are reasonably close to 

what will happen for a GAMBIT CUBED forward look, however, 

and hence are applicable to that camera as well. 

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FIGURE 3-13 

RELATIVE GRD FOR VARIOUS TYPES OF TARGET 

ILLUMINATION FOR SUMMER ACQUISITION 

t ;t ·, 

40 20 . 0 -20 -40 -60 

SCAN ANGLE (degrees) 

Target in Object Shadow 

Vertical Target in 

Cloud ShadOiv 

Horizontal Target in Cloud Shadow 

Horizontal Target 

in Daylight 

NOTE: Solar Altitude= 63° 

Arrows indicate GAMBIT CUBED cut-off 

H GON GAMBIT 

--fGP--SffiRff- RUFF 

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FIGURE 3-14 

RELATIVE GRD FOR VARIOUS TYPES OF TARGET 

ILLUMINATION FOR WINTER ACQUISITION 

40 20 0 -20 -40 .. 60 

SCAN ANGLE (degrees) ' 

Horizontal Target in Object Shadow 

Vertical Target in 

Object Shadow 

Horizontal Target 

Cloud Shadow 

Vertical Target in 

Cloud Shadm·1 

Horizontal Target 

in Day1-ight 

NOTE: Solar Altitude= 17° 

Arrows indicate GAMBIT CUBED cut-off 

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level, the real GRD for this condition produced would be 36 

inches (three feet) due strictly to the illumination conditions. 

The above discussion considered horizontal and vertical 

targets of a given constant set of reflectances (33% and 7%). 

As such, Figures 3-13 and 3-14 present the effect on GRD of 

two variables only, illumination and target orientation (i.e. 

horizontal or vertical). Each target, however, has its own 

unique set 0£ reflectances (contrasts) that will also influence 

the ground resolution produced. Over the years, data has been 

collected that allows assigning a general set of highlight and 

lowlight reflectances to classes of intelligence targets. These 

'reflectances can be used to predict the GRD of specific classes 

of targets with a program such as CRYSPER. Figure 3-15 illustrates the GRD's that could be expected for three classes of 

intelligence targets: ICBM's (C0MIREX Class lA), Military 

Installations(C0MIREX 7A) and Surface-to-Air Missiles (C0MIREX 

Class II). 

The difference in mean expected GRD between the three 

classes of targets is obvious from the graph. The difference 

in GRD's is due solely to the different reflectance nature of 

the targets. If five feet GRD is used as an arbitrary definition 

of an acceptable picture, ICBM complexes can be (on the average) 

satisfactorily acquired out to scan angles of 45°, while military 

installations can only be satisfactorily acquired within approximately +35°; and SAM's can only be satisfactorily acquired 

within approximately ~25°. · 

3.3.2 Contrast and Time of Year 

The discussions presented in Sections 3-1 and 3-2 alluded 

to the fact that, for a constant solar altitude, photographic 

image quality is better in December than June and stated that 

this was due to better (clearer) haze conditions. This is a 

difficult problem to evaluate accurately because the modeling 

of haze is extremely difficult. The problem is further complicated by the fact that there is no known way to measure, describe or otherwise report on haze conditions in a way that is 

meaningful to the satellite photography case. Therefore, data 

on haze and its statistics must be inferred. 

One way to make this inference is by evaluating the brightness range recorded on the film of several urban/industrial 

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HEXAGON GAMBIT 

scenes as a function of time of year. Figure 3-16 illustrates 

such data collected from both HEXAGON and GAMBIT CUBED photography. From this data, it can be stated that the summer time 

is generally the worst from a contrast point of view; and 

from that it can be inferred that haze is the predominant factor. Clearly, however, as one departs from the summer, the 

apparent contrast is rising rapidly. 

3.4 The Relationships between Photographic Image Quality and 

PI Suitability 

The previous discussions attempted to point out the numerous 

factors that both individually and in combination can dramatically influence the quality of the final photographic image. 

The real questions are: Are these truly reflected in the 

imagery and do they really affect the photointerpreter's ability 

to interpret the photography? This section attempts to deal 

with these questions. It should be noted, however, that the 

discussion will be more complete for HEXAGON than GAMBIT CUBED 

since there are more analytical tools available with HEXAGON 

with which to conduct such an analysis. 

3.4.1 GAMBIT CUBED 

3.4.1.1 Exposure Time 

From the Section 3.1.1 discussion, it could be concluded that overall image quality should not vary significantly 

(due to camera performance) if the solar altitude is maintained 

above 20-25°. This observation can be practically demonstrated 

by comparing the results of four recent GAMBIT CUBED missions. 

Mission 4337 was launched on 21 December 1972. The acquisitions 

on this mission were at an average solar altitude of 26°. Of 

the targets read out by the PI's, 39% were rated good. This 

percentage compares favorably with Missions 4336 (39% good), 

4334 (32% good) and 4332 (36% good), even though the average 

acquisition solar altitudes on the later missions were 44°, 

44° and 40° respectively. In addition, if solar altitude was 

the dominating factor, one would expect summertime missions to 

produce (on the average) the highest percentage of targets 

rated fair or better. Such is not the case, as is discussed 

in Section 3.4.1.2. 

HEXAGON GAMBIT 

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FIGURE 3-16 

SCENE BRIGHTNESS RANGE DATA FOR 

URBAN/INDUSTRIAL SCENES FOR 

1200- AND 4300-SERIES MISSIONS 

J F M A M' J J A 

--- 1200-SERIES CAMERA 

x Forward-looking 

• Aft-looking 

A 4300-SERIES CAMERA 

s 0 N D 

NOTE: This data should not be inferred as representing the average apparent contrast of intelligence targets. It is collected by 

raster scanning (with a microdensitometer) urban/industrial scenes. 

2000 data points are collected per area. These are collected into 

a histogram and the 5% min. and 95% max. values are used as the 

definition of the scene brightness range. As sucht these contrast 

values are higher than the brightness range of contiguous areas or 

of a typical target. 

H 60M BlT 

~, OP S(Cjtf i' RUF f 

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3.4.1.2 Time of Year 

The discussion in both Sections 3.1 and 3.3.2 allow 

the conclusion that, other factors being equal, image quality 

will vary as a function of time of year due to the varying 

effects of haze. Those discussions noted that haze tends to 

be worse in the summer time and best (clearest) in the winter. 

If this is so, this should be reflected in the photointerpreter 

ratings. Taking all the 4300-series missions to date and evaluating the percentage of targets rated fair or better by the 

photointerpreters provides the following data: 

Season % Targets Rated Fair or Better* 

Fall (Sep-Oct) 79 

Winter (Nov-Feb) 76 

Summer (Jun-Aug) 71 

Spring (Mar-May) 70 

The above data bears out the general obseTvations made. Fall 

missions produce the highest percentage of targets rated fair 

or better by the PI's. In addition, fall missions have resulted 

in the largest percentage and most frequent occurrence of targets rated excellent by the photointerpreters. Mission 4333 

(launched 23 October 1971) had 6% of its targets rated excellent 

by the PI's. Only seven other missions had excellent ratings 

as high as 3%; and of these, only one was a summer mission 

(4332, 12 August 1971). Considering all factors, however, 

these observations should be expected. Not only is the contrast data favorable in the fall, but the sun angles are still 

reasonably high, so that acquisition solar altitudes in excess 

of 20-30° are easy to maintain for most targets of interest. 

It is somewhat surprising that the winter missions performed so 

well in that longer exposure times are required, but again the 

winter should produce the clearest (best contrast) acquisitions. 

It is interesting to note that the mission that produced 

*Approximately 100,000 photointerpreter ratings of intelligence 

targets is included in this data base so that differences 

noted are most likely significant. 

HEXAGON Gi~ri1B1T 

ron {'rri;~,c·~ nnrr 

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HEXAGOH GAMBl1 

the highest number of target rated good (60%) was 4310. 4310 

was launched on 5 December 1967. The mission that produced the 

second highest percentage of targets rated good (54%) was 4308. 

4308 was a fall mission, being launched on 19 September 1967. 

The important observation from this discussion, however, is that 

solar altitude and exposure time are not the dominant factors 

in considering the image quality that will be produced by a 

satellite camera. 

3.4.1.3 Target Dependency 

Section 3.3.2 indicated that ground resolution should 

be dependent on the nature of the target itself. That is, each 

target has its own unique set of reflectances,and these will 

affect the contrast and the ultimate ground resolution. This 

factor is hard to evaluate since most targets acquired are not 

rated by the Pl's, making it difficult to collect accurate 

statistical data. However, two COMIREX target categories, 

missiles and air installations, do have sufficient numbers of 

targets rated to allow comparisons. Based on the target reflectance data in CRYSPER, the mean contrast of air installations 

(on the ground) is approximately 1.8:1. Similarly, the mean 

contrast for missile and missile-related targets is approximately 1.6:1. If the nature of the target is important, then, 

on the average, air installations should receive a higher percent of targets rated good than missiles due simply to the higher 

inherent contrast of the targets. Indeed, this is the case. 

For all the targets rated in these two categories on Missions 

4332 through 4337, 55% were rated good on air installations 

versus only 31% for missile categories.* 

3.4.2 HEXAGON 

3.4.2.1 Exposure Time and Smear 

The question of the effect of exposure time and smear 

on quality can be addressed directly on HEXAGON from the visual 

edge match (VEM) data. Indeed, it is possible to evaluate 

*It is certain that contrast is not the only factor that causes 

this difference in% targets rated good between the two categories. Many missile targets are mandatories; that is, they 

are taken at every opportunity and thereby are more likely to 

be taken under poor acquisition conditions. The data is 

generally consistent with what would be expected, however, if 

target contrast is a contributory factor. 

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each mission camera in terms of the resolution (inc/mm) produced in the film plane on operationally acquired photography 

and ignore the effects of haze, contrast, etc.* The data for 

the first five missions is summarized in Table 3-1, where the 

missions are listed in order of decreasing camera performance. 

TABLE 3-1 

HEXAGON Mission Resolving Power Data from VEM 

(Values inc/mm) 

Dates Mean 

Mission Launch Completion Resolving Power 

1202 20 Jan 72 28 Feb 72 170 

1201 15 Jun 71 16 Jul 71 156 

1205 9 Mar 73 11 May 73 155 

1203 7 Jul 72 2 Sep 72 137 

1204 10 Oct 72 17 Dec 72 135 

The table illustrates that the best mission, from a 

camera performance point of view, was 1202, a winter mission. 

This occcurred in spite of the fact that this mission required 

longer exposure times than any other. The worst mission, from 

a resolving power point of view, was 1204. Yet, as later 

discussion will show, in most respects, this was the best HEXAGON 

mission to date. 

3.4.2.2 Achieved Mission Performance 

It is not possible to evaluate HEXAGON performance 

as a function of time of year (as was done with GAMBIT CUBED) 

because there have been a far fewer number of missions and 

*VEM resolution values are for a constant 2:1 contrast and are 

not affected by the specific contrast of the scene. 

r.«,..XA"O'~ .. ,~t u lJ r,~ i\~DIT :UlL,D. ! ':tor n- ["P'.li~r rP"~F i Ji.:tdit iHit' · Approved for Release: 2023/04/03 C05140951 

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the statistics would be shakey at best. It is possible, however, 

with the CRYSPER Program and knowle~ge of the acquisition conditions, to evaluate the five missions to date and arrive at 

conclusions about the factors that influence PI suitability. 

It is also possible to illustrate how these factors are in 

agreement with previous discussions. 

With HEXAGON, the vehicle altitude, amount of photography 

at high scan angles and contrast are all important factors in 

determining how the PI will rate the imagery. These factors 

cannot be considered alone but must be considered together. The 

following discussion illustrates this point. 

Table 3-2 presents a summary of the "all weather" 

photointerpreter ratings for the OAK and OAK Supplement targets. 

TABLE 3-2 

Summary of All Weather PI Suitability Ratings 

(Percent) 

Rating 

Categorr 1201 

Excellent 1.0 

Good 22.4 

Fair 47.7 

Poor 28.9 

1202 1203 

0.5 0.4 

22.9 14.8 

48.4 56.7 

28.2 28.1 

1204 

0 

23.5 

52.1 

24.4 

1205 

0 

15.0 

58.6 

26.4 

From this table, one would conclude that 1201, 1202 and 1204 

were all of about the same quality, with 1204 having a slight 

advantage. By this rating, 1203 was the worst system. 

Altitude could also be used as·a criteria in evaluation 

of mission performance. The nominal acquisition altitudes for 

these missions is noted below. 

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Mission Altitude (nm) 

1201 

1202 

1203 

1204 

1205 

103 

84 

100 

91 

86 

Based solely on altitude, one would expect 1202 and 1205 to be 

clearly superior to the other missions. From Table 3-2, this 

is obviously not the case, particularly in the instance of 1205. 

Evaluating the amount of high scan angle photography 

does not totally answer the question either. The amount of 

area covered at high scan angles on the several missions is noted 

below. 

% Area Covered Beyond 

Mission 30° Scan 45° Scan 

1201 50.1 10.5 

1202 62.9 34.8 

1203 57.2 30.3 

1204 40.8 3.9 

1205 44.7 11.5 

Based on this data, 1202 looks by far the worst mission, and 

120p the best. 

°' While the amount of photography at high scan angles is 

not the only consideration in assessing the general perfort 

mance, it is a very important factor. In detailed studies conducted on both 1201 and 1203, it was found that the vast majority 

of targets rated poor for interpretation were acquired at high 

scan angles. On 1201, 54% of the targets rated poor were acquired 

beyond +45° of scan and 80% beyond +30° of scan. On 1203, 40% 

HEXAGON GAMBIT 

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of the targets rated poor were acquired beyond ~45° of scan and 

85% beyond ~30° of scan. 

To try and illustrate the confusion that only looking 

at one factor produces, Table 3-3 lists the missions from best 

to worst based on the several factors discussed above. 

TABLE 3-3 

Mission Ranking, Best to Worst, for Several Factors 

Mean Min. Area at 

Camera PI Acquisition High Scan 

Ranking Resolution Ratings Altitude Angles 

1 1202 1204 1202 1204 

2 1201 1202 1205 1201 

3 1205 1201 1204 1205 

4 1203 1205 1203 1203 

5 1204 1203 1201 1202 

The CRYSPER Program combines all these factors in its 

prediction of the GRD for any given location on the film format. It is possible, using CRYSPER, to estimate the overall 

mean area weighted* GRD produced by a mission. If all these 

variables are properly treated, then, the GAWA obtained for 

the mission should have some relationship to overall quality 

from a PI suitability point of view. The basic process employed 

and the results obtained are discussed below. 

Major axis VEM profiles are used to calibrate the 

CRYSPER Program. That is, 2:1 contrast resolution predictions 

are made with CRYSPER and then compared to actual VEM data. 

The actual average of the combined VEM data from all scan 

angles and scan modes is used. The differences between the 

actual and predicted VEM are computed and applied to the CRYSPER 

*Referred to as the Grand Area Weighted Average (GAWA) resolution. 

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predictions for the "average" intelligence target.* The final 

data used for the GAWA computations combines forward and aft 

camera resolving power data. The GRD predictions, then, are 

for the average intelligence target and are based on ground 

reflectances of 10% and 20%. In most cases, the seasonal haze 

model is used. There has been, however, one exception to this. 

The GAWA is computed based on the total cloud-free area coverage 

as a function of scan sector. The GAWA computations for the 

past five missions are presented in Table 3-4 for the "average" 

intelligence targets. 

TABLE 3-4 

Area Weighted GRD Summary 

for Typical Intelligence Targets 

(Values in feet) 

Mission 

1201 

1202 

1203 

1204 

1205 

45-60 

10.5 

8.0 

12.4 

11.8 

13.5 

Scan Sector (Degrees) 

30-60 

6.5 

6.3 

9.3 

5.9 

8.6 

NOTES: 1Based on 120° scan mode only. 2Based on the forward camera only. 3Based on heavy haze model. 

+30 

3.6 

3.1 

3.7 

3.3 

4.3 

GAWA 

5.0 1 

s.1 2 

6.9 

4.4 

6.2 3 

*In effect, this is a calibration of the camera model portion 

of the CRYSPER Program. 

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The relationship of GAWA to PI suitability ratings is 

shown in Figures 3-17 and 3-18. Figure 3-17 gives the average 

intelligence target GAWA for each mission versus the percent 

of all weather targets rated good. The figure shows that there 

is a reasonable relationship between overall mission performance as reflected in the GAWA computation and PI suitability. 

The importance of contrast is further highlighted by comparing GAWA computations for constant 2:1 contrast*. This can be done 

by simply employing the VEM data, converting it to GRD and 

making the same area weighted computation. This data is shown 

in Table 3-5. 

TABLE 3-5 

Area Weighted GRD Summary for 2:1 Contrast 

(Values in feet) 

Scan Sector (Degrees) 

Mission 45-60 30-60 

1201 6.5 4.6 

1202 5.8 4.5 

1203 8.6 6.6 

1204 9.0 4.0 

1205 6.0 4.1 

NOTES: 1 Based on 120° scan mode only. 2 Based on the forward camera only. 

+30 

3.0 

2.1 

3.0 

2.8 

2.3 

GAWA 

3.8 1 

3.7 2 

5.1 

3.6 

3.1 

*That is,, the CRYSPER computations are, on the average, more 

reflective of the quality from a PI point of view than is the 

VEM. This is to be expected since the CRYSPER Program employs 

a haze model and considers fundamental illumination considerations. VEM is calibrated to a constant 2:1 contrast and hence 

ignores these variables. This is highly desirable for camera 

performance assessment but not for PI-related factors. 

11

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ON GAMBIT 

FIGURE 3-17 

GRAND AREA WEIGHTED AVERAGE (GAWA) RESOLUTION 

VERSUS OAK TARGETS RATED GOOD 

UNDER ALL WEATHER CONDITIONS 

-l,I! 

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24 

20 

16 

12 

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GAWA Resolution 

FIGURE 3-18 

6 7 8 

(GRD, ft) 

MEAN GRD (FT) WITHIN +30° OF SCAN 

VERSUS OAK TARGETS RATED GOOD 

" UNDER CLEAR WEATHER CONDITIONS 

-c 50 

0 

0 

c, 40 

-a 

cu 

...., 

~ 30 

fl 

+» 

g 20 

s... 

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2.8 3.2 3.6 4.0 

Mean GRD (ft) Within 

+30° of Scan 

If. - GON G11MB]T 

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Based on the GAWA data from Table 3-5, 1203 would be expected to 

be worst. This agrees with the Table 3-4 observation, but that 

is the extent of the agreement. The constant 2:1 contrast data 

would say that 1205 was the best mission, whereas the data in 

Table 3-4 shows this mission to have produced the second worst 

GAWA; and the PI rating data shows it to have been the worst 

mission. 

Table 3-6, then, provides a ranking of HEXAGON 

performance based on the GAWA computations. Table 3-6, 

addition to Figure 3-17, illustrates that there is good 

ment between the mission rankings based on the GAWA and 

mission rankings based on the photointerpreter ratings. 

comments relative to the mission ranking are included. 

mission 

in 

agreethe 

Key 

The all weather PI rated target GAWA comparison will, 

of course, have more scatter in the data due to the fact that 

CRYSPER can only estimate the haze based on statistics. This 

often will not correlate with the real acquisition situation. 

To minimize this variable, it is useful to compare the percent 

targets rated good in clear weather and acquired within +30° of 

scan with the mean GRD estimate within +30° of scan. The 

summary of these clear suitability ratings is given in Table 

3-7. The percent goods is plotted against the mean GRD, as 

estimated from CRYSPER, for within +30° of scan. 

TABLE 3-7 

Summary of PI Suitability Ratings from 

Stereo, Clear and Complete Coverage of OAK Targets 

(Percent) 

Rating 

Categorr 1202 

Excellent 0.3 

Good 41. 9 

Fair 44.8 

Poor 13.0 

1203 1204 

0 0 

23.5 34.7 

64.7 60.9 

11.8 4.4 

1205 

0 

24.1 

65.3 

10.6 

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Rank 

1 

2 

3 

4 

5 

Mission 

1204 

1201 

1202 

1205 

1203 

TABLE 3-6 

Summary of HEXAGON Mission Performance 

GAWA 

li!l 

4.4 

5.0 

5.1 

6.2 

6.9 

% Targets 

Rated Good 

23.5 

22.4 

22.9 

15.0 

14.8 

Average 

Acquisition 

Altitude (nm) 

91 

103 

84 

100 

86 

Comments 

Reasonable altitude; small% of 

photography at high scan angles; 

fall/winter mission. 

High altitude, reasonable amount of 

photography at high scan angles. 

Good altitude; however, large 

amount of photography at high 

scan angles. 

High altitude; reasonable amount of 

photography at high scan angles; 

very poor haze conditions dominated this mission. 

Good altitude; however, large 

amounts of high scan angle photography. 

108499 73 

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HEXAGON GAMBIT 

Since these targets were all rated clear by the interpreters, 

only the seasonal haze model was used in the average GRD computation. The plot of the average GRD within +30° of scan and 

the percent goods from Table 3-7 is given in Figure 3-18. 

Figure 3-18 allows some interesting observations*. The 

- sensitivity of the percent goods to small changes in GRD is 

somewhat surprising. Changes of a fraction of a foot GRD result 

in significant changes in the percent targets rated good. The 

GRD that produced the highest percentage of targets rated good 

(42%) was 3.1 feet. A mean GRD of 3.7 feet produced only 29% 

of the targets being rated good. What this indicates is that 

the ability of the HEXAGON system to produce "good" photography 

from a PI point of view is very sensitive to any factor which 

produces relatively small changes in GRD. This is not surprising 

considering the resolution range HEXAGON produces within +30° 

of scan; namely, 2.5 to 5 feet depending on the altitude.- This 

is a critical resolution range for many order of battle targets, 

and it is not surprising to find that relatively small decreases 

in GRD affect the interpreters' ability to perform these kinds 

(i.e. OB) readouts. 

A separate but related study reported on in the 1204 

PFA report (TCS-363502-73, 6 April 1973) illustrated that of 

all the targets rated good by the interpreters, 50% had (based 

on CRYSPER predictions) a GRD of 3.0 feet or better. This 

points out that small increases in altitude, for example, can 

be expected to affect the percent of targets rated good by the 

interpreters. Indeed, Figure 3-18 could be related to altitude 

as well. This is done below: 

% Clear Nominal Acquisition 

Mission Targets Rated Good Altitude (nm) 

1202 42 84 

1204 34 91 

1203 24 100 

1205 24 86 

*It should be noted that 1201 is not included on Figure 3-18 

because the PI rating data was not collected in this manner 

and is, therefore, not available. 

HE 

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Only 1205 does not fit the pattern, but it was severely affected 

by haze. 

3.4.2.3 Effect of Specular Reflections and Shadowless Acquisitions on Quality 

This report started with a discussion of the effect of 

launch time on quality. In that discussion, it was pointed out 

that specular reflections and shadowless acquisitions were byproducts of improper launch time that could cause image degradation. Mission 1206 was so launched. The effect of these 

problems on image quality was addressed by the Post-Flight 

Analysis Team in their preliminary report on the quality of 

1206-1. The applicable portions of this report are quoted below. 

The tate launch time of Mission 1206 caused specular reflections and futt front lighting (shadowless acquisitions) to 

ocaur at nadir and between 40-30° north latitude on this 

mission segment. The PFA conducted a preliminary investigation of the effect of this phenomenon. The validity of 

the pre-mission predictions was easily established. 

Numerous excanptes of specular reflections on the forl.iXa'd 

camera were found within the latitude bands indicated at 

nadir. In addition, several cases of bloomed highlights 

were found outside the latitude bands indicated above at 

nadir. This is to be expected. The problem of specular 

reflections is not as severe as the problem of shadowless 

acquisitions because the occU!'rence of specutars is largely 

dependent on the nature of the target and not sotety on the 

ittwnination geometry of the acquisition. Shadowless acquisitions are target independent and occur, with varying 

degrees of severity, at nadir on every frame within the 

latitude band noted above. The futt front lighting problem 

is the reverse of the specular reflection problem and hence 

affects the aft camera. The effect on photography is to 

produce poor quality imagery as there is a severe Zoss in 

contrast due to the lack of any shadows in the scene. 

Several ops evaluated by the PFA (both domestic and denied 

area) exhibited shadowless target conditions and the 

attendant poor quality under the predicted latitude and 

scan angle constraints. The effect is most severe within 

approximately +3° of nadir. Under magnification, the 

imagery looks very flat and dimensionless. In addition, 

edges cannot be readily determined due to the tack of edge 

contrast enhancement provided by shadows. In the most 

severe cases, detail is totatty tost on the aft camera 

imagery. 

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This problem ia most severe with imagery that already 

haa poor target contrast such as desert scenes. The PFA 

recommenda that: 

a. For those acquisitions where maximwn image quality 

is desired, the conditiona noted in ref A should be avoided. 

b. Swrrmer time missions should be launched early 

(approximately 0900 hours). 

The effects of full front lighting are best shown with pictures. 

Figure 3-19 illustrates a typical case of front-lighting in an 

urban area. The aft camera imagery can be seen to be extremely 

flat and dimensionless. The lack of shadows gives the picture 

an almost "bombed out" appearance. The specular reflection off 

the river on the forward camera photograph can also be noted. 

Figure 3-20 illustrates a more severe case of front lighting. 

In this example, considerable detail has actually been lost. 

In comparing the portions of the aft camera photography, highlighted by the arrows, with the forward camera photography, it 

can be seen that significant details are missing in the aft 

camera photograph due to the complete lack of shadows. Figure 

3-20 illustrates the effect of shadowless acquisition on an 

actual intelligence target. Mission 1206 was launched such that 

the specular reflection/shadowless acquisition problems occurred 

near nadir and started at about 40°N latitude. As such, approximately 20% of the 1206-1 acquisitions were affected by these 

related problems. 

3.5 Summary 

These discussions illustrate that certain fundamental conditions control the quality that will be achieved by a satellite 

photoreconnaissance camera. Scan or roll angle obviously produce losses due simply to the geometry involved. The image 

gets smaller as the scan (roll) angle increases. Smear also 

influences quality up to a point. There is a minimum solar 

altitude that produces sufficient illumination and, as a result, short enough exposure times. Further reductions in 

exposure time (while necessary to properly expose the image) 

are not significant from an image quality point of view. In 

fact, as solar altitude becomes very high (70-90°), image 

quality will start to decrease due to the loss of contrast 

that results from the ever-decreasing shadows. 

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Contrast must also be considered as a function of solar 

altitude because it also affects performance. In general, 

the lower the solar altitude, the worse the contrast. Again, 

there is some solar altitude where this problem stabilizes. 

Considering all these factors, it can be concluded that the 

image quality produced by a satellite camera will not, on the 

average, change significantly if the solar altitude is 30° or 

higher. Increasingly significant losses in quality can be 

expected as the solar altitude decreases below 30°. Camerainduced losses, however, start to become a problem below solar 

altitudes of 20°. 

Overall, contrast is also a function of time of year because the haze conditions vary during the year. The data 

clearly indicates that, on the average, the atmospheric conditions are clearest during the fall/winter seasons and worst 

during the spring/summer seasons. 

The nature of the target itself and its illumination are 

also significant contributors to the quality of the final 

image. Changes in the illumination of the target can change 

the GRD produced by a foot or more. The target also has a 

unique inherent contrast, and resolution is a function of 

c0ntras·t. In considering the quality that will be -produced 

from a photograph of any given target, or class or targets, 

the nature of the target and the acquisition conditions to be 

employed must be carefully considered, particularly if the best 

possible quality is desired, This is an area for which the community has only the most basic and limited understanding and 

one that deserves considerably more attention. 

Most significant, however, the majority of these observations and analyses are reflected in the PI suitability 

ratings. The importance of time of year (and clarity of the 

photography) are reflected in the fact that on GAMBIT missions 

the highest percent of targets rated fair or better occurred 

on the fall missions. Winter missions, despite the longer 

exposure times, rated second best when evaluated in this manner. 

Analysis of HEXAGON missions illustrates that it is possible to 

combine all the camera/acquisition factors into a model that 

provides GRD predictions that, on the average, correlate with 

the PI suitability ratings. · 

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4.0 EFFECTS OF THE REPRODUCTION PROCESS 

This discussion would not be complete without at least 

highlighting the major influences on the quality of imagery 

due to the reproduction process. The photointerpreters receive and, in nearly all cases, use duplicate copies made from 

the original negative. The quality of the imagery viewed by 

the interpreters is dependent on how well the "dupes" reproduce the original. T'.his section is not intended to be a 

treatise on the subject but is intended to highlight the key 

areas that affect image quality. They are two: tone transfer 

and image quality transfer. 

4.1 Tone Transfer 

The ground scene is made up of an array of brightnesses 

(luminances). These are, of course, modified in the imaging 

pro~ess, but they end up as an array of densities on the original 

negative. The purpose of the reproduction process is to capture 

those densities and reproduce them as another set of densities 

on the dupe positive that will be most meaningful to the interpreter. If the reproduction of densities (referred to as tone 

transfer) is not done properly, information can be actually 

lost or impaired on the PI' s copy. Unfortunately, this is not 

an infrequent occurrence. 

There are a number of problems in reproduction that must 

be dealt with, the most fundamental one being how to reproduce 

the densities of the original. Because of all the factors 

discussed in the previous sections, scenes vary dramatically 

in their contrast. This means that one seldom wants to reproduce the densities on the original with the same (1:1) relationship on the duplicate. For example, a very low contrast 

(low density range) scene should be reproduced to enhance 

(expand) the contrast. Conversely, a very high contrast scene 

may have such an extreme density range on the original negative 

that all the densities can not be recorded on the dupe film 

being used. In this case, two duplicates may be required to 

provide all the tonal information. If the PI only uses one 

of these~ he will not be seeing all the information recorded 

on the original negative. Needless to say, the more copies 

required to reproduce all the information inherent in the 

original negative, the more complicated the PI's task becomes. 

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The fact remains, however, that no one reproduction process 

is completely satisfactory for all the pictures taken, and other 

processes are necessary to attempt to reproduce as much photography as possible under the optimum conditions. 

An example of such specialized printing is useful in understanding the problems. On Mission 1205, there were a total of 

556printing parts. Of these, a total of 31.7 required multiple 

printing. That is, the original negative density range was too 

great on these to be returned within the desired limits on a 

single "medium" copy. Therefore, two or three prints (at different print levels) were necessary to reproduce all the information. In addition,. 57 printing parts were reproduced at higher 

than normal contrast for the benefit of low contrast areas on 

the original negative. It should be noted that considerably 

more photography benefited from high contrast printing, and 

these were delivered in addition to the normal copies. The 

above printing parts are those where the entire part benefited, 

and.hence only the high contrast copy was delivered. 

Special copies of specific targets are also required to 

maximize the tone transfer of the target only. On 1205, 96 

such reproductions were made. The number of such reproductions 

-.,11 GAMBIT CUB·ED is usually higher. 

The problem of reproducing mission photography accurately 

is decidedly more difficult on spring missions. On spring 

missions, there tends to be a significant number of areas with 

partial snow cover. That is, wide areas of the Soviet Union 

contain snow in the country and no snow or dirty snow in the 

target areas. This not only causes an exposure problem but a 

reproduction problem as well. For example, if you expose for 

the snow, the target area ends up under-exposed, and target 

detail can be harmed. If one exposes for the target area, the 

snow scene will be overexposed and searching could be impaired. 

This problem is compounded when attempting to reproduce this 

imagery because no matter how such a scene is exposed, the contrast is very high. 

Figure 4-1 illustrates what happens to an urban scene 

when it is given the snow bias (for exposure compensation) 

when there is no snow in the city. This can occur either if 

snow is predicted in the scene but is not there or if snow is 

in the surrounding area but not in the city. From the graph, it is clear that the density range of the improperly exposed 

MBIT 

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FIGURE 4-1 

Density Distribution of Urban Areas 

BIASED 

/ EXPOSURE 

0.5 1.0 

NORM.AL 

/ EXPOSURE 

1.5 

ORIGINAL NEGATIVE EQUIVALENT MACRODENSITY 

2. 0 

area is greatly reduced over that of the properly exposed one. 

In this case, information will definitely be lost, 

The real extent of the problem is shown in Figure 4-2. 

This figure illustrates the density range that exists on a 

frame of original negative for an industrial area with no 

snow and the surrounding area with snow. In this case, a compromise in exposure was given in the attempt to optimize both 

areas as best could be done. The density range still is very 

high, and at least two duplicates are necessary to capture 

all the information on this original negative. 

4.2 Resolution Transfer 

The second major detrimental effect of the reproduction 

process is the loss of resolution that can occur, As the. 

HEXf1GON GAMBIT 

TOP t!• CRET HUFF 

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FIGURE 4-2 

Density Distribution of Industrial Target 

Area with Snow Surround 

I I 

0.5 

/ 

INDUSTRIAL AREA . SNOW 

/SURROUND 

~I 

1.0 1.5 2.0 

ORIGINAL NEGATIVE EQUIVALENT MACRODENSITY 

inherent resolving power of the camera gets higher, it is more 

difficult to reproduce all the resolution. For example, for 

HEXAGON •issions to .d-at.e, Ta.bJ.,e 4-1 ill.ucS.tr.a.t.e.s the t,yp.ical 

resolution losses from original negative to dupe positive. 

ON 

Resolution 

100 

120 

160 

240 

TABLE 4-1 

Resolution Losses in Reproduction 

(c/mm) 

2nd Gen. D.P. 3rd Gen. D.P. 

Resolution Loss {%) Resolution Loss (%) 

5 

8 

16 

20 

HE GO?! GAMBIT 

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17 

20 

30 

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The third generation copies, as would be expected, produce the 

worst resolution loss. These are used with HEXAGON for the 

target complex duplicates for a number of customers. A nominal 

performance level with GAMBIT CUBED is on the order of 120-140 

c/mm. For HEXAGON, the nominal performance level is on the 

order of 150 to 170 c/mm. At its best, however, HEXAGON performance will exceed 200 c/mm. Therefore, this problem of losses 

in quality due to duplication are more severe with HEXAGON than 

with GAMBIT. 

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