# FRAME CAMERAS

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```					CEE 6100 / CSS 6600 Remote Sensing Fundamentals                                                 1
Topic 3: Frame Cameras

FRAME CAMERAS

Some definitions:
• Frame Camera
– A camera which exposes the entire image frame simultaneously

• FOV – Field of View
– The total solid angle (or ground area) viewed by an imaging system or
– Commonly specified as a plane angle or length on the ground.
(Assumes that the area is square.)
• IFOV – Instantaneous Field of View
– The smallest solid angle (or ground area ) uniquely detected by an
imaging system when all motion is stopped.
– Commonly specified as a plane angle or length, as above.

FOV @ aperture = 2H tan (θFOV)

s = IFOV = As / H2 sec3 = angle subtended by a
source element at a distance R
sec
a
H
a = Aa / H2 sec3  = angle subtended by a camera
θFOV                 s                      aperture at a distance R sec


P       P
La           
A s  a A a s
source element              As
AFOV
–
CEE 6100 / CSS 6600 Remote Sensing Fundamentals                                           2
Topic 3: Frame Cameras

Radiance at the aperture from the viewing direction, La(), is related to the
radiance leaving the surface element, Ls(), by:
La() = Ls()  + L*()
where:        is the atmospheric attenuation factor
The radiance at the focal plane is further reduced by transmission through the
camera optics (including filters), i.e.,
Ld () = [ Ls ()  + Ls () ] τo
where: τo = optical transmission factor
Finally, irradiance at a point on the focal plane illuminated by radiance, L s(), is
given by:
Ed = Ld ()  s = (Ls ()  + L*()) os

working with most detectors. Irradiance is the power per unit area on
the detecting surface.
Exposure is defined as the product of the irradiance, E f, at the focal plane with
exposure interval, Δt. Exposure = Ef Δt [W m-2 sec]
Photographic exposure is usually defined in photometric rather than radiometric
units. [lux sec]
Photometric units: measurements weighted by the theoretical response of the
human visual system.

Radiant Flux       watts (W)            Luminous flux        lumens (lm)
Radiant Intensity    W sr -1           Luminous intensity candela (cd = lm sr -1)
Radiance        W m-2 sr -1            Luminance            cd m-2
Irradiance         W m-2               Illuminance        lux = lm m-2
CEE 6100 / CSS 6600 Remote Sensing Fundamentals                                                                     3
Topic 3: Frame Cameras

Photographic materials                                      Solid State Detectors
emulsion

 film,

base    glass, or
 paper


anti-halation
coating

• emulsion: most commonly a silver halide in
a gelatin base
• Each photodiode collects light independently
• base: paper, film, or glass
• The active area is smaller than the
• anti-halation coating: an absorbing layer to                      photodiode area
suppress "halos" -- the spreading of a
photographic image beyond its proper
boundaries. Halation is caused primarily                     http://home.sandiego.edu/~ekim/photodiode/pdtech.html

Characteristic (D log E) curve                                            Response function
(darkening on the negative)

Dmax

linear
Density

response
Dmin
(D)

gross       range
fog

log E
• Each film has a unique D log E curve
(Exposure)
• The shape of the curve varies with                             Solid state analogs:
conditions of development                                 characteristic curve  response function
• A film's sensitivity is determined from the                    Dmin  dark current
film's characteristic curve.                              Dmax  saturation
• "Gross fog" = film base density + net fog
(dark current for film)                                   The gain of a photodiode under reverse bias is
extremely linear over a very wide dynamic
range..
CEE 6100 / CSS 6600 Remote Sensing Fundamentals                                               4
Topic 3: Frame Cameras

Film gamma,  : The slope of the straight line portion of the characteristic curve. (A
measure of contrast.)
ΔD
γ = tan  θ  =             high gamma
ΔlogE        a small change in
E produces a large
change in D.
Density (D)

low gamma
a small change in

(D)

E produces a small
change in D.

Increasing the time of development will
increase the film gamma

log E (Exposure)

Solid state analog: gamma  gain

speed: The faster the film, the less the exposure required to produce a grain density.
• film A is faster than film B
• Speed is determined by measuring the exposure at some measurable amount of density
above gross fog, e.g., ASA ratings are based on a "speed point" (log E values)
corresponding to 0.1 density above gross fog.
CEE 6100 / CSS 6600 Remote Sensing Fundamentals                                                           5
Topic 3: Frame Cameras

Solid state detectors

CCD image array ( Kodak KAF-6303E ).
HU                      UH
CMOS image array ( Samsung
HU

Active area: 27.65 x 18.48 mm                                S5K4AW ).UH

Active pixels: 3072 x 2048 (6 Mpixel)                        Active area: ???
Pixel size: 9x9 m                                           Active pixels: 1280 x 960 (1.2 Mpixel)
Pixel size: 2.8 x 2.8 m

Feature             CCD             CMOS
Signal out of pixel Electron packet      Voltage
Signal out of chip Voltage (analog)   Bits (digital)
Signal out of
Bits (digital)    Bits (digital)
camera
System Noise           Low           Moderate
System Complexity        High              Low
Sensor Complexity         Low              High
Dynamic Range          High           Moderate
Uniformity           High        Low to Moderate
Speed         Moderate to High      Higher

http://digitalimagingu.com/articles/microscopyimaging.html

Currently most imaging systems use CCD technology
CEE 6100 / CSS 6600 Remote Sensing Fundamentals                                      6
Topic 3: Frame Cameras

Detector & Filter response characteristics

http://www.rags-int-
inc.com/PhotoTechStuff/DigitalFilm

Vignetting: Darkening of an image away from the optic axis of the
imaging system.

Cos4θ falloff (also "natural" vignetting) is inherent to each lens
design and becomes more troublesome for wide angle lenses.
Optical Vignetting: Optical vignetting is related to aperture size.
The effect is most pronounced when the lens is used wide open and
will disappear when the lens is stopped down by a few stops.

http://www.vanwalree.com/optics/vignetting.html#optical
CEE 6100 / CSS 6600 Remote Sensing Fundamentals       7
Topic 3: Frame Cameras

Leica RC-10A Aerial Camera
System includes the following:

•    Lens Cone - 153mm
•    Drive Unit
•    PAV 20 mount
•    2 ea. PKA4 film cassettes
•    Manuals
•    Toolbox
•    Cables and Filters
•    Shipping containers

\$120,000

RMK TOP - Aerial Survey Camera System
CAMERA TOP
RMK TOP 15
focal length 153 mm (6 "),
angular field 93° (diagonal),
aperture f/4 to f/22 continuously,
distortion <= 3µm

RMK TOP 30
focal length 305 mm (12")
angular field 56° (diagonal),
aperture f/5.6 to f/22 continuously,
distortion <= 3µm

SUSPENSION MOUNTT-TL
(gyro-stabilization suspension mount)
•    Stabilization range:
•    ± 5° in omega,
•    ± 5° in phi,
•    ± 6.5° in kappa
•    max. angular speed: 10°/s
•    max. angular acceleration: 20°/s²
CEE 6100 / CSS 6600 Remote Sensing Fundamentals                    8
Topic 3: Frame Cameras

•   Ground pixel size: 5 cm @ 300 m
•   Forward Motion Compensation (FMC)
•   12-bit per pixel radiometric resolution

http://www.ziimaging.com/Products/AerialCameraSystems/DMC.htm

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