sensors fill factor is 100% and in APS CMOS sensors fill factor
for standard sensor is around 30%. Meynants at el. (1998) and
Dierickx at el. (1997) in their works shows that fill factor of
100% can also be achieved in APS CMOS technology.
3.3 Power
Power Consumption is one of characteristic in which CMOS is
far away in positive way from CCD. It takes almost 10 times
more energy for CCD then for CMOS sensors. While CMOS
needs about 20-50 Miliwatts for operation CCD needs 2-5
Watts.
The two significant power advantages are:
1. A CMOS sensor can be designed as a camera-on-
a-chip, whereas, a CCD imaging system contains
at least two, but more typically four, chips.
2. A CCD sensor requires multiple supplies and high-
voltage clocks. (Marston, 1998)
3.4 Access Flexibility
The simple X-Y pixel addressing method used in CMOS
sensors allows direct access to a single pixel or to a group of
pixels resulting in extremely high frame rates when working
with smaller "areas of interest" on the sensor. Also this yields
advantages in applications such as motion detection, tracking,
and edge detection (Marston, 1998)
3.5 Programmability
Most significant difference between CMOS and CCD is to add
some additional functions or to integrate signal processing
within the pixel site. It leads to development of completely new
imaging devices. Very good example is acquisition of 3D
information but not from stereo photos, which is common way
in photogrammetry. The time-of-flight is radar base technology
for 3D acquisition of information about objects (Lange, 2000).
3.6. Quantum efficiency.
CCD and CMOS sensors are made from same material, silicon.
Because of that fact the quantum efficiency (QE), like ratio of
collected electrons to incident photons is for standard sensors
the same. For visible light, 400-700nm, it is above 50%. To
increase QE back illumination of thinned CCDs can lead to 90%
QE. Almost every photon of incident light will produce one
electrical charge.
3.6 Resolution
Largest CCD currently available is sensor with 9216 x 9216
pixels (Fairchild Imaging, 1998). CMOS sensor with 4096 x
4096 pixels has been manufactured in a 0.18 um technology.
(Foveon, 2000)
4. CONCLUSION
Answer on the question IS ERA OF CCD ALMOST OVER
BEFORE IT REALLY BEGUN IN PHOTOGRAMMETRY
is still. For some period of time CCD still will be dominate
technology in Imaging Sensing Devices, but real question is for
how long? Development of CMOS is rapid and for sure will
stay that way. Achievements that were made in field of CMOS
devices are almost revolutionary (Foveon X3 technology) in
digital image sensing. When will photogrammetry take
advantages from this technology? I hope very soon. Era of
specially developed devices with special designed functions,
edge detection for example or 3D measurements, will come for
sure.
“The photon will be to the 21st century what the electron
was to the 20th*, Sen. Daniel Moynihan, New Yorker,
20.3.2000. is very promising statement for everyone who is
digital imaging field. I believe for photogrammetry especially.
Camera Type Effective Output Effective Pixel size
pixels image size imager size (um)
(millions) (mm)
Canon
EOS- CMOS 3.25 2160x 1440 | 22.7x15.1 | 9.9x9.9
D30
Canon
EOS- CMOS 6.30 3072x2048 | 227x151. | 74x74
D60
Sigma Boveon | 543x353 | 2268x 1512 9.12x
SD9 XS (10.28) x3 20 Ss 9.12
CMOS j
Canon
EOS- CMOS 11.1 4064 x 2704 | 358x238 | 88x88
IDs
KO an | CMOS 13.8 4536x3004 | 360x240 | 79x79
Table 1.: Comparison of some professional SLR cameras currently available on market
based on CMOS image sensor
76
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