Instructor: Dr. M. M. Yagoub
URL:
https://www.angelfire.com/mo/yagoub
Questions and Answers (Q/A) on Eelectro-optical
Sensors (2)
Textbook:
Thomas Eugene Avery and Graydon Lennis Berlin, Fundamentals of Remote
Sensing and Airphoto Interpretation, Fifth Edition, Macmillan Publishing
Company, New York, 1992.
What is the difference between
across track and along track scanners?
Along track from an image without a scanning mirror. This is accomplished with the use of a linear arrays of small (13x13 um) charged Couple Device (CCD). See Figure 6.14 on page 118.
List four advantages of along track
scanner?
1.
Improved spectral resolution (longer time means stronger signal)
2. Reliability and longer operating life due to
elimination of moving components
3. High geometric accuracy
4. Light weight and lower power consumption
Compare between photogrammetry and remote sensing, illustrate by figures?
|
Function |
Photogrammetry |
Remote sensing |
|
Sensor |
camera |
Electro-optical scanners |
|
Number of bands |
Limited (visible, IR) |
Multi-spectral |
|
Recording of data |
Film |
Digital (signal) |
|
Distribution of data |
Hard copy film |
CC tapes, CDs, internet |
|
Space carrier |
Aero-plane |
Satellite |
|
Altitude |
Low (+/- 10 km) |
High (+/- 500 km) |
|
Coverage |
Small area (one photo may cover an area of 3x3 Km) |
Large area (one image may cover an area of 185X60 km) |
|
Spatial resolution |
High (you can see a house) Resolution depends on the scale which also depends on altitude. Large scale means high resolution |
Generally
low (e.g. minimum features of size 30x30 m can be seen in Landsat 5. New
satellites such as IKONOS have a high resolution of 4 m |
|
Processing |
Film development-photo interpretation using human eye |
Signal conversion-images processing using computer |
|
|
|
|
Compare between Landsat 5 (see page 134-136) and SPOT (see page 148) satellites?
The unique characteristics of SPOT imagery is the ability to obtain
Stereoscopic View which is important in 3D applications
panchromatic (P) (black and white images with a pixel of 10 m)
and multispectral (XS)
(with a pixel size of 20 meters)
|
|
Landsat 5 |
SPOT1 |
|
Country |
USA |
France |
|
Agency |
American Space Agency
(NASA) |
French Space Agency (CNES) |
|
Date of launch |
1984 |
1986 |
|
Onboard sensor |
MSS and TM |
HRV1 amd HRV2 |
|
Altitude |
705 km |
832 km |
|
Swath width |
185 km |
60 km |
|
Spatial resolution |
80 m for MSS and 30 for TM |
20m for multi-spectral and
10m for panchromatic mode |
|
Temporal resolution |
16 days |
26 days |
|
Spectral resolution |
7 bands |
3 bands |
Write the full term for the following abbreviations?
•ISPRS- International Society for Photogrammetry
and Remote Sensing
•NASA -National Aeronautic and Space Administration (USA)
•ESA- European Space Agency (Europe)
•NASDA- National Space Development Agency (Japan)
•CNES- Centre National d'Etudes Spatiales (France )
•CSA - Canadian Space Agency
