1. Colour air photo: 15th / University Way

2. Panchromatic air photo: 15th / University Way

3. satellite / aerial imagery
Remote sensing =
“Gathering information from a distance”
… the acquisition and processing of
satellite / aerial imagery
1960s:
development of satellites (space race) and
b. wider use of the electromagnetic spectrum

4. Remote sensing and the electromagnetic spectrum

5. "The range of wavelengths of energy" e. g
"The range of wavelengths of energy" e.g. from the sun radiates from long (metres) to short: billionths of a metre
[Its not all temperature]

6. Wavelengths and Frequencies of different electromagnetic Waves
micrometres 'microns' : millionths of a metre nanometres; billionths of a metre

7. Wavelengths and Frequencies:
Longer Waves – Low Frequency Shorter Waves – Higher Frequency

8. micrometres 'microns' : millionths of a metre nanometres; billionths of a metre
Blue  μm (microns) = 400 to 500 nm
Green μm = 500 to 600 nm Red   μm = 600 to 700 nm

9. 1950s: Infra-red (IR) photography
IR was developed during the Korean War to distinguish between healthy vegetation (refelectin IR) and camouflage. Hence it was  known as 'camouflage detection' film or 'false colour’.

10. PGmap IR2014: http://pgmappub. princegeorge. ca/PGMapPubSV/

12. Near IR: 0.7 – 1.4 μm Vegetation health – NOT temperature!
Mid IR: μm (Vegetation) moisture
also known as SWIR – Shortwave IR– some refer to 3-8 μm as ‘mid-IR’

13. Landsat 5 Thematic Mapper bands (1984-2011)

14. Landsat bands ( )

15. Landsat TM band combinations: Visible versus IR combination
Visible wavelengths image Including Infrared (NIR / SWIR)
e.g. Google maps, earth (3-2-1) e.g. BC imap / GEOG432 labs (5-4-3)
The best displays include one band each from the visible, near-IR and mid-IR

16. Sentinel 2 Sensor
Somewhat different approach.

17. Summary of advantages of (near) Infra-Red wavelengths:
Vegetation differences are enhanced 
e.g. coniferous v deciduous etc..
Land-water distinctions are enhanced
Blue -the most susceptible to haze-  is removed

18. Spectral Reflectance Curves
advantages of (Near) Infra-Red wavelengths: contrast
Spectral Reflectance Curves

19. Thermal Infrared (3-14 microns)
This records longer wavelengths (shown in orange) and a measure of temperature as it is emitted NOT reflected IR - Works day / night

20. Thermal Infrared (3-14 microns)

21. This image shows Visible – reflected, not temperature
Night-time satellite image using visible light (city lights)

22. Microwave: (passive) 1mm – 1 metre wavelength
These wavelengths beyond the infra-red can ‘see through' clouds, light rain, and snow, but there is a low amount of it (… why we use these wavelengths for communications).
It is used to monitor sea pollution, global ice cover and atmospheric ozone.

23. Radar image, Vancouver RADARSAT 2 (Microwave – active)
Passive sensor (Landsat)
Active sensor (Radar)

24. As wavelength increases, so does atmospheric penetration ….

25. Summary
Remote Sensing activity is classified into three groups based on the wavelengths used:
1. Visible and Near/Mid Infrared (reflected) = ‘optical’
2. Thermal Infrared (emitted)
3. Microwave (= cloud-free … includes Radar)
see

26. Google Homework
Why do deciduous tree leaves change colour in the fall ?
What happens to their reflectance in:
Visible wavelengths
Near IR
Mid-IR (SWIR)