1. Remote Sensing What is Remote Sensing? Sample Images
What do you need for it to work?
Electromagnetic Radiation
Electromagnetic Spectrum
Platforms – Things to consider
Satellite Sensors
Image Processing
Analysis

2. What is Remote Sensing?
"Remote sensing is the science (and to some extent, art) of acquiring information about the Earth's surface without actually being in contact with it. This is done by sensing and recording reflected or emitted energy and processing, analyzing, and applying that information." (CCRS)
Aerial Photography – A whole discipline on its own
Satellite Imagery – Includes information beyond the visible spectrum. This is what we will focus on.

3. Advancements

4. Satellite Orbits Geostationary vs. Near Polar
Most satellite we will talk about are Near Polar

5. Data Collection
Passive vs. Active Passive Satellites: Satellites that record reflected and naturally emitted energy from the earth’s surface. (use the sun as energy source) ACTIVE SATELLITES: Satellites that send out their own source of energy to collect data that is not naturally emitted from the earth’s surface. It will record the amount of data reflected back from earth.

6. This is a true color composite

7. This is a true color composite

8. This is a false color composite

9. This is a false color composite

10. Why the Strange Colors?
Stay tuned to find out!

11. How does it work?
You need some sort of energy source: Naturally, this would be light from the sun.
Interaction with atmosphere
Object that reflects, absorbs, transmits energy.
You need a platform (satellite sensor) that records the reflected electromagnetic radiation.
You need a computer that can process the electronic information into an image.
You need a computer program and individual who can interpret the images.
Read the CCRS website for a detailed tutorial of remote sensing

12. Electromagnetic Radiation
This is the energy source provided by sun. This is the first requirement for remote sensing to work.
Energy is emitted from the sun in the form of electromagnetic radiation. Electromagnetic radiation is emitted at various wavelengths. Objects on the earth are sensitive to these different wavelengths. We call this the electromagnetic spectrum. See next slide..

13. Electromagnetic Spectrum
Below is a good picture of the electromagnetic spectrum. You can see examples of objects sensitive to different parts of the spectrum. Notice, the visible part of the spectrum! This is what we see. But look at all of the other information we cannot see at different wavelengths!

14. Electromagnetic Spectrum
Notice how small the visible part of the spectrum is! This is the only part we can associate with the concept of COLOUR. Everything else has “no colour”associated with it.
There is a lot of information at different wavelengths and frequencies that we cannot see. This is where remote sensing is so valuable.
Violet: mm Blue: mm Green: mm Yellow: mm Orange: mm Red: mm
(Wavelength is measured in metres (m) or some factor of metres such as nanometres (nm, 10-9 metres), micrometres (mm, 10-6 metres) (mm, 10-6 metres) or centimetres (cm, 10-2 metres). )
Short
Long

15. So What?…. Remote Sensing deals with the part that is reflected…
The electromagnetic radiation hits the earth’s surface. What happens to it when it hits? It can do three things:
Remote Sensing deals with the part that is reflected…
How much of the electromagnetic radiation is reflected in each wavelength? That is the question…

16. So What?….
Some things reflect more in parts of the electromagnetic spectrum (or wavelength) then other parts. We call this the object’s spectral signature….at what wavelength does it reflect most? The more familiar you become with this, the more easily you can interpret a remotely sensed image..

17. What do the satellites do?
Sensors record reflectance in each different parts of the spectrum (band) at the same time.
A black and white image is created for each band…values of assigned.
What’s the problem?
Technology cannot display all of this information at once!

18. Image Processing The result is a funny looking colourful image:
The more you know about the spectral signatures of features, the more you will understand this image.

19. Image Processing
Computers monitors can only display colours using a combination of red, green and blue dots.
These dots of light originate from three “Guns” at the back of the monitor.
These guns are called CHANNELS in the remote sensing world.
So, we can only display 3 BANDS of information at once by displaying them through the RED, GREEN, or BLUE CHANNEL.

20. Analysis Band Combinations: True Colour images (land cover detection):
Image Red through Red Channel
Image Green through Green Channel
Image Blue through Blue Channel
True Colour
False Colour images (vegetation detection):
Image Infrared through Red Channel
Image Red through Green Channel
Image Green through Blue Channel
False Colour

21. Platforms SPOT Landsat (TM) RadarSAT NOAA ERS
How do the various satellite platforms use this information? Below are some satellites in the sky right now. Each have different characteristics in terms of spectral, spatial, and temporal resolution.
SPOT
RADARSAT
SPOT
Landsat (TM)
RadarSAT
NOAA
ERS
LANDSAT
ERS
NOAA

22. Spectral Resolution Satellites Image in multiple bands:
SPOT XS 20m resolution
µm - Visible Green
µm - Visible Red
µm - Infrared
LANDSAT (TM) 30m resolution
µm Visible Blue
µm Visible Green
µm Visible Red
µm Near Infrared
µm Mid Infrared
µm Thermal Infrared
µm Mid Infrared

23. Spatial Resolution
What size are the pixels? What is the smallest object we can see?

24. Temporal Resolution
How many times does the satellite take an image of the same area? Important for change detection…
Don’t forget the satellites orbit and the earth orbits.
SPOT – 26 Days
LANDSAT – you find out!
RADAR – you find out!

25. Markets Planning Emergency Response Resource Management Environment
Agriculture

26. Sources
CCRS website
Virtual Hawaii website
ESRI Canada