Contents Remote Sensing for Studying Earth Surface and Changes

Transcription

1 Contents Remote Sensing for Studying Earth Surface and Changes Anupma Prakash Day : Tuesday Date : September 26, 2008 Audience : AMIDST Participants What is remote sensing? How does remote sensing work? Introduction to waves How do we interpret remote sensing data? Some application examples Image credits: NASA Geophysical Institute, University of Alaska Fairbanks 2 What is remote sensing? What is remote sensing? Some Unconventional Definitions The most expensive way to make a picture 3 4 1

2 What is remote sensing? What is remote sensing? Seeing what can't be seen, then convincing someone that you're right Staying as far away from the problem as possible 5 6 What is remote sensing? What is remote sensing? I don t know what it is but I am doing it STEP 2008 Acquire information about an object or phenomenon without being in direct contact with it (remotely) 7 Image credits: NASA 8 2

3 What is remote sensing? Flying height Viewing vertical rather than horizontal Viewing from a distance Recording digitally Making sense from digital numbers (image) Aircrafts ~ 1-3 km or more Satellites ~ km (polar earth observing) Weather satellites (~36,000 km) Image credits: CCRS 9 Source : Alaska A Bird s Eye View 10 So how remote is remote? From where to where? Original Image source unknown Earth observing polar satellites: km Geostationary (meteorological): 35,800km i.e. about one-tenth the distance to moon 1827 Original Image source unknown World's oldest photograph

4 From where to where? From where to where? 1903 Original Image source unknown Pigeon mounted cameras 1972 Image credits: USGS NASAs first Landsat Satellite was launched big BOOM!! From where to where? How remote sensing works 1999 Image credits: Space Imaging High resolution space imaging IKONOS 1m spatial resolution Today I ll tell you only half the truth

5 First stage in remote sensing Second stage in remote sensing Source Sensor Sensor Transmission Receiving and Processing Unit Target Third stage in remote sensing Source The sun gives out EM energy This energy travels though space (vacuum) in the form of EM radiations Processor Interpreter Application 19 Image credits: RST, NASA 20 5

6 Electromagnetic Spectrum The entire range of EM energy constitutes the EM Spectrum Let s stop and think about these electromagnetic radiations (waves) Image credits: RST, NASA Why do we discuss this? What is an image? We carry out remote sensing not only in the visible part of the spectrum but also beyond it for example in the infrared region Color by numbers The concept is very similar

7 What is an image? An image is simply numbers higher the number, brighter (whiter) the image Lower the number, darker the image 25 Original Image source unknown 26 Color image How do we get color from a black-andwhite image? Let us play with light waves and make some color

8

9

10 Color image False color image How do we get color from a black-andwhite image? Anupma Prakash, GI, UAF Why all that red color? That is because these are not natural color images These are color infrared images (infrared band shown in red) Healthy vegetation reflects very strongly in infrared What can you tell me about these two images? Source: John Horn, ITC Source: John Horn, ITC

11 Geological Mapping What can you tell me about these two images? Processed by A. Prakash, GI, UAF Processed by A. Prakash, GI, UAF 41 Landsat Data from USGS 42 Geological Mapping Glaciers Landsat data from USGS: Processed by A. Prakash 43 Image Credit: NASA 44 11

12 Glaciers Aerial Photography Compared to a satellite image you see a lot more detail on an aerial photo Photo credit: Todd Paris Image Credit: NASA 45 Aerial Photo UAF campus (Sept 2001) 46 The difference Tone Relative brightness on a gray scale image New York: A good satellite image Tanana River, south of Fairbanks, Alaska Credit: Space Imaging Copyright: USGS

13 Shape geometric aspects of the object Size Cincinnati, USA Chena River, flowing through Fairbanks, Alaska Copyright: USGS Copyright: USGS Terminus advancement Armenia before earthquake 1 km 1 km Source: Source: Final class project of Elsbeth Kuriger: Student GEOS 422, Fall 2003, UAF Source: Cees van Westen, ITC

14 Armenia after earthquake Information extraction and visualization Source: Cees van Westen, ITC Source: Cees van Westen, ITC Overlap Stereo viewing 3D Photo 1 Photo 2 Forward Forward Overlap Gain Flight direction Needed in order to measure 3-dimensionally Achieved by overlap in aerial photography Typically 60% overlap between images

15 3-D visualization 3-D visualization Image Credit: NASA 57 Image Credit: NASA D visualization 3-D visualization Image Credit: NASA 59 Image Credit: NASA 60

16 Examples Image Credit: NASA Seasonal variation in sea ice Coastal regions During summer months, the sea ice covers an average of 7,000,000 sq km, It grows to around 14,000,000 sq km during the winter. By comparison, the entire United States is just over 9,000,000 sq km Image processed by Anupma Prakash, GI, UAF: North is up and approximate width of image is 32 km Fish Creek coast shows anomalous amounts of suspended sediments Source : Alaska A Bird s Eye View

17 Coastal regions Volcano monitoring (AVO) Image processed by Anupma Prakash, GI, UAF: North is up and approximate width of image is 20 km Cape Simpson provides a potential oil prospect area 65 Source: Alaska Volcano Observatory 66 Volcano monitoring (AVO) Volcano monitoring (AVO) Source: Alaska Volcano Observatory 67 Hot areas emit more energy and therefore look brighter on a thermal infrared image 68 17

18 Volcano monitoring (AVO) Forest fires Source: Alaska Volcano Observatory Landsat color composite of Cleveland eruption. Hot area and ash clouds visible 69 Forest fire in Montana (2000) By John McColgan, Fairbanks, Alaska 70 Forest fires Cold climate river system Source: Prakash et al Colville river Drainage area km 2 Only one gauging station Braided and meandering pattern

19 Cold climate river system Cold climate river system Source: Final class project of Sean O Guinn: Undergraduate student GEOS 422, Fall 2002, UAF Measured rate of movement is roughly 46 meters per year 73 Source: Final class project of Sean O Guinn: Undergraduate student GEOS 422, Fall 2002, UAF 74 Questions? 75 19