Remote Sensing Workshop report 860 Kb

The increasing availability and accessibility of new technology and data for local governments and agencies are proving very helpful in day-to-day decision-making processes. In particular, remotely sensed data and Geographic Information Systems have been increasingly used together for a vast range of applications, spanning from land use/land cover mapping to emergency management to characterization and monitoring of environmental and human health conditions. 

Higher spatial and spectral resolutions, more frequent coverages, and increased availability of new sensors will bring remote sensing to an even more accessible level within local and state governments and help them in dealing with diverse issues in regional planning, resource management, public health, and environmental protection. 

SEDAC has developed five sets of Landsat-7 images covering parts of New York, New Jersey, and Connecticut, acquired during the fall 1999 and the winter 2000. The spatial resolution (ground cell or pixel size) varies between 15 and 60 meters and allows detection and mapping of quantities such as vegetation abundance and health, presence of standing water, forest clearing, agricultural usage, and other land cover changes. Take a look at the differences in spatial resolution between the following Landsat 7 images for the NYC Metropolitan area:

 
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NYC99tm8 		click to view image - hit "back" to return
NYC99tm17		 click to view image - hit "back" to return
NYC99tm6
  • NYC99tm8
    Landsat 7 ETM+ Panchromatic Band, acquired on September 23, 1999. Ground resolution: 15 meters.

  • NYC99tm17
    Landsat 7 ETM+ False Infrared Color, Band 7 (r), 4(g), 2(b), acquired on September 23, 1999. Ground resolution: 30 meters.
  • NYC99tm6
    Landsat 7 ETM+ Thermal Band, acquired on September 23, 1999. Ground Resolution: 60 meters.

                           LANDSAT 7 Spectral and Spatial Resolution:

Band Number

Spectral range (microns)

Ground Resolution (meters)

1

.45 to .515

30

2

.525 to .605

30

3

.63 to .690

30

4

.75 to .90

30

5

1.55 to 1.75

30

6

10.40 to 12.5

60

7

2.09 to 2.35

30

8

.52 to .90

15

For more information on Landsat 7, visit http://landsat7.usgs.gov/.

Examples of possible applications, based on some preliminary work on the above scenes, include:

·        Tailored land cover/land use classification.

The advantage of such a classification, compared with other available products such as the recently released USGS Land Cover/Land Use State Maps, lies within the word “tailored”: such classification will be produced based on inputs from local governments, according to their needs and potential uses of the product. Another advantage will be the possibility of  regular updating of the product, thanks to availability of repeat coverages.

Take a look at an example of a “simplified” classification and compare it with the USGS Land Cover map.

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  • NYC99tm17sub
    This image shows a close-up view of the Landsat 7 ETM + scene acquired on September 23, 1999, showing Paterson, NJ and the surrounding areas. The image is displayed in false infrared color (Red=Band 7, Green= band 4, Blue= Band 2).
 
  • NYC99tm17sub_class
    This image shows an example of classification applied to the Paterson subset of the Landsat 7 multispectral scene.

    The image has been classified using the Maximum Likelihood method, based on a set of six ground cover types, and resulting in the following:

    Red: Heavily urbanized (high intensity residential, commercial, transportation)
    Yellow: Low intensity residential
    Light Green: Urban, Recreational Grasses
    Green: Forests
    Blue: Water
    Coral: Bare Soil, Rock

 

·     USGS Land Cover for New York and New Jersey
NY_NJ_lc_zoom
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Paterson
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For more information on USGS Land Cover Map and available data visit the National Land Cover Characterization Project at http://edcwww.cr.usgs.gov/programs/lccp/nationallandcover.html

·        Vegetation Fraction Index and Vegetation/Urban Areas Change Detection


Greenness

 Such products will allow users to identify the green areas and quantify the proportions of vegetation versus urban. This may be useful in a variety of fields, from urban planning to resource management to environment and heath protection. The availability of repeat coverages will allow regular updating of the product (annually or seasonally) according to the needs of the users.


The above “Greenness” map is a simpler version of the Vegetation Fraction Index and was obtained performing a Tasseled Cap Transformation on the original Landsat 7 ETM+ data. The Tasseled Cap Transformation performs an orthogonal transformation of the original data into a new three-dimensional space, consisting of a “Brightness” index, a “Greenness” index, and a “Third” component related to soil features. Displayed here is a green and white color scale of the “Greenness” index, where the greener areas correspond to more vegetation. 

For more information on Urban Vegetation, Vegetation Fraction Index and for more images, go to http://www.ldeo.columbia.edu/~small/NYCveg.html

For more information about the workshop contact Francesca Pozzi, fpozzi@ciesin.columbia.edu.
CIESIN Home The Socioeconomic Data and Applications Center (SEDAC) is mantained by the Center for International Earth Science Information Network (CIESIN) of Columbia University, under contract with the U.S. National Aeronautics and Space Administration (NASA Contract NAS5-98162). 

Copyright © 2001. The Trustees of Columbia University in the City of New York. 

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