*Spatial Data
*GIS & Spatial Analysis
* Remote Sensing
* Satellite Imagery
* Aerial Photography
* Aerial Photograph and Image Classification
*Spatial Database Descriptions
*Spatial Survey Data
*Spatial Variables
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Remote Sensing and the Nang Rong Projects

        Remote sensing is an invaluable resource in the spatial analyses for the Nang Rong Projects. Spanning 1953 to 2003, the project utilizes a range of products, ranging from aerial photography, to the next generation satellite-based sensors, such as the Landsat Multispectral Scanner (MSS), Thematic Mapper (TM), and Enhanced Thematic Mapper (ETM) platforms. Taken together, these technologies allow for broad, regional views of the entire district, facilitating in analyses of changing land use and land cover, as well as in the tracking of development that has accompanied the increasing population and commercialization of the region.

Aerial Photography: 1950s-1990s
        In the days before the advent of satellite based sensing systems, remote sensing was done from cameras mounted on airplanes.  Aerial photography provided and still provides relatively high resolution snapshots of Nang Rong at discrete points in time.   As opposed to Landsat imagery, the crisp nature of the photos, ranging from 1:6000 to 1:50,000 in scale, allows for easy manual interpretation and examination, as well as a more micro-scale investigation of the landscape (below).  Additionally, stereo pairs of photos can be used to infer vegetation canopy and building heights.  However, as the generated products are nothing more than black and white snapshots, the data inherent in the photos is of limited utility owing to its lack of multispectral information.  As such, while features are clearly recognizable and identifiable from air photos, underlying information relating to vegetative health, subsurface material, moisture content, as well as a host of others, cannot be readily gleaned.   Moreover, as with any remotely collected information, the products invariably contain problems, such as camera anomalies, and, more commonly, inconsistencies in the flight path of the plane (roll, pitch, and yaw).  Thus, data problems relating to distortion, contrast and brightess, and flightline overlap are common.  The Nang Rong Project has air photos spanning nearly half a century: 1950s, 1960s, 1970s, 1980s (1:15,000 and 1:40,000), and 1990s.        

In this 1:50,000 aerial photograph from November 1994,
on the ground are easily discernable.  However,
any spectral information, interpretation is visual
in nature,
based on  patterns, shades of gray, and

In this Landsat TM image from Novmeber 1994, features are
vaguely recognizable owing to the relatively coarse
spatial resolution
of 30 meters.  Unlike the air photo to the
left, TM imagery contains
spectral data, allowing for
additional information to be gleaned.

Satellite Imagery: 1970s-2000s
        The primary sensor during the 1970s and 1980s, Landsat MSS, with its 79 meter resolution and 4 band (3 visible, and 1 near infrared) spectral set, provides a broad view of the major changes that began to occur throughout Nang Rong District in the 1970s. Following MSS, Landsat TM, with an increased spatial resolution of 30 meters and an increased spectral resolution of 6 bands (3 visible, 1 near infrared, and 2 middle infrared), is the major platform used by the Nang Rong Projects when examining and analyzing the changes and developments in Nang Rong during the 1990s. Enhanced Thematic Mapper, the latest Landsat sensor, began imaging the earth in the late 1990s. ETM provides the same resolution as TM, but it adds a 15 meter panchromatic band. When used in tandem with or when used as a supplement to the standard multispectral bands, the panchromatic band facilitates a more detailed spatial view of the landscape through its higher spatial resolution.  Click here to jump to the image inventory of the Nang Rong Project.

When the view is more regional in nature, the resolution
advantages of aerial photography are minimized.  Still,
the above photo mosaic affords the viewer an excellent
medium scale overview of Nang Rong.

The advantages of satellite imagery are accentuated from a
regional perspective.  Features that are not readily discernable
from the higher resolution aerial photos are more easily
recognizable owing to the spectral and spatial resolution of TM.

Aerial Photograph and Image Classification
          Satellite imagery, and to a lesser extent aerial photography, is used to track and analyze the changing land use and land cover (LULC) in Nang Rong through time.  In order to create datasets that facilitate such analyses, supervised and unsupervised classification methodologies and techniques have been implemented.  LULC classes that are both prevalent and detectable from the images and photos are part of the classification scheme.  The Nang Rong Project utilizes both a land use and a land cover methodology.  Land use classification produces broader, more general classes, while land cover breaks the land use classes into more detailed  classes.  To view the land use and land cover classes used in classifying the remotely sensed imagery, click here.  Click here to jump to the inventory of classified images. 

  Last Modified: 04/06/2004 UNC Carolina Population Center