*Spatial Database Descriptions
*Vector Data
* Raster Data
* 30 Meter Digital Elevation Model
* 90 Meter Digital Elevation Model
* Digital Raster Graphic
* Flow Direction
* Landforms
* Slope
* Wetness Index
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Raster GIS Data

       The following table lists the raster GIS data in the Nang Rong Project's spatial database.  Data layers range from satellite gathered imagery, to non-imagery grids relating to landscape and terrain features, to scanned topographic maps.  The imagery was acquired and processed in order to render it usable within the database, while scanning and GIS based analyses were utilized in the derivation of other raster datasets.  In other instances, existing raster data was acquired, if available.  For some of the data, click on the link to view a thumbnail overview.  However, since some of the layers contain or depict sensitive locational data, they are confidential, and their use is restricted.

Imagery Raster Data
Satellite Imagery

Landsat Multispectral Scanner (MSS): Landsat MSS was the primary sensor during the 1970s and early 1980s.  It has a spatial resolution of 79 meters, and a spectral resolution of 4 bands: 3 visible, and 1 near infrared.  Much like all Landsat products, it provides an excellent region view of the study site.  The Nang Rong Project has 8 MSS scenes in its holdings.   Thumbnail View
Landsat Thematic Mapper (TM): Landsat TM, the next sensor in Landsat's evolution, increased its spatial resolution to 30 meters, as well as adding 2 middle infrared and 1 thermal band to its spectral suite.  TM is invaluable in examining and analyzing the landscape dynamics in the late 1980s through the 1990s.  The Nang Rong Project has 30 TM scenes in its holdings.  Thumbnail View
Landsat Enhanced Thematic Mapper (ETM): Landsat ETM, the latest Landsat sensor, began collecting imagery in the late 1990s.  Its  resolution is the same as that of TM, but it adds a 15 meter panchromatic (black-and-white) band.  The panchromatic band complements the standard suite of multispectral bands quite well, allowing sharper, more crisp images to be derived. The Nang Rong Project has 12 ETM scenes in its holdings.  Thumbnail View
IKONOS: Space Imaging's IKONOS sensor collects imagery in 5 bands: 3 visible, 1 near infrared, and 1 panchromatic.  The multispectral channels have a spectral resolution of 4 meters, while the panchromatic collects at 1 meter.  Combining the multispectral with the panchromatic allows for heightened detail and analysis.  The Nang Rong Project has 2 IKONOS scenes, for portions in downtown Bangkok, in its inventory.
Thumbnail View
Aerial Photography
Air Photos: The inventory of aerial photographs stretches back to the 1950s through the 1990s.  Presently, there are 3252 separate photographs, as well as mosaics for each decade.  The scale of the photos ranges from a relatively coarse 1:50,000, to a much finer 1:6000 for a small section in the district.  While features are easily identifiable from air photos, a lack of multispectral information prohibits higher level image processing.  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.         Thumbnail View

Non-Imagery Raster Data
Digital Raster Graphics (DRGs) Thai Ministry of Defense Maps: A set of 36 1:50000 scale Thai Ministry of Defense maps were scanned, registered, and rectified.  Of the 36 maps, 11 of them fall either within the boundary of Nang Rong district, or are adjacent to maps that contain portion of the district.  The remaining 25 fall well outside the district, but are useful in providing a broader, regional perspective of Nang Rong.    
Thumbnail View
Land Use/Land Cover (LULC) Data LULC Grids: Nearly the entire inventory of Landsat images has been classified into both Land Use and Land Cover types.  A hybrid supervised and unsupervised classification approach was utilized, with several post-processing techniques applied to increase accuracy.  "Land Use" and "Land Cover" are similar, but differ slightly in their specificity.  "Land Use" is more general, describing the broad categories of use, such as rice or field crops, that humans have introduced on the landscape.  "Land Cover", however, is more specific, describing the physical cover of the land, independent of a human element.  Examples of "Land Cover" are inundated and burned rice, and emergent field crops.
Thumbnail: Use
Topographic and Terrain Data
Digital Elevation Model (30 meter): The 30 meter elevation model was derived from the 10 meter contour lines that were digitized from the 1:50,000 scale Thai Ministry of Defense maps.  This moderate resolution 30 meter DEM has been the basis for a number of derivative datasets, some of which are listed below.
Thumbnail View
Digital Elevation Model (90 meter): A second DEM, with a resolution of 90 meters, was acquired through the Shuttle Radar Topography Mission (SRTM), a joint project between the National Geospatial-Intelligence Agency (NGA) and the National Aeronautics and Space Administration (NASA).  SRTM used a method called radar interferometry, whereby radar images taken from slightly different locations allow for the calculation of surface elevation.  Though the resolution of the SRTM dataset  is more coarse than the 30 meter DEM, it still provides a useful regional perspective.      Thumbnail View
Flow Direction: This data layer, derived from the 30 meter DEM, shows the flow direction from each cell to its steepest downslope neighbor.  Flow direction is useful for several other analyses, such as watershed modeling and flow accumulation. 
Thumbnail View
Landforms: Derived from the 30 meter DEM, this data layer breaks the landscape into 6 distinct terrain classes.  The classes are: Alluvial Plain, Lowland Terrace, Middle Terrace, High Terrace, Uplands, and Broken Uplands.  Since land use practices in Nang Rong are highly dictated by terrain, this grid is helpful in understanding land use decisions.
Thumbnail View
Slope: Slope was derived from the 30 meter digital elevation model.  Agricultural practices in Nang Rong are limited by water resources and terrain.  As such, slope helps determine the availablity of usable water and suitable arable land.
Thumbnail View
Wetness Index: A derivitive product of the 30 meter DEM, the Wetness Index combines shape measures of several  landscape elements to quantify the availability of water.  The Wetness Index incorporates such elements asslope, relative slope postion, aspect, and flow accumulation. 
Thumbnail View

  Last Modified: 04/21/2004 UNC Carolina Population Center