The Nang Rong Project maintains a vast collection of geospatial
data. The database consists of products ranging from vector and
raster GIS layers, to high resolution satellite imagery and aerial
photography. The vector data consists of point, line, and polygon
vector layers, such as dwelling unit locations, rivers, and reservoirs,
while the raster GIS is comprised of cell-based layers, such as a
digital elevation model (DEM). The set of raster data is composed
of Landsat satellite imagery, aircraft collected air photos, and high
resolution IKONOS satellite imagery.
Much of the vector data within the Nang
Rong database were digitized from 1:50,000 scale Thai Military maps, as
well as other government issued maps. From these products,
transportation, hydrography, administrative and political boundaries,
point elevations, contour lines, soils, and geology were
digitized, stored as both Arc/INFO coverages and ArcView
shapefiles. Additional vector layers, such as national
administrative and political boundaries, were digitized from smaller
scale, 1:250,000, government maps. Harcopy cadastral maps,
depicting the location and limited attributes about land parcels, were
also incorporated into database through digitization. Since
digitizing is highly labor and time intensive, data already in a
digital format was sought whenever possible.
Vector data within the database
was also gathered through use of global positioning systems
. A variety of coverages were generated from GPS collected
points, including Land Use/Land Cover (LULC) points, village centroids,
dwelling units, and geodetic control throughout the region.
The raster data holdings of the Nang
Rong Project are of two major types: images and non-images. The
former is comprised of a time series of satellite imagery
, as well as a vast collection of aerial photography
while the latter is of two major types: land use/land cover (LULC)
and terrain/topographic layers. The time series of Landsat
imagery stretches back to the early 1970s, with several Multispectral
Scanner (MSS) collected images, through the 1980s and 1990s, during the
era of Thematic Mapper (TM), and up to the present, where Enhanced
Thematic Mapper (ETM) is the primary sensor. An excellent
regional perspective is afforded by these images, with the eastern
United States county sized Nang Rong falling easily within a Landsat
footprint. For portions of Bangkok, high spatial resolution
provides a much more detailed view of the city.
Aerial photography provides a much finer scale view of the study site,
for a much deeper temporal period, dating back the 1950s. While
the spatial resolution of the photographs is excellent, they are
limited in scope owing to their lack of multispectral information.
The non-image raster data is comprised
mostly of the LULC classifications, which totals 37 data layers.
In addition to the satellite image derived classifications, the other
raster datasets deal with the terrain and topography of the
landscape. Included in the terrain/topography data are the
digital elevation models (DEMs), at both 30 and 90 meter
resolution. Additionally, there are a host of products derived
from the 30 meter DEM, such as topographic moisture index, aspect,
slope, flow direction, and landforms.