PostGIS Raster : Extending PostgreSQL for The Support of ... - CoDE

Figure D.1: Synthetic aperture radar image of Death Valley [37].
can be mapped, imaged, tracked and observed. The process of remote sensing is also helpful for city
planning, archaeological investigations, military observation and geomorphological surveying.
The data collected by remote sensing is often called geo imagery. The wavelength, number of
bands, and other factors determine the radiometric characteristics of the geo images. The geo images
can be single-band, multiband, or hyperspectral, all of which can be managed by PostGIS Raster.
These geo images can cover any area of the Earth (especially for images sensed by satellite).
Generally, remote sensing works on the principle of the inverse problem. While the object or
phenomenon of interest (the state) may not be directly measured, there exists some other variable
that can be detected and measured (the observation), which may be related to the object of interest
through the use of a data-derived computer model. The common analogy given to describe this
is trying to determine the type of animal from its footprints. For example, while it is impossible to
directly measure temperatures in the upper atmosphere, it is possible to measure the spectral emissions
from a known chemical species (such as carbon dioxide) in that region. The frequency of the emission
may then be related to the temperature in that region via various thermodynamic relations.
The quality of remote sensing data consists of its spatial, spectral, radiometric and temporal
resolutions. The temporal resolution can be high, such as with meteorological satellites, making
it easier to detect changes. For remote sensing applications, various types of resolution (temporal,
spatial, spectral, and radiometric) are often important.
D.2 Photogrammetry
D.2.1 Introduction
Photogrammetry is used to determine the geometric properties of objects from measurements
made on photographic images. In the simplest example, the distance between two points that lie on
a plane parallel to the photographic image plane can be determined by measuring their distance on
the image, if the scale (s) of the image is known. This is done by multiplying the measured distance
by 1/s. Most photogrammetry applications use airborne photos or high-resolution images collected by
satellite remote sensing. In traditional photogrammetry, the main data includes images such as black
and white photographs, color photographs, and stereo photograph pairs.
Photogrammetry rigorously establishes the geometric relationship between the image and the object
as it existed at the time of the imaging event, and enables you to derive information about the
object from its imagery. The relationship between image and object can be established by several
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