Specifications

Remote Sensing and Photogrammetry, State of the Art Technologies

spatially referenced data (data could be remote sensed or retrieved through a

photogrammetric process) named Geomatics [Ref. (2)]. It uses terrestrial, marine,

airborne, and satellite-based sensors to acquire spatial and other data. It also includes the

process of transforming spatially referenced data from different sources into common

information systems with well defined accuracy characteristics. Geomatics applications

areas include: the environment, land management and reform, urban and subdivision

planning, infrastructure management, natural resource monitoring and development,

coastal zone management and mapping, archaeological excavation and survey and

disaster informatics for disaster risk reduction and response.

In the last twenty years, thanks to the development of digital sensors, one of the fields

that had the strongest growth is that of high or very high resolution imagers both airborne

and spaceborne. This type of instruments played a major role in the development of

modern geographic information systems (GIS), constituting one of the main data source

for land management and mapping; but also other applications, like precision farming or

air pollution monitoring, can take serious advantages from increasing resolution. The new

generation of Earth observation satellites are able to acquire image data at 0.4 m of

ground resolution almost reaching the values obtained by aerial surveys.

In the following sections a review of the state of the art technologies used for

airborne sensors is presented in order to better identify the subject of this work.

3.1 Airborne Sensors

In the last decade, digital photogrammetry has progressively replaced traditional

aerial photography based on large format films, leading to a great reduction in size and

cost of the instruments. One of the major benefits of digital photogrammetry is the

elimination of degrading effects of film which improves the dynamic range of the images

(thus the overall image quality). This means that image acquisition can be done under

poorer illumination conditions than required for film increasing the number of acquisition

per day and throughout the year, [Ref (3)]. Digitalized data is also easier to be managed

allowing a faster post processing phase reducing the delivery time of the final product.

Available airborne sensors differs for technical realization, geometric, radiometric

and spectral properties but also image formats vary greatly. These instruments typically

have an high geometric performance level but recently there have been significant

improvements regarding spectral and radiometric performances becoming usufeul also for