VIA Technologies EPIA SN-Series Specifications download pdf (Page 37)

FASTER

Chapter 4. FASTER

The review of the state of the art technologies presented in Chapter 3, allowed a

better understanding of the major issues related to the photogrammetric field. In

particular, it is clear that one of the most important innovations in this field was the

introduction of the GPS and IMU sensors to determine, in a direct way, all parameters of

the instrument external orientation

. This solution is aimed at reducing the necessary

number of ground control points always used in aerial triangulation (or resection), which

is the process to retrieve the 6 external orientation parameters of the acquired images,

without any other attitude or position sensors, using at least 3 ground control points for

each image. Direct georeferncing systems, based on digital devices are also considerably

less expensive than standard analogue systems and many steps of the photogrammetric

production process can be skipped.

In this Chapter a fully digital, direct georeferencing system is proposed for both

photogrammetric and remote sensing purposes. During the development, running costs

have been considered so the result is a fully autonomous system, independent from the

aerial platform, which is able to manage multiple acquisition instruments in order to

achieve multispectral capabilities.

4.1 Underlying Idea

The project underlying idea was the development and realization of a direct

georeferencing, photogrammetric system able to acquire high resolution images and fully

independent from a specific aerial platform. Providing the system the possibility to be

moved from an airplane to another, means that no further modifications have to be done

to the aircraft structure, fuselage or avionic subsystem.

The external, or extrinsic, parameters indeed, define location and orientation of the instrument reference

frame with respect to the world frame, while internal, or intrinsic, parameters define pixel coordinates of

image point with respect to coordinates in camera reference frame.

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VIA Technologies EPIA SN-Series Specifications Page 37