Liguria on the fly. Perspective aerial photos for coastal area management

Corinna Artom1, Luca Isgro'2

1Regione Liguria, 2IBR SISTEMI (IT)

The project, promoted by APAT (Italian National Agency for Environment and Technical Services) and Regione Liguria, has been carried out by Studio Merlo (aerial flights) and IBS (application sw). The object was to set-up a methodology for the analysis of the coastal zone using "panoramic" aerial imagery and digital videos, that have been acquired in a low-height flight along the coast, from the sea; making then available an image of the coastal area that is closer than nadir imagery to the natural 3D view.
Oblique aerial photos, with a suitable inclination angle, can offer:

• a comprehensive view that can be immediately understood and interpreted, able to single out at the best the state of the coast and of the protective infrastructures, the urban and landscape context and the state-of-the-art of environment
• indications about morphology and altimetry of the coast
• a support to qualitative analyses of the existing maritime structures, updating the archive already created by nadir aerial photo-survey

This kind of survey is easier than nadir survey to be interpreted, but it is more difficult to locate and measure elements to build maps on it. However, if the take points are geo-referenced, it is possible to merge the two different perspectives overcoming the problem.

Moreover, the perspective aerial survey carried out creates a documentation source that is more updated than the already existing one (the IT2000 series of orto-photos, years 1998-1999) and is then able to single out the changes of coast-line and of existing structures, the state of conservation, the new and the not any longer existing structures.

The project aim is summarised by the following specific objectives:

• perspective aerial photos and videos from the sea of the entire Ligurian coast-line, acquired by the project and realization of an ad-hoc flight
• catalogue of the survey in a digital archive specifically structured to store the data with identification and characterisation of the parameters of each image
• development of an application sw to retrieve and analyse images

The application sw allows to:

1. retrieve images via:

• a search for toponyms, geographical co-ordinates or other associated data
• selection on a vector map

2. display the selected image
3. display the video frame corresponding to the selected image

The interface is a vector map where all the points, where the available imagery (photos, videos) have been acquired, are represented.

The coastal stretch considered is in the North-western Italy including all the Ligurian coast, the morphology of which (highly variable) is a good test to evaluate the efficacy of the work also for the remaining Italian coastline. The work carried out allowed to set up a methodology transferable to the whole Italian territory, especially to rocky coasts, high and with falaises (e.g Campania, Gargano, Conero). These areas need, in fact, a perspective view as it can be acquired from sea for a complete knowledge.