Orthoimage of the coast
The ICGC generates the “Orthophoto of the Coast” product within the set of cartographic products intended for the study and management of the coastal environment of Catalonia.
The Orthophoto of the Coast of Catalonia is a high-resolution cartographic product produced by the ICGC. This orthophoto is generated from georeferenced and geometrically corrected aerial photographs to accurately represent the land surface without distortions.
This product provides a detailed view of the Catalan coastline, with a resolution of 10 or 15 cm, which allows the identification of elements such as beaches, cliffs, ports, breakwaters and other coastal infrastructures. The images are captured through periodic flights of the coastal area that the ICGC has carried out with an annual frequency since 2008 and biannually since 2022. Orthophotos of the coast are also generated from photographic flights that the ICGC has been carrying out since 2017, in coastal areas affected by a storm.
This data is used to evaluate the changes that occur in the coastal environment over time or due to the effects of storms, and thus be able to determine the preservation policies of this environment in constant evolution due to human action and the effects of climate change.
The coordinate system adopted is the official one in Catalonia: ETRS89 reference system and orthometric heights using the EGM08D595 geoid model..
Imatge
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A coastal orthoimage is an aerial photograph of the coastal area that has been processed to correct distortions and represent the terrain with great precision. It is like a photographic map that shows the coast as it is in reality, without deformations caused by perspective or terrain relief.
These orthophotos are obtained from the different flight missions of periodic coverage of the coast, carried out by the ICGC from a photographic sensor on board an aircraft.
Resulting products
To generate an orthoimage, aerial photographs are first captured by flights carried out with aircraft or drones equipped with high-resolution cameras. These images are taken following programmed routes that guarantee complete coverage of the coastline, with an overlap between photos to facilitate subsequent processing.
Once the images are obtained, geometric distortions caused by the capture angle and differences in terrain altitude are corrected using orthogonal rectification techniques. This is done with the help of digital terrain models (DTMs), which allow each point in the image to be adjusted to its actual position on the map.
The final result is a georeferenced orthoimage, that is, an image aligned with the real coordinates of the Earth, which allows it to be used for cartographic analysis, environmental studies and land management. This process ensures that the measurements and distances taken on the image are accurate and can be compared with other geospatial data.
Use cases
Coastal orthophoto - periodic
Coastal dynamics are constantly evolving due to multiple factors, such as sediment transport, waves, changes in sea currents, wind and human interventions, such as the construction and modification of ports, breakwaters and artificial beach regeneration. Coastal orthoimagery allows us to track this evolution, for example, by using it to trace the coastline, and measure how it moves over time.
Having an updated and periodic coastal orthophoto is essential for efficient management of the territory, as it allows informed decisions to be made in areas such as urban planning, the conservation of beaches and coastal ecosystems, and protection against extreme phenomena, such as storms and sea level rise.
Arenal Beach, Hospitalet de l'Infant (Autumn 2022 and 2023).
Coastal orthophoto - storms
The coastal orthophoto is a key tool for assessing material damage after a maritime storm. Thanks to its high resolution and geographic precision, it allows the identification and quantification of damage to coastal infrastructures such as promenades, ports, breakwaters, buildings near the coast and tourist facilities. It also facilitates the detection of alterations in the profile of beaches, such as the loss of sand, the formation of ravines or the impact on dune systems.
Compared to images taken before the storm, these orthoimages allow the analysis of the extent of the damage and support the planning of repair and recovery actions, helping public administrations and territory managers to make quick and efficient decisions. They are also a valuable tool for processing aid and insurance, as they provide objective visual evidence of the impact of the storm on infrastructures and the coastal landscape.
Evolution of the Tordera Delta: images from before, during, and after Storm Gloria (January 19-23, 2020). Photographs taken in February 2019, January 2020, May 2020, and May 2021 with the ICGC aerial photogrammetric camera.