El Instituto de Investigación para Protección Geo-hidrológica de Turín — gestión de archivo de fotos aéreas

El Instituto de Investigación para la Protección Geo-Hidrológica de Turín (IRPI), miembro del Consejo Nacional de Investigaciones Italiano (CNR), comenzó sus actividades en 1970. Los conocimientos acumulados desde su fundación se desarrollan en los siguientes sectores de investigación: p. e. El estudio de las características geológicas e hidrológicas del sistema fluvial del Po-Alpino (Norte de Italia) o la monitorización, predicción y prevención de desastres naturales. Estas tareas se llevan a cabo por el empleo de un enfoque multidisciplinario de ciencias de la tierra, ingeniería y geomática.

In order to carry out exhaustive researches and studies, in addition to field survey, modelling and historical records analysis, aerial photograms are employed. Their use varies, from “simple” visual analyses to complex processing as stereoplotting or image segmentation.

The institute, for the explained purposes, keeps in its archive about 170000, recent and historical, photograms — the oldest one dating back to 1920s (Figure 1) — covering, in different years, the Po basin or part of it. Some photograms cover other basins in northern Italy. In addition the archives keeps flight plans of the described photograms (Figure 1).

1929 photogram (left) and 1954 flight plan (right)

Fotograma 1929 (izquierda) y plan de vuelo 1954 (derecha).

Gestión de archivo

In order to cope with such amount of data a GIS approach was adopted. First each flight plan, showing photograms’ footprints, was scanned, georeferenced and digitized in shapefile format. Then photograms were scanned, at 600 DpI, and files were named according to a code including map sheet, year of acquisition, strip number, photogram’s serial number and code of property (IRPI’s or external).

Each footprint in digitized flight plan was provided, in its attributes, with the previous codes in order to link shapefile to scanned photograms, by the use of eVis plugin (Horning et al, 2009), and to allow a user friendly interface to search and refer to (Figure 2). Data concerning photogram code were stored in attribute table fields than, by field calculator, a “Link” field was created storing photograms’ file paths.

Photogram display (eVis Plugin)

Despliegue fotograma (complemento eVis)

Moreover, due to the amount of searchable data a geographical search interface was developed. Thanks to the graphical modeler (in Processing, formerly SEXTANTE, plugin) capabilities, the developed tool, by different selection masks and input boxes, allows the user to select among three layers (administrative boundaries, map sheets and rivers), find a feature by querying its table and employ it to spatially query a digitized flight plan with the purpose of selecting photograms’ footprints intersecting the selected feature (Figure 3). With this procedure, is then possible to point out selected photogram and simply display them with the previously described tool or extract, by their filenames and path, photograms’ files for further processing.

Graphic modeler scheme used in the selection tool (in background: purple polygons-map sheets; labeled orange polygons-photogram footprints; brown polygons-municipalities administrative borders)

Graphic modeler scheme used in the selection tool (in background: purple polygons-map sheets; labeled orange polygons-photogram footprints; brown polygons-municipalities administrative borders)

The photogram collection is of great interest both in research (e.g. Godone et al, 2014) and professional environments (Figure 4). Now thanks to the described procedures and tools the collection is fully accessible and since 2009 the photograms were employed in several projects both internal and external to the Institute. QGIS features and plugins allowed developing tools and procedures to optimize photogram archive both in the implementation of its management and in its exploitation.

Pie chart showing different area of interest employing photograms in year 2013

Gráfico de torta mostrando diferentes áreas de interés empleando fotogramas en el año 2013

Referencias

  • Godone D., Garbarino M., Sibona E., Garnero G., Godone F. (2014) “Progressive fragmentation of a traditional Mediterranean landscape by hazelnut plantations: The impact of CAP over time in the Langhe region (NW Italy)”, Land use policy, ISSN: 0264-8377
  • Horning N., Koy K., Ersts P. (2009) “eVis (v1.1.0) User’s Guide. American Museum of Natural History, Center for Biodiversity and Conservation” Available from http://biodiversityinformatics.amnh.org/

Autores

Danilo Godone

Danilo Godone

Danilo Godone is a Postdoc grant holder, at Turin University, studying geomatic contribution in landslide, glacier and, more generally, natural disasters monitoring. He is a member of NATRISK — Research Centre on Natural Risks in Mountain and Hilly Environments, in the same University. He acts as a freelance consultant in the same topics, too.

Franco Godone

Franco Godone

Franco Godone is a specialized technician at Research Institute for Geo-hydrological Protection of Turin (IRPI-CNR) since 1972. He is involved in topographical and aerophotogrammetrical surveys and data analysis in the alpine regions.