Measuring long-term landscape change using historical photographs and the WSL Monoplotting Tool

ABSTRACT

This paper assesses the potential of software developed by the research group of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) in order to georeference and vectorise historical landscape photographs. The use of this ‘Monoplotting’ Tool introduces a new application for topographical photographs and opens up the possibility of using such photographs for measuring land-use change. This paper reviews the literature on the use of historical photographs for landscape history. It introduces the new software and then goes on to examine how vectorised topographical photographs may help in the measurement of land-use changes in the mountainous landscape of Liguria and Trentino in the late nineteenth and twentieth century.

KEYWORDS:

• GIS technologies
• historical photographs
• land-use change
• Liguria
• Trentino
• Italy
• WSL Monoplotting Tool

PRIMARY SOURCES

Carta degli Stati di S. M. Sarda in Terraferma, 1:9450, Corpo di Stato Maggiore dell’Esercito Sardo, 1827–1833, sheet Levanto 20.

Carta Tecnica Regionale (CTR) Regional Technical Map 2009, 2012; CTR and DTM of Liguria Region territory. www.cartografia.regione.liguria.it/ [accessed 1.6.2018].

Carta Uso del Suolo, 1:10,000, 2015, Regione Liguria. http://www.cartografia.regione.liguria.it [accessed 25.6.2018]).

Geoportale Nazionale of Italian Ministry of Environment. http://www.pcn.minambiente.it/geoportal [accessed 6.6.2018].

Gran Carta degli Stati Sardi, Real Corpo di Stato Maggiore dell’Esericto Sardo, 1:50.000, 1853, sheet n. LXIX, Monte Penna

La voce del nordest, newspaper website. https//www.lavocedelnordest.eu/allvione [accessed 6.6.2018].

Qgis, an open source geographic information system: https://www.qgis.org/en/site/

Swiss Federal Institute for Forest, Snow and Landscape Research WSL website https://www.wsl.ch/en/ services-and-products/software-websites-and-apps/ monoplotting-tool.html [1.6.2018].

Notes

1 The software is freely downloadable from the Swiss Federal Institute for Forest, Snow and Landscape

Research WSL website. https://www.wsl.ch/en/services-and-products/software-websites-and-apps/monoplotting-tool.html.

2 The CTR and DTM of Liguria Region territory are available on the website www.cartografia.regione.liguria.it/.

3 The Monoplotting software provides also the value of the georeferencing error for each control point. The height of the calculated error depends on the difference between the pixel values of the photo and the corresponding world coordinates in the DEM of the control points. Moreover, a statistical mean value represents the average of all point errors. In this georeferencing, the average error is around 30 metres. The maximum precision is in the centre of the picture and in the upper part (9.7 metres error value); the maximum of the error value (450 metres) is located in the right and left borders.

4 The Gran Carta degli Stati Sardi was created by the Sardinian Kingdom Army in 1850s to map the whole territory of the Kingdom. The document shows information on the settlement, roads and cultivation (Gran Carta degli Stati Sardi, Real Corpo di Stato Maggiore dell’Esericto Sardo, 1:50.000, 1853, sheet n. LXIX, Monte Penna). The Land Use Map was created in 2015 by the Liguria Region through photointerpretation of aerial photos (Carta Uso del Suolo, 1:10,000, 2015, Regione Liguria, available online by WMS service on the Ligurian Region cartography website http://www.cartografia.regione. liguria.it).

5 In this case, the calculated average error of the georeferencing is 600 metres. The lower degree of accuracy is due to the lower quality of the picture. Nevertheless, the maximum of the error value is located in the lower part of the picture, which represents the flat area (around 7,000 metres); terraced areas are located where the error value is minor (8.9 metres).

6 Carta degli Stati di S. M. Sarda in Terraferma, 1:9450, Corpo di Stato Maggiore dell’Esercito Sardo, 1827– 1833, sheet Levanto 20. Current aerial photographs are at website of Regione Liguria.

7 The calculated average error of the georeferencing is around 40 metres. Nevertheless, around the town the error values are less than 7 metres, while in the most distant cliffs the values are more than 500 metres.

8 Both photographs are at websites that commemorate the disaster.

9 Aerial photos of 1988–89 are at the Geoportale Nazionale of Italian Ministry of Environment. (http://www.pcn.minambiente.it/geoportal); https//www.lavocedelnordest.eu/alluvione.

10 In this case, the calculated average error is around 50 metres. The upper part of the picture have calculated error values of more than 700 metres, while the central part has higher precision (9.2 metres error value).

11 In this case, the calculated average error is around 50 metres. The upper part of the picture have calculated error values of more than 700 metres, while the central part has higher precision (9.2 metres error value).