Claudio Bozzini

Depuis sa création, la photographie est un moyen simple et immédiat de documenter le paysage. Les photographies obliques terrestres historiques ou actuelles qui documentent les catastrophes naturelles montrent souvent des informations très détaillées et peuvent aujourd'hui être facilement prises avec différents appareils accessibles à tous. Le logiciel, initialement développé au WSL (wsl.ch/monoplotting) et désormais repris par la société image2world GmbH (i2w.ch), permet d'utiliser des photos obliques terrestres ou aériennes individuelles pour cartographier les phénomènes naturels (ainsi que d'autres caractéristiques du paysage) de manière économique et efficace. Des photos ordinaires prises à l'aide d'un smartphone, d'un drone ou d'un hélicoptère deviennent des cartes en 3D disponibles pour les professionnels.
 
Die Fotografie ist seit ihrer Entstehung ein einfaches und unmittelbares Mittel zur Dokumentation der Landschaft. Historische oder aktuelle terrestrische Schrägaufnahmen, die Naturkatastrophen dokumentieren, zeigen oft sehr detaillierte Informationen und können heutzutage mit verschiedenen Geräten von jedermann leicht aufgenommen werden. Die Software, ursprünglich an der WSL entwickelt (wsl.ch/monoplotting) und nun von der Firma image2world GmbH (i2w.ch) übernommen, ermöglicht den Einsatz einzelner terrestrischer oder Luftschrägaufnahmen, um Naturereignisse (und auch andere Landschaftsmerkmale) kostengünstig und effizient zu kartieren. Gewöhnliche Fotos, mit einem Smartphone, einer Drohne oder einem Hubschrauber aufgenommen, werden zu 3D-Karten, die der Fachwelt zur Verfügung stehen.

In this study, we investigate a novel application of the photogrammetric monoplotting technique for assessing wildfires. We demonstrate the use of the software program WSL Monoplotting Tool (MPT) to georeference operational oblique aerial wildfire photographs taken during airtanker response in the early stages of fire growth. We located the position of the fire front in georeferenced pairs of photos from five fires taken 31-118 min apart, and calculated the head fire spread distance and head fire rate of spread (HROS). Our example photos were taken 0.7 to 4.7 km from fire fronts, with camera angles of incidence from -19 to -50° to image centre. Using high quality images with detailed landscape features, it is possible to identify fire front positions with high precision; in our example data, the mean 3D error was 0.533 m and the maximum 3D error for individual fire runs was less than 3 m. This resulted in a maximum HROS error due to monoplotting of only ~0.5%. We then compared HROS estimates with predictions from the Canadian Fire Behavior Prediction System, with differences mainly attributed to model error or uncertainty in weather and fuel inputs. This method can be used to obtain observations to validate fire spread models or create new empirical relationships where databases of such wildfire photos exist. Our initial work suggests that monophotogrammetry can provide reproducible estimates of fire front position, spread distance and rate of spread with high accuracy, and could potentially be used to characterize other fire features such as flame and smoke plume dimensions and spotting.

Historical or present-day oblique terrestrial photographs documenting natural disasters are abundant in archives and may be easily taken nowadays. While in most cases they provide highly informative details, they can hardly be georeferenced, which prevents their systematic use for analyzing and documenting the events and any related signs of damage. In this chapter, we present a monoplotting software program developed at WSL (the WSL Monoplotting Tool) that allows the georeferencing of ordinary individual photographs in order to produce georeferenced vector data by drawing them directly on the photographs and exchanging them with traditional geographic information systems (GIS-Systems). We report on the application of the monoplotting tool on selected study cases of natural events or protection infrastructures in Switzerland.

L’istituto federale svizzero di ricerca per la foresta, la neve e il paesaggio - WSL ha sviluppato un software per rendere operativa la monofotogrammetria nell’ambito delle attività forestali, di gestione e pianificazione territoriale. Questa tecnica, immediata e poco costosa, può risultare molto utile per tecnici e ricercatori perché in grado di sfruttare normali fotografie terrestri per poi applicarle ai sistemi GIS.

While aerial photography and satellite imagery are the usual data sources used in remote sensing, land based oblique photographs can also be used to measure ecological change. By using such historical photographs, the time frame for change detection can be extended into the late 1800s and early 1900s, predating the era of aerial imagery by decades. Recent advancements in computing power have enabled the development of techniques for georeferencing oblique angle photographs. The WSL Monoplotting Tool is a new piece of software that opens the door to analyzing such photographs by allowing for extraction of spatially referenced vector data from oblique photographs. A very large repeat photography collection based on the world's largest systematic collection of historical mountain topographic survey images, the Mountain Legacy Project, contains >6000 high resolution oblique image pairs showing landscape changes in the Rocky Mountains of Alberta between ca. 1900 - today. We used a subset of photographs from this collection to assess the accuracy and utility of the WSL Monoplotting Tool for georeferencing oblique photographs and measuring landscape change. We determined that the tool georeferenced objects to within less than 15 m of their real world 3D spatial location, and the displacement of the geographic center of over 121 control points was less than 3 m from the real world spatial location. Most of the error in individual object placement was due to the angle of viewing incidence with the ground (i.e., low angle/highly oblique angles resulted in greater horizontal error). Simple rules of control point selection are proposed to reduce georeferencing errors. We further demonstrate a method by which raster data can be rapidly extracted from an image pair to measure changes in vegetation cover over time. This new process permits the rapid evaluation of a large number of images to facilitate landscape scale analysis of oblique imagery.

Surface temperature increases since the 1990s have often been associated with an increase in the speed of rock glaciers. Evidence of similar links on the centennial to millennial scale are, however, still lacking due to less focus to date on the medium- and long-term kinematics of these landforms. In order to assess (palaeo)climatic variations in rock glacier kinematics, we analysed the movements of the Stabbio di Largario rock glacier in the southern Swiss Alps using three different timescales. The Schmidt hammer exposure-age dating (SHD) was applied to study long-term kinematics in order to extrapolate the minimal age of the formation of the rock glacier, which may have started its development after the Mid-Holocene climate optimum, and to detect possible accelerations of the horizontal surface velocity during the Medieval Warm Period. Georeferentiation and orthorectification of six historical photographs of the rock glacier taken between ad 1910 and today were analysed using monoplotting to detect the rock glacier displacement on the decennial scale from the end of the Little Ice Age. Finally, differential global positioning system (dGPS) monitoring data available since ad 2009 were used to assess annual and seasonal creep rates of the rock glacier at present. Our results show a link between the periods of increase in mean air temperature on different timescales and variations in rock glacier kinematics and provide important new insights into rock glacier development and evolution on the long-term scale.

Historical or present oblique terrestrial photographs documenting natural disasters are abundant in archives, may be easily shot nowadays, and often depict very informative details. In most cases, however, they can hardly be georeferenced, what prevents a systematic and technical use of such material for analyzing and documenting the disaster-induced damage traces. The monoplotting software developed by the Swiss Federal Institute for Forest, Snow and Landscape Resarch (WSL) in Bellinzona has been conceived to meet these needs and allows georeferencing and orthorectifying ordinary individual photographs in order to produce georeferenced vector data by drawing them directly on the pictures and exchanging them with traditional GIS-Systems. In the present contribution we report on the results of selected applications of the monoplotting tool showing the suitability of the tool for the geographical processing of historical and present natural events, which are difficult to map in the field.

Since its invention in the first half of the nineteenth century, photography has assumed a leading role as a means for documenting the real world. With the improvement of technology, photography developed into photogrammetry, enabling the mapping and georeferencing of landscape elements beginning with stereo photographs. With the introduction of aerial photography, terrestrial oblique photography became obsolete for cartographic purposes and was nearly forgotten by most specialists in photogrammetry. In recent times, the improvement of computing power and the production of high resolution Digital Elevation Models has made the spatial georeferincing of single oblique pictures (monoplotting) more approachable. In this paper, we focus on a new monoplotting tool developed by our research group and we illustrate the basic concept, the solutions implemented and options as well as the results of a case study on land-use and vegetation evolution over a 100-year period. The tool has been conceived to georeference ordinary individual photographs in order to orthorectify the visible landscape or to produce and export map layers (e.g. georeferenced vector data) by drawing them directly on these pictures. The basic requirements of the system are the digital version of the historical picture, the DEM of the depicted landscape, the real-world coordinates of a suitable number of control points unambiguously recognizable on the picture, and – suitable but not mandatory - the real-world coordinates of the precise shooting point and of the centre of the picture.

Grosse Verfügbarkeit von alten Bildern, die viel weiter zurückliegen als die Luftbilder und Satellitenbilder; gute Auflösung und besonderer Reichtum an Landschaftsdetails; einfachere und intuitivere Interpretierbarkeit dank einem für den Mensch gewohnten Blickwinkel: terrestrische einzelne Schrägbilder bieten eine einmalige Gelegenheit für das Studium der Landschaftsentwicklung ab dem 19. Jahrhundert. Die WSL hat seit 2010 eine neue Software entwickelt, welche die Hauptlücken im Gebiet der Monophotogrammetrie schliesst. Die aktuelle Version des Tools besteht bereits aus vielen funktionsfähigen Modulen und erlaubt es, ausgehend aus einigen Passpunkten, die Bilder zu georeferenzieren und als Karten zu benutzen.

Frühe Landschaftsfotografien sind von hohem Wert für Studien über die Landschaftsentwicklung. Die Forschungsgruppe Insubrische Ökosysteme der WSL hat nun eine Software entwickelt, mit der sich die Fotos ins Koordinatensystem einbinden lassen.

Since its invention in the first half of the nineteenth century, photography has assumed a leading role as a means for documenting the real world. With the improvement of technology, photography developed into photogrammetry, enabling the mapping and georeferencing of landscape elements beginning with stereo photographs. With the introduction of aerial photography, terrestrial oblique photography became obsolete for cartographic purposes and was nearly forgotten by most specialists in photogrammetry. This evolution is understandable from a technical point of view, but regrettable from the historical and landscape dynamic perspectives. In fact, although they do not systematically cover all territory, terrestrial photographs date back significantly earlier than aerial photography and are generally rich in landscape-relevant details that are easily interpretable because they coincide with normal human view-points. In recent times, the improvement of computing power and the production of high resolution Digital Elevation Models has made the spatial georeferincing of single oblique pictures (monoplotting) more approachable. To our knowledge, however, no specific user-friendly monoplotting tool has been developed so far. We have therefore developed a new tool specially conceived to georeference ordinary individual photographs and then produce map layers (e.g. georeferenced vector data) by drawing them directly on these pictures. The basic requirements that have to be fed into the system are the digital version of the historical picture, the DEM of the depicted landscape, and the real-world coordinates of a suitable number of control points unambiguously recognizable on the picture. Although not absolutely necessary, the tool naturally performs best if the real-world coordinates of the precise shooting point and of the center of the picture are known as well. In this contribution we will illustrate the present version of the tool and the results of the first study cases we have developed thus far. We will also discuss future developments as well as potential fields of application.

Nel corso dell'Ottocento la tecnica fotografica s'impose come mezzo prodigioso per fissare e documentare a futura memoria ogni aspetto visibile della realtà. Nel secolo successivo si diffuse anche la fotografia aerea che in breve si accaparrò un ruolo preminente per la sua vocazione di tecnica molto efficace al servizio della cartografia. Di conseguenza, la fotografia terrestre si ritrovoò perlopiù accantonata in campo artistico o ricreativo, lasciando alla stereofotogrammetria aerea il ruolo principale quale strumento scientifico di misurazione e documentazione sistematica del paesaggio. Così ai giorni nostri per studiare le trasformazioni del paesaggio si utilizzano soprattutto le foto aeree, le immagini satellitari e il confronto cartografico, ritenendo le fotografie terrestri meno interessanti in quanto difficilmente georeferenziabili e quantificabili. [...]

Erfindung wurde Fotografie in kurzer Zeit extrem populär zur Dokumentation der realen Welt. Die Fortschritte in der Einzelbildauswertung ermöglichten präzise räumliche Messungen und die Kartierung von Landschaftselementen auf der Grundlage von Halbbildpaaren. Mit dem Erfolg der Luftfotografie wurde die kartografische Nutzung von terrestrischen Schrägbildern obsolet. Erdbildmessungen bieten jedoch für die Untersuchung von Landschaftsveränderungen eine Reihe von Vorteilen wie die Ähnlichkeit mit der Perspektive des Menschen, bessere Ergebnisse in Berggebieten, bessere Auflösungsstufen und einen reichhaltigen Bildbestand, der bis ins neunzehnte Jahrhundert zurückzieht. In jüngster Zeit wurde die räumliche Georeferenzierung eines einzelnen terrestrischen Schrägbilds (Monoplotting) dank verbesserter Computerleistungen und der Erstellung von hochauflösenden digitalen Höhenmodellen vereinfacht. Keines der bisher entwickelten Monoplotting-Softwareprogramme überzeugt jedoch in Bezug auf Eigenständigkeit als komplettes Kartografieprogramm, Anspruchslosigkeit im Hinblick auf die erforderlichen Daten und Benutzerfreundlichkeit. Daher haben wir ein neues Tool entwickelt, das ausgehend von gängigen Einzelnbildern Kartenlayer erstellt (z.B. georeferenzierte Vektordaten). Als Basisinformation ist nur das entsprechende DHM erforderlich, gemeinsam mit den Weltkoordinaten einer angemessenen Anzahl von Kontrollpunkten in der dargestellten Landschaft. In diesem Beitrag werden die aktuelle Version des Tools sowie die Ergebnisse der ersten Fallstudien dargestellt, zukünftige Entwicklungen erörtert und Anwendungsfelder aufgezeigt.

In questo breve contributo presentiamo, come ogni anno, alcune attività del gruppo dì ricerca Ecosistemi Insubrici del WSL di Bellinzona. Con la conclusione del 2010 siamo arrivati al 20 anniversario di attività. Questo traguardo verrà sottolineato con una giornata delle porte aperte che avrà luogo sabato 16 aprile 2011.