Talks and Poster Presentations (with Proceedings-Entry):
H. Kager, M. Rickenbacher, A. Roncat:
"The Geometry of the "Prospect Geometrique" by Micheli Du Crest (1754) - a Quantitative Analysis Within a Hybrid Least-Squares Adustment Framework";
Talk: 16th International Conference on Geometry and Graphics (ICGG 2014),
- 2014-08-08; in: "Proceedings of the 16th International Conference on Geometry and Graphics",
H. Schröcker, M. Husty (ed.);
Innsbruck University Press,
The "Prospect Geometrique" by Jacques-Barth´elemy Micheli du Crest (1690-1766) is the oldest panorama visualization of the Alps with a scientific background. Its creator was a remarkable figure in Swiss history: He studied physics, astronomy, geodesy, and cartography in France and invented a temperature scale which was in use until the 19th century. On the other side, his political activities led to a sentence to death in absence, later transformed into a life sentence which he spent mostly in Aarburg castle (canton of Aargau, Switzerland). During his imprisonment, he developed a concept of land survey and realized the most possible in his situation with primitive instruments: the Prospect Geometrique, i.e. a central perspective surveying of his field of view mapped onto a circular cylinder with vertical axis. This technique was once considered as photogrammetry without photographs by the renowned Swiss cartographer E. Imhof.
The term Prospect used by Micheli means the correct geometric representation of the landscape from the observer´s viewpoint. A first numerical investigation of its "correctness" was conducted in 1995  and later refined in 2012 . While the referenced publications have a more cartographic scope, this paper is intended as a sequel to the latter, focusing on the geometry and stochastics for analysing the Prospect thoroughly in a hybrid adjustment approach by least squares. Several input categories for the adjustment have been considered: (a) the upper and lower scale bars for azimuth and (b) left and right scale bars for elevation given on the outlines of the Prospect (see facsimile in Figure 4) and (c) control points identifiable in contemporary official geodetic maps. The core issue of this study was to determine how exact Micheli could construct the Prospect, based upon the determination of the actual projection centre, the calibration of the radius and orientation of the projection cylinder and further a potential exaggeration of the elevation scale.
Photogrammetry, Central Perspective, Map Projection, Adjustment by Least Squares
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