VALIDATING PHOTOGRAMMETRIC ORIENTATION STEPS BY THE USE OF RELEVANT THEORETICAL MODELS. IMPLEMENTATION IN THE "ARPENTEUR" FRAMEWORK

The new advance in photogrammetry using the automatic procedures such as the famous algorithm which was proposed by David Lowe (Lowe, 2004) features descriptors and matching (SIFT) and then the recent development of external orientation (Nister (Stewenius et alii, 2006) or Snavely (Snavely et alii, 2010)) have changed drastically the way of measuring space with photogrammetry. The complexity of the process and the huge quantity of processed data (thousands of photographs) makes difficult validating the different process steps. We propose in this paper several theoretical model generation methods in order to validate the complete photogrammetric orientation process. A theoretical photogrammetric model generation has been developed in order to produce photographs, photo orientation, 3D points and 2D observations according to some defined camera and a parametric photograph distribution in the scene. In addition the use of synthesis image software generation as POV-Ray allow us to generate set of photographs with pre-computed internal and external orientation in order to check the whole pipeline from feature extraction to Photographs External Orientation. We apply this model generation approach to several typical geometry of photogrammetric scene, stereo, parallel triplet, parallel strip and convergent models

Breakdown of the electron-spin motion upon reflection at metal-organic or metal-carbon interfaces

Spin-polarized electron scattering experiments on different metal-organic and metal-carbon interfaces are performed. A completely unexpected behavior of the spin-motion angles as well as of related quantities as a function of the organic layer or carbon coverage is observed. In fact, by deposition of organic molecules or carbon onto ferromagnetic as well as nonmagnetic metal surfaces in the submonolayer thickness range, the electron reflection amplitude, i.e., both the reflectivity and the reflection phase, become spin independent. Our findings show that this behavior is a very general phenomenon which is independent of the electron energy and the choice of the metal as well as of the organic molecules and thus does not depend on the choice of the specific interface