COSTLESS PLATFORM FOR HIGH RESOLUTION STEREOSCOPIC IMAGES OF A HIGH GOTHIC FACADE

In October 2011, the PPMD specialized master's degree students (Photogrammetry, Positionning and Deformation Measurement) of the French ENSG (IGN’s School of Geomatics, the Ecole Nationale des Sciences Géographiques) were asked to come and survey the main facade of the cathedral of Amiens, which is very complex as far as size and decoration are concerned. Although it was first planned to use a lift truck for the image survey, budget considerations and taste for experimentation led the project to other perspectives: images shot from the ground level with a long focal camera will be combined to complementary images shot from what higher galleries are available on the main facade with a wide angle camera fixed on a horizontal 2.5 meter long pole. This heteroclite image survey is being processed by the PPMD master's degree students during this academic year. Among other type of products, 3D point clouds will be calculated on specific parts of the facade with both sources of images. If the proposed device and methodology to get full image coverage of the main facade happen to be fruitful, the image acquisition phase will be completed later by another team. This article focuses on the production of 3D point clouds with wide angle images on the rose of the main facade

CLOSE-RANGE PHOTOGRAMMETRIC TOOLS FOR SMALL 3D ARCHEOLOGICAL OBJECTS

This article will focus on the first experiments carried out for our PHD thesis, which is meant to make the new image-based methods available for archeologists. As a matter of fact, efforts need to be made to find cheap, efficient and user-friendly procedures for image acquisition, data processing and quality control. Among the numerous tasks that archeologists have to face daily is the 3D recording of very small objects. The Apero/MicMac tools were used for the georeferencing and the dense correlation procedures. Relatively standard workflows lead to depth maps, which can be represented either as 3D point clouds or shaded relief images

Orthoimages of the outer walls and towers of the château de Chambord

The château de Chambord is one of the most famous castles in the world as it is an emblem of French Renaissance architecture. It was built at the beginning of the 16th century and has been part of the UNESCO World Heritage list since 1981. The monitoring of such a monument involves the organization and visualization of data sets such as archive documents, survey data, scientific documentation, restoration reports, meteorological data, etc. This process requires the realization of a support for documentation which may be an orthoimage. A photogrammetric survey was recently performed, in the framework of the traditional fieldwork of the students in the PPMD master's degree (Specialized Master’s in Positionning, Photogrammetry and Deformation Measurement) at the French National School of Geographic Sciences (ENSG). High resolution images were taken from the ground level, using two off-the-shelf reflex cameras, equipped with a 35 mm, a 100 mm and a 200 mm focal length lens according to the needs. The MicMac software was used for the bundle adjustment, the georeferencing and the dense correlation procedures, including orthoimage calculation. Added to plane-based orthoimages, cylinder-based orthoimages were generated for the 2D representation of the outer walls of the château de Chambord including façades and towers. Fitting the 2D projection to the mean characteristics of the geometry has a promising documentation potential for GIS applications in heritage studies