(VIA MAGNA s.r.o., Vrútky, Slovakia)

Keywords: Čachtice, castle, medieval period, photogrammetry, structure from motion

The Čachtice castle is a coherent ruinal architecture situated on the top of a  limestone peak (375 m) within the Čachtice carstic hills in Male Karpaty mountains between the villages Čachtice and Višňové. Former  frontier  castle served as  a control point on the cross way from the Myjava valley to Váh valley. According to written sources  castle is supposed to have been errected after the year 1260 under the patronage of Kazimir of the Hunt-Poznan house.
In 2012 the project of castle restoration and statical treatment was launched. Restoration works made archeological excavations of the concerned castle parts inevitable. Excavations were limited to specified areas subjected to earthen activities mostly as a part of the masonry statical treatment. During excavations bottom pavement levels of existing architectures as well as architectural fragments of earlier castle building phases were discovered.  Remedation project together with archeological and architectural research continues in 2013.
Prior to the excavation begining basic measurement conducted with GNSS Rtk rover was conducted to obtain point field in national coordinates (S-JTSK). It was applied as an fast and efficient robust low cost method for documentation purposes of 2D and 3D photogrammetry. Prime photogrammetry output were rectified ortophotoplans determined for CAD vectorisation. 3D photogrammetry served extra for georeferenced digital elevation model generation of particular trenches . Photo acquisition was done with unmanned aerial vehicles (AUV), pole areal photography (PAP) and hand handled camera. Data processing was based upon intersection method “Structure from motion” using SW Agisoft Photoscan Pro.