Geometrical characterization of roof timbers in S.Lorenzo church (Tenno, Italy) using close range photogrammetry

For the conservation of load bearing timber structures in historical buildings, geometrical and material characterization of each single structural timber element is a preliminary requirement, for safety evaluation and intervention design. The paper is focused on the application of close range photogrammetry for the geometrical characterization of the timber roof in the porch of St. Lorenzo church in Tenno (Italy, XII century). Multi-resolution data were acquired using two different non-metric cameras. Photogrammetric models were used for high-definition representation of both geometrical and textural features of the structural elements. In particular, three-dimensional metric models were built, for to analyse irregular geometry of the timber elements. From metric images of the element faces, detailed maps of visible wood strength affecting characteristics were produced. Image analysis techniques were then applied for the automatic/semi-automatic detection of the relevant features, to support metric analysis of both natural and pathological visible characteristic of the wood material. Information gathered from geometrical characterization can be used for further structural computations, taking into account variability of geometric and material characteristics in each structural member.