Photogrammetric Evaluation Options of an Ancient Monument for Different Survey Levels

Abstract

Recently, for the purpose of data management, more advanced digital data are required for different survey levels of irregular ancient monuments. For irregularly formed monuments and amorphous surfaces, 2D photographs and 2D measured surveys are inadequate to illustrate the condition of the building for condition reports or relationships between components and materials for structural surveys and conservation decisions, especially in archeological remains. However, image-based documentation techniques can be used as simple tools for different types of surveys due to their ease of use and fast and economical properties. Therefore, the aim of the study is to test multi-image photogrammetric documentation techniques to improve and standardize visual data appending condition reports and further detailed reports regarding conservation of irregular ancient monuments.In the literature, there are many studies about image-based documentation techniques. However, the innovation of the study is to provide an improvement of the pipeline of condition and structural surveys of irregular ancient monuments by making use of photogrammetric techniques.In order to measure the effects of the relationship between the type of documentation technique and survey level on the photogrammetric documentation process of an ancient monument, a series of experiments were designed and the results compared. For this purpose, automated image orientation packages Autodesk 123D and Photosynth and manual image orientation package Tgi3D were evaluated in terms of process time, reliability and level of detail to identify appropriate techniques for different survey levels.This study proved that documentation of the structural characteristics of ancient monuments can be achieved successfully with the Tgi3D package, which has manual workflows. The documentation results might support structural intervention decisions. The 3D models based on automatic workflows might support a preliminary condition survey, since their production takes a relatively short time and scaled models are acceptable for identifying mass characteristics.