3D modeling for documentation, restoration and determination of the area of Dolatabad Castle in Qom using UAV images

Cultural heritage is precious and irreplaceable capital that the importance of documentation in preservation and conservation of this heritages is clear to every person. The production of a digital model and 3D documentation of these heritages due to the shortcomings of traditional methods, is significantly expanding. The development of sensors, data collection methods, and the promotion of 3D visualization techniques, along with the presentation of diverse algorithms in computer vision, have had a tremendous role in 3D documentation But the vacancy of a comprehensive and integrated study that evaluates all three-dimensional documentary disciplines and presents a suitable process to achieve a controlled output is well felt. Over the past years, there have been papers on documentation of cultural heritages with a variety of tools and methods that, after reviewing them from 2000 to 2018, methods have been evaluated for collecting 3D data, visualization, software and modeling algorithms. active and passive methods in 3D modeling have been compared with 8 criteria; time, quality, time flexibility, cost, data density, geometric precision, performance in large locations and noise levels. It should be noted that selecting the appropriate method according to the objective and conditions of the region is possible. In the visualization section, standards and templates have been compared with eight criteria; geometry, based on XML, topology, building texture, showing complications,semantic information, descriptive information, web content, and georeferencing. In the software section, open source, commercial, and cloud computing software has also been reviewed. Due to the advantages and limitations of UAV photogrammetry mentioned earlier, flight planning for UAV photogrammetry projects and 3D documentation with it is more complex and influenced by several factors, so in UAV photogrammetry project, all aspects must be considered. the studied area is Dolatabad historical castle in Dolatabad of Qom Province in the center of Iran. This village castle is located in the west of Anar Bar (Qamroud) river, which, of course, has decreased with the construction of 15 Khordad dam. Apparently, in the past, this castle was one of the castles of the main villages of this region, around which crops such as wheat, barley, melon, and sunflower were cultivated, but today only wheat and barley are produced. Dolatabad castle with a longitude of "656´34 ° 49 and latitude" of 922´19 ° 32 and an altitude of 1547 meters above sea level. dimensions of area is more than 100000. this castle belongs to the Safavid era and has its own unique architecture but unfortunately it has been damaged over time. The most important pathological factors that have caused damage to the castle in past years are two important and influential factors of natural and human damage. after the 3D documentation of the castle and its restoration, using the 3D model obtained to determine the privacy of the fortress, and the protective, intuitive and functional boundaries are examined and the proposed privacy is provided and the boundary of the area is determined and the necessary factors for the Cadastre of Cultural Heritage are provided. Following the three-dimensional documentation of the Dolatabad historical castle and restoration and determination of the boundary, the necessary pre-requisites for registering the fortress as a national heritage were prepared and the Dolatabad historical castle with a registration number of 30,533 as a national heritages of Iran was recorded. A digital model is also made out of the castle, which can be used to create virtual museums or to rebuild and repair of castle again.