Ridracoli Dam Survey with Radio-controlled Drone

    Bagno di Romagna - Santa Sofia, Forlì-Cesena, Italy

Project Summary


Completed in 1982, Ridracoli Dam provides drinking water for 48 municipalities in the Emilia-Romagna region of Northern Italy. Periodic surveys contribute data for modeling static and dynamic behavior of the dam to predict deterioration and plan preventive maintenance. In this EUR 23,000 project, the owner of the dam, Romagna Acque, worked with ITALDRON and the University of Perugia to verify the accuracy of unmanned aerial vehicle (UAV) photogrammetry compared to terrestrial LiDAR survey methods.


To provide baseline data, the team performed a topographic survey of the dam and ancillary structures using total station, GPS station, and terrestrial laser scanner. They also placed 175 targets to delineate the aerial survey area. ITALDRON sent remotely piloted aircraft systems (RPAS) on 19 flights to capture 4,600 images, then used ContextCapture’s structure-from-motion (SfM) function to reconstruct the dam geometry. Bentley’s 3D reality modeling software generated dense point clouds and 3D mesh models of the dam body and ancillary buildings.


Compared to the traditional survey results, the UAV survey data exceeded expectations. The accuracy of UAV photogrammetry not only compared favorably to terrestrial LiDAR but also had the advantage of providing better coverage at a lower cost. The innovative technique provided an economical solution for acquiring 3D data within a short turnaround time. Properly calibrated and updated, the resulting model will provide better insight into the dam’s response to environmental conditions, especially earthquakes.


Bentley’s ContextCapture software produced highly detailed 3D reality models of the existing infrastructure using photos taken with ordinary cameras. The SfM imaging technique aligned the 2D photographic images of the dam and ancillary buildings in a 3D geo-referenced space to create 3D models of the structures. Validating the results against known design geometry proved that the technique delivered an accurate, realistic representation of the dam and ancillary buildings.

Project Playbook: ContextCapture

  • Ridracoli Dam is a 103.5-meter-high, 432-meter-wide double-curved, arch-gravity structure that retains 33 million cubic meters of water.
  • UAV photogrammetry proved to be a low-cost source of accurate 3D data for modeling and preventive maintenance of Ridracoli Dam.
  • The UAV data was typically accurate within 2 centimeters and sometimes within less than 1 centimeter.
  • ITALDRON calibrated the reality model with material properties, and assigned static and dynamic loads for realistic forecasting.
  • “The synergy between the use of unmanned aerial systems and ContextCapture produces an ideal and efficient combination for capturing and returning data in 3D."

    Tommaso Solfrini CEO ITALDRON