Hyderabad-based drone startup Terra Drone India successfully completed multi-sensor, multi-platform scanning of internationally recognized landmark Charminar on Thursday, June 13, 2019.
Built in 1591, the monument, which is often called as ‘Arc de Triomphe of the East’, suffered a major damage in May 2019 when a huge chunk of lime-plaster broke and fell from its south-west minaret.
This incident made the digital preservation of Charminar extremely time-sensitive and important for the Indian government, and the IT department of Telangana state invited Terra Drone India to provide innovative technological solutions for the digital preservation of Charminar.
Digital preservation of a historic monument like the Charminar is a progressive way of ensuring that heritage is preserved. It would involve 3D modelling and documentation of the monument, a technique which has garnered attention in the recent years. Also, it would enable accurate preservation of the monument. Digital preservation of the document would also ensure that the monument is protected and similar incidents are not repeated.
On Thursday, Terra Drone India scanned and surveyed the damaged minaret using multiple technologies. The solution-set included:
1. Air Gap Measurement through Ultrasonic Pulse Velocity Testing technique: The Archaeological Survey of India, the government body responsible for archaeological research and the conservation and preservation of cultural monuments in the country, had expressed concern regarding the increasing air gap between the plaster and the actual facade of Charminar. Terra Drone India carried out Ultrasonic Pulse Velocity Testing, a non-destructive testing technique, to measure the air gaps that have developed in the areas of concern till date.
2. True Color 3D Model Creation using Visual (RGB) Sensor: A high-accuracy Visual (RGB) scan was carried out to maintain a record of the facade, actual color, and any visible cracks or crevices. Through this, a true color 3D model will be created.
3. Thermal Scanning: The scan was conducted to detect differences in temperature between different areas of the monument and identify how the different materials used in the monument are reacting to heat and how they are at risk of damage.
4. LiDAR 3D Profiling and Model Generation using LiDAR: In order to preserve the current existing infrastructural design and layout of the monument for future rebuilding or repair works, a LiDAR survey was carried out to create a high accuracy 3D model, accurate up to the millimetric level.