Doug Murphy
Equipment provided by Leica Geosystems has been integral to the comprehensive 3D surveying of Istanbul, which was mandated as part of its cultural preservation by UNESCO.
Large portions of the Turkish city were designated as protected areas by the UN’s heritage body in 2003. All development in those areas was stopped until a highly accurate, as-built 3D city model could be created for the city’s planning commission.
The scale of the modeling and the speed with which it needed to be completed saw it become the largest terrestrial scanning project ever undertaken.
Over 18 months, 120 field and office staff, using five Leica Geosystems HDS scanners – including one in mobile mode – surveyed 1,500 hectares of the city. This area broke down into 400 kilometres of city streets, 5.5 million square metres of facades, and 48,000 buildings, of which 11,000 had great historic importance.
Four short-range, Leica HDS phase-based scanners – the HDS4500 models – on tripods were used, working from control points set by total stations. Leica Geosystems’ versatile, high accuracy time-of-flight HDS3000 scanner was used for particularly intricate and important cultural landmarks, such as the Süleymaniye mosque and its 76-metre minaret and 55-metre dome.
After the data was collected, it was geo-referenced in Leica Cyclone Register software, before 3D wire frame models were created and combined with high resolution photographs, to create a finished product with an incredible 2-3 centimetre overall accuracy.