Articles

Croatia: Zadar City walls
01Documenting the City walls
Feasibility of a defined methodology for gaining a trademark of cultural tourism destination HERA will be tested on Zadar County's territory by implementing two pilot projects: one being the integration of Zadar city walls into the route of cultural tourism and the other  being  setting up of a visitor center in Mali Arsenal.
A pre-requisite for investing in these pilot projects is elaborating the project documentation for the city walls, particularly for Mali Arsenal, Gate of St. Krševan and city walls in the Passage of Emperor Augustus, using 3D laser scanning.
 
Zadar city walls, preserved only on the southeastern and on the northeastern side of Old town, were built from 1537 till the end of the 16th century, as a unique project of Michele and Giangirolamo Sanmicheli. This renaissance fortification belt was built as a system of Bastion fortresses with connecting walls (cortinas).
The total area of described city walls (including a medieval wall with a tower beside Five Wells Square (Trg pet bunara) and the remains of the medieval city wall between City Market (Gradska pijaca) and Gate of St. Krševan (Vrata svetog Krševana)) amounts to 15,720 m2.
Mali Arsenal is the entry part of a castle, which was, since the 13th century until today, located at the entrance to the harbor, and is its only part preserved to this day. It is a vaulted ground floor house 7x12 m large, which stood above the moat and included a drawbridge for horsemen and pedestrians.
0203
Gate of St. Krševan was open in the city walls in the 1573. Works foreseen in the project include restoration and conservation of Gate itself from both sides: from the land side, towards the city, an integral part of the Gate are the remains of an ancient monumental gate, with dedicatory plate and rounded gable with the city coat of arms. From the sea side, along with the Lion of St Mark, two carved boys, built as spolias, are holding coats of arms. From the land side, Gate is 9.5 m high and 4.8 m wide and from the sea side its height is 7 m and its width is 3.3 m.
0405
For these two sites a complete documentation of the existing situation was elaborated in June and July 2014, based on the 3D model gained by 3D laser scanning. Architectural shot of each site contains individual floor plans and cross sections with detailed views of inner and outer parts. A 3D measurable model was gained by objects scanning in the form of a cloud of dots where each dot is determined in a coordinate system with high precision. Such a model is used for CAD drafting of the current situation for the restoration project, conservation and related works necessary for the preservation of the object. The advantage of 3D models is the possibility of further analysis, processing and testing without the need to repeat the field work. Also, this unique model can be digitally stored forever and processed as required. 3D laser scanning with these innovative solutions plays a major role in projects that deal with preservation of cultural heritage.
Rendering is performed in a specialized CAD application program that provides highly advanced photogrammetric methods of data connectivity, 3D laser scanning and terrestrial photogrammetry. Additional data processing was done in Autodesk AutoCAD software application.
As far as the location of Passage of Emperor Augustus is concerned, complete documentation of an existing condition of the part of the city walls (the city gate from early antiquity, late antiquity city walls with remains of a tower and a tower from the middle ages) was elaborated in August 15 2014.  In order to perform 3D laser scanning of the area, a few existing wild bushes have been removed from the Passage of Emperor Augustus, and after the tourist season, protective archaeological research and conservation of the remains will follow.
The main risk in documenting the city walls was organizing the scanning of above mentioned three locations during the tourist season. The total value of finished and future works on these three locations and scanning of the entire city walls will approximately be 450.000 EUR.
For the complete fortification system of Zadar city walls, documentation will be delivered till 7 February 2015 and will contain geodetic base in a 1:200 scale, an architectural shot of the existing condition with all schemes and ground plans in a 1:200 scale, cross sections and facades in a 1:50 scale and orthophoto representation of the surface of the city walls - complete from the outer side (towards the sea and the land) and, where possible, also from the inner side (towards the city) – in a 1:50 scale. Also, all available spaces inside the ramparts will be laser scanned in a 1:50 scale and a technical description of the current condition will be made.