the requirements

An understanding of the paving configuration in plan and elevation is essential when high tides occur, both to guarantee pedestrian circulation, and to predict the damage that could be caused by flooding.
The model of paving used in Venice through the year 2010 was based on a database continuously updated thanks to the surveys completed to develop integrated projects for the maintenance of the city. But this led to a collection of heterogeneous and composite information in terms of density, accuracy and reliability, which made it possible to develop an elevation model of the city discretized at an average of only 10 cm.
Almost twenty years after the last major comprehensive campaign to survey the city of Venice, the model often proved inaccurate due to the low density of the source data and had little significance given the large interval of discretization. On the basis of this database it would not, however, have meant much to discretize the model at elevation intervals of less than 10 cm. The use of this reference to predict the consequences of high water in Venice often led to errors in the evaluation of pedestrian circulation routes in relation to the tide level, the length of the segments for which raised walkways would be required ( es1, es2 ) and the level at which private building thresholds would be flooded. At the same time, it would have meant little to discretize the model at elevation intervals of less than 10cm on the basis of this data base.
Ascertainment of the need to rely on the support of a more detailed tool led to the adoption of Ramses, a topographic survey with more homogeneous precision (1cm in elevation and 2cm in plan) and methods of implementation, and a grid with far greater density (2500 points to the meter and square meter) which makes it possible to generate a more precise three-dimensional model of contour lines, discretized at 1 cm. Thus, Ramses makes it possible to reduce errors by a considerable margin in the assessment of pedestrian circulation conditions, in the estimation of raised walkway routes and the flooding level of building thresholds, in relation to tide level.