Introduction > The data

Before you can produce acoustic maps, it is necessary to integrate the topographical and geometric data that defines the relief, buildings, land use, acoustic protection (acoustic barriers, mounds and banks) and the sources (road, rail or industrial). Physical data, such as the type of land use, characteristics of materials, characteristics linked to sources (traffic flow, speeds, surfaces, etc.) must also be set. When all the data is integrated and structured, you obtain a MithraSIG Model.

Development of MithraSIG Model is based on the following data:

•The ground (points, 3D lines and contours).

•The buildings.

•Land use.

•Acoustic protection (noise barriers, retaining walls, mounds, banks).

•The sources:

oRoad sources.

oRail sources.

oIndustrial sources (punctual, linear, in facade, surface/volumic).

Calculation receivers can also be positioned to obtain, after simulation, the sound level at these predefined points.

The model is never fixed, it is possible to make it evolve by adding objects or modifying existing ones. All this data can come from different sources, in different forms and in different formats.

MithraSIG offers all the tools of manual creation of objects, but above all offers the tools of integration and conversion of existing data in order to transform them into data usable by the simulation engine.

Possible input formats

•Format vector: DXF, DWG, DGN, MIF/MID, TAB, SHP, GML3, etc.

•Format raster: BMP, JPEG2000, TIFF, GeoTIFF, ECW, MrSID, ASC, etc.

Types of input data usable by MithraSIG

The table below describes the expected geometries and what they should represent, as well as any expected attributes:

Creation of MithraSIG objects	Expected input geometries	How is it used in MithraSIG?
Ground	Point Line Grid	3D data: x,y,z values are used to create the ground. 2D data: x,y values are used, z value must be present as attributes. Without z, the ground will be "flat".
Mounds Banks	Line	These lines must represent the top of the object (ridge line). Data can be in 3D (x,y,z) or in 2D if the z is an attributes.
Buildings	Closed line Polygon	3D data: z must represent the top of the roof and the z on the ground sol. The height will be calculated according to the DTM. 2D data: one or several attributes can be used for the calculation of the height (building height, floor numbers, z of the roof).
Land use	Polygon
Noise barriers Retaining walls	Line	3D data: z must represent the top or the bottom of the wall, the ground will be modified according to the wall. 2D data: the line will be draped on the DTM.
Road sources Railway sources	Line	The lines must represent the axis of the road or the railway (if possible). 3D data: during integration, the axis will be predominant on the ground. The DTM will be modified according to the platforms of the sources deployed. 2D data: during integration, the axis will be draped on the DTM.
Punctual industrial sources	Point

The linear, in facade or volumic/surface industrial sources cannot be integrated from input data. The XML integration is possible when the structure of the XML sources is the one expected by MithraSIG.