Define Material Properties for Objects in the Database

Material Concept

The consideration of the different material properties of the buildings/walls has a significant influence to the results of the wave propagation models. Therefore, for each object (building in urban databases and wall/subdivision in indoor databases), the corresponding material properties should be assigned.

The handling of the different materials in a so-called material catalogue will be explained in the following. The consideration of different materials is even more important for the indoor scenarios (as there is a large spectrum of wall properties concerning thickness and material) while for urban databases in most cases the same default material for all buildings is utilized (due to lack of information concerning the individual building materials).

Material Catalogue

In order to allow an easy handling of the different materials used within an indoor or urban building database the materials are organised is a so called material catalogue, which can be displayed by the menu item Edit > Materials used in database or by clicking on the button, see Figure 1.

In the Material Catalogue dialog the different materials used in the loaded database are organised. This means for indoor environments the materials of the walls, floors, ceilings, and also of the subdivisions (doors, windows) must be entered, while for urban scenarios the materials of different building types and for vegetation can be handled.

With the checkbox Show color of materials in table, the color of an each material is shown in the table. By clicking on the column headers, the table will be sorted with respect to the selected column. In the third column the type of material is shown (material, vegetation, and furniture) and in the last column the number of objects with the corresponding material is displayed.

Figure 1. The Material Catalogue dialog.

Material properties can be imported from other vector databases by using the button Import and can be exported to user-defined material catalogues with the button Export. Using the button Replace existing materials in the list can be replaced with material properties from another file.

In the following, the user is guided through the steps of specifying individual materials. By clicking on Add material or Edit (if a material is already selected) the dialog for the definition of material properties appears, see Figure 2. For each material the name and the corresponding thickness should be defined. For urban scenarios the thickness has no influence at all, while for indoor environments the thickness can be considered for the display of the database in 2D mode (if the corresponding option within Edit > Settings is chosen). So for both scenarios the transmission properties of the walls are not influenced by the thickness as the transmission loss is specified as a separate value (independent of the thickness). Besides name and thickness, a color can be defined for each material which is used for the graphical visualisation of the database within WallMan. Additionally, it can be chosen, whether to have the whole object filled with this color (only possible when option Fill Objects is enabled in the Settings > Local Settings menu item) or just the wire frame of the object. This might be important when verifying the correct assignment of materials by using the 3D-view of the building database. It is recommended not to utilize the red color, as this color is already used by WallMan to mark selected objects.

Figure 2. The Material Properties dialog.

When working with indoor databases it is possible to enable or disable propagation phenomena like diffraction, reflection, transmission and scattering for each material. Additionally the user can decide by using the corresponding check box if the current material can be calibrated or not.

Electrical Properties

Because the electrical properties of the materials depend on the frequency, individual electrical properties for different frequency bands can be defined. For each material as many frequency bands as required are possible. The definition/modification of the electrical properties is done by clicking on Add/Edit in the Material Properties dialog, see Figure 2. Then the following window will appear representing the Frequency Depending Material Properties, see Figure 3. The individual parameters of the material properties for the defined frequency are entered here.

Before starting the propagation prediction in ProMan the user can decide which kind of interaction model for the determination of the interaction losses due to reflection, diffraction, transmission and scattering should be used. Different material properties are available for the empirical and the deterministic (physical) interaction model. Not all propagation models are able to support all kinds of propagation phenomena. More information about this can be found in the ProMan user manual, for example, scattering is only supported by the 3D Intelligent Ray Tracing.

Figure 3. The Frequency Dependent Material Properties dialog.
Among the WinProp examples in the installation directory, a Global Material Catalogue can be found. In order to specify the values of the parameters for the selected material the Global Material Catalogue can be imported.

Figure 4. The Import material from catalogue dialog.

From the Global Material Catalogue the required material can be selected. The Global Material Catalogue includes materials commonly used with different thickness’s. For user convenience it is possible to extend and modify this Global Material Catalogue either by adding new materials or by changing already existing ones. The user can also replace an existing material in his local Material Catalogue by a material from the Global Material Catalogue.

After definition of the electrical properties of the selected material for a special frequency, this step can be repeated for other frequencies (if required). In this context it is important to mention that for the prediction within ProMan always the electrical properties of the nearest frequency band will be considered automatically according to the defined frequency within ProMan.

It is not required to define the different materials at the very beginning before converting or entering new objects. By just clicking OK in the window presented in Figure 5 at the very beginning all objects are initialised with the default values. The individual material properties can be defined when the different objects (for example, walls, subdivisions) are created. However, it is recommended to establish the Material Catalogue at the beginning, because then the assignment of the material properties to the different objects will be easier. Nevertheless it is also possible to extend / modify the Material Catalogue at a later step during the generation of the building database.

Figure 5. The Default Values for New Objects dialog.