### Surfaces properties window |  |

When a scene is activated and shown using a parallel projection in the main view pane, you can select one or more faces and open the surfaces properties window by using mouse right-clic that shows the short cut actions menu and selecting the Surfaces properties item.

The surfaces properties available in this version :

Use vegetation mask: | If you check this field, the selected surfaces are considered as vegetal surfaces (i.e. faces of tree volumes). The opacity value is specified for each month (mean value) in the Settings/Solar Access panel. The diffusion value is set to 0.
Opacity [%]: | Amount of direct radiation energy stopped by the surface (in %).
Diffusion [%]: | Amount of direct radiation energy transformed into diffused energy and transmitted throwgh the surface (in %).
Reflection [%]: | Coefficient of energy reflected by the surface (in %). The reflection calculated by TownScope is only the diffused one. No specular reflection is computed. In the following table shows the reflection coefficient for some types of surfaces [R. DOGNIAUX, Royal Institute of Meterology, Belgium, J. Teller LEMA-University of Liege-Belgium] Roads Asphalt : 0.05-0.2 Walls Concrete : 0.10-0.35 Brick/Stone : 0.20-0.40 Clear brick : 0.30-0.50 Red brick : 0.20-0.30 White marble : 0.55 Limestone : 0.30-0.55 Aluminum sheet : 0.85 Roofing Asphalt : 0.10-0.15 Gravel : 0.08-0.18 Tile : 0.10-0.35 Corrugated iron : 0.10-0.16 Painting White, pastel : 0.50-0.90 Red, brown, gray : 0.20-0.35 Black : 0.02-0.15 Other Clear sand : 0.40-0.60 Dry grass : 0.30 Clean snow : 0.60-0.90 Water surface (pond) : 0.70
Emissivity [%]: | Amout of the long-wave energy emission in (%). It is used only in comfort evaluation.
Surface T. [deg C]: | This parameter is used for the long-wave radiation calculation (only used in comfort evaluation).
Color: | Set the surface color (in hidden views). This may be useful if you wish to highlight some surfaces.

The properties values can be stored in the items list on the left side of the window. The tool bar right to this list is used to manage the stored properties items.

- By clicking on the double left-arrow (<<) tool, you will be asked to give the name of edited properties. This name will appear in the left list.
- A double-clic on one item in the list, or using the single right-arrow(>) tool, the first selected item will be copied to fields on the right.
- The tool deletes all the selected items in the list.

All the items in the list are saved in an independant file and will be available for the next sessions.

Important notes :
- To save the properties applied to the surfaces of any loaded scene, you have to export the scene in a .URB file format as it is the only format supporting this option.
- When vegetation surfaces are defined in the scene, the solar access and the comfort calculations are longer. The vegetation surfaces are considered separately for each calculated day, and so requires extra calculations.
- For direct energy calculation, the total mask of a surface is the sum of its opacity and its diffusion factors. For diffused energy calculation, only the opacity value in considered. The sum of masks is defined as follows : M = 1 - (1 - M1) * (1 - M2)
- In Solar energy calculations (direct and diffused), often, many surfaces can obstruct the radiation at the same time. Therefore the total radiation mask at a specific hour is defined by the sum of masks of all the obstructing surfaces.
- The properties are applied to surfaces. If the scene contains volumes representing vegetal entities (i.e. trees), and if you apply an opacity value to all the faces of one volume, than the volume's opacity will be less than wanted. If the volume is convex and the required volume's opacity is Mv than you have to give an opacity value of 1 - sqrt(Mv) to all of its faces.

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