Grid Evaluation
The grid evaluation features to compare grids based on a numerical expression. Thus, grid results representing different planning scenarios can be numerically assessed and evaluated.
Note
In the meantime, the grid evaluation is a historical CadnaA feature since the same functionality - but offering much greater flexibility - is achieved by the object scan (see Object-Scan).
Dialog options
box „Name“
Enter the designation of the valuation operation here. This name will be saved on the „Evaluation“ list after clicking OK.
List „Evaluation“
Select a location where to save a new evaluation to. Click an existing evaluation to load this operation.
Decimals
decimals (default: 0)
Input Box „Expression“
Enter a numerical expression being used for evaluation of „Day“ (evaluation parameter LP1) and „Night“ (evaluation parameter LP2). The evaluation occurs just for the active (i.e. the selected) variant.
Option „Special Expression for Night time“
Activating this option enables to enter a distinct expression for „Night“ (evaluation parameter LP2).
The following variables are available within an expression:
| Variable | Explanation |
| r0 | value (level) at a grid point (Day LP1, Night LP2) |
| r01..r04 | value (level) for evaluation parameters LP1..LP4 (grids r01..r04) |
| fl | area of a grid element in m2 |
| na | limiting value |
| naein | population density in inhabitants/km2 |
| nages | limiting value from all noise types together |
| naind | limiting value from industry |
| nastr | limiting value from road traffic |
| nasch | limiting value from railway |
| naflg | limiting value from air traffic |
| naog | grid point in area of land us, yes/ |
| nagfz | floor space ratio FSR |
| namiete | rental rate/m²/a |
| namind | rental abatement (in monetary unit, by increase of the noise level by 1 dB), e.g. 1% percent abatement of rent per 1 dB (according to BUWAL) |
All commonly available operators can be used (see Chapter 5 - Operators & Functions in the CadnaA manual „Attributes, Variables, and Keywords“).
Double Arrow (>>)
Via the double arrow (>>) available variables and predefined expressions can be selected.
Examples for expressions
| Expression | calculates ... |
| 1 | number of raster elements |
| fl | total raster area |
| naein*fl/1e6 | number of inhabitants in all areas of designated land use |
| iif(r0>=65,naein*fl/1e6,0) | number of inhabitants subject to levels of more than 65 dB |
| iif(r0>=nastr,naein*fl/1e6,0) | number of inhabitants subject to excess road noise |
| max(naein*fl/1e6*r0,0) | the above-mentioned value of noise impact, if applied to the conflict maps |
| iif((r0<Lo)*(r0>Lu),fl,0) | qm-area of a certain level(Lo = upper level, Lu = lower level) |
Button „Calculate“
Clicking the button „Calculate“ toggles the calculation for „Day“ (evaluation parameter LP1) and „Night“ (evaluation parameter L2) displaying the results in boxes „Day/Night“.