Skip to content

Scanning into a Table

The number of buildings within height intervals shall be evaluated using a table.

Example

Path: Examples\Extras\SmallCity04.cna

Open the file "SmallCity04.cna" and then the dialog Object-Scan on the Grid menu. Select the object type „Building“ and the „Action/Sum into Table“.

The „Formula for Summation“ is:

iif((int_lo<=HA)*(HA<int_hi), 1, 0)

By the operator „iif“ an IF-THEN-ELSE structure is defined. The condition consists of two parts:

  • part 1: int_lo<=HA: The condition is met if the lower interval limit is smaller than the building height.
  • part 2: HA<int_hi: This condition is met if the building height is smaller than the upper interval limit.

When a conditions is met, the logical result value is 1 (TRUE), otherwise 0 (FALSE). In order to consider a building on summation, either conditions must be met at the same time (THEN=). The resulting product from the two conditions is 1 (TRUE) only when both parts are true. If the product is <>1 (FALSE) the building will not be counted (ELSE=0).

The „Formula for Total“ is the sum (sum).

Click on the button „Table“. On this table, the interval limits are defined as required. Additional rows can be inserted by pressing the INS key or via the table’s context menu. Enter figures for the interval limits on the columns „min - max“.

Example when evaluating buildings heights

Close the table by OK and also close the dialog Object-Scan by OK to execute the evaluation. Finally, the result is displayed on the table showing the scanning result for the first evaluation parameter in intervals of 2 m.