Thin out Height Points

Digital terrain models often consist of a large number of height points or contour lines, unnecessary in noise modeling. As for each triangulated contour and for each section of the entered contour lines it has to be checked within the calculation whether it intersects with each sound ray, this may lead to unnecessarily long computation times. Therefore, it is useful to delete height points based on a specified accuracy of the height z.

The command Thin out Height Points from the Extras menu deletes height points from the actual file. The procedure applied in CadnaA considers with each iteration step the entire terrain model. The user specifies the desired upper limit of the z-difference of each deleted point and the finally resulting simplified terrain model. The simplified terrain model deviates from the original model by the maximum tolerance specified.

Thin out Height Points, Multifile

Thin out height points can also be done before importing height points. To this end, select the command Thin out Height Points - Multifile on the Extras menu. Enter - as before - a height tolerance. After click on OK an import dialog is displayed enabling to select several ASCII files. When confirmed, new files in which the height points are thinned are written with the extension *.mod. Afterwards these files can be imported via the file type ASCII-Objects (see ASCII-Objects).