Interpolationsplugin¶

The Interplation plugin can be used to generate a TIN or IDW interpolation of a point vector layer. It is very simple to handle and provides an intuitive graphical user interface for creating interpolated raster layers (see Figure_interpolation_1). The plugin requires the following parameters to be specified before running:

• Input Vector layers: Specify the input point vector layer(s) from a list of loaded point layers. If several layers are specified, then data from all layers is used for interpolation. Note: It is possible to insert lines or polygons as constraints for the triangulation, by specifying either “points”, “structure lines” or “break lines” in the Type combo box.

• Interpolationsattribut: Wählen Sie die Attributspalte für die Interpolation oder aktivieren Sie Z-Koordinate für Interpolation verwenden um die im Layer gespeicherten Z-Werte zu verwenden.

• Interpolation Method: Select the interpolation method. This can be either ‘Triangulated Irregular Network (TIN)’ or ‘Inverse Distance Weighted (IDW)’. With the TIN method you can create a surface formed by triangles of nearest neighbour points. To do this, circumcircles around selected sample points are created and their intersections are connected to a network of non overlapping and as compact as possible triangles. The resulting surfaces are not smooth. When using the IDW method the sample points are weighted during interpolation such that the influence of one point relative to another declines with distance from the unknown point you want to create. The IDW interpolation method also has some disadvantages: the quality of the interpolation result can decrease, if the distribution of sample data points is uneven. Furthermore, maximum and minimum values in the interpolated surface can only occur at sample data points. This often results in small peaks and pits around the sample data points.

• Spalten-/Zeilenanzahl: Geben Sie die Anzahl von Zeilen und Spalten für die Ausgaberasterdatei an.

• Ausgabedatei: Legen Sie einen Namen für den Ausgabelayer fest.

• Ergebnis zum Projekt hinzufügen um das Ergebnis in die Kartenansicht zu laden.

Note that using lines as constraints for the interpolation the triangulation (TIN method) you can either use ‘structure lines’ or ‘break lines’. When using ‘break lines’ you produce sharp breaks in the surface while using ‘structure lines’ you produce continous breaks. The triangulation is modified by both methods such that no edge crosses a breakline or structure line.

Figure Interpolation 1:

Interpolation Plugin