QGIS » QGIS Application

Notes from the mailing list, to be added to the manual:

So, how are line features supposed to work in interpolation plugin? Or how can i give structure lines hight values that make sense?

Well, somehow you need to say the plugin what the values to interpolate are. Currently possible is to take from attribute or from z-value (for 2.5D geometry types). Where do you have the height values in your data?

So, how are line features supposed to work in interpolation plugin?

The line features are used to modify the triangulation. The triangulation is modified such that no edge crosses a breakline or structure line (constrained Delaunay triangulation). The difference between handling of breaklines and structure lines is that cubic interpolation produces a sharp break rather than a continuous one.

Please note that the interpolation plugin has some numerical problems in the TIN creation that may lead to crashes (especially for data in degrees). There is the option to dump the generated triangle net, so you can see what the plugin does.