[Qgis-user] Working with DEMs

[Håvard Tveite]

Hi Dave,

When "Use Z-coordinate for interpolation" is checked, it must be
assumed that the Z coordinate will be used *instead* of the
value in the "Elevation" attribute.

But it is strange that this should cause the Exception / error
you experience.

The TIN Interpolator seems to works fine here (QGIS 3.4.14 on
Ubuntu 18.04) when using an attribute for the elevation.
I have not tested with Z-values.

Håvard

On 13.12.19 08:50 Dave Gardiner wrote:
> I see them all and every one I use fails. Take the TIN Interpolation for
> example for which my input was:
>
> Vector Layer = Vertices (this is the layer with the extracted vector
> endpoint nodes on)
> Interpolation Attribute = Elevation
> Use Z point for Interpolation - ticked
> Input Layer = (Vector Layer = Vertices, Attribute=ZCOORD, type=POINT)
> Interpolation Method=Linear
> Extent=Canvas Extend
>
> This is my error.
>
> Traceback (most recent call last):
> File
> "C:/PROGRA~2/QGIS3~1.4/apps/qgis-ltr/./python/plugins\processing\algs\qgis\TinInterpolation.py",
> line 187, in processAlgorithm
> writer.writeFile(feedback)
> Exception: unknown
>
> Execution failed after 16.94 seconds
>
> Any thoughts please?
>
> Dave