QGIS: SAGA-GIS module “Add raster value to point” Error: unknown option 'INTERPOL'

Question

I encountered an error while using the "Add raster value to point" SAGA-GIS module in QGIS (2.16) to retrieve altitude values from a raster DEM previously interpolated from TIN points (as vector features).

I use SAGA-GIS version 2.3.1.

This bug is fully reproducible for me.

I've selected an other points layer in the first field of the module window.
The raster DEM in the the second field.
The interpolation method was set to "[0] Nearest neighbor".
File saved to /temp
[x] Open output file after running algorithm.

Here is the log:
http://pastebin.com/raw/1F5NGz8b

The same operations are working on SAGA's side.

Answer 1

The fact is that the "saga_cmd io_gdal" command makes use of these options as you can see in the previously pasted output:

0 [-GRIDS ] [-FILES ] [-SELECTION ] [-SELECT_SORT ] [-TRANSFORM ] [-RESAMPLING ]

With:

-RESAMPLING: Resampling
Choice
Available Choices:
[0] Nearest Neighbour
[1] Bilinear Interpolation
[2] Bicubic Spline Interpolation
[3] B-Spline Interpolation
Default: 3
Unknown option 'INTERPOL'
___________________________

So, the 'INTERPOL' value seems to be now called 'RESAMPLING'.

The exactly same behavior exists for the "saga_cmd shapes_grid" command options:

0 [-SHAPES ] [-GRIDS ] [-RESULT ] [-RESAMPLING ]

With:

-RESAMPLING: Resampling
Choice
Available Choices:
[0] Nearest Neighbour
[1] Bilinear Interpolation
[2] Bicubic Spline Interpolation
[3] B-Spline Interpolation
Default: 3
___________________________

Also here, there is no 'INTERPOL' value but a 'RESAMPLING' one. Anyway, this one doesn't seem to be problematic, but within the QGIS module, the user cannot set this one.

AND: the 'RESULTS' flag it now 'RESULT' (without ending 'S').

I do not know how to fix this, buy AFAIK every useful information is here. Thanks.

Answer 2

In ubunut go to /usr/share/qgis/python/plugins/processing/algs/saga/ (your location may vary). Open the SagaAlgorithm214.py file and find and replace INTERPOL with RESAMPLING

See the link for more details