[Qgis-developer] Kriging interpolation functionality in QGIS?

[Barry Rowlingson]

On Fri, Sep 25, 2015 at 4:14 PM, Stefan Keller <sfkeller at gmail.com> wrote:
> Hi,
>
> I'm looking for a Kriging interpolation from an irregular point data
> set to raster data in QGIS without dependencies, if possible. There's
> 1.       Interpolation plugin (C++) [1]
> 2.       „Raster Interpolation“ plugin von Denis Rouzaud (Python) [2]
>
> I know that GRASS and SAGA implemented Kriging [3].
> But these are are dependencies I'd like to avoid in order to make QGIS
> even more easier to use.
> AFAIK even Denis' "Raster Interpolation" plugin requires Scipy
> separately installed.
>
> So eventually, I'm considering to extend "Raster Interpolation" Python
> plugin (or [1])
> Any suggestions or activities regarding this?

 You want Kriging in QGIS? You now have to implement a full
statistical analysis system in QGIS. Kriging is hard, or even
impossible to do properly as an automatic points-to-raster process
without statistical diagnostics. You'll need to plot your variogram.
You'll need to fit your variogram. You may need to transform your
variables, and transform results back (and the back-transform of
Kriging standard-errors is not trivial).

 The simplest points-to-raster Kriging system I've seen is autoKrige
from the R automap package. Even so this has about 7 parameters and
options to choose from. Plus working in R makes it easy to plot
diagnostics and histograms and do transforms and testing....

 If you want to try all that, there's a few python kriging
implementations that you could use, or this blog poster shows how to
do it from scratch with basic matrix ops:

http://connor-johnson.com/2014/03/20/simple-kriging-in-python/

Barry