4

enter image description here

I have raster data (1km resolution) of nationwide multiannual precipitation. Unfortunately, the raster layer does not completely cover the extent of an underlying vector layer (see picture below).

I would like to interpolate the original raster values to a slightly bigger raster layer, which completely covers the vector layer.

My approach (conversion of raster values to points and interpolation of point values to a new raster layer with a bigger extent) has not been very straightforward. I guess, there is a better way.

  • What do you mean by "not been very straightforward"? What kind of results have you gotten so far? – JoshC Feb 2 '18 at 12:58
3

I imagine your current workflow would be:

  1. Convert raster values to points
  2. Interpolate point to a new raster
  3. Buffer the vector layer
  4. Clip the raster using the buffer layer as cutline

Honestly I do not know a tool which does whole this task. However, you may be able to do the steps 1 and 2 quicker, using Close gaps tools.

Without interpolation (step2), it also reduces the risk of changing the cell values of your original raster.

In QGIS geoprocessing toolbox, there are such tools in SAGA | Raster tools.

  • Close gaps
  • Close gaps with spline
  • Close gaps with stepwise resampling

My preferred tool is Close gaps with spline, which can fill big holes smoothly. But in your case Close gaps (which is based on nearest neighbor) will give you better result, because you would want to extrapolate without much changes in cell value.

I have no experience with Close gaps with stepwise resampling. It may also worth a try.

  • 1
    thank you very much indeed. "Close gaps" was exactly what I was looking for! – nilsoleplambeck Feb 2 '18 at 22:23
  • 1
    @nilsoleplambeck Great. FYI please find helpful Q&A about Close gaps. – Kazuhito Feb 3 '18 at 5:09

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.