I am using OS Terrain 50 data, mosaicked with R, to make some nice 3D maps using Rayshader. However, for coastal and island areas, there are large gaps where the sea is. How can I easily fill these in in QGIS to prevent gaps in my rayshader model? Screenshot below of what I mean.

enter image description here

  • Being the sea, do you wish to fill the gap by a constant value such as zero? Or interpolate them by nearby cell values?
    – Kazuhito
    Apr 29, 2020 at 7:30
  • @kazuhito Just zero would be fine, to avoid a gap in the 3D model.
    – user36735
    Apr 29, 2020 at 17:00

1 Answer 1


There would be several approaches; one tool I would recommend is SAGA Reclassify values (single) in the Processing Toolbox > SAGA > Raster tools.

Assuming your NoData value is -99999,

(1) Activate Reclassify values (single) tool.

(2) Set parameters and run the tool:

  • old value = -99999
  • new value = 0.0000
  • operator - [0] =

enter image description here

The tool will return a new layer Reclassified Grid of which -99999 is replaced by 0. Please check the cell value by Identify Features tool.

enter image description here

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

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