I use the Point Sampling Tool in QGIS to transfer gridvalues (of DEMs) to point features. This goes well with grids from f.i. MapMart (SRTMHARRIS_DEM), but I get only NULL-values when using grids from USGS (SRTM 1 Arc-Second Global). Does anybody know why and how to get proper values from SRTM 1 Arc-Second Global?

  • 1
    Are you sure that DEM and point layer are in the same CRS? I.e. turn OTF OFF and see if they still align. – AndreJ Jul 3 '15 at 18:00
  • I tried different CRSes which might apply, but using others the maps do not align. So I would think the CRSes are okay. – Jan Hoogendoorn Jul 3 '15 at 18:17
  • Mmm, yes, with OTF off the maps don't align. I need some more study. How to transform a map/grid from one to the another CRS? – Jan Hoogendoorn Jul 3 '15 at 18:38
  • In QGIS, Raster -> Projection -> Reproject to another file name and the CRS of the point file. For vector layers, you can use Save As ... to the CRS of the raster. – AndreJ Jul 3 '15 at 19:00

Yes, AndreJ, you are right, thanks. For applying the “Point sample tool” the maps and grids should align with OTF off. After transforming the maps/grids to the same (Project) CRS (with "save as") everything went fine.

| improve this answer | |

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.