I am perplexed by the results generated by the SAGA 2.3.1 Extract Values to Points tool in QGIS 2.18.
I am working with Vegetation Index raster layers, which means the values are between -1 and 1. According the min-max of the raster values (prior to the SAGA calculation), all the minimum values are above 0. The Extract Values to Points tool generates negative values up to -3. I have tried saving the No Data values to 0, but that doesn't change the output.
Has anyone else run into this problem? I understand that there was a known bug in the algorithm; however, I don't believe this is my issue. The tool is generally working, except for the occasional new negative numbers (I say new because they were not present in the original input raster). Additionally, I know people also recommend using the Point Sampling plugin in QGIS; however, I am working with huge datasets and (according to this forum), the plugin cannot handle that type of volume.
This issue has me questioning my results.