I am trying to extract values of raster cells on Points using 'Extract' function in R(similar to 'Extract Values to Points' in ArcGIS-10.2). After doing so in order to check integrity, I computed the total value of all the raster cells (i.e. sum) ~ 66,000 and total extracted values on points ~ 49,000. We have tried both techniques 'Simple' and 'Bilinear' interpolation techniques. Data Loss gets only slightly reduced with 'Bilinear' technique ~ 50,000. There is a huge data loss, if anyone can provide a way forward or has experienced the same.