This question doesn’t make any sense. GPR can not discriminate one type of metal from another. GPR is actually a poor tool for large area metal detection. Voxler is a software program from a Golden Software that is used to generate 3D volume images from data. I use to visualize GPR data collected with my Sensors & Software GPR units. We collected tightly spaced parallel lines of data in a grid layout. The 2D B-Scan GPR profiles are processed in Sensors & Software’s EKKO Project software and then exported in a format that Voxler can utilize for 3D imaging. All of my other GPR instruments (GSSI, 3D-RADAR, Impulse Radar) do the 3D analysis in the same software that I use for the GPR processing. Voxler can not be used for GPR processing, it is just a visualization tool to create 3D volume data from tightly spaced already processed GPR data in this specific case.