Hi Peter, thank you for your reply, unfortunately you had to use the bad words - "significant...effort". Ouch! But actually this seems to a general prolem beyound Feflow and Voxler. I suspected a solution could be doing all the math off site both Voxler and Feflow platform, say by an VB app in a spreadsheet calculation. Just to combine the xyz from feflow slice with the nearest C in Voxler e.g., whithout any interpolation. O.K. agreed, obviously significant effort.