To convert a series of raster contour lines

Select Convert Contour Lines.
Select the appropriate color mask.
Set the active Z for the first contour line.
Set the interval between two consecutive contour lines (positive number).
Select Up or Down to tell how you will progress from one line to the next.
Turn on Auto Continue.
Proceed to the conversion of the first raster line.
Identify this line with a data point. If the raster contour line is not completely converted, use the Continue Element tool, which is automatically selected, to complete it.
When you finish converting this line, the active Z is incremented accordingly.
Proceed to the conversion of the second raster line, and so on.