I wish to display land seismic lines on a map. Land seismic lines are often not straight so often there is survey data for each shotpoint or every 5 shotpoints. Typically a shotpoint (SP) could be 25m or 50m apart. There are often many hundreds of SPs. The TDL loads as discrete points. I need to be able to identify the seismic line (that is in the TDL file) and also say every 100 SP.
I cannot find a way to label SPs every 100 points, or to just label the line at the start and end.
A typical file looks like:
Rad PROFIL_ID SP SWRF99TM_N SWRF99TM_E 1 MC-81-313E 4 6414971 735192 6414387 1687468 2 MC-81-313E 5 6414988 735192 6414404 1687468 3 MC-81-313E 6 6415004 735192 6414420 1687468 4 MC-81-313E 7 6415020 735192 6414436 1687468
PROFIL_ID = Line number, SP is Shotpoint and the other 2 columns are XY coordinates.