[Therion] How to locate points on the surface above a survey station?

[McLendonJP at aol.com]

I would appreciate any suggestions regarding the best (easiest, quickest)  
way to locate points on the surface that directly overlie survey stations in 
the  cave. For example, suppose we find a place in the cave with surface 
debris and  would like to examine the surface directly above for an entrance 
or dig. The  ideal solution would allow me to input surface survey data in 
the field using a  laptop and would generate an azimuth and distance from the 
last station to the  desired point. I've sometimes overlayed the cave map or 
lineplot onto a topo or  satellite image to identify the general area, but 
I'm looking for a much more  precise solution. Currently, I survey overland 
from the  entrance toward the area overlaying the station I want to get 
above. As I  get close, I temporarily rename the last surface survey station to 
the name  of the station in the cave below. This tells Therion that I've 
closed a loop and  it gives me the closure error in all three axes. The x and y 
axis tell me  how close I am, and I can guesstimate an approximate azimuth 
for the next shot  to get closer. This eventually gets me close, but it is 
subject to blunders and  overly time consuming. Is there a better way, 
perhaps through some  function of Therion with which I am unfamiliar? Thanks for 
any ideas.
 
JP
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