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extend [2018/08/08 02:19]
brucemutton [Extended elevation scrap drawing considerations] add -flip none
extend [2019/01/14 05:47]
brucemutton [Summary of all extend options, for survey centrelines] add some confusion or not
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 ''​extend ignore <​leg>''​ - generation of extended centreline shall not take this leg, it will take the (an)other leg if possible.\\ ''​extend ignore <​leg>''​ - generation of extended centreline shall not take this leg, it will take the (an)other leg if possible.\\
-  * If the leg is an open branch (does not loop back to the main centreline),​ then this has the effect of hiding the entire branch from this leg onwardsat this leg.+  * If the leg is an open branch (does not loop back to the main centreline),​ then this may have the effect of hiding the entire branch from this leg onwardor it may offset the leg to a random location (in which case ''​extend hide''​ may be of use.
   * If leg is part of a loop, it beaks the loop.  ie a loop connection gap, with joining map-connection line will be formed between two instances of the first station in the leg specification.   * If leg is part of a loop, it beaks the loop.  ie a loop connection gap, with joining map-connection line will be formed between two instances of the first station in the leg specification.
-The order of stations in your ignore statement should usually match the direction of extended elevation centreline generation. ​ However if Therion seems to ignore ​this ignore statement, try reversing the order of the stations in your ignore statement, and it might work!  Sometimes the leg specification needs to follow the direction of survey, if it differs from the current direction of extend generation.\\ +The order of stations in your ignore statement should usually match the direction of extended elevation centreline generation. ​ However if Therion seems to ignore ​your ignore statement, try reversing the order of the stations in your ignore statement, and it might work!  ​In any case, try reversing the order to get a different effect (loop connection gap arrangement). ​Sometimes the leg specification needs to follow the direction of survey, if it differs from the current direction of extend generation.\\ 
-''​extend ignore <​station>''​ - where <​station>​ is one leg past a junction in the direction of generation. ​ The generation of extended centreline shall not take this leg. I have found this syntax unreliable, and the following may explain ​why. Marco Corvi says (if I understand correctly) this does not work where there are only three legs meeting at a junction ie the usual case.  So only for use where 4 or more legs meeting at junction(?​).+''​extend ignore <​station>''​ - where <​station>​ is one leg past a junction in the direction of generation. ​ The generation of extended centreline shall not take this leg. I have found this syntax unreliable, and the following may offer an insight as to why. Marco Corvi says (if I understand correctly) this does not work where there are only three legs meeting at a junction ie the usual case.  So only for use where 4 or more legs meeting at junction(?​).
 Also do not use this syntax where <​station>​ IS the junction station, obviously that will have unpredictable results. \\ Also do not use this syntax where <​station>​ IS the junction station, obviously that will have unpredictable results. \\
 +Try to avoid ''​ignore''​ing the same looped passage (ie an oxbow) at each of its junctions to a main passage. ​ This can have the effect of offsetting the whole oxbow to the far end of the map (which of course is undesirable). \\
 <​del>''​extend break''</​del>​ is mentioned in some Therion posts, presumably as an alias for extend ignore (Survex terminology). ​ It will trigger a Therion error “unknown extend flag – break”.\\ <​del>''​extend break''</​del>​ is mentioned in some Therion posts, presumably as an alias for extend ignore (Survex terminology). ​ It will trigger a Therion error “unknown extend flag – break”.\\
 Sometimes branch centrelines will be ignored (hidden?) by default, and an extend right (or similar) statement will be required to stimulate it’s generation.\\ Sometimes branch centrelines will be ignored (hidden?) by default, and an extend right (or similar) statement will be required to stimulate it’s generation.\\
 +\\
 +//There is a lot about ''​extend ignore''​ behaviour that I do not understand and cannot explain. ​ If anyone has insight or explanations for odd behaviour, please amend this page or post on the forum.// \\
 \\ \\
 ''​extend hide <​leg>''​ - hides the centreline part of the specified leg only, but NOT its stations. ​ Stations that form the leg remain visible! ​ Does not hide subsequent stations or legs. \\ ''​extend hide <​leg>''​ - hides the centreline part of the specified leg only, but NOT its stations. ​ Stations that form the leg remain visible! ​ Does not hide subsequent stations or legs. \\
  • extend.txt
  • Last modified: 6 months ago
  • by brucemutton