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extend [2019/01/14 09:25]
brucemutton [Summary of all extend options, for survey centrelines] independent splay control
extend [2019/12/07 01:51] (current)
brucemutton [Summary of all extend options, for survey centrelines] delete unimaginative comment
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   * They must be followed either by a valid survey **<​station>​** id, or a valid survey **<​leg>​** (pair of stations).\\   * They must be followed either by a valid survey **<​station>​** id, or a valid survey **<​leg>​** (pair of stations).\\
   * Generally specifying a **<​leg>​** applies the option to ONLY that leg, and specifying a **<​station>​** applies the option to all subsequent **<​legs>​** within the centreline. ​ But there is an exception with hide, and perhaps ignore, so read the notes below carefully.\\   * Generally specifying a **<​leg>​** applies the option to ONLY that leg, and specifying a **<​station>​** applies the option to all subsequent **<​legs>​** within the centreline. ​ But there is an exception with hide, and perhaps ignore, so read the notes below carefully.\\
-  * You can include multiple caves in the same extended elevation, or [[extend#​how_to_export_correct_extended_elevation_from_zig-zag_centerline|straighten out zig-zag surveys]], by way of ''​data nosurvey''​ legs.+  * You can include multiple caves in the same extended elevation, or [[tips#​how_to_export_correct_extended_elevation_from_zig-zag_centerline|straighten out zig-zag surveys]], by way of ''​data nosurvey''​ legs.
  
 ''​extend start <​leg>''​ - start generating extended elevation centreline with this leg. (In one case i have found, it can have unexpected effects, even far from the starting leg.  I think i prefer '​extend start station'​ as below.)\\ ''​extend start <​leg>''​ - start generating extended elevation centreline with this leg. (In one case i have found, it can have unexpected effects, even far from the starting leg.  I think i prefer '​extend start station'​ as below.)\\
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 ''​extend left <leg> or <​station>''​ - same as for extend right, but extending left!\\ ''​extend left <leg> or <​station>''​ - same as for extend right, but extending left!\\
 \\ \\
-''​extend normal <​leg>''​ - extend this leg only, in the same direction as the leg immediately previous, then continue extending subsequent legs as per leg immediately previous ​[I’m not sure when this is particularly useful! ​ I tend to be explicit, and use right or left in preference to normal and reverse.]\\ +''​extend normal <​leg>''​ - extend this leg only, in the same direction as the leg immediately previous, then continue extending subsequent legs as per leg immediately previous.\\ 
-''​extend normal <​station>''​ - continue generating all extended centreline legs from this station onwards, in the same direction as the leg immediately previous.\\+''​extend normal <​station>''​ - continue generating all extended centreline legs from this station onwards, in the same direction as the leg immediately previous. \\ If extent normal is the first statement after extend start, then it will extend to the right.\\
 ''​extend reverse <​leg>''​ - extend this leg only, in the opposite direction to the leg immediately previous, then continue extending subsequent legs as per leg immediately previous.\\ ''​extend reverse <​leg>''​ - extend this leg only, in the opposite direction to the leg immediately previous, then continue extending subsequent legs as per leg immediately previous.\\
-''​extend reverse <​station>''​ - continue generating all extended centreline legs from this station onwards, in the opposite direction to the leg immediately previous.\\+''​extend reverse <​station>''​ - continue generating all extended centreline legs from this station onwards, in the opposite direction to the leg immediately previous.  \\ If extent reverse is the first statement after extend start, then it will extend to the left.\\
 \\ \\
 ''​extend vertical <​leg>''​ - do not extend this leg horizontally,​ extend only the vertical component of this leg, then continue extending subsequent legs as per leg immediately previous. ​ The order of stations in your vertical statement should usually match the direction of extended elevation centreline generation. However if Therion seems to ignore this vertical statement, try reversing the order of the stations in your vertical statement, and it might work!\\ ''​extend vertical <​leg>''​ - do not extend this leg horizontally,​ extend only the vertical component of this leg, then continue extending subsequent legs as per leg immediately previous. ​ The order of stations in your vertical statement should usually match the direction of extended elevation centreline generation. However if Therion seems to ignore this vertical statement, try reversing the order of the stations in your vertical statement, and it might work!\\
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   * 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 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.\\ 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 unreliableand 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(?​). +''​extend ignore <​station>''​ - where <​station>​ is one or more legs past a junction in the direction of generation.  ​ie The generation of extended centreline shall not take this leg, but take another one instead.  ​The map-connection break will occur at <​station>​.  A bug in this functionality was resolved with Therion version 094ac85 14Nov2019.\\
-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). \\ 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 ​the continuation of the centreline ​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 behaviourplease amend this page or post on the forum.// \\+For more details of how to use ''​extend ignore'', ​see the article [[breakingextend|Breaking extended elevations ​on specific stations]]. 
 \\ \\
 ''​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. \\
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   * Often specifying one <leg> then in the next line specifying a <​station>​ will stimulate the desired autogeneration.   * Often specifying one <leg> then in the next line specifying a <​station>​ will stimulate the desired autogeneration.
  
-  * Don't miss Martin Sluka'​s [[extend#​how_to_export_correct_extended_elevation_from_zig-zag_centerline|hot tip for obtaining realistic extended centrelines]] from zig-zagged survey data (uses ''​data nosurvey''​)+  * Don't miss Martin Sluka'​s [[tips#​how_to_export_correct_extended_elevation_from_zig-zag_centerline|hot tip for obtaining realistic extended centrelines]] from zig-zagged survey data (uses ''​data nosurvey''​)
  
   * Caves, or parts of caves that comprise a linear passage with one or two dead-end branches are easiest to generate extended centrelines for.   * Caves, or parts of caves that comprise a linear passage with one or two dead-end branches are easiest to generate extended centrelines for.
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