extend

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extend [2019/12/07 01:51] – [Summary of all extend options, for survey centrelines] delete unimaginative comment brucemuttonextend [2019/12/21 09:59] – Typo tarquinwj
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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 both the leg used to reach that station, and 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 [[tips#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.
  
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 ''extend hide <station>'' - hides [the station* and] all leg centrelines (usually two of these) that emanate directly from THIS station.  Unlike with other extend options, it does not hide subsequent stations or legs. \\ ''extend hide <station>'' - hides [the station* and] all leg centrelines (usually two of these) that emanate directly from THIS station.  Unlike with other extend options, it does not hide subsequent stations or legs. \\
 Note that the centreline generation is carried out as per normal, the stations and legs are just made ‘not visible’.\\ Note that the centreline generation is carried out as per normal, the stations and legs are just made ‘not visible’.\\
 +
 +**Important note:** with ''left'', ''right'', ''normal'', ''reverse'', ''vertical'' and ''hide'', Therion and Pocket Topo both apply the selected options to the leg before the station (in whichever direction Therion is traversing the centreline), as well as the ones following it - that is to say, it applies it to the leg that creates the station. Survex, on the other hand, applies the selected option to all legs after the selected station. This rare difference from Survex is by design. Because of this, and because it helps clarification too, it is a common approach to specify two lines, one saying to apply the option to the initial leg where it is wanted, and one saying to apply the option to that station. This also avoids some bugs mentioned above.
 +
 +  extend left 3 4
 +  extend left 4
  
 //* Something I don't understand with 'hide' above, stations are sometimes hidden, and sometimes not.// //* Something I don't understand with 'hide' above, stations are sometimes hidden, and sometimes not.//
  • extend.txt
  • Last modified: 2 months ago
  • by brucemutton