1 | <refmeta> |
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2 | <refentrytitle>extend</refentrytitle> |
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3 | <manvolnum>1</manvolnum> |
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4 | </refmeta> |
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5 | |
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6 | <refnamediv> |
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7 | <refname>extend</refname> |
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8 | <refpurpose>produce an extended elevation from a &x3d; file |
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9 | </refpurpose> |
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10 | </refnamediv> |
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11 | |
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12 | <refsynopsisdiv> |
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13 | <cmdsynopsis> |
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14 | <command>extend</command> |
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15 | <arg choice="opt">--specfile configuration .espec file</arg> |
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16 | <arg choice="req"> input .3d file</arg> |
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17 | <arg choice="opt">output .3d file</arg> |
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18 | </cmdsynopsis> |
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19 | </refsynopsisdiv> |
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20 | |
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21 | <refsect1><title>Description</title> |
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22 | |
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23 | <Note> |
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24 | <Para> |
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25 | The <command>extend</command> program can also work on |
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26 | <Application>Compass</Application> <filename>.plt</filename> (as can |
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27 | <command>aven</command> and any other &survexsuite; program which reads &x3d; |
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28 | files). |
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29 | </Para> |
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30 | </Note> |
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31 | |
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32 | <Para> |
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33 | If no specfile is given, extend starts with the highest station marked |
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34 | as an entrance which has at least one underground survey leg attached |
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35 | to it. If there are no such stations, the highest deadend station in |
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36 | the survey (or the highest station if there are no deadends) is used. |
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37 | Extend puts the first station on the left, then folds each leg out |
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38 | individually to the right, breaking loops arbitrarily (usually at |
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39 | junctions).</Para> |
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40 | |
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41 | <Para>If the output filename is not specified, extend bases the output |
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42 | filename on the input filename, but ending "_extend.3d". For example, |
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43 | <command>extend deep_pit.3d</command> produces an extended elevation |
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44 | called <filename>deep_pit_extend.3d</filename>.</Para> |
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45 | |
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46 | <Para> |
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47 | This approach suffices for simple caves or sections of cave, but for more |
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48 | complicated situations human intervention is required. More complex |
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49 | sections of cave can be handled with a specfile giving directions to |
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50 | switch the direction of extension between left and right, to |
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51 | explicitly specify the start station, or to break the extension at |
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52 | particular stations or legs. </Para> |
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53 | |
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54 | <Para> |
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55 | The specfile is in a format similar to cavern's data format:</Para> |
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56 | |
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57 | <programlisting> |
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58 | ;This is a comment |
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59 | |
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60 | ; start the elevation at station entrance.a |
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61 | *start entrance.a ;this is a comment after a command |
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62 | |
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63 | ; start extending leftwards from station half-way-down.5 |
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64 | *eleft half-way-down.5 |
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65 | |
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66 | ; change direction of extension at further-down.8 |
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67 | *eswap further-down.8 |
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68 | |
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69 | ; extend right from further-down.junction, but only for |
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70 | ; the leg joining it to very-deep.1, other legs continuing |
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71 | ; as before |
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72 | *eright further-down.junction very-deep.1 |
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73 | |
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74 | ; break the survey at station side-loop.4 |
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75 | *break side-loop.4 |
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76 | |
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77 | ; break survey at station side-loop.junction but only |
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78 | ; for leg going to complex-loop.2 |
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79 | *break side-loop.junction complex-loop.2 |
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80 | </programlisting> |
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81 | |
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82 | <Para> |
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83 | This approach requires some trial and error, but gives useful results |
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84 | for many caves. The most complex systems would benefit from an |
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85 | interactive interface to select and view the breaks and switches of |
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86 | direction.</Para> |
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87 | |
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88 | </refsect1> |
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