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<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>Laurent<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>Welcome to the list.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>As the gradient of a survey shot increases, therion
switches from the assumption that passages are measured LRUD to an assumption
that they are measured LR-front-back and then at 90 deg to NSEW. At
present the user has some control of this, but not complete control.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>From the therion book (and slightly rephrased by me)...<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><b><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt;font-weight:bold'>vthreshold</span></font></b><span
lang=EN-NZ> <number> <units> </span><font face="Times New Roman"><span
lang=EN-NZ style='font-family:"Times New Roman"'> <b><span
style='font-weight:bold'>threshold for interpreting LRUD readings as left-</span></b></span></font><b><span
lang=EN-NZ style='font-weight:bold'>right-front-back reading perpendicular to
the shot.<o:p></o:p></span></b></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>If passeges are <i><span style='font-style:italic'>near</span></i>
horizontal (inclination < vthreshold), LR is perpendicular to the<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>shot and UD is vertical.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>If passages are <i><span style='font-style:italic'>near</span></i>
vertical (inclination > vthreshold), UD becomes perpendicular to the shot
– otherwise passages would not look very good. <o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>In the case of vertical shots, UD is interpreted as
north-south dimension from the station to allow tube-like modelling of
verticals.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>It is the feature in the last sentence which is
upsetting your output. You may have noticed the recent posts discussing
the merits or otherwise of this behaviour.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>I have never concerned myself much with this, as my
focus is cartographed drawings, not models, so I just ignore the spurious ‘walls’
at pitches. Hence this advice might not be perfect. Try using 89.9 deg in
place of 90 deg as a workaround.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>Incidentally, does anyone know what the default value
of vthreshold is?<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-NZ
style='font-size:10.0pt'>Bruce<o:p></o:p></span></font></p>
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