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<p class=MsoNormal><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma'>-----Original Message-----<br>
<b><span style='font-weight:bold'>From:</span></b> James C Robinson
[mailto:j.robinson@kepler-systems.com] <br>
<b><span style='font-weight:bold'>Sent:</span></b> </span></font><font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>11 May 2005</span></font><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> </span></font><font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>14:39</span></font><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'><br>
<b><span style='font-weight:bold'>To:</span></b> 'John Platt'<br>
<b><span style='font-weight:bold'>Subject:</span></b> ResetClippingpLane</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Dear John,</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>I can’t seem to send the message below to the
group (something is blocking it as spam?).</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Could you send it on if possible (and any comments
welcomed).</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Regards,</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Jim</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Dear All,</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>I have been having a problem with the AutoResetCameraClippingRange
facility, in that when viewing objects of certain dimension, zooming in causes
detail to be lost when it is too close to the camera. This is, of course,
deliberate behaviour, in that objects that are between the camera and the near
clipping plane are not rendered. However, the issue is with the distance of the
near clipping plane from the camera (when in auto mode). It is set to 0.01
times (1%) the distance of the far clipping plane (which is related to the
perpendicular distance of the farthest bounding box vertex from the
camera….). The reason for this is related to Z buffering and the quality
of images when the near clipping plane is too close to the camera (I think
– pure layman’s understanding – that it may be to do with integer
maths etc…). Anyway, on investigating deeper into the VTK code for void
vtkRenderer::ResetCameraClippingRange I see what looks like an error…..</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> // Make sure near
is at least some fraction of far - this prevents near</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> // from being
behind the camera or too close in front. How close is too</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> // close depends
on the resolution of the depth buffer</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> int ZBufferDepth =
16;</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> if
(this->RenderWindow)</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> {</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>
ZBufferDepth = this->RenderWindow->GetDepthBufferSize();</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> }</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> //</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> if ( ZBufferDepth
<= 16 )</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> {</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>
range[0] = (range[0] < 0.01*range[1])?(0.01*range[1]):(range[0]);</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> }</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> else if (
ZBufferDepth <= 24 )</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> {</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>
range[0] = (range[0] < 0.01*range[1])?(0.01*range[1]):(range[0]);</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> }</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> else</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> {</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>
range[0] = (range[0] < 0.01*range[1])?(0.01*range[1]):(range[0]);</span></font></p>
<p class=MsoNormal style='margin-left:108.0pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> }</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>The error is that (I may be misreading the code in my
haste to find a solution) range[0] will be reset to 1% range[1] regardless of
the value of ZBufferDepth. I would have thought that (a) if this is the case,
there is no need for these 10 lines and (b) the larger z buffer depth (number
of bits in the z buffer – usually 24 nowadays?) would mean that the near
plane could be significantly closer to the camera? Say 0.01% - which would suit
my needs as I am viewing objects with a dimension of up to 3000 units and I
would like to be able to see detail in objects within as close as 0.3 units.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Please advise.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Regards,</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Jim</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'> </span></font></p>
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<p class=MsoNormal><b><font size=3 color=navy face=Arial><span lang=FR
style='font-size:12.0pt;font-family:Arial;color:navy;font-weight:bold'>James C
Robinson</span></font></b><b><font size=2 color=navy face=Arial><span lang=FR
style='font-size:10.0pt;font-family:Arial;color:navy;font-weight:bold'>, </span></font></b></p>
<p class=MsoNormal><b><font size=3 color=navy face=Wingdings><span lang=EN-GB
style='font-size:12.0pt;font-family:Wingdings;color:navy;font-weight:bold'>+</span></font></b><b><font
color=navy><span lang=FR style='color:navy;font-weight:bold'> 42
Rivergrove</span></font></b><b><font size=2 color=navy face=Arial><span
lang=FR style='font-size:10.0pt;font-family:Arial;color:navy;font-weight:bold'>,</span></font></b></p>
<p class=MsoNormal><b><font size=2 color=navy face=Arial><span lang=FR
style='font-size:10.0pt;font-family:Arial;color:navy;font-weight:bold'>
<ns0:City w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z"><ns0:place w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z"><ns0:City w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z"><ns0:place w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z">Glanmire</ns0:place></ns0:City></ns0:place></ns0:City>,</span></font></b></p>
<p class=MsoNormal><b><font size=2 color=navy face=Arial><span lang=FR
style='font-size:10.0pt;font-family:Arial;color:navy;font-weight:bold'>
</span></font></b><b><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;font-weight:bold'>Co.</span></font></b><b><font
size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy;font-weight:bold'> </span></font></b><b><font
size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy;font-weight:bold'><ns0:City w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z"><ns0:place w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z"><ns0:City w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z"><ns0:place w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z">Cork</ns0:place></ns0:City></ns0:place></ns0:City></span></font></b><b><font
size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy;font-weight:bold'>,</span></font></b></p>
<p class=MsoNormal><b><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;font-weight:bold'>
</span></font></b><b><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;font-weight:bold'><ns0:place w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z"><ns0:place w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z">Eire</ns0:place></ns0:place></span></font></b></p>
<p class=MsoNormal><b><font size=3 color=navy face="Wingdings 2"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Wingdings 2";color:navy;
font-weight:bold'>'</span></font></b><b><font color=navy face=Arial><span
lang=EN-GB style='font-family:Arial;color:navy;font-weight:bold'>
+353 21 4822028</span></font></b></p>
<p class=MsoNormal><b><font size=3 color=navy face="Times New Roman"><span
lang=EN-GB style='font-size:12.0pt;color:navy;font-weight:bold'>
+353 87 2393010</span></font></b></p>
<p class=MsoNormal><b><font size=3 color=navy face=Wingdings><span lang=EN-GB
style='font-size:12.0pt;font-family:Wingdings;color:navy;font-weight:bold'>-</span></font></b><b><font
color=navy face=Arial><span lang=EN-GB style='font-family:Arial;color:navy;
font-weight:bold'> </span></font><ns0:PersonName w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z"><ns0:PersonName w:insAuthor="Jim" w:insDate="2005-05-11T14:37:00Z" w:endInsAuthor="Jim" w:endInsDate="2005-05-11T14:37:00Z"></ns0:PersonName></b><b><font
color=blue><span lang=EN-GB style='color:blue;font-weight:bold'><a
href="mailto:jrobinson@eircom.net">jrobinson@eircom.net<font color=black><span
style='color:windowtext;text-decoration:none'></ns0:PersonName>></span></font></a></span></font></b><b><font
color=navy face=Arial><span lang=EN-GB style='font-family:Arial;color:navy;
font-weight:bold'> </span></font></b></p>
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