<div dir="ltr">I think Modified time is independent of the clock. I believe it is a 64bit integer that starts at zero and goes up by one each time something is modified by VTK. So maybe something else is going on here...</div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, May 8, 2017 at 7:25 AM, Paul <span dir="ltr"><<a href="mailto:paul@3dimageautomation.com.au" target="_blank">paul@3dimageautomation.com.au</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal">Hi,<u></u><u></u></p>
<p class="MsoNormal">We are using VTK in a 3D LiDAR based mining automation application which operates continuously.<u></u><u></u></p>
<p class="MsoNormal">VTK in medical application is great but VTK controlling the world’s largest autonomous machine is interesting for engineering types.<u></u><u></u></p>
<p class="MsoNormal">If anyone is interested we can post some screenshots.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Many of the vtk developers will remember the vtk code impact of our original issue with overflow of ModifiedTime on a Win64 build.<u></u><u></u></p>
<p class="MsoNormal">Thanks again for the effort, it was certainly a relief as it was so critical for our application success.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Subsequent to the overflow fix the application has been running without issues on two system equipped with dual Xeon processors.<u></u><u></u></p>
<p class="MsoNormal">However one system with a four core i7 was having rendering issues at intervals of a week or more.<u></u><u></u></p>
<p class="MsoNormal">Our initial thoughts was that the issue was related to high processor loading.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">It turns out that the issue is related to ModifiedTime.<u></u><u></u></p>
<p class="MsoNormal">Rendering breaks if the PC time is changed in a negative direction.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">It took us some time to discover this.<u></u><u></u></p>
<p class="MsoNormal">The i7 system is running Windows 7 and the Windows Time service was in the Scheduled Tasks to run once a week on Sunday morning.<u></u><u></u></p>
<p class="MsoNormal">Vtk rendering only breaks if the time synchronisation has a negative correction.<u></u><u></u></p>
<p class="MsoNormal">This can be reproduced by manually changing the PC time backwards.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Q. Could this be resolved by making ModifiedTime independent of the PC clock.<u></u><u></u></p>
<p class="MsoNormal">We run a PLC (real time automation controller) in kernel mode on the same platform.<u></u><u></u></p>
<p class="MsoNormal">PLC’s are used in time critical applications such as motion synchronisation and use a SystemTime that does not jump.<u></u><u></u></p>
<p class="MsoNormal">I am not sure what mechanism the PLC uses but suspect that the time is initialised to the PC time on application start and then incremented at 100nS intervals (the timer resolution).<span class="HOEnZb"><font color="#888888"><u></u><u></u></font></span></p><span class="HOEnZb"><font color="#888888">
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Paul<u></u><u></u></p>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div>Ken Martin PhD<div>Distinguished Engineer<br><span style="font-size:12.8px">Kitware Inc.</span><br></div><div>28 Corporate Drive<br>Clifton Park NY 12065<br><div><br></div><div><span style="font-size:10pt;font-family:Tahoma,sans-serif">This communication,
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