[vtkusers] vtkStreamTracer
James C. Robinson
j.robinson at kepler-systems.com
Mon Apr 26 11:40:43 EDT 2004
Dear Berk,
You say (I think):
I don't understand why it is so difficult to get the array from the output.
It belongs to the output after all. It is not a "property" of the filter.
I would suggest that the reason for termination is a property of the filter
(assuming by filter you are referring to the vtkStreamTracer). The output is
just a set of points etc. It is the vtkStreamTracer that gives this data
context. Otherwise, it is reason for termination of what? The answer is
"reason for termination of the stream tracer", so as a developer I want to
know why the generation of this object terminated. That is why I suggest
writing an interrogation method for this object. By reference to difficulty
is that, again as a user (and given the nature of the object-oriented
paradigm as I (perhaps mistakenly) understand it, is the entire behaviour of
the object should be encapsulated in the object. It is the generation of the
vtkStream Tracer that terminates and I should be able to ask that object
why?
Just my two cents....
Regards and thanks for the help.
Jim
______________________
James C. Robinson, PhD,
Chartered Engineer,
Kepler Simulation Systems Ltd.,
42 Rivergrove,
Glanmire, Co. Cork,
Eire
Tel: +353-21-4822028
Tel: +353-87-2393010
Fax: +353-21-4822028
E-mail: j.robinson at kepler-systems.com
______________________
-----Original Message-----
From: Berk Geveci [mailto:berklist at nycap.rr.com]
Sent: 26 April 2004 15:42
To: goodwin.lawlor at ucd.ie
Cc: j.robinson at kepler-systems.com; 'Jeff Lee'; 'Vtk Users'
Subject: RE: [vtkusers] vtkStreamTracer
> Looking at the code, if the filter executes without seeds (no Source or
> StartPosition) then the ReasonForTermination array isn't allocated...
> The allocation is done in ::Integrate() rather than ::Execute() as Jim
> points out.
>
> 3 changes could be make to the class:
>
> 1. Instantiate and add the ReasonForTermination array to the output in
> ::Execute()
I disagree. If the output is empty, there is no reason to create the
array. The application should check for this.
> 2. Define the ReasonForTermination array in the class definition along
> with a vtkGetObjectMacro(ReasonForTermination, vtkIntArray) and allocate
> in the constructor
I don't understand why it is so difficult to get the array from the
output. It belongs to the output after all. It is not a "property" of
the filter.
> 3. Put a caveat in the documentation.
This I agree with :-)
By the way, a warning: I have been running into some strange behavior
when using RK 45. I didn't have time to track this yet. I would
appreciate any bug reports.
Also, Jeff has quite a few bug fixes he hasn't committed yet. If you
guys pressure him, he might commit them :-) I have been trying...
>
> Just my thoughts,
>
> Goodwin
> -----Original Message-----
> From: James C. Robinson [mailto:j.robinson at kepler-systems.com]
> Sent: 26 April 2004 13:19
> To: goodwin.lawlor at ucd.ie; Jeff Lee
> Cc: Vtk Users
> Subject: RE: [vtkusers] vtkStreamTracer
>
>
> Gents,
>
> Many thanks for the continued interest. Goodwin, I am using the adaptive
> integrator. I will try the other two types as an experiment, but a big
> part of going to the vtkStreamTracer is to avail of the adaptive
> integrator, so it may indicate whether or not it is the issue, but will
> not resolve it.
>
> Jeff, the issue of being able to generate a set of streamtracers from a
> rake doesn't negate the possibility of having a method to interrogate it
> directly. The argument could point the vtkSTreamTracer to the seed
> particle for which one wants to determine the reason for termination -
> e.g. vtkStreamTracer::ReasonForTermination(int particlenumber).
>
> Now, more information: I have discovered that the crash was due to the
> fact that
> vtkIntArray* ReasonForTermination =
> (vtkIntArray*)pStreamLine->GetOutput()->GetCellData()->GetArray("ReasonF
> orTe
> rmination") ;
>
> was returning a NULL pointer (sometimes) and I was trying (naughty me)
> to use that pointer without checking for this condition. However, the
> question is now, why is the pointer coming back as NULL. I assume that
> it is because some condition is not met before it gets to the
> vtkStreamTracer::Integrate method (which is where "ReasonForTermination"
> is set up). The seed particle points that cause trouble are generally in
> zones where the flow rate is very low. In other areas the two
> ReasonForTermination messages that I am getting are either the stream
> tracer "generated and unexpected value" or exceeded the "max propagation
> time".
>
> Again many thanks.
>
> Regards,
>
> Jim
>
> ______________________
>
> James C. Robinson, PhD,
> Chartered Engineer,
> Kepler Simulation Systems Ltd.,
> 42 Rivergrove,
> Glanmire, Co. Cork,
> Eire
>
> Tel: +353-21-4822028
> Tel: +353-87-2393010
> Fax: +353-21-4822028
> E-mail: j.robinson at kepler-systems.com
> ______________________
>
> -----Original Message-----
> From: Goodwin Lawlor [mailto:goodwin.lawlor at ucd.ie]
> Sent: 26 April 2004 12:00
> To: j.robinson at kepler-systems.com
> Subject: RE: [vtkusers] vtkStreamTracer
>
> Hi Jim,
>
> Which integrator are you using? If its vtkRungeKutta45 try using
> vtkRungeKutta4 and see if vtkStreamTracer still crashes where the flow
> rate is close to zero. If this solves the problem then it's the adaptive
> time step causing the problem...
>
> Regards,
>
> Goodwin
>
> Ps Actually try each of the integrators and see if they make a
> difference.
>
> -----Original Message-----
> From: James C. Robinson [mailto:j.robinson at kepler-systems.com]
> Sent: 26 April 2004 10:07
> To: goodwin.lawlor at ucd.ie; Jeff Lee
> Cc: Vtk Users
> Subject: RE: [vtkusers] vtkStreamTracer
>
>
> Gents,
>
> Thanks for your efforts. You have confirmed what I did myself is
> reasonable (Note, for all those harping on about the manual.... Where is
> the syntax for accessing that array explicitly stated in the manual? One
> would think that, since the reason for termination is a kernel part of
> the object, there would be a simple method to interrogate the object
> such as a vtkStreamTracer::ReasonForTermination()).
>
> You may have more contributions to make. I am finding two main problems
> (and a crash) with the vtkStreamTracer object:
> 1) The streamtube generated is not as long as the one attained using
> vtkStreamLine,
> 2) There is a crash when I use a source point where the flow rate is
> close to (or equal to) zero.
>
> Any ideas?
>
> Regards,
>
> Jim
> PS: Again, for those saying "give us some example code...". My programme
> is written as an MFC View/Doc with a very structured list of methods for
> newing, creating (setting up) and deleting all the objects that I use.
> It would be an arduous (though perhaps fruitful and worthwhile)
> procedure to extract all the objects and use them in the same way as I
> use them in the overall programme.
>
>
> ______________________
>
> James C. Robinson, PhD,
> Chartered Engineer,
> Kepler Simulation Systems Ltd.,
> 42 Rivergrove,
> Glanmire, Co. Cork,
> Eire
>
> Tel: +353-21-4822028
> Tel: +353-87-2393010
> Fax: +353-21-4822028
> E-mail: j.robinson at kepler-systems.com
> ______________________
>
> -----Original Message-----
> From: Goodwin Lawlor [mailto:goodwin.lawlor at ucd.ie]
> Sent: 25 April 2004 13:05
> To: vtkusers at vtk.org
> Cc: j.robinson at kepler-systems.com
> Subject: RE: [vtkusers] vtkStreamTracer
>
> Hi Jim
>
> Tracer->GetOutput()->GetCellData()->GetArray("ReasonForTermination");
>
> Hth,
>
> Goodwin
>
> Message: 3
> Reply-To: <j.robinson at kepler-systems.com>
> From: "James C. Robinson" <j.robinson at kepler-systems.com>
> To: "Vtk Users" <vtkusers at vtk.org>
> Date: Sat, 24 Apr 2004 20:50:06 +0100
> Subject: [vtkusers] vtkStreamTracer
>
> Dear All,
>
> In vtkStreamTracer:
>
> The reason for the termination is stored in a cell array named
> ReasonForTermination.
>
> How do I access it? (I am probably tired and slow at the moment).
>
> Thanks,
>
> Jim
>
> ______________________
>
> James C. Robinson, PhD,
> Chartered Engineer,
> Kepler Simulation Systems Ltd.,
> 42 Rivergrove,
> Glanmire, Co. Cork,
> Eire
>
> Tel: +353-21-4822028
> Tel: +353-87-2393010
> Fax: +353-21-4822028
> E-mail: j.robinson at kepler-systems.com
> ______________________
>
>
>
>
>
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--
Berk Geveci <berklist at nycap.rr.com>
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