[vtkusers] vtkStreamTracer

[Goodwin Lawlor]

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()
2. Define the ReasonForTermination array in the class definition along
with a vtkGetObjectMacro(ReasonForTermination, vtkIntArray) and allocate
in the constructor
3. Put a caveat in the documentation.

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
______________________