Thanks Zhanping.
I'm not sure this answers the question of why it is crashing though, as
it only happens when the streamline output is connected to a contour
filter, and happens even when generating what appear to be valid
streamlines. I also did some testing, and the behavior appears to be
independent of whether Mask Points or something else (e.g. SphereSource)
is used for the seed points...
David
On 5/7/2010 1:23 PM, Zhanping Liu wrote:
Hi David:
The streamline integrator sometimes is sensitive to the selection
of the initial step size (which is currently kind of large to incur
some issues, given a complex dataset particularly containing multiple
blocks of irregular boundaries, with some extreme topological
structures). Whenever possible, please use RK-45 (which may not
necessarily be slower than RK-2, particularly when your dataset is not
large) and small values for the step sizes (initial, max) as well as
the error threshold.
In addition, care needs to be taken when using 'Mask points'
to select the seed points. Sometimes many resulting seeds reside
exactly on the boundaries between different blocks. In some rare
cases, such seeds may cause problems when 'OUT-OF-DOMAIN' status is
detected by the integrator.
-Zhanping
On Fri, May 7, 2010 at 12:39 PM, David Borland <[email protected]
<mailto:[email protected]>> wrote:
I have some steady-state vector field data that I am visualizing
using streamlines and particles via the following pipeline:
Mask Points on the input (~100 points) to generate seeds
Stream Tracer with Custom Source to generate the streamlines
Contour on Integration Time to generate particles, which can then
be animated by animating the Isosurface value.
This was working fine in v3.6.2, but started crashing in v3.8.0.
*Note: The crashing only occurs when the streamline filter
output is attached to a contour filter.* After some
investigating, I realized that part of the problem is with
different default values for the Stream Tracer in 3.8.0 vs. 3.6.2.
From what I have been able to figure out so far, it looks like
different values for the Integrator Type (default of Runge-Kutta 2
in 3.6.2 and Runge-Kutta 4.5 in 3.8.0) and Initial Step Length
(default of 0.5 in 3.6.2 and 0.2 in 3.8.0). After experimenting
with these values, I have found the following:
Windows 3.6.2 64-bit binaries: Crashes for any Runge-Kutta with
Initial Step Size 0.5
Works for any
Runge-Kutta with Initial Step Size 0.2
Windows 3.8.0 64-bit binaries: Crashes for any Runge-Kutta with
Initial Step Size 0.5,
Hangs for
Runge-Kutta 4 and 4.5 with Initial Step Size 0.2
Ubuntu Linux 3.6.2 64-bit build: Crashes for any Runge-Kutta with
Initial Step Size 0.5,
Crashes for
Runge-Kutta 4.5 with Initial Step Size 0.2
Ubuntu Linux 3.8.0 64-bit build: Crashes for any Runge-Kutta with
Initial Step Size 0.5,
Crashes for
Runge-Kutta 4.5 with Initial Step Size 0.2
The results on Linux seem to be more consistent than on Windows
(go figure...), and different data sets on Windows seem to have
slightly differnt behavior, but there certainly seems to be some
interaction between the initial step size and the integrator type.
I'd be happy to log a bug if that is more appropriate than
posting to the mailing list.
David
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Zhanping Liu, PhD
Kitware, Inc.
28 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-371-3971 x 138
http://www.zhanpingliu.org
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