[Paraview] Velocity vectors and more......

Ulrik Ullum ulrik@ullum.dk
Thu, 8 May 2003 15:11:16 +0200


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Hi,
 
I am practically a newbie to ParaView and VTK and I am trying to
visualize CFD-generated or measured velocity vector fields on top of a
geometry file exported from our CAD system (VRML format). However, I
find it difficult to get a satisfying result. Any response from somebody
who has experience with the presentation of velocity vector fields in
ParaView is very welcome. Some of the problems I struggle with are:
 
I would like to show velocity vectors as thin arrows (lines) instead of
the 'volume' representation I get when I choose Glyph and
Arrow0/Cone0/Sphere0 - is there another way to display vectors than
using the glyph-tool? - or can the glyph arrows be modified to be lines
instead of cylinders and cones?
 
I have been using a vtk data format where i have a POLYDATA dataset with
a definition of VERTICES and subsequently a definition of VECTORS - this
format has been working in conjunction with another VTK-viewer (MayaVi),
however I can not make ParaView read my files. Am I doing something
completely wrong? - I've attached a small example which can be read by
MayaVI!
I have been able to make a readable data file with the UNSTRUCTURED_GRID
dataset but wonder why my POLYDATA format doesn't succed - ParaView
simply crashes (WinXP).
 
If I could get a working example (or maybe a few) of a vtkdata file with
a velocity vector field I would be grateful!
 
Regards,
Ulrik Ullum

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<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D734272911-08052003>Hi,</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D734272911-08052003></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D734272911-08052003>I am =
practically a=20
newbie to ParaView and VTK and I am&nbsp;trying to visualize =
CFD-generated=20
or&nbsp;measured velocity vector fields on top of&nbsp;a geometry file =
exported=20
from our CAD system (VRML format). However, I find it difficult to get a =

satisfying result. Any response from somebody who has experience with =
the=20
presentation of velocity vector fields in ParaView is very welcome. Some =
of the=20
problems I struggle with are:</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D734272911-08052003></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D734272911-08052003>I =
would like to show=20
velocity vectors as thin arrows (lines) instead of the 'volume' =
representation I=20
get when I choose Glyph and Arrow0/Cone0/Sphere0 - is there another way =
to=20
display vectors than using the glyph-tool? - or can the glyph =
arrows&nbsp;be=20
modified to be lines instead of cylinders and cones?</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D734272911-08052003></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D734272911-08052003>I have =
been using a=20
vtk data format where i have a&nbsp;POLYDATA dataset with a definition =
of=20
VERTICES&nbsp;and subsequently a definition of VECTORS - this format has =
been=20
working in conjunction with another&nbsp;VTK-viewer (MayaVi), however I =
can not=20
make ParaView read my files.&nbsp;Am I doing something completely =
wrong?&nbsp;-=20
I've attached a small&nbsp;example which can be read by=20
MayaVI!</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D734272911-08052003>I have =
been able to=20
make a readable data file with the UNSTRUCTURED_GRID dataset but wonder =
why my=20
POLYDATA format doesn't succed - ParaView simply crashes=20
(WinXP).</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D734272911-08052003></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D734272911-08052003>If I =
could get a=20
working&nbsp;example (or maybe a few) of a vtkdata file with a velocity =
vector=20
field I would be grateful!</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D734272911-08052003></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D734272911-08052003>Regards,</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D734272911-08052003>Ulrik=20
Ullum</SPAN></FONT></DIV></BODY></HTML>

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# vtk DataFile Version 2.0
VTK test on CR4x2 data
ASCII
DATASET POLYDATA
POINTS 20 float
0.04782 -0.00083 -0.01710  0.04780 -0.00167 -0.01710  0.04776 -0.00250 =
-0.01710  0.04771 -0.00334 -0.01710  0.04765 -0.00417 -0.01710
0.04757 -0.00500 -0.01710  0.04747 -0.00583 -0.01710  0.04736 -0.00666 =
-0.01710  0.04724 -0.00748 -0.01710  0.04710 -0.00831 -0.01710
0.04695 -0.00913 -0.01710  0.04678 -0.00994 -0.01710  0.04660 -0.01076 =
-0.01710  0.04641 -0.01157 -0.01710  0.04620 -0.01238 -0.01710
0.04598 -0.01318 -0.01710  0.04574 -0.01398 -0.01710  0.04549 -0.01478 =
-0.01710  0.04522 -0.01557 -0.01710  0.04495 -0.01636 -0.01710

VERTICES 20 40
1    1  1    2  1    3  1    4  1    5 =20
1    6  1    7  1    8  1    9  1   10 =20
1   11  1   12  1   13  1   14  1   15 =20
1   16  1   17  1   18  1   19  1   20 =20

POINT_DATA 20
VECTORS scalars float
 1.459 -2.718  0.000   1.424 -2.775  0.000   1.317 -2.781  0.000   1.186 =
-2.805  0.000   1.065 -2.800  0.000 =20
 0.982 -2.781  0.000   0.901 -2.775  0.000   0.911 -2.776  0.000   0.793 =
-2.755  0.000   0.602 -2.713  0.000
 0.609 -2.698  0.000   0.409 -2.645  0.000   0.484 -2.637  0.000   0.277 =
-2.572  0.000   0.272 -2.536  0.000
 0.031 -2.442  0.000   0.101 -2.422  0.000   0.125 -2.387  0.000   0.041 =
-2.313  0.000  -0.244 -2.180  0.000

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