[Paraview] Problem reading/using STRUCTURED_GRID data

[Berk Geveci]

I think what Ken is recommending against using the color map defined
in a VTK file. ParaView has its own way of loading custom color maps
defined as XML files.

-berk


On Mon, Aug 18, 2008 at 11:27 AM, Phil Goddard <philgoddard at telus.net> wrote:
>
> If I read you correctly then you're saying that using (or at least loading)
> a custom color map is not recommended as it may lead to unexpected results.
> That seems strange for a visualization package.
>
> That being said, I have upgraded to the latest version, and the default
> lookup table is fine for my initial purposes.
>
> Thanks
> Phil.
>
>> -----Original Message-----
>> From: Moreland, Kenneth [mailto:kmorel at sandia.gov]
>> Sent: August 18, 2008 6:34 AM
>> To: Phil Goddard; paraview at paraview.org
>> Subject: RE: [Paraview] Problem reading/using STRUCTURED_GRID data
>>
>>
>> First, let me recommend that you update your version of
>> ParaView (which you can download from www.paraview.org).
>> Version 2.4 was released several years ago and is no longer supported.
>>
>> That said, I see that the behavior you describe also exists
>> in the latest released version (3.2).  It looks like the data
>> file is defining a lookup table with a domain from 0 to 1.
>> You can fix the problem by simply not defining a lookup table
>> for the data in the file.  Change the line "LOOKUP_TABLE lut"
>> to "LOOKUP_TABLE default" and the ParaView lookup table will
>> be used as expected.  You can also delete the entire
>> LOOKUP_TABLE section at the bottom of the file.
>>
>> Why the lookup table defined in the file is scaling from 0 to
>> 1 and how to get past that, I don't know.  Personally, I
>> don't use this feature and don't recommend it to any ParaView
>> users because it has dubious value and usually leads to
>> confusing results (as you have just found).  If you really
>> care about this feature, you should bring it up with the
>> vtkusers list.
>>
>> -Ken
>>
>> > -----Original Message-----
>> > From: paraview-bounces at paraview.org
>> > [mailto:paraview-bounces at paraview.org]
>> > On Behalf Of Phil Goddard
>> > Sent: Sunday, August 17, 2008 11:38 PM
>> > To: paraview at paraview.org
>> > Subject: [Paraview] Problem reading/using STRUCTURED_GRID data
>> >
>> >
>> > I'm attempting to use Paraview for the first time, and
>> trying to get a
>> > feel for it by reading in a simple sample data set.
>> > However the results are not as I expect and I'm wondering
>> if someone
>> > could give me some idea of what I am doing wrong.
>> > I'm using version 2.4, release 4 from the CD that comes
>> with the VTK
>> > Users Guide (VTK 5.0.4) on Windows 2000.
>> > My data file is appended below.
>> >
>> > From my understanding of my .vtk file I expect to see all points at
>> > z=0 as red, z=1 as green and z=2 as blue.
>> > What I actually see is the points at z=1 being blue (z=0
>> and z=2 are
>> > red and blue respectively).
>> >
>> > If I use a probe to look at the data, those at z=1 seem to have a
>> > value of
>> > 1
>> > as I expect.
>> >
>> > If I change the Representation to Surface then the sides of
>> the cube
>> > have the colours
>> > 0<red<0.33
>> > 0.33<green<0.66
>> > 0.66<blue<2
>> >
>> > Also, if I display the Scalar Bar and set its Resolution
>> property to 3
>> > then I get a Scalar Bar showing 0<blue<0.66<green<1.33<red<2.
>> > This is the reverse of the lookup table that I have read in.
>> >
>> > So several questions:
>> > 1. Why when viewed as points are those at z=1 not green?
>> > 2. Why when viewed as a Surface do I get the colors described above?
>> > 3. Why does the Scalar Bar have the colours reversed (from
>> what I expect)?
>> >
>> > Much appreciated
>> > Phil.
>> >
>> >
>> > %%%%%%%%%%%% CUT HERE %%%%%%%%%%%%%%%% # vtk DataFile
>> Version 2.0 Test
>> > data for a cube in 3D space ASCII
>> >
>> > DATASET STRUCTURED_GRID
>> > DIMENSIONS 3 3 3
>> > POINTS 27 float
>> > 0 0 0
>> > 1 0 0
>> > 2 0 0
>> > 0 1 0
>> > 1 1 0
>> > 2 1 0
>> > 0 2 0
>> > 1 2 0
>> > 2 2 0
>> > 0 0 1
>> > 1 0 1
>> > 2 0 1
>> > 0 1 1
>> > 1 1 1
>> > 2 1 1
>> > 0 2 1
>> > 1 2 1
>> > 2 2 1
>> > 0 0 2
>> > 1 0 2
>> > 2 0 2
>> > 0 1 2
>> > 1 1 2
>> > 2 1 2
>> > 0 2 2
>> > 1 2 2
>> > 2 2 2
>> >
>> > POINT_DATA 27
>> > SCALARS CubeData float 1
>> > LOOKUP_TABLE lut
>> > 0.0
>> > 0.0
>> > 0.0
>> > 0.0
>> > 0.0
>> > 0.0
>> > 0.0
>> > 0.0
>> > 0.0
>> > 1.0
>> > 1.0
>> > 1.0
>> > 1.0
>> > 1.0
>> > 1.0
>> > 1.0
>> > 1.0
>> > 1.0
>> > 2.0
>> > 2.0
>> > 2.0
>> > 2.0
>> > 2.0
>> > 2.0
>> > 2.0
>> > 2.0
>> > 2.0
>> > LOOKUP_TABLE lut 3
>> > 1.0 0.0 0.0 1.0
>> > 0.0 1.0 0.0 1.0
>> > 0.0 0.0 1.0 1.0
>> > %%%%%%%%%%%% CUT HERE %%%%%%%%%%%%%%%%
>> >
>> >
>> > _______________________________________________
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>> > ParaView at paraview.org
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>>
>>
>>
>
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