[Paraview] Manually set UGrid point IDs for time-series plotting?

[Eric Monson]

Hey Dave,

I have now been able to successfully use the SetGlobalIds() method for  
my vtkUnstructuredGrid PointData, but there seem to be some issues  
with reading the *.vtu files into ParaView properly.

ParaView recognizes that there are Global Ids set (the Use Global Ids  
check box becomes available in both the Plot Point Over Time and the  
Selection Inspector), but they don't seem to be valid for some reason.  
For example, when points are selected, the Selection Inspector shows  
the Index for the points, but if you check Use Global Ids the list  
goes blank (and plotting using these Global Ids doesn't work, and in  
the Selection Inspector if you try to uncheck Use Global Ids, ParaView  
crashes).

ExodusII files seem to work fine in all these cases, but not VTK XML  
Unstructured Grids. If I save either box.ex2 or can.ex2 as a vtu file,  
then reload it, PV behaves just like with my data. (In case it helps,  
I noticed that the global IDs' Data Type are listed for ex2 files as  
"idtype", while they are listed as "int" for an unstructured grid  
loaded from a vtu file.)

Any clues as to where the problem might lie (me, VTK, ParaView...)?

Thanks,
-Eric


On Dec 13, 2007, at 11:04 AM, David E DeMarle wrote:

> Hello,
>
> vtkDataSetAttributes::SetGlobalIds(vtkDataArray*da) will flag the
> array of ids as "the ids" and then the plot over time filters will be
> able to use them instead of using the index into the cell/point
> arrays.
>
> hth,
> Dave DeMarle
>
> On 12/13/07, Eric Monson <emonson at cs.duke.edu> wrote:
>> Hello,
>>
>> I'm wondering if there is any way of manually setting point ID values
>> within a vtkUnstructuredGrid? (I'm using Python to populate a UGrid
>> from HDF5 data and then writing to *.vtu and *.pvd files for multiple
>> time steps.)
>>
>> I'm visualizing a time series of points diffusing in a space, where
>> some particles appear and disappear over time. This presents a  
>> problem
>> when I want to plot with Extract Points Over Time, because the point
>> "index" that ParaView sees isn't consistent (doesn't correspond to a
>> single particle) over the whole time series.
>>
>> I have a scalar array of IDs associated with the point data, which I
>> successfully use with John Biddiscombe's Temporal Trails Filter  
>> (since
>> it has an option for using a scalar array for ID), but I don't know
>> how to use that same info for XY plotting.
>>
>> I see that the ExodusII reader puts some global ID info into a
>> vtkModelMetadata object and packs it into the UGrid field data.  
>> (Then,
>> I'm guessing that the Extract Points Over Time might be able to sense
>> this and "un-grey" the Use Global Ids check box...?) Is there any
>> other way (besides using a vtkExodusIIReader) to do the equivalent
>> process, such that the info will be viewable by the plotting  
>> routines?
>>
>> Thanks a lot,
>> -Eric
>>
>> -----------------------------------------------------
>> Eric E. Monson
>> Duke Visualization Technology Group
>>
>>
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