[Paraview] using vtkInformation in 3.10

[burlen]

Hi Utkarsh,

Yes, I had connected the reader or source directly to the filter with no 
other filters intervening.

I have used the keys for a number of things. In addition to passing meta 
data I also implemented dynamic load balancing in a couple of algorithms 
by passing vtkObjects. For example the demand loading strategy in our 
stream tracer expects to receive a reader object in the pipeline 
information. The reader object also implements a LRU block cache to 
reduce I/O footprint.

We've used a similar strategy to generate seed cell geometry on demand, 
where our volume source passes a cell generator object downstream in the 
pipeline information which the stream tracer uses to access any cell in 
any order (dynamic load balancing part) with a minimum communication and 
memory footprint. We did that because we  ran our of memory when both 
the source and the stream tracer had a copy of the seed geometry.

The use case I'm describing is the generation of topographic maps of the 
magnetosphere which in the 3D case requires 10's of millions of stream 
traces and the seed geometry is colored in the mapper output. Dynamic 
load balancing of the stream tracing provides a nice speed up.

The vtkPVPostFilter looks to add nice new features to extracting 
components form vectors and converting cell to point data and so on. I 
do see why PV can't copy keys from input to output blindly.  But, do you 
think vtkPVPostFilter could copy the information from input to output as 
well? It doesn't after all modify the existing arrays or geometry (if 
I'm reading it right it only adds arrays if they are requested).? Or is 
there another work around that would get our filters working again?

Thanks
Burlen

On 05/05/2011 05:51 AM, Utkarsh Ayachit wrote:
> Burlen,
>
> Keys are not propagated by pipeline by default. So your approach would
> only work when there's no other filter between the reader and your
> filters. With ParaView 3.10, vtkPVPostFilter get inserted always into
> the pipeline after every algorithm. As a result your keys maybe
> getting eaten up by the post-filter.
>
> What keys are these?
>
> Utkarsh
>
> On Wed, May 4, 2011 at 10:35 PM, Burlen Loring<bloring at lbl.gov>  wrote:
>> Hi All,
>>
>> I have a reader that gets the information object from it's output and adds
>> some keys for downstream filters to use. This recently stopped working with
>> version 3.10. Can anyone shed some light on what might have caused the
>> change in behavior in version 3.10? Was this a deliberate change?
>>
>> Thanks
>> Burlen
>>
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