[Paraview] Comparing results computed with 2 different meshes

[Evan Kao]

> No, that appears to not be the case in a quick test I ran. They appear
> to be ordered in the order in which they appear in the pipeline
> browser..


Unfortunately, it doesn't seem like it follows that order either (in a
quick test I did using Python Calculator).  Perhaps it's random?  I also
tried at the documentation for
vtkProgrammableFilter<http://www.vtk.org/doc/nightly/html/classvtkProgrammableFilter.html#details>but
couldn't find any answers (though I could've missed something).  For
the Python Calculator, this might not be as big a deal since you can
quickly check the output, but it seems more cumbersome to check in the
Programmable Filter (at least for me - I don't have much experience with it
or Python generally).  Is there an easy method to check with the
Programmable Filter?

- Evan


On Mon, Feb 3, 2014 at 5:12 AM, Cory Quammen <cory.quammen at kitware.com>wrote:

> On Fri, Jan 31, 2014 at 1:04 PM, Evan Kao <tossin at gmail.com> wrote:
> > Thanks a lot for the help.  I think Merge Blocks > Resample With Dataset
> >
> > Python Calculator (or Append Attributes > Calculator) allows me to do
> what I
> > originally asked for, although now I'm realizing the Python Calculator
> may
> > not be enough to do the calculations I want.  I had some questions
> regarding
> > the Python Calculator and the Programmable Filter:
> >
> > 1.  The data I'm looking at is from a transient simulation.  If I wanted
> to
> > standardize a parameter for each time step by dividing it by the standard
> > deviation of the population for that time point, am I understanding
> > correctly that I would either have to calculate the standard deviation
> first
> > and then manually type in the number into the Python Calculator or use
> the
> > Python Programmable Filter?
> >
> > 2.  Additionally, I've been looking around and it seems the only way to
> > perform a summing operation is to use the Programmable Filter.  Is that
> > correct?
>
> For doing anything mildly complicated like summing data arrays, you're
> probably better off with the Programmable Filter. You might
> theoretically be able to use the Python Calculator, but you'll have
> some long expressions to fit into that small Expression line.
>
> > 3.  Regarding both the Python Calculator or Programmable Filter, is
> there an
> > easy way to tell which index corresponds to which input?  I thought
> perhaps
> > it had to do with just order you click the inputs in, but I'm not so sure
> > about that.
>
> No, that appears to not be the case in a quick test I ran. They appear
> to be ordered in the order in which they appear in the pipeline
> browser..
>
> > Thanks for your time,
> > Evan
> >
> >
> > On Thu, Jan 30, 2014 at 12:25 PM, Cory Quammen <cory.quammen at kitware.com
> >
> > wrote:
> >>
> >> On Thu, Jan 30, 2014 at 2:31 PM, Evan Kao <tossin at gmail.com> wrote:
> >> > Hi Cory,
> >> >
> >> > Thanks for the suggestion.  Resample With Dataset solves the problem
> of
> >> > matching up the Point IDs, but only passes data from the Input (which
> I
> >> > guess makes sense given its purpose), so I think regardless of what I
> >> > rename
> >> > the arrays, the data will always be from only one of the meshes
> meaning
> >> > I
> >> > can't use Calculator to compare the data.
> >>
> >> How about using Append Attributes to combine the arrays of Resample
> >> With Dataset and the Source?
> >>
> >> > I think my main obstacle is the data type.  Paraview reads in Ensight
> >> > data
> >> > as a Multi-Block data set, but neither Append Datasets nor the Python
> >> > Calculator seem to work on that data type.  Is there a simple way to
> >> > convert
> >> > them into a format that can be read by those filters?
> >>
> >> You can use Merge Blocks to combine all the blocks in a Multi-Block
> >> data set to an unstructured grid.
> >>
> >> Best,
> >> Cory
> >>
> >> > Thanks,
> >> > Evan
> >> >
> >> >
> >> > On Thu, Jan 30, 2014 at 6:10 AM, Cory Quammen <
> cory.quammen at kitware.com>
> >> > wrote:
> >> >>
> >> >> Evan,
> >> >>
> >> >> You might want to take a look at the Resample With Dataset filter.
> One
> >> >> of your meshes would be the Input and one would be the Source. What
> >> >> this filter will do is sample the data values in the Input mesh at
> the
> >> >> locations of points in the Source. If I understand the setup of your
> >> >> meshes, this should essentially take care of the problem where your
> >> >> point IDs are not the same. The result will be a single mesh with two
> >> >> data arrays that you can then compare point by point.
> >> >>
> >> >> You might run into a problem if both meshes use the same name for the
> >> >> point array from which you want to get values (one will clobber the
> >> >> other). You can take care of that by using the Calculator to rename
> >> >> one of the mesh's arrays, then using the result of the calculator as
> >> >> the Input or Source.
> >> >>
> >> >> Hope that helps,
> >> >> Cory
> >> >>
> >> >> On Mon, Jan 27, 2014 at 4:18 PM, Evan Kao <tossin at gmail.com> wrote:
> >> >> > Hello all,
> >> >> >
> >> >> > I'm trying to compare the results of 2 CFD simulations (which are
> >> >> > imported
> >> >> > into Paraview as Ensight data) point-by-point but I'm having
> trouble
> >> >> > figuring out how to even combine the data into a single Pipeline
> >> >> > object
> >> >> > so
> >> >> > that I can do some simple calculations with the Calculator Filter.
> >> >> > I'd
> >> >> > appreciate it if anyone could let me know if what I'm trying to do
> is
> >> >> > natively possible in Paraview, and if not, provide some suggestions
> >> >> > on
> >> >> > how
> >> >> > to approach it.
> >> >> >
> >> >> > What might complicate the process is that the results were obtained
> >> >> > using
> >> >> > two different meshes (in fact, it's a mesh comparison test).  The
> >> >> > points
> >> >> > I
> >> >> > want to look at are the same for both meshes, but the point IDs are
> >> >> > different.
> >> >> >
> >> >> > So what I'd like to do in summary is:
> >> >> > 1) Is there a way to extract and sort the data in a way such that
> the
> >> >> > point
> >> >> > IDs are the same for both meshes?
> >> >> >
> >> >> > 2) Is there a way to convert/manipulate the data into a single
> >> >> > Pipeline
> >> >> > object for comparison?  Or to compare the results of different
> >> >> > Pipeline
> >> >> > objects?  I've tried various combinations of filters like
> >> >> > AppendDatasets,
> >> >> > GroupDatasets, and MergeBlocks with little success.
> >> >> >
> >> >> > Thanks,
> >> >> > Evan
> >> >> >
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