[Paraview] Slow with just 1M cells

[Moreland, Kenneth]

Michele,

I took a look at the data you sent me. I experienced many of the issues you brought up.

After taking a closer look at the data, I realized that many of the cells in your data are of the general polyhedral type. Unlike the standard cell shapes like tetrahedron and hexahedron, polyhedral shapes are general polyhedra formed by specifying the face polygons. They allow you to specify any flat faceted shape, but computing basic operations on them such as interpolations, derivatives, and location finding is very expensive. This is why operations like streamlines are going so slowly.

If the cells are represented as standard shapes, things go much faster. For example, if you tetrahedralize the data, streamlines takes well under 10 seconds. That gets the operations to about the range where your nameless commercial product is running. I suspect, but cannot verify, that this other visualization package is probably downgrading the cells to something like hexahedra, which makes it run faster.

I don’t recommend running the tetrahedralization filter all the time on your data. It is also slow and really bloats the data. If you could write out an alternate form of the data that wrote hexahedra instead of polyhedra, I suspect things would run much faster. You would probably have a problem with faces not being aligned, though.

One final note, although the clip filter is taking a long time, I found the slice filter to be much faster. Generally, when dealing with large data, you should favor slice over clip. It’s much faster, uses much less memory, and usually gives you the same information.

-Ken

On 5/21/16, 9:47 AM, "Moreland, Kenneth" <kmorel at sandia.gov> wrote:

>Michele,
>
>Taking over a minute to process a data set with 1 million cells does seem like an unreasonably long time, even for a moderately powered PC. Perhaps something odd is happening here. Can you describe in more detail what your data look like and what you are doing with them?
>
>-Ken
>
>On 5/20/16, 11:55 AM, "ParaView on behalf of Michele Battistoni" <paraview-bounces at paraview.org on behalf of michele.battistoni at unipg.it> wrote:
>
>>Paraview is awesome for lots of functionalities, however I find it extremely slow in processing data with any filter type, or in changing timestep as soon as the model size is around one million cells or above. I have experience with a commercial tool which on the same model and pc is 100x faster. Let's say a second vs. a min!
>>
>>Is there any specific settings for ram of parallelization among cores?
>>
>>Thanks 
>>Michele
>>
>>
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