[Paraview] Memory explosion and strange behaviour -- Linux -- 'clip' -- 360 MB file needs 60 GB ??

[Brian Corrie]

Hi All,

I have one question regarding this conversation, as I have run into this 
issue before. It intrigues me as to why one can't clip a structured data 
set efficiently.

http://www.paraview.org/pipermail/paraview/2012-December/026976.html

The question I have is - does clip REALLY require all that memory - in 
my case it was a structured grid of 698x693x665 growing to in excess of 
20 GB (see the question on the list above). That seems pretty excessive 
given the original size of the data set... I haven't done the math on 
the data set size of an unstructured data set, but 320MB to 20GB is a 
pretty big step.

Assuming one does need 20GB of memory for an unstructured data set of 
this size (making it impractical to use clip), is there not an 
implementation of clip that can run on structured data. This seems like 
a common operation that one would want to perform, and therefore seems 
like something that would be worth implementing for structured data.

I find a clip on a volume to be extremely useful, as you can slice 
through a plane in the data and see the internal structure of the data 
set at the clip plane location. This is a very useful exploratory 
capability. Slice just doesn't cut it (pun intended 8-) from this 
perspective...

Thanks for the interesting discussion, this one has intrigued (and 
frustrated) me for some time. I would think implementing clip on 
structured data would be possible (probably simpler than on unstructured 
data) and would be quite a useful tool for exploratory analysis of large 
gridded data sets... Am I missing something - Is there a reason why such 
a thing doesn't exist?

Brian

On 6/10/2014 4:20 AM, Utkarsh Ayachit wrote:
>> With 'clip' I wanted to see half the volume cut away, while being able relatively easily to move that cut plane up and down.
>
> You can use the "Extract Subset" filter, however that does not  give
> you an widget to play with instead you have to enter the i,j,k values
> to subset out.
>
> Alternatively if you are not interested in a volume but just a "slice"
> through the data, then you can simply change the "Representation" type
> from "Outline" or "Surface" to "Slice". You should then can move the
> slice plane using the widgets under "Slicing" group on the Properties
> Panel.
>
>> I don't quite understand what the intended purpose of 'clip' is if not this? Is it for clipping meshes then rather than clipping volume images?
>
> That is correct. Clip is intended for non structured datasets or when
> you need non-orthogonal clipped volumes but at the cost of more
> memory.
>
> Utkarsh
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