The gradient filter works specifically on image-based data. (An AMR grid is 
essentially a hierarchy of image data.) It computes the gradient by taking 
differences in the x, y, and z directions of the grid. The unstructured 
gradient filter makes no such assumption about the directionality of the edges. 
Instead, it computes the gradients within the cells and averages the results. 
The intention is to get valid results on unstructured grids, but the 
implementation actually works on any dataset object. Thus, it will work on 
image-based data, but slower (and will probably give a slightly different 
answer).

I am guessing that the warning message you are getting is only supposed to be 
outputted once, but the filter is being independently executed on each block of 
the AMR and so gives the warning each time. Rather than fix this specific 
instance, it might be better to have a smarter output window that recognizes 
when a message is repeated and reports only once with an indicator of how many 
times it was raised. Now that I think about it, it would be nice if the output 
window also cleaned up all messages to hide some of the diagnostic information 
that comes with every message (like file location). That would make 
warnings/errors more helpful in general.

-Ken

Sent from my iPad so blame autocorrect.

On Dec 24, 2014, at 6:50 PM, Scott, W Alan 
<[email protected]<mailto:[email protected]>> wrote:

What is the difference between the Gradient and Gradient Of Unstructured 
Dataset filters?  The Gradient filter puts out a few million lines of warning 
with a structured (CTH AMR) dataset, but the Gradient of Unstructured Dataset 
filter seems to work fine with structured data (once again, CTH AMR data).

Thanks,

Alan

--------------------------------------------------------
W. Alan Scott
ParaView Support Manager

SAIC
Sandia National Laboratories, MS 0822
Org 9326 - Building 880 A1-C
(505) 284-0932   FAX (505) 284-5619
---------------------------------------------------------



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