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-   -   Paraview's "read-values" capability (http://www.cfd-online.com/Forums/openfoam-post-processing/113638-paraviews-read-values-capability.html)

VSass February 23, 2013 15:40

Paraview's "read-values" capability
 
Hey lads,

i have these values in one of my results files for p :

83333.29727559452
83333.29727116377
83333.29728432324
83333.29726004707
83333.29726903667
83333.29726512189
83333.2972572857
83333.29729613037
83333.29731830103
83333.29732028065 and many more for all the points in the grid.

As you can see, the difference starts from the fourth significant digit and there is a difference in the values, but paraview plots only two values, 83333.306514 for max and 83333.290024 for min, and not the intermediate values. It just show two colours, blue for the min and red for the max.

Why it doesn't plot the other values???

wyldckat February 23, 2013 17:32

Greetings VSass,

Actually, it's not the 4th significant digit, it's the 9th! ;)

ParaView has some issues with precision, which AFAIK is due to hard-coded limits in the source code.
If you do need to see the results with more precision, you will have to rescale values. Some possible options:
  • Subtract the reference value "83333" to the "p" field. This way you increase colour resolution, as long as the rest of the field has similar values.
  • You can also try increasing the colour mapping... and label ranges and so on... but I'm not sure if this is what you need.
  • Last but not least, you can modify ParaView's source code and rebuild from source. If you do need to do this, I suggest you try asking in ParaView's mailing list: http://www.paraview.org/mailman/listinfo/paraview
In addition, it would help to know how you loaded the values into ParaView.

And have you tried the "spreadsheet view"? http://www.paraview.org/Wiki/ParaVie...readsheet_View - this way you can confirm if ParaView has actually loaded those values you listed!

Best regards,
Bruno

VSass February 23, 2013 20:36

Thanks Bruno,

i'm working on setting the reference value for p right now, and see if this works.
I've checked the spreadsheet view, values are loaded with exact precision on each point, that's why i was so concerned for the colour mapping.

Thanks a lot!

VSass February 24, 2013 14:27

Bruno,

i didn't exactly caught your advise of how to subtract the reference value 83333.3. You meant rescaling from the colour map?

Anyway,this is the last step before entering to the source code, 'cause nothing else seems capable of solving the matter.

wyldckat February 24, 2013 16:02

Hi VSass,

Sorry, I thought you knew. You can use the "Calculator" filter: http://www.paraview.org/Wiki/ParaVie...ide/Calculator

Best regards,
Bruno

wyldckat March 24, 2013 15:08

Quick update: there was an answer in the ParaView mailing list: http://markmail.org/message/pwhpq2p6kdsdvayy


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