Histogram or Data Binning of a Mesh Based Plot in Visit Software

[vikramroybarc]

Subject: Help with Creating Histogram in VisIt

Hi VisIt Team,

I am a new user of VisIt, and I'm using the software for visualization and post-processing of Paradis Dislocation Dynamics files.

Below is a plot I created in VisIt using the Threshold filter on the "BurgID" variable.

Now, I would like to generate a histogram or data bins showing the Length of Segments (X-axis) vs Number of Segments (Y-axis). However, I am having trouble locating the option to do this in VisIt.

Could you please guide me on how to accomplish this?

Thank you!

Best regards,
Vikram Roy

[markcmiller86]

@vikramroybarc what you describe seems like it would have to involve the Connected Components operator. In fact, I think that operator that some built-in features for exactly the kind of curve you want to produce. Also, have a look at this tutorial about it. Have a look at those resources and if the path forward is not obvious, please reach out here again.

[markcmiller86]

@vikramroybarc VisIt's connected components features are available both as an Operator, and as a Query and as an Expression, which is demonstrated in the above referenced tutorial.

[JustinPrivitera]

You may try the data binning operator under operators/analysis

[JustinPrivitera]

let us know if you have further questions if that is the route you choose to go down.

Here are some docs on data binning from Ascent, a sister tool to VisIt: https://ascent.readthedocs.io/en/latest/Actions/Binning.html#binning

It works very similarly to how it does in VisIt, but we seem to be lacking docs on it.

[vikramroybarc]

Hi @JustinPrivitera @markcmiller86

Thankyou very much for your replies.

I think, the query connected components length gives the length of each of the indivdual meshes.

But I am unable to figure out how to add this query to data bining or to Expression as shown in the image from the visit tutorial. I think the formula of connected components length will be different.

As where use the same expression as shown in the Tutorial, I get different result from what I m getting when I use the Query -
connected components length

Max Value when I use query - 199
Max Value when I use expression conn_components(segments) - 176

Could you please help me regarding this.

Thankyou

[markcmiller86]

Apologies for not being clear...

1. Plot your Pseudocolor ccl variable as you have above
2. Do the connected components summary query.
   • That will produce a file either in ~ or in . named cc_summary.okc.
3. Open that file in VisIt
4. Open a new window in VisIt
5. Create a Histogram plot of comp_length
6. Adjust parameters of the plot in terms of bin count and mins and maxs

[markcmiller86]

output.mp4

[markcmiller86]

Regarding a discrepency in the max value reported between query and conn_components() expression, we need to try to duplicate that and report back.

[vikramroybarc]

Thank you, @markcmiller86, for your generous gesture in sharing the video tutorial. I was finally able to complete the task by following the steps outlined in the video.