Start ParaView on OnDemand

Status: draft. Verified steps and screenshots to come.

In this lesson you will open a dataset in ParaView on a compute node, color it by a variable, and save a picture. Time: 10 minutes · Branch: Your program · Program: ParaView 6 (AMA27 ParaView module)

Why this matters

ParaView reads the formats simulation codes usually write: Exodus, VTK, NetCDF, OpenFOAM, CSV and image stacks. It can work on datasets larger than a laptop's memory. Running it on the cluster leaves the data where it was written. The compute node reads it and draws the picture, and only the picture travels to your browser.

Key idea

The pipeline. ParaView builds a picture as a chain: a reader loads the data, filters change it, and each item can be shown or hidden. The Pipeline Browser on the left is that chain. Nothing in it changes until you press Apply. Each step reads its input and writes a new output. The file on disk is left alone, and any step can be adjusted later. → Glossary: visualization pipeline

Steps

Step 1: Start ParaView

On the OnDemand dashboard choose Interactive Apps ▸ ParaView. Fill in the form as in the start lesson: AMA27 queue name, 1 hour, 4 cores. Launch, then connect.

You should see: the ParaView window in your browser, with the Pipeline Browser on the left and an empty render view in the middle.

Screenshot: the Pipeline Browser and render view, marked

Screenshot to come: ParaView's window, with the Pipeline Browser on the left and the empty render view in the middle marked

Step 2: Open the example data

Choose File ▸ Open…, click Examples in the left-hand list, select disk_out_ref.ex2 and click OK. In the Properties panel, make sure every variable is ticked, then click Apply.

You should see: a gray, roughly cylindrical shape in the render view, and disk_out_ref.ex2 in the Pipeline Browser.

Screenshot: the Open File dialog, with Examples marked

Screenshot to come: ParaView's Open File dialog, with Examples marked in the left-hand list and disk_out_ref.ex2 selected

Step 3: Move around

In the render view:

• drag with the left mouse button to rotate;
• scroll, or drag with the right button, to zoom;
• drag with the middle button (or Shift + left) to move sideways.

The Reset Camera button on the camera toolbar brings the whole object back into view.

You should see: the shape turn and move as you drag.

Screenshot: the Reset Camera button

Screenshot to come: The camera toolbar above the render view, with the Reset Camera button marked

Step 4: Color by temperature

With disk_out_ref.ex2 selected, open the coloring drop-down on the toolbar (it says Solid Color) and choose Temp. Then click Rescale to Data Range on the same toolbar.

You should see: the surface colored from cool to hot, with a color legend labeled Temp.

Screenshot: the coloring drop-down and the legend

Screenshot to come: The toolbar's coloring drop-down set to Temp, and the color legend labeled Temp in the render view

Step 5: Use a color map that doesn't mislead

In the Properties panel, find Coloring and click Choose Preset (the icon beside Edit). Search for Viridis, choose it, click Apply, then Close.

You should see: colors running from dark purple (cool) to yellow (hot). Viridis keeps the order of its colors in grayscale and for red-green color blindness, which a rainbow color map does not.

What you should see

Picture to come: The practice data as a roughly cylindrical shape colored by temperature with Viridis: dark purple where cool, yellow where hot

Screenshot: the Choose Preset dialog

Screenshot to come: The Choose Preset dialog, with Viridis typed in the search box and selected

Step 6: Save a picture

Choose File ▸ Save Screenshot…. Set the file name to ~/scratch/paraview-first.png and the size to 1600 by 1200, then click OK.

You should see: paraview-first.png in the Files app, in your scratch folder.

Screenshot: the Save Screenshot dialog

Screenshot to come: The Save Screenshot dialog, with the image size set to 1600 by 1200

Step 7: Finish

Choose File ▸ Exit to close ParaView. Then delete the session on My Interactive Sessions, as in the start lesson.

You should see: the session card gone.

Check your understanding

After choosing a new variable, the whole object is one flat color. What single click usually fixes it?

Rescale to Data Range. The color scale was still set for the previous variable's values, so every value in the new one fell at one end of it.

Where did ParaView actually run, and why does that matter for a 200 GB dataset?

On one of the cluster's compute nodes. The data is read where it already lives, and only the rendered picture is sent to your browser. The size of the file has little to do with your connection.

If something goes wrong

The ParaView family

ParaView is several programs that share one engine. The lessons use:

Next

Credits

Data: disk_out_ref.ex2, ParaView example data (Kitware/Sandia), BSD-3-Clause. ParaView is BSD-3-Clause. Menu names follow the ParaView 6.0.1 documentation. Written for SBSC; text CC-BY 4.0.