9. Multiblock Inspector

Composite datasets (Section 3) such as partitioned dataset collections, multiblock datasets and AMR are often encountered when visualizing results from several scientific simulation codes e.g. OpenFOAM, Exodus, etc. Readers for several of these simulation file formats support selecting which blocks to read. Additionally, you may want to control display properties such as visibility, color, color array, use separate color map, interpolate scalars before mapping, opacity, and map scalars for individual blocks or sub-trees. You can use the Multiblock Inspector panel for this.

Fig. 9.1 shows the Multiblock Inspector showing the hierarchy from an Exodus dataset. The panel tracks the active source and reflects the structure for the data produced by the active source. The display properties reflect their state in the active view.

Fig. 9.1 The Multiblock Inspector

To show or hide a block you have to click on the checkbox next to the block name. Toggling the visibility of a non-leaf block, affects the visibility of the entire sub-tree.

The first column reflects the state of all properties used for the block. and the second column is a reset button that allows you to reset all properties for the block to the default values. Block properties can be specified in multiple ways. First, you can choose to not use any block specific overrides and simply let the default display properties ( Section 4.3) affect the rendering. This is the default behavior. When that is the case for any block, it is indicated in the state column with , if no block is selected, and with if a block is selected. Second, you can explicitly override the display of any block or a subtree. To do this, simply select a block or blocks in the multiblock inspector, and change any display property as you would in the Properties panel. Upon changing any property, the state column will reflect the change. If the property is set for the block, the state column will show . When an explicit property is set on a non-leaf node, all its children (and their children) inherit that property unless explicitly overridden. For such nodes that have a property inherited from their parent, we use the icon . Since a block has many properties, or many blocks might have been selected, we also show a few more icons to capture all possible states. is shown when at least one property is inherited from block(s) and the representation. is shown when at least one property is explicitly set and inherited from the representation. is shown when at least one property is explicitly set and inherited from the block(s). is shown when at least one property is explicitly set and inherited from block(s) and the representation.

Each property or widget that captures a collection of properties also has a state icon and a reset button specific to that property or collection of properties.

Did you know?

In most cases with multiblock datasets, ParaView uses the vtkBlockColors array for coloring. This is an array filled with discrete values so that each block can be colored using a different color. That makes it easier to visually see each of the blocks in the view.

Besides using the Multiblock Inspector to set color and opacity overrides for blocks, you can also directly change these parameters from the Render View itself. Simply right-click in the render view on the block of interest and you’ll get a context menu, Fig. 9.2, that allows changing some block properties and more.

Fig. 9.2 Context menu in Render View can be used to change block display properties.

Another useful feature with the Multiblock Inspector is selection. If you simply click on any row in the inspector, you will select the block (or subtree) and the active view will highlight the selected block(s). Conversely, if you make a block-based selection in the active Render View using or , you will see the corresponding blocks highlighted in the Multiblock Inspector panel.