Each time a data set is opened from a file, a source is selected, a filter is applied, or an existing reader, source, or filter (hereafter simply referred to as filter) is selected in the Pipeline Browser, ParaView updates the Object Inspector for the corresponding output data set. The Object Inspector has three tabs. In this chapter we are primarily concerned with the Properties tab, which you use to specify the parameters of the given filter. The Display tab gives you control over the visual characteristics of the data produced by the filter as displayed in the active view and the Information tab presents meta-information about the data produced by the filter.
From the Properties tab, you can modify the parameters of the reader, source, or filter being used to load or create a new data set. A filter that extracts an isocontour will have a control with which to set the isovalue to extract at for example. The controls and information provided on the tab are dependent upon the reader, source, or filter selected in the Pipeline Browser; these features are located below the row of buttons labeled Apply, Reset, Delete and ? (Help).
When a reader, source, or filter is first selected, the associated data set is not immediately created. By default (unless you turn on Auto-Accept in ParaView‚Äôs options) it will not happen until the Apply button is pressed. Pressing the Apply button passes the values on the Properties tab to the data processing engine. When the values of the user interface controls located below the row of Apply, Reset, and Delete buttons do not match the values of the underlying data set, the Apply button will be highlighted (in blue or green depending on your operating system). This is the case when a reader, source, or filter is first added to the visualization pipeline or when the value of at least one of the user interface controls on the Parameters tab has been modified. This delayed acceptance behavior is essential when working with large data sets, for which any given operation may not complete until after a significant delay.
Beside the Apply button is the Reset button. It sets the GUI controls for this data set to the state they were in the last time Apply was pressed. If Apply has not been pressed yet, the controls are set to their initial values for this data set. Apply and Reset allow you to review changes you make to filter settings before they become active. If you make a mistake and Apply a change that you do not like, you can use the Undo button on the Undo/Redo toolbar to reverse the action. You can in fact undo all the way to the beginning of your ParaView session and redo back up to your most recent Apply.
Pressing the Delete button (beside the Reset button) when it is enabled removes the current filter (that selected in the Pipeline Browser) from the visualization pipeline. If the output of that filter is being used as the input to another filter, the Delete button will be disabled. To delete a data set that is in such a state, all filters that are using it as input must be deleted first. If you wish to delete all of the data sets currently loaded in ParaView instead of just the current data set, select Delete All from the Edit menu.
The specific parameter control widgets vary from filter to filter and sometimes vary depending on the exact input to the filter. In all cases the widgets give you control over exactly what the filter does. If you are unsure of what a filter does or what the controls do, hit the ? button to the right of the Delete button to open up the documentation for that filter.
Note that ParaView attempts to provide reasonable default settings for the parameter settings and to some extent guards against invalid entries. A numeric entry box will not let you type in non-numerical values for example. Sliders and spin boxes also typically have minimum and maximum settings beyond which they cannot be moved. Note that in most cases, when there is a numeric entry beside the widget, you can exceed those ranges if you need by typing in any value manually.
Some filters have additional controls that you work with directly in the View windows. Take the Slice filter for example. Slice extracts slices from the data that lie on a set of parallel planes in oriented in space. You can use textual widgets on the Display Tab to manually specify the exact location and orientation of the slice planes but you often do not need such exact control and it is faster then to orient the slice planes visually. You can do that very easily by clicking on and dragging a 3D Plane widget in the 3D scene.
In the same way that sliders and numeric entry boxes in the Properties tab always stay in synch, the orientation of the drawn plane and the widgets in the Properties tab are always kept in synch too. Again, changes you make with 3D widgets do not take effect until you hit accept and can be undone via the Reset and Undo buttons. For more information about the various widgets, refer to Chapter <????>