View source for ParaView/Displaying Data

The goal of visualization is to generate representations of the data in
a visual form. In this chapter we will see different mechanisms available in
ParaView to look at the data to gain insight into it.

==Views==

When the ParaView application starts up, one sees a 3D viewport with
an axes at the center. This is a ''View''. In ParaView, ''Views'' are frames in
which the data can be ''seen''. There are different types of views. The default
view that shows up is a ''3D View'' which shows rendering of the geometry
extracted from the data or volumes or slices in a 3D scene. You can change the
default view '''Settings''' dialog (Edit | Settings (in case of Mac OS X,
ParaView | Preferences)).

[[Figure 1]]

There maybe parameters that are available to the user that control how the data
is displayed e.g. in case of 3D View, the data can be displayed as wireframes or
surfaces, you choose to change the color of the surface or use a scalar for
coloring etc. All these options are known as ''Display'' properties and are
accessible from the '''Display''' tab in the '''Object Inspector'''.

Since there can be multiple datasets shown in a view, as well as multiple views,
the '''Display''' tabs shows the properties for the active pipeline object
(changed by using the Pipeline browser, for example) in the active view.

==Multiple Views==

ParaView supports showing multiple views side by side. To create multiple views,
simply use the controls on the top-right corner of the view to split the frame
vertically or horizontally. You can even maximize a particular view to
temporarily hide other views. Once a view-frame is split, you will see a list of
buttons showing the different types of views that you can create to place in
that view. Simply click the button to create the view of your choice.

[[Figure 2]]

Some filters, such as '''Plot Over Line''' may automatically split the view
frame and show the data in a particular type of view suitable for the data
generated by the filter.

===Active View===

Once you have multiple views, the active view if indicated by a colored border
around the view frame. Several menus as well as toolbar buttons affect the
active view alone. Also they may become enabled/disabled based on whether that
corresponding action is supported by the active view.

The '''Display''' tab affects the active view. Similarly, the ''eye icon'' in
the '''Pipeline Browser''' next the pipeline objects, indicates the visibility
state for that object in the active view.

When a new filter or source or reader is created, it will be displayed by
default in the active view, if possible (otherwise, if may create a new view).


==3D View==

3D View is used to show the surface or volume rendering for the data in a 3D
world. This is the most commonly used view type. 

When running in client-server mode, 3D View can render data either by bringing
the geometry to the client and then rendering it there or by rendering it on the
server (possibly in parallel) and then delivering the composited images to the
client. Refer to the '''Client-Server Visualization''' chapter for details.

===Interaction===

Interacting with the 3D view will typically update the camera. This makes it
possible to explore the visualziation scene. The default buttons are as follows,
they can be changed using the '''Application Settings''' dialog.

{|Modifier | Left Button | Middle Button | Right Button
|-
|          | Rotate      | Pan           | Zoom
| Shift    | Roll        | Rotate        | Pan
| Control  | Zoom        | Rotate        | Zoom
|}

This view supports selection. One can select cells or points either on the
surface or those within a frustum. Selecting cells or points makes it possible
to extract those for further inspection or label them etc.

===View Settings===

The view settings dialog accessible through the Edit | View Settings menu or the
tool button on the left-corner of the view is used to change the view settings
per view. 

====General====

This tab allows the user to choose the background color. One can use a solid
color or a gradient or even a background image.

By default the camera uses perspective projection. To switch to parallel
projection, check the "Use Parallel Projection" checkbox in this panel.

====Lights====

The 3D View requires lights to illumniate the geometry being rendered in the
scene. Once can control these lights using this pane.

====Annotation====

The annotation pane enables controlling the visibility of the center axes and
the orientation widget.

===Display Properties===

-------  View  --------------------
|   Control | Use
|-  View    | Checkbox to toggle the visibility of the data in the active view.
|-  Selectable | Checkbox to toggle whether the data gets selected when using
the selection mechanisms
|- Zoom to Data | Zooms the camera to show the data in the active view

-------- Color -----------------------
| Interpolate Scalars | If on, the scalars will be interpolated within polygons
and the scalar mapping happens on per pixel basis. If off, then color mapping
happens at points and colors are interpolated which is typically less accurate.
This only affects when coloring with point arrays. Has no effect otherwise.
| Map Scalars | If the data array being color with can be directly interpreted
as colors then one can uncheck this to not use any lookup table. Otherwise, when
on, a lookup table will be used to map scalars to colors.
| Apply Texture | Makes is possible to apply a texture over the surface. This
requires that the data has texture coordinates. Once can use filters like
'''Texture Map to Sphere''', '''Texture Map to Cylinder''' or
'''Texture Map to Plane''' to generate texture coordinates when not present in
the data. To load a texture, select '''Load''' from the combo-box which will
popup a dialog allowing you to choose an image. Otherwise pick from already
loaded textures listed in the combo-box.
| Color By | This enables coloring of the surface/volume. Either choose the
array to color with or set the solid color to use. When volume rendering, solid
coloring is not possible, one has to choose the data array to volume render
with.

-------------Slice ---------

These setting are only available when showing a slice of an uniform grid
dataset. Allows the user to pick the slice direction as well as the slice
offset.

------------ Annotation----------

Cube axes is a annotation box that can be used so show a scale around the
dataset. Use the '''Show cube axes''' checkbox to toggle its visibility. You can
further control the apperance of the cube axes by clicking '''Edit''' once the
cube-axes is visible.

[[Image:Cube Axes.png]]

==2D View==

2D View is similar to 3D view except that it can only show slices from uniform
grid datasets. The interaction is also limited to a 2D place i.e. rotation is
not available.

===Interaction===

===View Settings===

===Display Properties===

==Spreadsheet View==

Spreadsheet View is used to inspect the raw data in a spreadsheet. When running
in client-server mode, to avoid delivering the entire dataset to the client for
displaying the spreadsheet (since the data can be very large), this view streams
only visible chunks of the data to the client. As the user scrolls around the
spreadsheet, new data chunks are fetched.

Unlike some other views, this view can only show one dataset at a time. For
composite datasets, it shows only one block at a time. One can pick the block
to show using the '''Display''' tab.

===Interaction===

* Choosing attributes to show
* Sorting
* Selection
* Show selected only

===View Settings===

Currently, no user settable settings are available for this view.

===Display Properties===

==Line Chart View==

===Interaction===

===View Settings==

===Display Properties===

==Bar Chart View==

===Interaction===

===View Settings==

===Display Properties===