Comparison Viewer Workspace

In the comparison viewer workspace, users can view one or more images and perform various image manipulation tasks. The viewer workspace allows compositing of multiple layers for analysis. The following diagram shows an example Viewer workspace:

The comparison viewer workspace has the following components:

• Layer Controls panel: The layer control panels contains a list of GUI controls for each layer and a toolbar of buttons at the bottom. The layer GUI controls allow the user to adjust the properties of each individual layer. The toolbar buttons allow the user to open data from files or the cart, add and remove layers, and change the order of the layers. The layers are ordered from top to bottom (the same order that they are composited together). By default, the layers control frame is docked to the left-side of the main application window. The layer controls frame can be docked anywhere on the main frame or can be completely undocked. A detailed view of the layer control panel toolbar is shown below:

• Data display canvas: The data display canvas contains a panel for displaying the composited layers and a toolbar for manipulating the layers. Users can load data into the data display canvas and then they can apply different transformations such as repositioning, scaling and rotation. Users can zoom in/out to view details of the image and switch between dual view or single view options by clicking on the Dual View button. By default, the image display shows the fullscreen view.

Layers Control Panel

Showing/hiding layers

Users can show/hide different layers in the main display by clicking on the green checkbox button located on the top right side of each layer GUI in the layer control panel.

Opening a File

To open data from a file, select the dropdown menu of the Open File button in the layer controls toolbar menu. A list of rendering plugins will be displayed, as shown below. Clicking the Open File button itself will automatically use the last chosen plugin.

• Opening 2D image: Click on Open File > 2D image(s). The system displays an open file dialog window in which the user can specify the 2D image file. Any errors encountered while opening the image are displayed in a pop-up window. If the file is successfully loaded, the system will load the image into a layer and add a GUI layer control to the layers control panel. See the 2D image(s) plugin documentation for more detailed information. Following is an example error message:

• Opening 3D volume file: Click on Open File > 3D volume(s). The system displays an open file dialog window in which the user can specify the 3D volume file. Any errors while encountered while opening the image are displayed in a pop-up window. If the file is successfully loaded, the system will load the image into a layer and add a GUI layer control to the layers control panel. See the 3D Volume(s) plugin documentation for more detailed information.
• Opening 3D atlas: Click on Open File > 3D atlas. The system displays an open file dialog window in which the user can specify the .atlas file to use. System displays an error in a pop-up window if the user does not select an .atlas file. If the file is successfully loaded, the system will load the image into a layer and add a GUI layer control to the layers control panel. See the 3D Atlas plugin documentation for more detailed information. Following image shows the error that is displayed:

Opening data from the cart

• To open a cart item, select the object(s) in the cart and click on the Open button located at the bottom of the cart manager window. Clicking on this button will display a drop-down list. Based on the type of the object, select the appropriate 'Open' option from the list. For example, for opening a 2D image, select "Open 2D image(s)" option. The system should now start loading the object into currently active viewport. While loading is in progress, a progress update window is displayed to the user.
• System behavior on error conditions is as follows:
  • Load error: The errors encountered while opening a cart object are displayed in a pop-up window. Following diagram shows an example of such type of errors:

• • Incorrect image type selection: This type of error happens if the user selects an image type from the Open dropdown list that does not match with the type of the cart object. For example, selecting a "Image 2D" type object from the cart, and trying to open it with "Open 3D volume(s)" option will cause this error. The system should display the error message in a pop-up window in this case.

Adding/Removing layers

• Adding a new empty layer:
  • Users can add empty layers using the Add button located at the bottom in the layer control toolbar. Select the dropdown menu of the Add button in the layer controls toolbar menu. A list of rendering plugins will be displayed. Upon selection, the system will create an empty layer of the selected type and add a GUI layer control to the layer control panels section. Clicking the Add button itself will automatically add an empty layer with the last chosen plugin. Not all rendering plugins allow adding data to an existing or new layer so consult the plugin documentation for more detailed information.

• Removing layers from the viewer workspace:
  • To remove a single layer:
    • Click on the Delete button located in the top right side of each layer GUI in the layer control panel.
  • To remove all the layers:
    • Click on the Recycle Can in the layer control toolbar.

Changing the layer ordering

• Moving a layer behind another layer: To place a layer behind another layer, select the layer in the control panel, and click on the Down arrow. System should update the display in the viewport so that the selected layer's object is displayed one level back. The system should also update the "Controls panel" section by moving the selected layer 1 position downwards.
• Moving a layer in front of another layer: To place a layer in front of another layer, select the layer in the control panel, and click on the Up arrow. System should update the display in the viewport so that the selected layer's object is displayed in front. The system should also update the "Controls panel" section, by moving the selected layer 1 position upwards.

Data Display controls

To manipulate the layers, users can use the controls in the Data Display toolbar as shown below. The actions are applied to the currently selected layers. For linked layers, the actions are applied to all linked layers.

• Mouse mode controls: The buttons in this group set the input mode of the mouse buttons.
  • Drag button (drag to reposition the layer in the viewport):
    • Left mouse button: drag
    • Middle mouse button: rotate
    • Right mouse button: scale
  • Scale button (drag to stretch the image): The stretch direction is determined relative to the center of the image when dragging.
    • Left mouse button: scale
    • Middle mouse button: rotate
    • Right mouse button: pan
  • Rotate button (drag to rotate the image): The rotation amount is determined relative to the center of the image when dragging.
    • Left mouse button: rotate
    • Middle mouse button: stretch
    • Right mouse button: drag
• Zoom in / Zoom out: Click on the Plus button to zoom in and click on Minus button to zoom out. This can also be done using the mouse scroller.
• Reset: Resets all translation, scaling, and rotation values to the original state.
• Full screen/Dual View:
  • By default, the system is in Fullscreen mode. In full screen mode, system displays only one viewport. A Full screen button is displayed in the top toolbar. Users can switch to Dual view mode by clicking on this button.
  • In dual mode, system displays two viewports. A DualView button is displayed in the top toolbar. Users can switch to the Full screen mode by clicking on this button.

Linking layers

The viewer supports linking of layers together to synchronize controlling multiple layers at the same time. The layers can be in the same viewport or in different viewports.

To link layers together:

1. Shift + Mouse left-click on the target layers in the Data Display panel. The border of the selected layers will be yellow.
2. Click on the Link button in the toolbar. The current master layer will be in yellow and the slave layers will be in blue. All actions done on the master layer will be mirrored by the slave layers (not all the rendering plugins behave similarly so consult the plugin documentation for more detailed information).
3. To change master layers, simply Mouse left-click on another layer.

To unlink layers:

1. Mouse left-click on one of the layers in the linked layer group.
2. Click on the Unlink button in the toolbar. All layers linked to the selected layer will be unlinked.

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