Slicer3 design & usability goals

1. Enable a user to understand and effectively use the content and tools being presented;

2. Enable a user to accomplish a principle task by following an appropriate and satisfying workflow or a curiosity-driven exploration, at an appropriate pace;

3. Enhance and support the developer’s experience with GUI infrastructure and guidelines that simplify and clarify their work.

Core values

This is a working list of the core values the interface and interaction should reflect/support (please refine). These are not "specifications", but rather, think of them as concepts that our user communities would value highly and which would effectively and honestly distinguish the software. These are the concepts we'd like Slicer3 to strongly project:

Simplicity
Clarity
Control & Precision
Information-rich
Open source & cross-platform
Furthering scientific research
Assisting treatment/therapy
Advanced research showcase
Easily extensible
Interactive & responsive
Reliable
Longterm viability

Embodiment

Current schematic of the main application GUI: Media:GUIMap.png
Current schematic of a Slice Viewer and Controller: Media:SliceGUI.png
Design sketch for the 3D navigation & Slice magnifier widget Media:NavZoomWidgetSketch.png
Early look and feel draft Media:SlicerLookFeelDraftSmall.jpg
First sketch of the GUI layout design Media:LayoutSketch.gif
Link to a running visual blog highlighting progress in the Slicer3 embodiment.

Current status and TO-DO

The existing base classes form a basic framework for the UI. For the Alpha deadline, we provided a main application window with the general layout described in our current design. For the Beta deadline, we are focusing on:

clean up vtkDebug Leaks
copyright existing icons and logo
working on improving the Theme to enhance module GUI appearance and readability,
implementing functionality for view control widgets,
implementing lightbox viewer

Special topic: controlling the mouse mode

We are currently deciding a good paradigm for controlling mouse modes in Slicer's 3D viewer and 2D slice windows. We'd like the paradigm to:

be consistent in all slice windows and 3D viewer
be intuitive and easy for beginners
be fast for intermediate and expert users
rely on only one mouse button (since some mice have only two, and some laptops give us less to work with)
support direct manipulation

Current behavior (and implicit problems to solve):

Mouse motion always in "view transform" mode
Relies on three mouse buttons (for rotate, pan, zoom, slice scroll)
Relies on hot-keys for non-transform mouse actions (tough for novice users, or forgetful intermediate users)
3D viewer bindings and Slice viewer bindings not entirely consistent.

Bindings:

3D viewer: left mouse >> rotate
3D viewer: middle mouse >> pan
3D viewer: mouse wheel >> zoom
3D viewer: right mouse, pull drag >> zoom in
3D viewer: right mouse, push drag >> zoom out

---

Slice viewer: left mouse >> select/move a fiducial point
Slice viewer: middle mouse >> pan
Slice viewer: mouse wheel >> scroll slices
Slice viewer: right mouse, pull drag >> zoom in
Slice viewer: right mouse, push drag >> zoom out
special keys enable placing of fiducials

We believe that, most importantly, slicer users are used to clicking the left mouse button in the 3D viewer to rotate the view; so we want to support this expectation.