Slicer3:EditorUsabilitySessions

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User feedback for design of the Editor Module

Slicer application interface

General:

• In Slicer2 workflow, “apply” is currently being used as a “preview” and “undo” is used to back out of an unsatisfactory operation. In Slicer3, instead of “apply” and “undo”, we should consistently implement “preview”, and “apply”. Though these may be implement the same operations programmatically, the concept of preview has less implicit stress for the user, who won’t worry that their original data may become unrecoverable.
• Visual cue: Should we assign a reserved color or visual appearance for ‘Editor preview’ so that in complicated visualizations, it will be clear which regions are being affected by the operation in preview?
• Provide multiple undo and redo as well.
• Inside editor module, users agree that having the hidden slice controller (which reappears on mouse-over) is very useful. However, sometimes while scrolling thru slices using the slice controller’s scale, the mouse travels off the controller bringing focus back to the slice window by mistake, and resulting in unintended drawing in that slice. This is very frustrating and requires time to clean up. We need to consider a workaround that
• Editing is done in all orientations, but the original acquisition plane is used, when possible, to make challenging decisions. Feature request: Might be good to visually indicate which of the slice viewers is displaying slices in the plane of acquisition.
• Nobody we spoke to is using the Draw2 module, though having a simple spline tool in addition to points, lines and polygons to draw regions would be nice.
• Within the editor, it would be nice to have a single location in which a user can: ask for a statistics/metrics report (including intensity min, max, mean, std.dev., and volume) for a single region or for all defined regions, and to have the option to save this information out to a text-file. Currently, MeasureVol module will give volume measurements for all labels (user can’t select a single one) and writes a text file; and Editor->Details Drawmode has the intensity statistics, no volume measurements, and no ability to write the text file.
• Existing hot-keys: Strong recommendation not to remap. Very efficient keyboard operations are used by everyone we spoke with: left hand using index and ring fingers on right and left arrows to move between slices, middle finger on up arrow to apply a point, and on shift key to view in all slice planes simultaneously; right hand moves the mouse to specify point location. Remapping the up and down arrows to also move between slices would strongly impact what has become very natural and efficient keyboard drawing.

Region drawing:

• Might be useful in some cases to have coarse region-specification tools like rectangle, circle, oval.
• Absolutely need to be able to draw polygons that may, under some circumstances be self-intersecting.
• “Outline labelmap” should be off by default, not on. This feature is only infrequently used by this group in a pathological way, to approximate the viewing of two labelmaps at once (one in Foreground, and a different one outlined in the label map layer).
• Strong agreement among all users: Need multiple undo and multiple redo commands for drawing.
• When drawing regions, PNL doesn’t much use the magnifier window in Slicer2’s lower left panel. Instead, users often zoom in and out repeatedly in the slice plane in which they’re working. Feature request: In this context, a simple interface that remembers the current working zoom-factor, and lets a user zoom in, out and snap back in one click or with hot-keys (Ctrl+, Ctrl-, Ctrl0?) could be useful (and save a lot of mouse click-and-drag time).
• One strategy for specifying an ROI is to identify first and last plane in which the region must be drawn, to draw these, then outline in the middle slice plane, then fill in all slices between. Feature request: Might be handy to have a simple interface for setting and clearing “keyframes” which bracket a ROI, or snap the slice viewer to slices that contain anatomical markers.
• When drawing a region, if points or vertices on lines, polygons are wrong, instead of deleting and starting over, users select offending points or vertices and move them. Good ways to select and move points
• Selecting points or vertices: might be useful to have lasso or rubber band tool to select points or vertices, rather than having to individually click on them.
• In Editor->Effects Draw: Draw/Select/Move modes are good. May want to modernize some of the drawing and painting tools and exploit common paint software conventions: How about: Path editing section on GUI that includes tools for outlining a path with pencil (points), with lines (vertices), or polygon (vertices), and using a paintbucket fill? Plus the options to select points/vertices, move them or delete them. Then a painting section on the GUI that lets user choose brush tool, set brush-size, shape and brush-mode (Threshold paint is an idea that raised a lot of excitement). We should mock this up. Offer all current functionality, just modernized, and a few more tools.
• Feature request: a tool to report the length of a curved line drawn in the Editor (used for instance, to measure length of curvature lines drawn along sulci).
• One concern is with making principled sub-voxel decisions, and designing tools that assist that decision. Worth thinking about this issue more deeply.
• Tools to assist in region drawing: in a very zoomed-in view in the slices windows, it might be nice to see the intensity values of each voxel as annotations on the voxels – often decisions about whether to include a voxel or not are based on an intensity range, and having this information at hand might make such decisions faster and less error-prone.
• Having the ability to quickly toggle interpolation might also assist in voxel inclusion decisions.
• Having a hot-key or icon/hot-key to toggle crosshairs in the slice viewers would be useful; the crosshairs are often used to most clearly inspect an individual voxel in all slice views.