Example — Ions
Simulated data sets have been calculated using the parametric equations for cyclotron/magnetron motion of ion clouds in a one inch trap placed in the center of a large (3+ tesla) magnetic field generated by a cylindrical superconducting magnet. Ions are injected along the Z axis of the trap/magnet, energized by a temporary electrical charge on the excite (X axis) trap plates, then detected by measuring charge on the detect (Y axis) trap plates induced by the motion of the ion cloud. The calculated trajectory consists of the motion which occurs during the detection phase of an experiment.
The visualization displays different spatial and temporal aspects of a simulated ion cloud trajectory. A highly coordinated set of stereoscopic projections, orthogonal plane projections, and timeseries plots reveal different characteristics of oscillatory motion. The trajectory is displayed in a variety of ways by the views in the visualization:
  • A left-right stereogram pair shows the trajectory in space. These views are navigationally coordinated with the miniature views in the list.
  • A table view shows the actual {T,X,Y,Z} positions of points along the trajectory.
  • Three time series scatterplots show ion motion over time relative to each pair of trap plates (excite, detect, inject).
  • An 3-D matrix of overview scatterplots shows the entire trajectory as seen from three sides of the ion trap.
  • A second 3-D matrix of detail scatterplots shows the subtrajectory that intersects the space selected by the portals in the overview scatterplots.
  • Three parallel coordinate plots show the same subtrajectory.
  • Monoscopic stereo views show the trajectory and selected subtrajectory next to the corresponding scatterplot matrices.
All views map time into a translucent red-to-black color gradient that suggests (but does not map precisely to) decreasing energy of the ion cloud over time.
The user starts by selecting a particular trajectory of interest from a list that displays each of the trajectories in miniature. Ubiquitous brushing and overview+detail coordinations between views support drill-down to subsets of points within and subvolumes of space along trajectories. Using the time slider, the user can select a range of times perceptually and fluidly on gradient color rather than as precisely entered values. All views except the overview scatterplots and stereoscopic view are filtered to show only the selected range of colors.
It is important to note that this visualization was designed with the goals of demonstrating and evaluating high levels of coordination in multiple view interfaces, but not necessarily to be a useful tool for people involved in research on ion cyclotron resonance. Although the data sets displayed in this visualization are small (512 records for the selected trajectory in the screenshot above), most of the views are coordinated with each other through eight range variables (X Overview, Y Overview, Z Overview, X Detail, Y Detail, Z Detail, Visible Time, Selected Time). This means that even small mouse interactions result in the data set being projected, filtered, and rendered multiple times. For instance, when a mouse drag or keystroke in a view or axis changes the X Detail range, eleven views update by processing 11 x 512 = 5632 records. Four axis and two portals (translucent yellow rubberband boxes) also repaint to reflect the change.
Visualization (48 KB)
Video Tour (16.5 MB). Earlier version, no audio.
Shenheng Guan and Alan G. Marshall. “Stereoscopic Views of Three-dimensional Ion Trajectories in Ion Cyclotron Resonance and Quadrupole Ion Traps”. Rapid Communications in Mass Spectrometry, 10(14), 1996.