attribute property value default
off axis dimming start dim-off-axis-start >= 0.0% 1.0
off axis dimming finish dim-off-axis-finish >= 0.0% 4.0
too big dimming start dim-too-big-start >= 0.0% 1.0
too big dimming finish dim-too-big-finish >= 0.0% 10.0

too small dimming start

also turns of display of labels

dim-too-small-start >= 0.0% 0.04
too small dimming finish dim-too-small-finish >= 0.0% 0.01
image too big dimming start image-too-big-start >= 0.0% 1.0
image too big dimming finish image-too-big-finish >= 0.0% 10.0
image too small dimming start image-too-small-start >= 0.0% 0.04
image too small dimming finish image-too-small-finish >= 0.0% 0.01
label levels min label-min-level 0-100 0
label levels max label-max-level 0-100 100
label scale label-time-scale > 0.0 0.0
label distance label-distance 0.0 - 1.0 1.0

Hiding information is an important aspect of Quotidian. By minimizing visual (and audio) clutter, the author of a timeline can show what is important while still allowing the user to explore the display space and get more information. There are a number of aspects to hiding and there is no single approach that is best for all kinds of event data.

This hiding mostly occurs at the category level and there are a number of variables that allow tuning of event hiding. Reasonable default values are given, but the best results will occur when the author experiments with the values to achieve the desired presentation. The hiding of events and images is usually a gradual process where the object becomes more and more transparent until it disappears entirely. Labels do not become more transparent and either are displayed or not.

The category hiding list is a way to organize a number of parameters that control aspects of hiding. If no values are set in a field, the default value is used.

The descriptions for the individual hiding values refer to the size of the category. Categories are not visible, but do have dimension in the category plane and extend (infinitely) forward and backward in time, thus they always intersect the plane that represents the display time. It is their size and location at the display time that is used when the QViewer calculates the dimming or hiding values.

Off Axis Dimming

Categories that are farther from the center of the screen are probably of less immediate importance to the user. However, when the view direction is towards the future or past, events in the distant past or future may still appear, since all categories have a common vanishing point at the center of the screen. Events in perspective will tend to get smaller and move towards the center of the screen as they become farther from the viewer, even when nearer events in the same category are off the edges of the screen and not visible.

This value allows control of how fast all the events in a category fade away as the category is moved away from the center of the screen. The numbers are a percentage of the screen width. The start value is the distance from the center of the screen where the dimming starts. The finish value is the distance where dimming finishes and the category becomes completely invisible. The start value should be less than or equal to the finish value. When start is set to 100%, the category begins to vanish as soon as its edge is moved off the edge of the screen. When start is set to 400%, the category begins to disappear when the edge is 4 times the width of the screen from the center of the screen. When set to 5% it will begin to vanish when the category is still on the screen, but slightly off center. The dimming is linear. At a distance halfway between start and finish, a category's opacity will be 50% of its initial (un-dimmed) opacity (or twice as transparent). The default start value is 100%. The default finish value is 400%.

Too Big Dimming

As the XY scale is increased, categories may become very large. It is likely that the user is more interested in the categories that are nested in that category. To avoid visual clutter, categories begin to disappear as they grow larger. Again, the values are the percentage of the category height of the screen height. The start value should be smaller than the finish value. The default start value is 100%. The default finish value is 1000%.

Too Small Dimming

As the XY scale is decreased, categories can become very small. Sometimes this is useful and just what is intended. Other times having many small events is a distraction and it is desirable to have them fade away. Again, the values are the percentage of the category height of the screen height. In this case, the start value should be greater than the finish value. The default start value is 4%. The default finish value is 1%.

When the size of the category becomes less that the start value, labels are no longer drawn.

Sound Rolloff

Sounds can be associated with events. As the category containing the event is moved off-screen it may be desirable to have the sound's volume turned down. The start value is the distance from the screen's center where the volume starts to decrease. The factor is the fraction of the category's width where sound volume is reduced by 1 db. The default start value is 0%. The default value for the rolloff factor is 0%. This means that volume normally does not decrease with distance.

Label Levels

These values allow for hiding labels for all the events in a category based on the current level of detail. The level of detail normally comes from the manual setting in the QViewer window, but it can also be changed by applying a level/scale map to the category. Labels are shown only when the level of detail is greater than or equal to the min value and less than or equal to the max value.

This is similar to the way level of detail is defined when categories are attached to events. Rather than being defined individually for each event, here it is defined for all the labels of events in a category.

The default value is 0 for min and 100 for max.

Label Time Scale

As the time scale decreases, the events in a category become closer together. The QViewer will try to show all the labels and will stack the labels as the events get pushed together. One can reduce the clutter by not drawing the labels even when their events are still visible. There is no one scale where this makes sense as categories can show events of many different durations. The best approach is for the author to load the timeline into the QViewer and decrease the time scale until to the point where labels should be suppressed, read the time scale indicator at the bottom of the QViewer and put that value in the label scale field. The default value is 0.0, which means the time scale is ignored when labels are drawn.

Label Distance

The QViewer does not change the size of labels as they move farther from the viewpoint in the three-dimensional drawing space. To avoid having too many labels on increasingly small and distant events, it is useful to stop drawing labels at some point as they move away from the display time. This value is in the range of 0.0 (closest to the viewer) to 2.0 (farthest from the viewer). Setting this value to 0.0 will cause labels never to be drawn. Setting the value to 2.0 will cause all labels to always be drawn. The default setting is 1.0.

© 2011 Quotidian Incorporated