Volume Series Volume Series icon

Volume Series displays an ordered sequence of volume data sets. A sequence could represent a time series or a comparison of states not necessarily ordered in time. See also: Morph Map

There are several ways to start Volume Series, a tool in the Volume Data category (including from the Volume Viewer Tools menu).

Clicking Open... raises a file browser for opening a volume series as either of the following:

A Priism time series file can also be opened in other ways, which will automatically start the Volume Series tool. Opening a volume series of any type also starts Volume Viewer. Each member of the series is treated as a separate set of data in in Volume Viewer.

Multiple volume series may co-exist in Chimera. A volume series is named after the single file it was read from, or the first file if read from multiple files. Choosing the name of a volume series from the Data listing switches the display to that series, and it can be closed with Close Series.

The members of a series are indexed 0, 1, 2, ... and these indices are referred to as the Time. Any numbers in the individual filenames are not used, except to sort the names.


The Time slider can be moved manually to show a particular set of data and make it the current set of data in Volume Viewer. Settings in Volume Viewer (display style, step size, threshold level/color, surface smoothing, etc.) control its appearance and will be applied automatically to other series members as they are displayed. For efficient playback, however, the Volume Viewer dialog will not update to show current settings until the Time value has not changed for 1 second.

Normalize threshold levels adjusts the thresholds (contour levels) to keep the enclosed volume constant throughout the series. This is useful when the signal level in the data changes over time or between states.

Clicking Play cycles through the series in the specified manner:

Clicking Stop halts playback. By default, playback is as fast as possible, which can be fairly slow for large data. If playback is too fast, it can be slowed with the Maximum playback speed option. If playback is too slow, it may be helpful to:


Show markers enables using Volume Tracer to place spherical markers on the data and to trace spatial and temporal paths. Each marker is labeled with the time of the data set on which it was placed. The labels are not shown. They are used by Volume Series to display only the markers for the currently displayed time. Markers for specified numbers of earlier and later time points can also be shown.

Volume Series controls the display of markers in the active set (current set) of markers in Volume Tracer. Using Volume Tracer,

The Color zone around markers option colors volume contour surfaces to match markers within a specified range. All of the markers associated with the current time are used to color the current surface. The coloring does not apply to solid displays.


No session support. The state of Volume Series is not included in session files. A saved and restored session will include the volume data sets in Volume Viewer, but the data sets will not be associated with Volume Series, and there is no way to specify that they should be. However, markers and paths can be saved for later use.

Slow playback when caching renderings. The second time a surface is displayed, a graphics optimization (building an OpenGL display list) is done to speed up future drawing of that same surface by putting it in graphics card memory. That optimization is time-consuming. The third time the surface is displayed will take much less time if the graphics card has sufficient memory.

Threshold normalization brightness glitches in solid mode. Sometimes a data set will appear dimmer than the preceding or following sets when solid rendering and threshold normalization are used. This can happen when only two nodes are used to specify the transfer function on the Volume Viewer histogram, with one of the nodes at the highest data value. If a particular data set has a maximum data value much higher than the adjacent sets, that will substantially lower the brightness at typical data values. This can be remedied by adding a third node between the high and low nodes by Ctrl-clicking on the Volume Viewer histogram.

UCSF Computer Graphics Laboratory / December 2007