An interval volume is a set of tetrahedra that span a space between two isovalues within a volume. Since a tetrahedral mesh is a solid, iVolume displays the outer surface of the mesh as a set of polygons. This surface cannot be translated, scaled, or rotated relative to the volume but does move with the volume.
To create an interval volume, select Operations ® Volume ® Interval Volume, and a dialog appears allowing you to set two isovalues.
If the volume is multi channel, you can select a channel for setting the isovalues and then create an interval volume for that channel by selecting OK.