This ID makes it possible to differentiate among cells when a single dataset is rendered to the screen at multiple timesteps. Timestep ID - uniquely identifies the timestep for a dataset.Source ID - uniquely identifies the dataset source.We propose a hierarchical naming scheme whereby each record in a selection set may contain one-or-more of the following tokens: Efficient - selection set size could grow to the size of the input data, so the internal representation of the data must be efficient.Flexible - selection sets should handle different selection modes or pipeline configurations by containing only pertinent data.In particular, the selection set must contain unique identifiers for the objects that are members of the set. Thorough - selection sets should return as much information about selected objects as the caller requires.The fundamental challenge in designing the selection interface is to define selection sets in a way that is selecting elements in the element inspector should return the same result structure(s) as selecting them on-screen. Ideally, it should be possible to use selection-related data structures for more than just interactive on-screen selection, e.g.'select all' should be representable without enumerating all possible IDs in a dataset.

It should be possible to represent ranges of data efficiently, i.e.It should be possible to select data at different timesteps, see Time Support.It should be possible to select arbitrary groupings of (filter-defined) data such as blocks, individual isosurfaces in a contour, etc.to select arbitrary sets of assemblies, sub-assemblies, blocks, cells, and points. It should be possible to select data at all levels of detail, i.e.Is there any interest in lasso selection, or should it be given the heave-ho?.Do we need to support selection of edges and points? It's critical for CAD & art applications, does it make any sense for viz?.Should rubber-band-selection select all of the objects that intersect the volume defined by the rubber-band, or only those objects that are visible? Do we need to provide both?.The selection mechanism should support rubber-band selection of data collections.The selection mechanism should support pick selection of individual data.Lasso Selection - selection of zero-to-many objects that fall within an arbitrary-shaped region defined by the user in screen space.Rubber-Band Selection - selection of zero-to-many objects that fall within a rectangular region defined by the user in screen space.Existing examples include vtkAbstractPicker and its derivatives. Pick Selection - selection of zero-or-one object by clicking the mouse within the viewport.Selection Implementation - the concrete implementation that processes data and user input to return a selection set.Selection Interface - the abstract interface used to map user input to a selection set, and communicate that selection set to components that will make use of it.Selection Policy - high-level user-observable behavior that controls interactive selection, such as selection modes, keyboard shortcuts, etc.This is distinct from subsetting because it references data, rather than copying it. Selection Set - references an arbitrary subset of available data, generated by the user through interaction with the viewport, element inspector, charts, etc.Examples include vtkExtractGeometry and vtkSelectVisiblePoints. This is distinct from a selection set because it is copying the source data, not referencing it. Subsetting - extraction of an arbitrary subset of available data, for further processing by the pipeline.This document is concerned with a more general-purpose selection capability, one that maps a region in screen space to a first-class selection set object that references an arbitrary collection of data, and is usable in a wide variety of applications and user interfaces.Д«ecause selection is a broad topic, this discussion makes a distinction between selection policy, selection interface, and selection implementation. Currently, VTK supports a wide variety of subsetting (extracting a subset of data based on some criteria) and picking (mapping a set of screen coordinates to zero-or-one result) functionality.

Paraview isosurface