Time Support

Thoughts on Time Support in ParaQ (and ParaView)

Overview

For some time now, we've known that we need 'time support' in ParaView, but there's been little written down about what this really means. Time support is a broad topic, and this wiki entry is an attempt to lay the groundwork for future debate on the topic.

What is time support?

This is our first question to address. Certainly, ParaView supports 'time', in that it reads data files that have a notion of time (in particular, timesteps), and the appliciation supports animation (stepping through time). However, there are several specific cases which are not supported by the current ParaView architecture.

Requirement	Description	What the heck do we need it for?
Multiple timesteps in a single pipeline.	Currently, ParaView supports a single data set in a pipeline, and there is no support for iterating over several 'timesteps' of data at a filter.	Any filter operation that needs previous or future timesteps to calculate its results. Example: would be a filter that calculates a time-based gradient (acceleration).
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Query of 'time series' data for particular nodes or elements.	The Exodus reader supports time-based query, but there is no standard method for transporting this data along the pipeline. There is no standard for discovering or dealing with this data.	Graphing data for a particular element over time (the extent of time in the source file).